Numerical calculation of streaming potential around osteocytes under human gait loading

Streaming potential is a type of stress-generated potential in bone that affects the electrical environment of osteocytes and may play a role in bone remodeling. Because the electrical environment around osteocytes has been difficult to measure experimentally until now, a numerical solid-liquid-streaming potential coupling method was proposed to analyze the streaming potential generated by bone deformation in the lacunae and canaliculus network (LCN) of the bone. Using this method, the cellular shear stress caused by liquid flow on the osteocyte surface was first calculated, and the results were consistent with those reported in the literature. Subsequently, the streaming potentials in the LCN caused by bone matrix deformation under an external gait load were calculated numerically. The results showed that the streaming potential increased slowly in the lacuna and relatively rapidly in the canaliculus and that the streaming potential increased with a decrease in the radius or an increase in the length of the canaliculus. The results also showed that relatively large gaps between the lacunae and osteocytes could induce higher streaming potentials under the same loading.

Highly efficient adsorption of ciprofloxacin from aqueous solutions by waste cation exchange resin-based activated carbons: Performance, mechanism, and theoretical calculation

This study focused on the preparation of a highly efficient activated carbon adsorbent from waste cation exchange resins through one-step carbonization to remove ciprofloxacin (CIP) from aqueous solutions. Scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectrometry, and X-ray photoelectron spectroscopy were used to characterize the physicochemical properties of the carbonized materials. The CIP removal efficiency, influencing factors, and adsorption mechanisms of CIP on the carbonized resins were investigated. Density functional theory (DFT) computations were performed to elucidate the adsorption mechanisms. The CIP removal reached 93 % when the adsorbent dosage was 300 mg/L at 25 °C. The adsorption capacity of the carbonized resins to CIP gradually decreased with an increasing pH from 3.0 to 7.0 and sharply declined with a pH from 7.0 to 11.0. The adsorption process better fitted by the pseudo second-order kinetic and Langmuir models, indicating that the interaction between CIP and the carbonized resins was monolayer adsorption. The maximum adsorption capacity fitted by the Langmuir model was 384.4 mg/g at 25 °C. Microstructural analysis showed that the adsorption of CIP on the carbonized resins was a joint effect of H-bonding, ion exchange, and graphite-N adsorption. Computational results signified the strong H-bonding and ion exchange interactions existed between CIP and carbonized resins. The high adsorption and reusability suggest that waste cation exchange resin-based activated carbons can be used as an effective and reusable adsorbent for removing CIP from aqueous solutions.

Tumor mutational burden assessment and standardized bioinformatics approach using custom NGS panels in clinical routine

BACKGROUND

High tumor mutational burden (TMB) was reported to predict the efficacy of immune checkpoint inhibitors (ICIs). Pembrolizumab, an anti-PD-1, received FDA-approval for the treatment of unresectable/metastatic tumors with high TMB as determined by the FoundationOne®CDx test. It remains to be determined how TMB can also be calculated using other tests.

RESULTS

FFPE/frozen tumor samples from various origins were sequenced in the frame of the Institut Curie (IC) Molecular Tumor Board using an in-house next-generation sequencing (NGS) panel. A TMB calculation method was developed at IC (IC algorithm) and compared to the FoundationOne® (FO) algorithm. Using IC algorithm, an optimal 10% variant allele frequency (VAF) cut-off was established for TMB evaluation on FFPE samples, compared to 5% on frozen samples. The median TMB score for MSS/POLE WT tumors was 8.8 mut/Mb versus 45 mut/Mb for MSI/POLE-mutated tumors. When focusing on MSS/POLE WT tumor samples, the highest median TMB scores were observed in lymphoma, lung, endometrial, and cervical cancers. After biological manual curation of these cases, 21% of them could be reclassified as MSI/POLE tumors and considered as "true TMB high." Higher TMB values were obtained using FO algorithm on FFPE samples compared to IC algorithm (40 mut/Mb [10-3927] versus 8.2 mut/Mb [2.5-897], p < 0.001).

CONCLUSIONS

We herein propose a TMB calculation method and a bioinformatics tool that is customizable to different NGS panels and sample types. We were not able to retrieve TMB values from FO algorithm using our own algorithm and NGS panel.

Modified intraocular lens power selection method according to biometric subgroups Eom IOL power calculator

This study evaluates the accuracy of a newly developed intraocular lens (IOL) power calculation method that applies four different IOL power calculation formulas according to 768 biometric subgroups based on keratometry, anterior chamber depth, and axial length. This retrospective cross-sectional study was conducted in at Korea University Ansan Hospital. A total of 1600 eyes from 1600 patients who underwent phacoemulsification and a ZCB00 IOL in-the-bag implantation were divided into two datasets: a reference dataset (1200 eyes) and a validation dataset (400 eyes). Using the reference dataset and the results of previous studies, the Eom IOL power calculator was developed using 768 biometric subgroups. The median absolute errors (MedAEs) and IOL Formula Performance Indexes (FPIs) of the Barrett Universal II, Haigis, Hoffer Q, Holladay 1, Ladas Super, SRK/T, and Eom formulas using the 400-eye validation dataset were compared. The MedAE of the Eom formula (0.22 D) was significantly smaller than that of the other four formulas, except for the Barrett Universal II and Ladas Super formulas (0.24 D and 0.23 D, respectively). The IOL FPI of the Eom formula was 0.553, which ranked first, followed by the Ladas Super (0.474), Barrett Universal II (0.470), Holladay 1 (0.444), Hoffer Q (0.396), Haigis (0.392), and SRK/T (0.361) formulas. In conclusion, the Eom IOL power calculator developed in this study demonstrated similar or slightly better accuracy than the Barrett Universal II and Ladas Super formulas and was superior to the four traditional IOL power calculation formulas.

Improving the accuracy of the SRK/T formula in Chinese with implanting less than 10 D IOL calculated by the SRK/T formula: the SRK/T-Li formula

PURPOSE

To explore the accuracy of the improved SRK/T-Li formula in eyes following implantation of intraocular lens (IOL) of less than 10 D as calculated by using the SRK/T formula in Chinese.

METHODS

A total of 489 eyes from 489 patients with cataracts were included in this study. These patients were divided into a training set (271 patients) and a testing set (218 patients). The IOL power calculated by using SRK/T was less than 10 D. We evaluated the accuracy of the modified SRK/T-Li formula (P = PSRK/T × 0.8 + 2 (P = implanted IOL power; PSRK/T = IOL power calculated by SRK/T)). We evaluated the mean absolute error (MAE), percentage of prediction error (PE) within ± 0.25, ± 0.50, and ± 1.00 D, and the percentage of postoperative hyperopia.

RESULTS

The MAE values in order of lowest to highest were as follows: 0.412 D (SRK/T-Li), 0.414 D (Barrett Universal II, (BUII)), 0.814 D (SRK/T), and 1.039 D (Holladay 1). The percentage of PE within ± 0.25 D, ± 0.50 D, and ± 1.00 D was 38.99%, 69.27% and 92.66% (BUII), 40.83%, 69.27% and 94.04% (SRK/T-Li), 20.64%, 41.28% and 71.56% (SRK/T), and 7.34%, 16.51% and 53.21% (Holladay 1), respectively. SRK/T-Li had the smallest postoperative hyperopic shift.

CONCLUSIONS

For Chinese patients with an IOL power of less than 10 D as calculated by using the SRK/T, the SRK/T-Li has good accuracy and is the best choice to reduce postoperative hyperopic shift.

Comparison of the prediction accuracy of 13 formulas in long eyes

PURPOSE

To investigate the accuracy of modern intraocular lens (IOL) power calculation formulas in eyes with axial length (AL) ≥ 26.00 mm.

METHODS

A total of 193 eyes with one type of lens were analysed. An IOL Master 700 (Carl Zeiss Meditec, Jena, Germany) was used for optical biometry. Thirteen formulas and their modifications were evaluated: Barrett Universal II, Haigis, Hoffer QST, Holladay 1 MWK, Holladay 1 NLR, Holladay 2 NLR, Kane, Naeser 2, SRK/T, SRK/T MWK, T2, VRF and VRF-G. The User Group for Laser Interference Biometry lens constants were used for IOL power calculation. The mean prediction error (PE) and its standard deviation (SD), the median absolute error (MedAE), the mean absolute error (MAE) and the percentage of eyes with PEs within ± 0.25 D, ± 0.50 D and <  ± 1.00 D were calculated.

RESULTS

The modern formulas (Barrett Universal II, Hoffer QST, Kane, Naeser 2 and VRF-G) produced the smallest MedAE among all methods (0.30 D, 0.30 D, 0.30 D, 0.29 D and 0.28 D, respectively). The percentage of eyes with a PE within ± 0.50 D ranged from 67.48% to 74.85% for SRK/T and Hoffer QST, Naeser 2 and VRF-G, respectively.

CONCLUSIONS

Dunn's post hoc test of the absolute errors revealed statistically significant differences (P < 0.05) between some of the newer formulas (Naeser 2 and VRF-G) and the remaining ones. From a clinical perspective the Hoffer QST, Naeser 2 and VRF-G formulas were more accurate predictors of postoperative refraction with the largest proportion of eyes within ± 0.50 D.

Intuitive Modification of the Friedewald Formula for Calculation of LDL-Cholesterol

Background

High LDL-cholesterol (LDL-C) is an established risk factor for cardiovascular disease and is considered an important therapeutic target. It can be measured directly or calculated from the results of other lipid tests. The Friedewald formula is the most widely used formula for calculating LDL-C. We modified the Friedewald formula for a more accurate and practical estimation of LDL-C.

Methods

Datasets, including measured triglyceride, total cholesterol, HDL-cholesterol, and LDL-C concentrations were collected and assigned to derivation and validation sets. The datasets were further divided into five groups based on triglyceride concentrations. In the modified formula, LDL-C was defined as total cholesterol - HDL-cholesterol - (triglyceride/adjustment factor). For each group, the adjustment factor that minimized the difference between measured LDL-C and calculated LDL-C using modified formula was obtained. For validation, measured LDL-C and LDL-C calculated using the modified formula (LDL-CM), Friedewald formula (LDL-CF), Martin-Hopkins formula (LDL-CMa), and Sampson formula (LDL-CS) were compared.

Results

In the derivation set, the adjustment factors were 4.7, 5.9, 6.3, and 6.4 for the groups with triglyceride concentrations <100, 101-200, 201-300, and >300 mg/dL, respectively. In the validation set, the coefficient of determination (R²) between measured and calculated LDL-C was higher for LDL-CM than for LDL-CF (R²=0.9330 vs. 0.9206). The agreement according to the National Cholesterol Education Program Adult Treatment Panel III classification of LDL-C was 86.36%, 86.08%, 86.82%, and 86.15% for LDL-CM, LDL-CF, LDL-CMa, and LDL-CS, respectively.

Conclusions

We proposed a practical, improved LDL-C calculation formula by applying different factors depending on the triglyceride concentration.

Mediating process between fine motor skills, finger gnosis, and calculation abilities in preschool children

Previous studies have found a relationship between fine motor skills, finger gnosis, and calculation skill. However, what mediates this association remains unclear. Therefore, this study investigated whether fine motor skills and finger gnosis are selectively associated with counting and symbolic comparison, and whether fine motor skills and finger gnosis are associated with calculation skills through numerical concepts to which they are selectively associated. We measured the counting, symbolic comparison, fine motor skills, finger gnosis, and working memory in preschool children (N = 48). The hierarchical multiple regression analysis results demonstrated that fine motor skills were selectively associated with counting, and finger gnosis with symbolic comparison. Moreover, based on the results of the mediation analysis, counting mediated the relationship between fine motor and calculation skills. However, the direct effects of fine motor skills and finger gnosis on calculation skills were also maintained. The findings were that fine motor skills and finger gnosis were related to numerical abilities, including counting, symbolic comparison, and calculations. Therefore, the findings were discussed in terms of the functional view and redeployment views, suggesting that the two views were complementary rather than exclusive.

The interplay between pressure, flow, and resistance in neonatal pulmonary hypertension

Pulmonary hypertension, conventionally defined by absolute pulmonary artery pressure, is the result of a range of diagnoses that can result in clinical problems in neonatal practice. Causes include persistent pulmonary hypertension of the newborn, congenital heart disease, and left heart dysfunction, as well as the normally high pulmonary artery resistance in neonates. Elucidating the cause of pulmonary hypertension is vital to guide appropriate management. A first principles approach based on hemodynamic calculations provides a framework for the diagnostic work up and subsequent therapy. Central to this is the equation 'pressure = flow x resistance' and knowledge of factors contributing to flow and resistance and their impact on pulmonary artery pressure. While formal, accurate, calculation of each element is usually not required or deliverable in small infants, clinical and echocardiographic parameters, combined with an understanding of the interplay between pressure, flow, and resistance, significantly improves the assessment and management of neonatal pulmonary hemodynamics.

Intraocular lens power calculation in patients with irregular astigmatism

PURPOSE

Accurate intraocular lens (IOL) calculation in subjects with irregular astigmatism is challenging. This study evaluated the accuracy of using Scheimpflug-derived central 2-mm equivalent keratometry reading (EKR) values for IOL calculation in irregular astigmatism.

METHODS

This retrospective study included subjects (31 eyes of 30 patients) who underwent cataract surgery and IOL calculation using the 2-mm central EKR methods. We compared prediction error (PE) and absolute PE (APE) outcomes using SRK/T and Barrett Universal II formulas for keratometry data obtained from the IOLMaster 500 and Pentacam (anterior corneal sim k) devices.

RESULTS

Cataract surgery and IOL calculation using the 2-mm central EKR methods resulted in improved visual acuity (uncorrected: from 1.13 ± 0.38 to 0.65 ± 0.46 logMar, p < 0.01; best-corrected: from 0.45 ± 0.24 to 0.26 ± 0.20 logMar, p < 0.01) after surgery. The percentage of subjects with best-corrected visual acuity of 6/6 was 22%, < 6/9 was 58%, and < 6/12 was 71%. For both the SRK/T and the Barrett formulas, the PE was similar to those obtained by IOLMaster (> 0.14) but lower than those obtained by the anterior corneal sim k (p < 0.02). IOLMaster provided keratometry reading in only 23/31 (74.1%) of cases.

CONCLUSIONS

The use of Scheimpflug central 2-mm EKR for IOL calculation in irregular astigmatism was beneficial in terms of visual acuity improvement. It had comparable refractive prediction performance to the IOLMaster 500 and better than the anterior corneal sim K. The 2-mm EKR method can be used when IOLMaster cannot provide a reliable reading in abnormal corneas.

Modeling a lunar base mushroom farm

To calculate the equivalent system mass of mushrooms, a conceptual configuration of a mushroom farm as part of a bioregenerative life support system on an inhabited lunar base was designed. The mushroom farm consists of two connected modules. Each module is a double-shell rigid pipe-in-pipe aluminum structure. The first module is used to prepare and sterilize the substrate, while the mushrooms are sown and grown in the second module. Planned productivity of the mushroom farm is 28 kg of fresh mushrooms per one process cycle lasting 66 days for 14 consumers. Mushroom production can be increased using additional modules. The calculated equivalent system masses of the mushroom farm and the mushrooms produced therein is 88,432 kg and 31,550 kg per 1 kg of dry mushrooms in one process cycle, respectively. At that, the biggest contributor to the equivalent system mass of mushrooms is the total pressurized volume of the farm - 68%. The results obtained may be a prerequisite for performing trade-off studies between different configurations of mushroom farm and calculating a space diet using the equivalent system mass of mushrooms.

Calculating clinical mastitis frequency in dairy cows: Incidence risk at cow level, incidence rate at cow level, and incidence rate at quarter level

The lack of standardization in reporting clinical mastitis incidence limits the ability to compare results across multiple studies without additional calculations. There is both a biological and statistical rationale for evaluating the at-risk period at the quarter level. This study aimed to: (1) to outline an applied method for calculating clinical mastitis (CM) incidence rate at the quarter level using currently available software; and (2) to present the results of three different measurements: incidence risk at cow level, incidence rate at cow level, and incidence rate at quarter level. In an open population prospective cohort of eight commercial dairy farms monitored from May 15, 2016, to May 31, 2017, all CM cases (n = 7513) were identified by trained on-farm personnel, who collected all milk samples from all quarters with visibly abnormal milk. Microbiological identification was determined by culture and MALDI-TOF. All lactating quarters were at risk for CM. A quarter was at risk for a new CM case if there was at least 14 d between a previously diagnosed case and the current case in the same quarter, or if a different pathogen was isolated in the same quarter within 14 d. A total of 17,513,429 quarters days at risk (QDAR) were estimated. A statistical software macro and Structured Query Language (SQL) were used to bring all data together. The monthly incidence rate at the cow level was 16.6 cases per 10,000 cow-days, the monthly incidence rate at the quarter level was 4.4 cases per 10,000 QDAR and the monthly incidence risk at the cow level was 4.8 cases per 100 cows. Although the evaluation of QDAR requires additional computation when compared to other methods, it might allow for a more precise evaluation of the data and a more accurate evaluation of mastitis incidence. Clearly defining the methods used to report mastitis incidence will improve our ability to discuss and learn about the differences and similarities across studies, regions, and countries.

Basic physiology and biochemistry in environmental/experimental plant studies: How to quantify and interpret metabolites correctly

As a reviewer of ca. 50 manuscripts per year submitted to various journals, I often come across questionable metabolic data (both over- or under-estimated) mainly in the journals from the section of Environmental Sciences of Web of Science. Though the trends of visibly incorrect metabolite values may be informative (changes in response to applied treatments or environmental factors), absolute values must be precise enough to allow inter-specific comparison and eventual subsequent calculations. Technical correctness of quantification and calculation of such data is therefore often questionable. One problem arises when calculating metabolites concentration (often nmol or μmol/g of biomass) and another problem is the impact of altered water content on metabolite level (then trend per gram of fresh or dry biomass will differ). Recent discrepancies I found when searching for the literature prompted me to write this technical note aimed at focusing attention of researchers on these problems. I exclude any conflict of interest when discussing the quoted published studies. I strongly urge interested researchers to verify the correctness of metabolite quantification (extraction, dilution/calculation and alternative methods) and also to study similar literature for comparison in order to prevent the spread of incorrect data in the scientific literature.

Closeness impeded self-perspective inhibition whereas facilitated explicit perspective calculation

This study examined whether and how closeness affected the calculation and selection processes underlying perspective taking. Using the visual dot perspective taking task, we introduced a close friend and a stranger from the participants' university as the perspective-taking targets. Friend and stranger trials were mixed in a block in Experiment 1 but separated in different blocks in Experiment 2. Results revealed a significant effect of closeness on egocentric but not altercentric interference. The analyses on other-consistent and other-inconsistent trials suggested that closeness impeded responding from the avatar's perspective when self and other perspectives differed but facilitated responding from the avatar's perspective when self and other perspectives were consistent. However, the analyses on self-consistent and self-inconsistent trials revealed that the processing cost induced by implicit perspective calculation and other-inhibition was comparable between friends and strangers. These suggested that closeness selectively impeded self-perspective inhibition whereas facilitated explicit perspective calculation.

Relations among spatial skills, number line estimation, and exact and approximate calculation in young children

Decades of research have established that spatial skills correlate with numerical skills. However, because both spatial and numerical skills are multidimensional, we sought to determine how specific spatial skills relate to specific numeracy skills. We used a cohort-sequential design, assessing a large diverse sample of students (N = 612, initially in pre-kindergarten [pre-K]-3rd grade, 4-9 years of age) at four time points spanning 2 years. We examined how initial levels of five spatial skills (visuospatial working memory [VSWM], mental transformation, mental rotation, proportional reasoning, and analog magnitude system [AMS] acuity) related to initial levels and growth rates in exact and approximate calculation skills, and we further investigated number line estimation as a potential mediator. We found unique patterns of relations between spatial skills and numeracy. Initial levels of mental rotation, proportional reasoning, and AMS acuity related to initial levels of exact calculation skill; initial levels of AMS acuity related to initial levels of approximate calculation; and initial levels of proportional reasoning related to initial levels of number line estimation. VSWM and mental transformation did not relate to numeracy skills after controlling for other spatial skills. Initial levels of number line estimation related to both exact and approximate calculation after controlling for spatial skills. Notably, neither spatial skills nor number line estimation predicted growth in exact or approximate calculation skills. These results indicate that there is specificity in the time-invariant relations between spatial skills and numeracy, and they suggest that researchers and educators should treat spatial skills and numeracy as multidimensional constructs with complex and unique interrelations.

Intraocular lens power calculation using adjusted corneal power in eyes with prior myopic laser vision correction

PURPOSE

To evaluate the prediction accuracy of the intraocular lens (IOL) power calculation using adjusted corneal power according to the posterior/anterior corneal curvature radii ratio in the Haigis formula (Haigis-E) in patients with a history of prior myopic laser vision correction.

METHODS

Seventy eyes from 70 cataract patients who underwent cataract surgery and had a history of myopic laser vision correction were enrolled. The adjusted corneal power obtained with conventional keratometry (K) was calculated using the posterior/anterior corneal curvature radii ratio measured by a single Scheimpflug camera. In eyes longer than 25.0 mm, half of the Wang-Koch (WK) adjustment was applied. The median absolute error (MedAE) and the percentage of eyes that achieved a postoperative refractive prediction error within ± 0.50 diopters (D) based on the Haigis-E method was compared with those in the Shammas, Haigis-L, and Barrett True-K no-history methods.

RESULTS

The MedAE predicted using the Haigis-E (0.33 D) was significantly smaller than that obtained using the Shammas (0.44 D), Haigis-L (0.43 D), and Barrett True-K (0.44 D) methods (P < 0.001, P = 0.001, and P = 0.014, respectively). The percentage of eyes within ± 0.50 D of refractive prediction error using the Haigis-E (78.6%) was significantly greater than that produced using the Shammas (57.1%), Haigis-L (58.6%), and Barrett True-K (61.4%) methods (P = 0.025).

CONCLUSION

IOL power calculation using the adjusted corneal power according to the posterior/anterior corneal curvature radii ratio and modified WK adjustment in the Haigis formula could improve the refraction prediction accuracy after cataract surgery in eyes with prior myopic laser vision correction.

Numerical activities of daily living: a short version

Specific impairments in numerical functions may cause severe problems in everyday life that cannot be inferred from the available scales evaluating instrumental activities of daily living. The Numerical Activities of Daily living (NADL) is a battery designed to assess the patient's performance in everyday activities involving numbers (Informal Test) and in more scholastic capacities (Formal Test). A downside of this battery is its duration (45 min). The aim of the present study is to build a shorter version of NADL to make it more suitable for clinical and research purposes. The shortening procedure involved only the Formal test, and followed two steps: (i) a correlation of subtests with the general scores, and (ii) an item-analysis within the subtests previously showing higher correlations. Correlations between NADL-Short and NADL original version, and the new cut-offs were calculated. Lastly, the relationship between NADL-Short and other brief cognitive screening tests used in the clinical practice was evaluated in neurological patients and healthy controls. The NADL-Short includes the original Informal Test and the shortened Formal Test. It is a quick and easy clinical tool (15 min) to assess numerical abilities applied to informal and formal situations. It correlates highly with the original battery (Kendall's tau greater than 0.6 across tasks) and the cut-offs correctly identify impaired performance (accuracy of 95% or above). Correlation analysis showed a low positive correlation between NADL-Short and other brief cognitive scales. These findings suggest that it is appropriate to use specific tools to make inferences about a person's numerical abilities.

Fetal dose evaluation for body CT examinations of pregnant patients during all stages of pregnancy

PURPOSE

CTDI_vol-to-fetal-dose coefficients from Monte Carlo simulations are useful for fetal dose evaluations, but the available data is limited to the fetus being completely inside the abdominopelvic scan range. Whereas in a chest examination, the fetus is completely outside the scan range. In an abdominal examination, the fetus after 16 gestational weeks is partly in the scan region, and an earlier fetus is completely outside of it. This work proposes a practical approach to evaluate fetal dose for pregnant patients undergoing body CT examinations, without using Monte Carlo simulation.

METHODS

The proposed method was based on the z-axis dose profile computed for a CT examination, considering CTDI_vol, scan range, mA, and maternal WED (water equivalent diameter) at the fetus centroid. Fetal average dose was calculated over the fetus z-axis coverage. For validation, we considered a reference dataset of 24 pregnant patients, each underwent two abdominopelvic examinations (fixed mA, tube current modulation). WED was 30.1 ± 3.3 (25.3-35.6) cm [mean(range)]. Gestational age was <5 weeks for one patient, and 20.3 ± 9.1 (5-35.9) weeks for the others. Fetal depth (from the anterior skin surface to the most anterior part of fetus) was 6.1 ± 2.1 (2.5-10.9) cm. We further considered three whole-body models of a pregnant patient (gestational age, 3, 6, 9 months; weight, 62-73 kg) undergoing chest, abdominal, and abdominopelvic examinations (fixed mA). For the patients and models, profile-based fetal dose calculations were compared with the results of Monte Carlo simulations. Statistical software (R, version 3.5.1) was used to determine the mean and 95th percentile.

RESULTS

The fetal dose difference between profile-based evaluations and Monte Carlo simulations was (5.9 ± 3.8)% for 24 fixed-mA examinations, (5.8 ± 4.6)% for 24 tube current modulated examinations, and (8.8 ± 5.9)% for the whole-body models in three scan ranges.

CONCLUSIONS

Profile-based fetal dose calculations can be performed for patients in body CT, considering maternal size, fetus size and location, and whether fetus is completely inside, partly inside, or outside scan ranges.

Intraocular lens power calculation for plus and minus lenses in high myopia using partial coherence interferometry

Purpose

We assessed the accuracy of lens power calculation in highly myopic patients implanting plus and minus intraocular lenses (IOL).

Methods

We included 58 consecutive, myopic eyes with an axial length (AL) > 26.0 mm, undergoing phacoemulsification and IOL implantation following biometry using the IOLMaster 500. For lens power calculation, the Haigis formula was used in all cases. For comparison, refraction was back-calculated using the Barrett Universal II (Barrett), Holladay I, Hill-RBF (RBF) and SRK/T formulae.

Results

The mean axial length was 30.17 ± 2.67 mm. Barrett (80%), Haigis (87%) and RBF (82%) showed comparable numbers of IOLs within 1 diopter (D) of target refraction. Visual acuity (BSCVA) improved (p < 0.001) from 0.60 ± 0.35 to 0.29 ± 0.29 logMAR (> 28-days postsurgery). The median absolute error (MedAE) of Barrett 0.49 D, Haigis 0.38, RBF 0.44 and SRK/T 0.44 did not differ. The MedAE of Haigis was significantly smaller than Holladay (0.75 D; p = 0.01). All median postoperative refractive errors (MedRE) differed significantly with the exception of Haigis to SRK/T (p = 0.6): Barrett − 0.33 D, Haigis 0.25, Holladay 0.63, RBF 0.04 and SRK/T 0.13. Barrett, Haigis, Holladay and RBF showed a tendency for higher MedAEs in their minus compared to plus IOLs, which only reached significance for SRK/T (p = 0.001). Barrett (p < 0.001) and RBF (p = 0.04) showed myopic, SRK/T (p = 002) a hyperopic shift in their minus IOLs.

Conclusions

In highly myopic patients, the accuracies of Barrett, Haigis and RBF were comparable with a tendency for higher MedAEs in minus IOLs. Barrett and RBF showed myopic, SRK/T a hyperopic shift in their minus IOLs.

Comparing refractive outcomes of a standard industry toric IOL calculator using anterior corneal astigmatism and total corneal refractive power

PURPOSE

To evaluate refractive outcomes for a standard industry calculator using anterior corneal astigmatism or total corneal refractive power.

METHODS

This prospective interventional study evaluated the refractive outcomes of 56 eyes using a standard industry calculator (Zeiss ZCalc) and a digital IOL alignment software. After A-constant optimisation the ZCalc was recalculated with two different keratometry values using appropriate refractive indices: anterior corneal astigmatism (ACA) by IOLMaster 700 and total corneal refractive power (TCRP) by Pentacam. The Barrett toric calculator was used as a reference.

RESULTS

Undercorrection of 0.04 ± 0.42 D after 1 week and 0.13 ± 0.48 D after 3 months was achieved for the spherical equivalent by using a standard industry calculator. IOL misalignment was 2.8° ± 3.4° using a digital alignment system. For the ZCalc, the mean absolute error could be reduced from 0.19 ± 0.40 D using ACA to 0.04 ± 0.48 D when considering total corneal refractive power (p = 0.06). The Barrett calculator delivered better refractive outcomes than using a standard industry calculator with ACA measurements only (- 0.06 ± 0.43 D; p < 0.01).

CONCLUSION

Reliable and accurate refractive outcomes in toric IOL calculation were achieved by using the ZCalc calculator. The prediction error for a widely used standard industry toric IOL calculator could be reduced by using measured total corneal refractive power.

Development and validation of a model that includes two ultrasound parameters and the plasma D-dimer level for predicting malignancy in adnexal masses: an observational study

Background

Pre-operative discrimination of malignant from benign adnexal masses is crucial for planning additional imaging, preparation, surgery and postoperative care. This study aimed to define key ultrasound and clinical variables and develop a predictive model for calculating preoperative ovarian tumor malignancy risk in a gynecologic oncology referral center. We compared our model to a subjective ultrasound assessment (SUA) method and previously described models.

Methods

This prospective, single-center observational study included consecutive patients. We collected systematic ultrasound and clinical data, including cancer antigen 125, D-dimer (DD) levels and platelet count. Histological examinations served as the reference standard. We performed univariate and multivariate regressions, and Bayesian information criterion (BIC) to assess the optimal model. Data were split into 2 subsets: training, for model development (190 observations) and testing, for model validation (n = 100).

Results

Among 290 patients, 52% had malignant disease, including epithelial ovarian cancer (72.8%), metastatic disease (14.5%), borderline tumors (6.6%), and non-epithelial malignancies (4.6%). Significant variables were included into a multivariate analysis. The optimal model, included three independent factors: solid areas, the color score, and the DD level. Malignant and benign lesions had mean DD values of 2.837 and 0.354 μg/ml, respectively. We transformed established formulae into a web-based calculator (http://gin-onc-calculators.com/gynonc.php) for calculating the adnexal mass malignancy risk. The areas under the curve (AUCs) for models compared in the testing set were: our model (0.977), Simple Rules risk calculation (0.976), Assessment of Different NEoplasias in the adneXa (ADNEX) (0.972), Logistic Regression 2 (LR2) (0.969), Risk of Malignancy Index (RMI) 4 (0.932), SUA (0.930), and RMI3 (0.912).

Conclusions

Two simple ultrasound predictors and the DD level (also included in a mathematical model), when used by gynecologist oncologist, discriminated malignant from benign ovarian lesions as well or better than other more complex models and the SUA method. These parameters (and the model) may be clinically useful for planning adequate management in the cancer center. The model needs substantial validation.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5629-x) contains supplementary material, which is available to authorized users.

Neuroenhancement of High-Level Cognition: Evidence for Homeostatic Constraints of Non-invasive Brain Stimulation

Neuroenhancement aims to improve cognitive performance in typically and atypically functioning populations. However, it is currently debated whether it is also effective in exceptionally high-functioning individuals. Present theories suggest that homeostatic set points for learning and cortical plasticity limit the beneficial effects of neuroenhancement. To examine this possibility, we used transcranial random noise stimulation (tRNS) to non-invasively stimulate bilateral dorsolateral prefrontal cortices (DLPFC) of the world champion in mental calculation, G.M. TRNS did not change G.M.’s calculation performance compared to sham stimulation on an exceptionally complex arithmetic task. However, a sample of mathematicians who were not calculation prodigies (N = 6) showed reduced accuracy on a complex multiplication task in response to tRNS, relative to sham. Our findings suggest that there may be an upper limit for cognitive enhancement and that further attempts to enhance performance using tRNS (at least with the current parameters) may impair optimal functioning. The discussion of potential negative effects of brain stimulation for cognitive enhancement is critical, as it may lead to unintended impairments in different subgroups of the population.

APOE-MS4A genetic interactions are associated with executive dysfunction and network abnormality in clinically mild Alzheimer's disease

PURPOSE OF THE RESEARCH

Although single nucleotide polymorphisms of membrane-spanning 4A (MS4A) (rs670139) and several other susceptibility genes have shown interaction effects on the risk of Alzheimer's disease (AD), little is known about the interaction effects of apolipoprotein E (APOE) with MS4A (rs670139) on cognitive performances, and the underlying pathogenesis is unclear. The study aimed to investigate the APOE-MS4A (rs670139) interaction effects on cognitive performances, cortical volumes, and functional connectivity (FC) in brain networks.

PRINCIPAL RESULTS

Cognitive performances were characterized in each genotypic group, and were compared between normal controls and patients in each genotypic group. APOE-MS4A interaction effects on memory and executive function scores, cortical volumes, and FC in brain networks were demonstrated. Significant effects of APOE-MS4A interactions on FC were observed in executive control network (ECN) (T maxima = 4.99, false discovery rate-corrected p < .001), the calculation score (F3, 87 = 6.218; p = .015), and the volume in prefrontal (F3, 87 = 4.374; p = .039) and orbitofrontal cortices (F3, 87 = 6.022; p = .016). The calculation score was correlated with each frontal volume (cc) (ρ = 0.304; p = .004) and genetic interaction-associated FC in ECN (ρ = 0.282; p = .008). Variations in genotypes affected the relationship between the calculation score and each frontal volume (cc).

MAJOR CONCLUSIONS

These findings indicate that the genetic interaction effects on FC in ECN might contribute to pathogenic mechanisms underlying the interaction effects of APOE-MS4A on calculation ability in AD.

Spin-orbit effects on the 125Te magnetic-shielding tensor: A cluster-based ZORA/DFT investigation

Cluster-based calculations of ¹²⁵Te magnetic-shielding tensors demonstrate that inclusion of spin-orbit effects is necessary to obtain the best agreement of theoretical predictions with experiment. The spin-orbit contribution to shielding depends on the oxidation state and stereochemistry of the ¹²⁵Te site. Comparison of the performance of various density functionals indicates that GGA functionals behave similarly to each other in predicting NMR magnetic shielding. The use of hybrid functionals improves the predictive ability on average for a large set of ¹²⁵Te-containing materials. The amount of Hartree-Fock exchange affects the predicted parameters. Inclusion of larger Hartree-Fock exchange contributions in hybrid functionals results in larger slopes of the correlation between calculated magnetic-shielding and experimental chemical-shift principal components, by 10-15% from the ideal value.

Patterning counts: Individual differences in children's calculation are uniquely predicted by sequence patterning

Many studies have examined the cognitive determinants of children's calculation, yet the specific contribution of children's patterning abilities to calculation remains relatively unexplored. This study investigated whether children's ability to complete sequence patterns (i.e., add the missing element into 2-4-?-8) uniquely predicted individual differences in calculation and whether these associations differed depending on the type of stimuli in these sequence patterns (i.e., number, letter, time, or rotation). Participants were 65 children in first and second grade (M_age = 7.40 years, SD = 0.44). All children completed four tasks of sequence patterning: number, letter, time, and rotation. Calculation was measured via addition and subtraction tasks. We also measured cognitive determinants of individual differences in calculation-namely symbolic number comparison, motor processing speed, visuospatial working memory, and nonverbal IQ-to verify whether patterning predicted calculation when controlling for these additional measures. We observed significant relationships between the patterning dimensions and calculation, except for the rotation dimension. Follow-up regressions, controlling for the aforementioned cognitive determinants of calculation, revealed that the number and time dimensions were strong predictors of calculation, whereas the evidence for the letter dimension was only anecdotal and the evidence for the rotation dimension was nonexistent, suggesting some degree of specificity of different types of sequence patterning in predicting calculation. Symbolic magnitude processing remained a powerful unique correlate of calculation performance. These findings add to our understanding of individual differences in calculation ability, such that sequence patterning could begin to be considered as one of the cognitive skills underlying calculation ability in young children.

Doses of Ukrainian female clean-up workers with diagnosed breast cancer

The Chernobyl reactor accident in 1986 has caused significant exposure to ionizing radiation of the Ukrainian population, in particular clean-up workers and evacuees from the exclusion zones. A study aiming at the discovery of radiation markers of the breast cancer was conducted from 2008 to 2015 within a collaborative project by HZM, LMU, and NRCRM. In this study, post-Chernobyl breast cancer cases both in radiation-exposed female patients diagnosed at age less than 60 from 1992 to 2014 and in non-exposed controls matched for residency, tumor type, age at diagnosis, TNM classification as well as tumor grading were investigated for molecular changes with special emphasis to copy number alterations and miRNA profiles. Cancer registry and clinical archive data were used to identify 435 breast cancer patients among female clean-up workers and 14 among evacuees from highly contaminated territories as candidates for the study. Of these, 129 breast cancer patients fit study inclusion criteria and were traced for individual reconstruction of the target organ (breast) doses. The doses were estimated for 71 exposed cases (clean-up workers and evacuees from which biomaterial was available for molecular studies and who agreed to participate in a dosimetric interview) by the use of the well-established RADRUE method, which was adjusted specifically for the assessment of breast doses. The results of 58 female clean-up workers showed a large inter-individual variability of doses in a range of about five orders of magnitude: from 0.03 to 929 mGy, with median of 5.8 mGy. The study provides the first quantitative estimate of exposures received by female clean-up workers, which represent a limited but very important group of population affected by the Chernobyl accident. The doses of 13 women evacuated after the accident who did not take part in the clean-up activities (from 4 to 45 mGy with median of 19 mGy) are in line with the previous estimates for the evacuees from Pripyat and the 30-km zone.

Cost calculation for a flash glucose monitoring system for UK adults with type 1 diabetes mellitus receiving intensive insulin treatment

AIMS

To estimate the costs associated with a flash glucose monitoring system as a replacement for routine self-monitoring of blood glucose (SMBG) in patients with type 1 diabetes mellitus (T1DM) using intensive insulin, from a UK National Health Service (NHS) perspective.

METHODS

The base-case cost calculation was created using the maximum frequency of glucose monitoring recommended by the 2015 National Institute for Health and Care Excellence guidelines (4-10 tests per day). Scenario analyses considered SMBG at the frequency observed in the IMPACT clinical trial (5.6 tests per day) and at the frequency of flash monitoring observed in a real-world analysis (16 tests per day). A further scenario included potential costs associated with severe hypoglycaemia.

RESULTS

In the base case, the annual cost per patient using flash monitoring was £234 (19%) lower compared with routine SMBG (10 tests per day). In scenario analyses, the annual cost per patient of flash monitoring compared with 5.6 and 16 SMBG tests per day was £296 higher and £957 lower, respectively. The annual cost of severe hypoglycaemia for flash monitoring users was estimated to be £221 per patient, compared with £428 for routine SMBG users (based on 5.6 tests/day), corresponding to a reduction in costs of £207.

CONCLUSIONS

The flash monitoring system has a modest impact on glucose monitoring costs for the UK NHS for patients with T1DM using intensive insulin. For people requiring frequent tests, flash monitoring may be cost saving, especially when taking into account potential reductions in the rate of severe hypoglycaemia.

Repeat lactate level predicts mortality better than rate of clearance

BACKGROUND

Lactate clearance has been developed into a marker of resuscitation in trauma, but no study has compared the predictive power of the various clearance calculations. Our objective was to determine which method of calculating lactate clearance best predicted 24-hour and in-hospital mortality after injury.

STUDY DESIGN

Retrospective chart review of patients admitted to a Level-1 trauma center directly from the scene of injury from 2010 to 2013 who survived >15min, had an elevated lactate at admission (≥3mmol/L), followed by another measurement within 24h of admission. Lactate clearance was calculated using five models: actual value of the repeat level, absolute clearance, relative clearance, absolute rate, and relative rate. Models were compared using the areas under the respective receiver operating curves (AUCs), with an endpoint of death at 24h and in-hospital mortality.

RESULTS

3910 patients had an elevated admission lactate concentration on admission (mean=5.6±3.0mmol/L) followed by a second measurement (2.7±1.8mmol/L). Repeat absolute measurement best predicted 24-hour (AUC=0.85, 95% CI: 0.84-0.86) and in-hospital death (AUC=0.77; 95% CI, 0.76-0.78). Relative clearance was the best model of lactate clearance (AUC=0.77, 95% CI: 0.75-0.78 and AUC=0.705, 95% CI: 0.69-72, respectively) (p<0.0001 for each). A sensitivity analysis using a range of initial lactate measures yielded similar results.

CONCLUSIONS

The absolute value of the repeat lactate measurement had the greatest ability to predict mortality in injured patients undergoing resuscitation.

Adaptation to life in aeolian sand: how the sandfish lizard, Scincus scincus, prevents sand particles from entering its lungs

The sandfish lizard, Scincus scincus (Squamata: Scincidae), spends nearly its whole life in aeolian sand and only comes to the surface for foraging, defecating and mating. It is not yet understood how the animal can respire without sand particles entering its respiratory organs when buried under thick layers of sand. In this work, we integrated biological studies, computational calculations and physical experiments to understand this phenomenon. We present a 3D model of the upper respiratory system based on a detailed histological analysis. A 3D-printed version of this model was used in combination with characteristic ventilation patterns for computational calculations and fluid mechanics experiments. By calculating the velocity field, we identified a sharp decrease in velocity in the anterior part of the nasal cavity where mucus and cilia are present. The experiments with the 3D-printed model validate the calculations: particles, if present, were found only in the same area as suggested by the calculations. We postulate that the sandfish has an aerodynamic filtering system; more specifically, that the characteristic morphology of the respiratory channel coupled with specific ventilation patterns prevent particles from entering the lungs.

Highlighted Article: The sandfish S. scincus spends nearly its whole life in fine desert sand. We discovered that it has an aerodynamic filtering system to prevent sand particles from entering the lungs.

Magnitude processing and complex calculation is negatively impacted by mathematics anxiety while retrieval-based simple calculation is not

Mathematics anxiety (MA) refers to the experience of negative affect when engaging in mathematical activity. According to Ashcraft and Kirk (2001), MA selectively affects calculation with high working memory (WM) demand. On the other hand, Maloney, Ansari, and Fugelsang (2011) claim that MA affects all mathematical activities, including even the most basic ones such as magnitude comparison. The two theories make opposing predictions on the negative effect of MA on magnitude processing and simple calculation that make minimal demands on WM. We propose that MA has a selective impact on mathematical problem solving that likely involves processing of magnitude representations. Based on our hypothesis, MA will impinge upon magnitude processing even though it makes minimal demand on WM, but will spare retrieval-based, simple calculation, because it does not require magnitude processing. Our hypothesis can reconcile opposing predictions on the negative effect of MA on magnitude processing and simple calculation. In the present study, we observed a negative relationship between MA and performance on magnitude comparison and calculation with high but not low WM demand. These results demonstrate that MA has an impact on a wide range of mathematical performance, which depends on one's sense of magnitude, but spares over-practiced, retrieval-based calculation.

Cortical dynamics during simple calculation processes: A magnetoencephalography study

OBJECTIVE

We elucidated active cortical areas and their time courses during simple calculation by using whole-scalp magnetoencephalography.

METHODS

Twelve healthy volunteers were asked to view meaningless figures (figure viewing) or digits (digit viewing) and add single digits (calculation). The magnetic signals of the brain were measured using a helmet-shaped 122-channel neuromagnetometer during the three tasks.

RESULTS

The occipital, inferior posterior temporal, and middle temporal areas of each hemisphere and the left superior temporal area (STA) were activated during all tasks (approximately 250 ms after the stimulus onset). The calculation-related sources were located in the left inferior parietal area (IPA) in 8 subjects, right IPA in 5, left STA in 3, right STA in 5, right inferior frontal area in 2, and left inferior frontal area in 1. The IPA and STA of the left hemisphere were activated more strongly and significantly earlier than those of the right hemisphere: the left IPA was activated first (mean activation timing: 301 ms), followed by activations of the left STA (369 ms), right IPA (419 ms), and right STA (483 ms).

CONCLUSIONS

Simple digit addition is executed mainly in the left IPA and left STA, followed by the recognition processes of results in the right IPA and right STA.

SIGNIFICANCE

This study clarified the cortical process during simple calculation, with excellent temporal and spatial resolution; the IPA and STA of the left hemisphere were activated more strongly and earlier than the corresponding areas of the right hemisphere.

Re-assessing acalculia: Distinguishing spatial and purely arithmetical deficits in right-hemisphere damaged patients

Arithmetical deficits in right-hemisphere damaged patients have been traditionally considered secondary to visuo-spatial impairments, although the exact relationship between the two deficits has rarely been assessed. The present study implemented a voxelwise lesion analysis among 30 right-hemisphere damaged patients and a controlled, matched-sample, cross-sectional analysis with 35 cognitively normal controls regressing three composite cognitive measures on standardized numerical measures. The results showed that patients and controls significantly differ in Number comprehension, Transcoding, and Written operations, particularly subtractions and multiplications. The percentage of patients performing below the cutoffs ranged between 27% and 47% across these tasks. Spatial errors were associated with extensive lesions in fronto-temporo-parietal regions -which frequently lead to neglect- whereas pure arithmetical errors appeared related to more confined lesions in the right angular gyrus and its proximity. Stepwise regression models consistently revealed that spatial errors were primarily predicted by composite measures of visuo-spatial attention/neglect and representational abilities. Conversely, specific errors of arithmetic nature linked to representational abilities only. Crucially, the proportion of arithmetical errors (ranging from 65% to 100% across tasks) was higher than that of spatial ones. These findings thus suggest that unilateral right hemisphere lesions can directly affect core numerical/arithmetical processes, and that right-hemisphere acalculia is not only ascribable to visuo-spatial deficits as traditionally thought.

A simple practice guide for dose conversion between animals and human

Understanding the concept of extrapolation of dose between species is important for pharmaceutical researchers when initiating new animal or human experiments. Interspecies allometric scaling for dose conversion from animal to human studies is one of the most controversial areas in clinical pharmacology. Allometric approach considers the differences in body surface area, which is associated with animal weight while extrapolating the doses of therapeutic agents among the species. This review provides basic information about translation of doses between species and estimation of starting dose for clinical trials using allometric scaling. The method of calculation of injection volume for parenteral formulation based on human equivalent dose is also briefed.

Non-invasive mapping of calculation function by repetitive navigated transcranial magnetic stimulation

Concerning calculation function, studies have already reported on localizing computational function in patients and volunteers by functional magnetic resonance imaging and transcranial magnetic stimulation. However, the development of accurate repetitive navigated TMS (rTMS) with a considerably higher spatial resolution opens a new field in cognitive neuroscience. This study was therefore designed to evaluate the feasibility of rTMS for locating cortical calculation function in healthy volunteers, and to establish this technique for future scientific applications as well as preoperative mapping in brain tumor patients. Twenty healthy subjects underwent rTMS calculation mapping using 5 Hz/10 pulses. Fifty-two previously determined cortical spots of the whole hemispheres were stimulated on both sides. The subjects were instructed to perform the calculation task composed of 80 simple arithmetic operations while rTMS pulses were applied. The highest error rate (80 %) for all errors of all subjects was observed in the right ventral precentral gyrus. Concerning division task, a 45 % error rate was achieved in the left middle frontal gyrus. The subtraction task showed its highest error rate (40 %) in the right angular gyrus (anG). In the addition task a 35 % error rate was observed in the left anterior superior temporal gyrus. Lastly, the multiplication task induced a maximum error rate of 30 % in the left anG. rTMS seems feasible as a way to locate cortical calculation function. Besides language function, the cortical localizations are well in accordance with the current literature for other modalities or lesion studies.

Quantitative aspects of drug permeation across in vitro and in vivo barriers

The kinetics of permeation across epithelial and endothelial cell sheets and across cell membranes is determinant for the pharmacokinetics of a drug. In vitro transport experiments with cultured cells or artificial barriers have tremendously improved the predictability of the in vivo behaviour of tested compounds. This article focuses on the parameters and calculation methods that are used to describe permeation quantitatively, with a focus on in vitro experiments and the prediction of intestinal absorption and blood-brain barrier passage. It shows under which in vitro experimental conditions standard calculations are adequate and under which conditions equations should be adapted to the experimental details. The impact of volume differences between donor and receiver compartments, pH gradients, addition of albumin, accumulation in the barrier and unidirectional transport by an efflux transporter on the results is shown in simulations. The article should make researchers aware of experimental factors that affect the outcome of a permeation experiment and how to account for this during data analysis. Finally, strategies to predict the in vivo behaviour of a compound based on the in vitro data are discussed. The goal of the article is to support researchers in choosing experimental conditions and calculation methods that deliver appropriate and reproducible results in permeation studies in vitro.

Identifying the cognitive predictors of early counting and calculation skills: Evidence from a longitudinal study

The extent to which phonological, visual-spatial short-term memory (STM), and nonsymbolic quantitative skills support the development of counting and calculation skills was examined in this 14-month longitudinal study of 125 children. Initial assessments were made when the children were 4 years 8 months old. Phonological awareness, visual-spatial STM, and nonsymbolic approximate discrimination predicted growth in early calculation skills.These results suggest that both the approximate number system and domain-general phonological and visual-spatial skills support early calculation. In contrast, only performance on a small nonsymbolic quantity discrimination task (where the presented quantities were always within the subitizing range) predicted growth in cardinal counting skills. These results suggest that the development of counting and the development of calculation are supported by different cognitive abilities.

A practical implicit solvent potential for NMR structure calculation

The benefits of protein structure refinement in water are well documented. However, performing structure refinement with explicit atomic representation of the solvent molecules is computationally expensive and impractical for NMR-restrained structure calculations that start from completely extended polypeptide templates. Here we describe a new implicit solvation potential, EEFx (Effective Energy Function for XPLOR-NIH), for NMR-restrained structure calculations of proteins in XPLOR-NIH. The key components of EEFx are an energy term for solvation energy that works together with other nonbonded energy functions, and a dedicated force field for conformational and nonbonded protein interaction parameters. The initial results obtained with EEFx show that significant improvements in structural quality can be obtained. EEFx is computationally efficient and can be used both to fold and refine structures. Overall, EEFx improves the quality of protein conformation and nonbonded atomic interactions. Moreover, such benefits are accompanied by enhanced structural precision and enhanced structural accuracy, reflected in improved agreement with the cross-validated dipolar coupling data. Finally, implementation of EEFx calculations is straightforward and computationally efficient. Overall, EEFx provides a useful method for the practical calculation of experimental protein structures in a physically realistic environment.

New method and installation for rapid determination of radon diffusion coefficient in various materials

The mathematical apparatus and the experimental installation for the rapid determination of radon diffusion coefficient in various materials are developed. The single test lasts not longer than 18 h and allows testing numerous materials, such as gaseous and liquid media, as well as soil, concrete and radon-proof membranes, in which diffusion coefficient of radon may vary in an extremely wide range, from 1·10(-12) to 5·10(-5) m(2)/s. The uncertainty of radon diffusion coefficient estimation depends on the permeability of the sample and varies from about 5% (for the most permeable materials) to 40% (for less permeable materials, such as radon-proof membranes).

The number processing and calculation system: evidence from cognitive neuropsychology

INTRODUCTION

Cognitive neuropsychology focuses on the concepts of dissociation and double dissociation. The performance of number processing and calculation tasks by patients with acquired brain injury can be used to characterise the way in which the healthy cognitive system manipulates number symbols and quantities. The objective of this study is to determine the components of the numerical processing and calculation system.

METHODS

Participants consisted of 6 patients with acquired brain injuries in different cerebral localisations. We used Batería de evaluación del procesamiento numérico y el cálculo, a battery assessing number processing and calculation. Data was analysed using the difference in proportions test.

RESULTS

Quantitative numerical knowledge is independent from number transcoding, qualitative numerical knowledge, and calculation. Recodification is independent from qualitative numerical knowledge and calculation. Quantitative numerical knowledge and calculation are also independent functions.

CONCLUSIONS

The number processing and calculation system comprises at least 4 components that operate independently: quantitative numerical knowledge, number transcoding, qualitative numerical knowledge, and calculation. Therefore, each one may be damaged selectively without affecting the functioning of another. According to the main models of number processing and calculation, each component has different characteristics and cerebral localisations.

Comparison of different breast planning techniques and algorithms for radiation therapy treatment

This work aims at investigating the impact of treating breast cancer using different radiation therapy (RT) techniques--forwardly-planned intensity-modulated, f-IMRT, inversely-planned IMRT and dynamic conformal arc (DCART) RT--and their effects on the whole-breast irradiation and in the undesirable irradiation of the surrounding healthy tissues. Two algorithms of iPlan BrainLAB treatment planning system were compared: Pencil Beam Convolution (PBC) and commercial Monte Carlo (iMC). Seven left-sided breast patients submitted to breast-conserving surgery were enrolled in the study. For each patient, four RT techniques--f-IMRT, IMRT using 2-fields and 5-fields (IMRT2 and IMRT5, respectively) and DCART - were applied. The dose distributions in the planned target volume (PTV) and the dose to the organs at risk (OAR) were compared analyzing dose-volume histograms; further statistical analysis was performed using IBM SPSS v20 software. For PBC, all techniques provided adequate coverage of the PTV. However, statistically significant dose differences were observed between the techniques, in the PTV, OAR and also in the pattern of dose distribution spreading into normal tissues. IMRT5 and DCART spread low doses into greater volumes of normal tissue, right breast, right lung and heart than tangential techniques. However, IMRT5 plans improved distributions for the PTV, exhibiting better conformity and homogeneity in target and reduced high dose percentages in ipsilateral OAR. DCART did not present advantages over any of the techniques investigated. Differences were also found comparing the calculation algorithms: PBC estimated higher doses for the PTV, ipsilateral lung and heart than the iMC algorithm predicted.

Differentiating core and co-opted mechanisms in calculation: the neuroimaging of calculation in aphasia

The role of language in exact calculation is the subject of debate. Some behavioral and functional neuroimaging investigations of healthy participants suggest that calculation requires language resources. However, there are also reports of individuals with severe aphasic language impairment who retain calculation ability. One possibility in resolving these discordant findings is that the neural basis of calculation has undergone significant reorganization in aphasic calculators. Using fMRI, we examined brain activations associated with exact addition and subtraction in two patients with severe agrammatic aphasia and retained calculation ability. Behavior and brain activations during two-digit addition and subtraction were compared to those of a group of 11 healthy, age-matched controls. Behavioral results confirmed that both patients retained calculation ability. Imaging findings revealed individual differences in processing, but also a similar activation pattern across patients and controls in bilateral parietal cortices. Patients differed from controls in small areas of increased activation in peri-lesional regions, a shift from left fronto-temporal activation to the contralateral region, and increased activations in bilateral superior parietal regions. Our results suggest that bilateral parietal cortex represents the core of the calculation network and, while healthy controls may recruit language resources to support calculation, these mechanisms are not mandatory in adult cognition.

Genetic and environmental contributions to brain activation during calculation

Twin studies have long suggested a genetic influence on inter-individual variations in mathematical abilities, and candidate genes have been identified by genome-wide association studies. However, the localization of the brain regions under genetic influence during number manipulation is still unexplored. Here we investigated fMRI data from a group of 19 MZ (monozygotic) and 13 DZ (dizygotic) adult twin pairs, scanned during a mental calculation task. We examined both the activation and the degree of functional lateralization in regions of interest (ROIs) centered on the main activated peaks. Heritability was first investigated by comparing the respective MZ and DZ correlations. Then, genetic and environmental contributions were jointly estimated by fitting a ACE model classically used in twin studies. We found that a subset of the activated network was under genetic influence, encompassing the bilateral posterior superior parietal lobules (PSPL), the right intraparietal sulcus (IPS) and a left superior frontal region. An additional region of the left inferior parietal cortex (IPC), whose deactivation correlated with a behavioral calculation score, also presented higher similarity between MZ than between DZ twins, thus offering a plausible physiological basis for the observable inheritance of math scores. Finally, the main impact of the shared environment was found in the lateralization of activation within the intraparietal sulcus. These maps of genetic and environmental contributions provide precise candidate phenotypes for further genetic association analyses, and illuminate how genetics and education shape the development of number processing networks.