Lightning Pose: improved animal pose estimation via semi-supervised learning, Bayesian ensembling, and cloud-native open-source tools

Contemporary pose estimation methods enable precise measurements of behavior via supervised deep learning with hand-labeled video frames. Although effective in many cases, the supervised approach requires extensive labeling and often produces outputs that are unreliable for downstream analyses. Here, we introduce "Lightning Pose," an efficient pose estimation package with three algorithmic contributions. First, in addition to training on a few labeled video frames, we use many unlabeled videos and penalize the network whenever its predictions violate motion continuity, multiple-view geometry, and posture plausibility (semi-supervised learning). Second, we introduce a network architecture that resolves occlusions by predicting pose on any given frame using surrounding unlabeled frames. Third, we refine the pose predictions post-hoc by combining ensembling and Kalman smoothing. Together, these components render pose trajectories more accurate and scientifically usable. We release a cloud application that allows users to label data, train networks, and predict new videos directly from the browser.

First Measurement of Hard Exclusive π^{-}Δ^{++} Electroproduction Beam-Spin Asymmetries off the Proton

The polarized cross-section ratio σ_{LT^{'}}/σ_{0} from hard exclusive π^{-}Δ^{++} electroproduction off an unpolarized hydrogen target has been extracted based on beam-spin asymmetry measurements using a 10.2  GeV/10.6  GeV incident electron beam and the CLAS12 spectrometer at Jefferson Lab. The study, which provides the first observation of this channel in the deep-inelastic regime, focuses on very forward-pion kinematics in the valence regime, and photon virtualities ranging from 1.5  GeV^{2} up to 7  GeV^{2}. The reaction provides a novel access to the d-quark content of the nucleon and to p→Δ^{++} transition generalized parton distributions. A comparison to existing results for hard exclusive π^{+}n and π^{0}p electroproduction is provided, which shows a clear impact of the excitation mechanism, encoded in transition generalized parton distributions, on the asymmetry.

First CLAS12 Measurement of Deeply Virtual Compton Scattering Beam-Spin Asymmetries in the Extended Valence Region

Deeply virtual Compton scattering (DVCS) allows one to probe generalized parton distributions describing the 3D structure of the nucleon. We report the first measurement of the DVCS beam-spin asymmetry using the CLAS12 spectrometer with a 10.2 and 10.6 GeV electron beam scattering from unpolarized protons. The results greatly extend the Q^{2} and Bjorken-x phase space beyond the existing data in the valence region and provide 1600 new data points measured with unprecedented statistical uncertainty, setting new, tight constraints for future phenomenological studies.

First Measurement of Λ Electroproduction off Nuclei in the Current and Target Fragmentation Regions

We report results of Λ hyperon production in semi-inclusive deep-inelastic scattering off deuterium, carbon, iron, and lead targets obtained with the CLAS detector and the Continuous Electron Beam Accelerator Facility 5.014 GeV electron beam. These results represent the first measurements of the Λ multiplicity ratio and transverse momentum broadening as a function of the energy fraction (z) in the current and target fragmentation regions. The multiplicity ratio exhibits a strong suppression at high z and an enhancement at low z. The measured transverse momentum broadening is an order of magnitude greater than that seen for light mesons. This indicates that the propagating entity interacts very strongly with the nuclear medium, which suggests that propagation of diquark configurations in the nuclear medium takes place at least part of the time, even at high z. The trends of these results are qualitatively described by the Giessen Boltzmann-Uehling-Uhlenbeck transport model, particularly for the multiplicity ratios. These observations will potentially open a new era of studies of the structure of the nucleon as well as of strange baryons.

Observation of Correlations between Spin and Transverse Momenta in Back-to-Back Dihadron Production at CLAS12

We report the first measurements of deep inelastic scattering spin-dependent azimuthal asymmetries in back-to-back dihadron electroproduction in the deep inelastic scattering process. In this reaction, two hadrons are produced in opposite hemispheres along the z axis in the virtual photon-target nucleon center-of-mass frame, with the first hadron produced in the current-fragmentation region and the second in the target-fragmentation region. The data were taken with longitudinally polarized electron beams of 10.2 and 10.6 GeV incident on an unpolarized liquid-hydrogen target using the CLAS12 spectrometer at Jefferson Lab. Observed nonzero sinΔϕ modulations in ep→e^{'}pπ^{+}X events, where Δϕ is the difference of the azimuthal angles of the proton and pion in the virtual photon and target nucleon center-of-mass frame, indicate that correlations between the spin and transverse momenta of hadrons produced in the target- and current-fragmentation regions may be significant. The measured beam-spin asymmetries provide a first access in dihadron production to a previously unexplored leading-twist spin- and transverse-momentum-dependent fracture function. The fracture functions describe the hadronization of the target remnant after the hard scattering of a virtual photon off a quark in the target particle and provide a new avenue for studying nucleonic structure and hadronization.

Observation of Azimuth-Dependent Suppression of Hadron Pairs in Electron Scattering off Nuclei

We present the first measurement of dihadron angular correlations in electron-nucleus scattering. The data were taken with the CLAS detector and a 5.0 GeV electron beam incident on deuterium, carbon, iron, and lead targets. Relative to deuterium, the nuclear yields of charged-pion pairs show a strong suppression for azimuthally opposite pairs, no suppression for azimuthally nearby pairs, and an enhancement of pairs with large invariant mass. These effects grow with increased nuclear size. The data are qualitatively described by the gibuu model, which suggests that hadrons form near the nuclear surface and undergo multiple scattering in nuclei.These results show that angular correlation studies can open a new way to elucidate how hadrons form and interact inside nuclei.

Measurement of the Nucleon F_{2}^{n}/F_{2}^{p} Structure Function Ratio by the Jefferson Lab MARATHON Tritium/Helium-3 Deep Inelastic Scattering Experiment

The ratio of the nucleon F_{2} structure functions, F_{2}^{n}/F_{2}^{p}, is determined by the MARATHON experiment from measurements of deep inelastic scattering of electrons from ^{3}H and ^{3}He nuclei. The experiment was performed in the Hall A Facility of Jefferson Lab using two high-resolution spectrometers for electron detection, and a cryogenic target system which included a low-activity tritium cell. The data analysis used a novel technique exploiting the mirror symmetry of the two nuclei, which essentially eliminates many theoretical uncertainties in the extraction of the ratio. The results, which cover the Bjorken scaling variable range 0.19<x<0.83, represent a significant improvement compared to previous SLAC and Jefferson Lab measurements for the ratio. They are compared to recent theoretical calculations and empirical determinations of the F_{2}^{n}/F_{2}^{p} ratio.

Multidimensional, High Precision Measurements of Beam Single Spin Asymmetries in Semi-inclusive π^{+} Electroproduction off Protons in the Valence Region

High precision measurements of the polarized electron beam-spin asymmetry in semi-inclusive deep inelastic scattering (SIDIS) from the proton have been performed using a 10.6 GeV incident electron beam and the CLAS12 spectrometer at Jefferson Lab. We report here a high precision multidimensional study of single π^{+} SIDIS data over a large kinematic range in Bjorken x, fractional energy, and transverse momentum of the hadron as well as photon virtualities Q^{2} ranging from 1-7  GeV^{2}. In particular, the structure function ratio F_{LU}^{sinϕ}/F_{UU} has been determined, where F_{LU}^{sinϕ} is a twist-3 quantity that can reveal novel aspects of emergent hadron mass and quark-gluon correlations within the nucleon. The data's impact on the evolving understanding of the underlying reaction mechanisms and their kinematic variation is explored using theoretical models for the different contributing transverse momentum dependent parton distribution functions.

Improved Λp Elastic Scattering Cross Sections between 0.9 and 2.0 GeV/c as a Main Ingredient of the Neutron Star Equation of State

Strange matter is believed to exist in the cores of neutron stars based on simple kinematics. If this is true, then hyperon-nucleon interactions will play a significant part in the neutron star equation of state. Yet, compared to other elastic scattering processes, there is very little data on Λ-N scattering. This experiment utilized the CEBAF Large Acceptance Spectrometer (CLAS) detector to study the Λp→Λp elastic scattering cross section in the incident Λ momentum range 0.9-2.0  GeV/c. These are the first data on this reaction since the 1970s. The new cross sections have significantly better accuracy and precision than the existing world data, and the techniques developed here can also be used in future experiments.

First Measurement of Timelike Compton Scattering

We present the first measurement of the timelike Compton scattering process, γp→p^{'}γ^{*}(γ^{*}→e^{+}e^{-}), obtained with the CLAS12 detector at Jefferson Lab. The photon beam polarization and the decay lepton angular asymmetries are reported in the range of timelike photon virtualities 2.25<Q^{'2}<9  GeV^{2}, squared momentum transferred 0.1<-t<0.8  GeV^{2}, and average total center-of-mass energy squared s=14.5  GeV^{2}. The photon beam polarization asymmetry, similar to the beam-spin asymmetry in deep virtual Compton scattering, is sensitive to the imaginary part of the Compton form factors and provides a way to test the universality of the generalized parton distributions. The angular asymmetry of the decay leptons accesses the real part of the Compton form factors and thus the D-term in the parametrization of the generalized parton distributions.

Use of personal protective equipment among waste workers of Sisdol landfill site of Nepal

Introduction: Solid waste management is a major issue in Nepal with Kathmandu valley generating the highest amount of solid waste. After recovery, the solid waste generated in Kathmandu valley is transferred to the Sisdol landfill site. There are waste workers in Sisdol landfill site who sustain their livelihood by collecting recyclables from those wastes. Personal protective equipment (PPE) is necessary to protect the frontline waste workers against infection. In addition, the waste workers need to know the proper usage of PPE in order to protect themselves from contamination. This study aimed to assess the awareness and proper usage of PPE along with the challenges faced by the waste workers at Sisdol landfill site. Methods: A descriptive cross-sectional study was conducted to collect data from landfill waste workers of Sisdol located at Kakani Rural Municipality in Nuwakot district of Nepal. A convenience sampling method was used based on the availability of landfill waste workers on that day and their willingness to participate. The data was collected using the structured questionnaire and personal interview of available waste workers. Results: The study comprised of 65% female and 35% male waste workers. The highest percentage of waste workers belong to 27-37 age group occupying 43% of total respondents.  Around 92% waste workers had participated in any orientation/training or session related to PPE and its usage. About 60% landfill waste workers were found only using mask and gloves. Conclusion: There is small number of waste workers who wish to wear full set of PPE. Most of them only like to wear mask and gloves. The gender, age group and the education level of waste workers had no association with the usage of PPE during the work.

Chronic, cortex-wide imaging of specific cell populations during behavior

Measurements of neuronal activity across brain areas are important for understanding the neural correlates of cognitive and motor processes such as attention, decision-making and action selection. However, techniques that allow cellular resolution measurements are expensive and require a high degree of technical expertise, which limits their broad use. Wide-field imaging of genetically encoded indicators is a high-throughput, cost-effective and flexible approach to measure activity of specific cell populations with high temporal resolution and a cortex-wide field of view. Here we outline our protocol for assembling a wide-field macroscope setup, performing surgery to prepare the intact skull and imaging neural activity chronically in behaving, transgenic mice. Further, we highlight a processing pipeline that leverages novel, cloud-based methods to analyze large-scale imaging datasets. The protocol targets laboratories that are seeking to build macroscopes, optimize surgical procedures for long-term chronic imaging and/or analyze cortex-wide neuronal recordings. The entire protocol, including steps for assembly and calibration of the macroscope, surgical preparation, imaging and data analysis, requires a total of 8 h. It is designed to be accessible to laboratories with limited expertise in imaging methods or interest in high-throughput imaging during behavior.

Standardized and reproducible measurement of decision-making in mice

Progress in science requires standardized assays whose results can be readily shared, compared, and reproduced across laboratories. Reproducibility, however, has been a concern in neuroscience, particularly for measurements of mouse behavior. Here, we show that a standardized task to probe decision-making in mice produces reproducible results across multiple laboratories. We adopted a task for head-fixed mice that assays perceptual and value-based decision making, and we standardized training protocol and experimental hardware, software, and procedures. We trained 140 mice across seven laboratories in three countries, and we collected 5 million mouse choices into a publicly available database. Learning speed was variable across mice and laboratories, but once training was complete there were no significant differences in behavior across laboratories. Mice in different laboratories adopted similar reliance on visual stimuli, on past successes and failures, and on estimates of stimulus prior probability to guide their choices. These results reveal that a complex mouse behavior can be reproduced across multiple laboratories. They establish a standard for reproducible rodent behavior, and provide an unprecedented dataset and open-access tools to study decision-making in mice. More generally, they indicate a path toward achieving reproducibility in neuroscience through collaborative open-science approaches.

Standardized and reproducible measurement of decision-making in mice

Progress in science requires standardized assays whose results can be readily shared, compared, and reproduced across laboratories. Reproducibility, however, has been a concern in neuroscience, particularly for measurements of mouse behavior. Here, we show that a standardized task to probe decision-making in mice produces reproducible results across multiple laboratories. We adopted a task for head-fixed mice that assays perceptual and value-based decision making, and we standardized training protocol and experimental hardware, software, and procedures. We trained 140 mice across seven laboratories in three countries, and we collected 5 million mouse choices into a publicly available database. Learning speed was variable across mice and laboratories, but once training was complete there were no significant differences in behavior across laboratories. Mice in different laboratories adopted similar reliance on visual stimuli, on past successes and failures, and on estimates of stimulus prior probability to guide their choices. These results reveal that a complex mouse behavior can be reproduced across multiple laboratories. They establish a standard for reproducible rodent behavior, and provide an unprecedented dataset and open-access tools to study decision-making in mice. More generally, they indicate a path toward achieving reproducibility in neuroscience through collaborative open-science approaches.

Observation of Beam Spin Asymmetries in the Process ep→e^{'}π^{+}π^{-}X with CLAS12

The observation of beam spin asymmetries in two-pion production in semi-inclusive deep inelastic scattering off an unpolarized proton target is reported. The data presented here were taken in the fall of 2018 with the CLAS12 spectrometer using a 10.6 GeV longitudinally spin-polarized electron beam delivered by CEBAF at JLab. The measured asymmetries provide the first opportunity to extract the parton distribution function e(x), which provides information about the interaction between gluons and quarks, in a collinear framework that offers cleaner access than previous measurements. The asymmetries also constitute the first ever signal sensitive to the helicity-dependent two-pion fragmentation function G_{1}^{⊥}. A clear sign change is observed around the ρ mass that appears in model calculations and is indicative of the dependence of the produced pions on the helicity of the fragmenting quark.

Photoproduction of the f_{2}(1270) Meson Using the CLAS Detector

The quark structure of the f_{2}(1270) meson has, for many years, been assumed to be a pure quark-antiquark (qq[over ¯]) resonance with quantum numbers J^{PC}=2^{++}. Recently, it was proposed that the f_{2}(1270) is a molecular state made from the attractive interaction of two ρ mesons. Such a state would be expected to decay strongly to final states with charged pions due to the dominant decay ρ→π^{+}π^{-}, whereas decay to two neutral pions would likely be suppressed. Here, we measure for the first time the reaction γp→π^{0}π^{0}p, using the CEBAF Large Acceptance Spectrometer detector at Jefferson Lab for incident beam energies between 3.6 and 5.4 GeV. Differential cross sections, dσ/dt, for f_{2}(1270) photoproduction are extracted with good precision due to low backgrounds and are compared to theoretical calculations.

Ruling out Color Transparency in Quasielastic ^{12}C(e,e^{'}p) up to Q^{2} of 14.2 (GeV/c)^{2}

Quasielastic ^{12}C(e,e^{'}p) scattering was measured at spacelike 4-momentum transfer squared Q^{2}=8, 9.4, 11.4, and 14.2  (GeV/c)^{2}, the highest ever achieved to date. Nuclear transparency for this reaction was extracted by comparing the measured yield to that expected from a plane-wave impulse approximation calculation without any final state interactions. The measured transparency was consistent with no Q^{2} dependence, up to proton momenta of 8.5  GeV/c, ruling out the quantum chromodynamics effect of color transparency at the measured Q^{2} scales in exclusive (e,e^{'}p) reactions. These results impose strict constraints on models of color transparency for protons.

Beam Spin Asymmetry in Semi-Inclusive Electroproduction of Hadron Pairs

A first measurement of the longitudinal beam spin asymmetry A_{LU} in the semi-inclusive electroproduction of pairs of charged pions is reported. A_{LU} is a higher-twist observable and offers the cleanest access to the nucleon twist-3 parton distribution function e(x). Data have been collected in the Hall-B at Jefferson Lab by impinging a 5.498-GeV electron beam on a liquid-hydrogen target, and reconstructing the scattered electron and the pion pair with the CLAS detector. One-dimensional projections of the A_{LU}^{sinϕ_{R}} moments are extracted for the kinematic variables of interest in the valence quark region. The understanding of dihadron production is essential for the interpretation of observables in single-hadron production in semi-inclusive DIS, and pioneering measurements of single-spin asymmetries in dihadron production open a new avenue in studies of QCD dynamics.

Lapses in perceptual decisions reflect exploration

Perceptual decision-makers often display a constant rate of errors independent of evidence strength. These ‘lapses’ are treated as a nuisance arising from noise tangential to the decision, e.g. inattention or motor errors. Here, we use a multisensory decision task in rats to demonstrate that these explanations cannot account for lapses’ stimulus dependence. We propose a novel explanation: lapses reflect a strategic trade-off between exploiting known rewarding actions and exploring uncertain ones. We tested this model’s predictions by selectively manipulating one action’s reward magnitude or probability. As uniquely predicted by this model, changes were restricted to lapses associated with that action. Finally, we show that lapses are a powerful tool for assigning decision-related computations to neural structures based on disruption experiments (here, posterior striatum and secondary motor cortex). These results suggest that lapses reflect an integral component of decision-making and are informative about action values in normal and disrupted brain states.

Probing the Deuteron at Very Large Internal Momenta

We measure ^{2}H(e,e^{'}p)n cross sections at 4-momentum transfers of Q^{2}=4.5±0.5  (GeV/c)^{2} over a range of neutron recoil momenta p_{r}, reaching up to ∼1.0  GeV/c. We obtain data at fixed neutron recoil angles θ_{nq}=35°, 45°, and 75° with respect to the 3-momentum transfer q[over →]. The new data agree well with previous data, which reached p_{r}∼500  MeV/c. At θ_{nq}=35° and 45°, final state interactions, meson exchange currents, and isobar currents are suppressed and the plane wave impulse approximation provides the dominant cross section contribution. We compare the new data to recent theoretical calculations, where we observe a significant discrepancy for recoil momenta p_{r}>700  MeV/c.

Extraction of Beam-Spin Asymmetries from the Hard Exclusive π^{+} Channel off Protons in a Wide Range of Kinematics

We have measured beam-spin asymmetries to extract the sinϕ moment A_{LU}^{sinϕ} from the hard exclusive e[over →]p→e^{'}nπ^{+} reaction above the resonance region, for the first time with nearly full coverage from forward to backward angles in the center of mass. The A_{LU}^{sinϕ} moment has been measured up to 6.6  GeV^{2} in -t, covering the kinematic regimes of generalized parton distributions (GPD) and baryon-to-meson transition distribution amplitudes (TDA) at the same time. The experimental results in very forward kinematics demonstrate the sensitivity to chiral-odd and chiral-even GPDs. In very backward kinematics where the TDA framework is applicable, we found A_{LU}^{sinϕ} to be negative, while a sign change was observed near 90° in the center of mass. The unique results presented in this Letter will provide critical constraints to establish reaction mechanisms that can help to further develop the GPD and TDA frameworks.

Probing Few-Body Nuclear Dynamics via ^{3}H and ^{3}He (e,e^{'}p)pn Cross-Section Measurements

We report the first measurement of the (e,e^{'}p) three-body breakup reaction cross sections in helium-3 (^{3}He) and tritium (^{3}H) at large momentum transfer [⟨Q^{2}⟩≈1.9  (GeV/c)^{2}] and x_{B}>1 kinematics, where the cross section should be sensitive to quasielastic (QE) scattering from single nucleons. The data cover missing momenta 40≤p_{miss}≤500  MeV/c that, in the QE limit with no rescattering, equals the initial momentum of the probed nucleon. The measured cross sections are compared with state-of-the-art ab initio calculations. Overall good agreement, within ±20%, is observed between data and calculations for the full p_{miss} range for ^{3}H and for 100≤p_{miss}≤350  MeV/c for ^{3}He. Including the effects of rescattering of the outgoing nucleon improves agreement with the data at p_{miss}>250  MeV/c and suggests contributions from charge-exchange (SCX) rescattering. The isoscalar sum of ^{3}He plus ^{3}H, which is largely insensitive to SCX, is described by calculations to within the accuracy of the data over the entire p_{miss} range. This validates current models of the ground state of the three-nucleon system up to very high initial nucleon momenta of 500  MeV/c.

Successful Multi-vessel Percutaneous Coronary Intervention for Recent Myocardial Infarction in a Patient with Dextrocardia and Situs Inversus

Dextrocardia with situs inversus is a state which is characterized by abnormal positioning of the heart and other internal organs. It is a rare congenital anomaly and the exact cause is not known. More than 60 recognized genes are significant for the proper positioning and patterning of the organs in the body. However, a specific genetic cause of dextrocardia with situs inversus has not been identified and inheritance prototypes have not been established in the majority cases. There are partial available case reports of successful percutaneous coronary intervention (PCI) in these patients who have atherosclerotic coronary artery disease, especially when presenting with myocardial infarction. PCI is technically difficult because of dextrocardia. We hereby describe a 51-year-old male, who had a recent inferior wall myocardial infarction and underwent successful coronary angiography and PCI at a tertiary level hospital in Dhaka, Bangladesh.

Exploring the Structure of the Bound Proton with Deeply Virtual Compton Scattering

In the past two decades, deeply virtual Compton scattering of electrons has been successfully used to advance our knowledge of the partonic structure of the free proton and investigate correlations between the transverse position and the longitudinal momentum of quarks inside the nucleon. Meanwhile, the structure of bound nucleons in nuclei has been studied in inclusive deep-inelastic lepton scattering experiments off nuclear targets, showing a significant difference in longitudinal momentum distribution of quarks inside the bound nucleon, known as the EMC effect. In this Letter, we report the first beam spin asymmetry (BSA) measurement of exclusive deeply virtual Compton scattering off a proton bound in ^{4}He. The data used here were accumulated using a 6 GeV longitudinally polarized electron beam incident on a pressurized ^{4}He gaseous target placed within the CLAS spectrometer in Hall-B at the Thomas Jefferson National Accelerator Facility. The azimuthal angle (ϕ) dependence of the BSA was studied in a wide range of virtual photon and scattered proton kinematics. The Q^{2}, x_{B}, and t dependencies of the BSA on the bound proton are compared with those on the free proton. In the whole kinematical region of our measurements, the BSA on the bound proton is smaller by 20% to 40%, indicating possible medium modification of its partonic structure.

Direct Observation of Proton-Neutron Short-Range Correlation Dominance in Heavy Nuclei

We measured the triple coincidence A(e,e^{'}np) and A(e,e^{'}pp) reactions on carbon, aluminum, iron, and lead targets at Q^{2}>1.5  (GeV/c)^{2}, x_{B}>1.1 and missing momentum >400  MeV/c. This was the first direct measurement of both proton-proton (pp) and neutron-proton (np) short-range correlated (SRC) pair knockout from heavy asymmetric nuclei. For all measured nuclei, the average proton-proton (pp) to neutron-proton (np) reduced cross-section ratio is about 6%, in agreement with previous indirect measurements. Correcting for single-charge exchange effects decreased the SRC pairs ratio to ∼3%, which is lower than previous results. Comparisons to theoretical generalized contact formalism (GCF) cross-section calculations show good agreement using both phenomenological and chiral nucleon-nucleon potentials, favoring a lower pp to np pair ratio. The ability of the GCF calculation to describe the experimental data using either phenomenological or chiral potentials suggests possible reduction of scale and scheme dependence in cross-section ratios. Our results also support the high-resolution description of high-momentum states being predominantly due to nucleons in SRC pairs.

First Measurements of the Double-Polarization Observables F, P, and H in ω Photoproduction off Transversely Polarized Protons in the N^{*} Resonance Region

First measurements of double-polarization observables in ω photoproduction off the proton are presented using transverse target polarization and data from the CEBAF Large Acceptance Spectrometer (CLAS) FROST experiment at Jefferson Lab. The beam-target asymmetry F has been measured using circularly polarized, tagged photons in the energy range 1200-2700 MeV, and the beam-target asymmetries H and P have been measured using linearly polarized, tagged photons in the energy range 1200-2000 MeV. These measurements significantly increase the database on polarization observables. The results are included in two partial-wave analyses and reveal significant contributions from several nucleon (N^{*}) resonances. In particular, contributions from new N^{*} resonances listed in the Review of Particle Properties are observed, which aid in reaching the goal of mapping out the nucleon resonance spectrum.

Conventional Brain MRI in Carbon Monoxide Poisoning

Carbon monoxide poisoning is a common fatal condition which can have acute or chronic presentation with varying severity. It commonly involves globus pallidus and putamen but can involve other parts of brain. Conventional MRI using T1 weighted,T2 weighted and FLAIR sequences are helpful in determining the extent of damage to the brain. However, appropriate clinical and laboratory findings should supplement findings on imaging.

Renal drug dosing recommendations: evaluation of product information for brands of the same drug

OBJECTIVES

To review the product information (PI) for various brands of the same generic drugs and investigate the extent to which information is currently available on dosing in renal impairment and the concordance between the dosing recommendations for the same generic drug.

METHOD

The Monthly Index of Medical Specialities (MIMS) was examined for 28 generic drugs recommended to be used with caution in renal impairment. For each generic drug all available brands listed as having solid oral dosage form were recorded. For each identified brand, the current PI was consulted and data referring to renal impairment was collated. The dissimilarity between these PI regarding the renal dosage recommendation was determined.

RESULTS

There was generally a lack of detailed information in the PI on the use of drugs in patients with renal impairment. The majority of PI documents (88 of 155 PI; 57%) provided quantitative dosage recommendations, but this was often not detailed enough to help users to make an informed decision. For 37 PI documents (24%), an altered dosage regimen was proposed without a quantifiable measure of renal function reported in the dose recommendation. The renal function severity category terms used and the associated quantitative values were also not consistent. It was observed that the recommendations varied among different brands of hydromorphone, morphine, oxycodone, tramadol, metformin and topiramate.

CONCLUSION

The reporting of renal function quantification methods, and associated dosage recommendations, in PI requires standardisation to ensure optimal drug dosing. Regularly updating of PI is also necessary.

Dose adjustment guidelines for medications in patients with renal impairment: how consistent are drug information sources?

BACKGROUND

It is known that patients with renal disease are often administered inappropriate dosages of drugs. A lack of quantitative data in the available drug information sources and inconsistency in dosing information may augment the problem of dosing error.

AIMS

To determine the concordance among five drug information sources regarding the dosing recommendations provided for drugs considered problematic in patients with renal impairment and to determine the consistency among the sources regarding the definition of renal impairment and categorisation of chronic kidney disease.

METHODS

Five standard drug information sources were reviewed for 61 drugs recommended to be used with caution in renal impairment. Information on recommendations for dosage adjustment in renal impairment was extracted and analysed. Further, the definition and classification of renal impairment were recorded. The recommendation for each drug was coded into six different categories and the intersource reliability was calculated.

RESULTS

Only slight agreement was observed among the sources (Fleiss Kappa: 0.3). Qualitative data were not well defined, and there was a lack of consistency in quantitative values. Some drugs marked as contraindicated in one source were not mentioned as such in others. Also, drugs considered as not requiring dosage adjustment in one source had explicit recommendations in other sources. The definition and classification of renal impairment differed among the five information sources.

CONCLUSIONS

There should be an evidence-based approach to drug dosage adjustment in order to bring uniformity to the recommendations. Regular updating of the content of the drug information sources is also important.

Evaluation of maxillofacial injury in the central part of Nepal

An evaluation of dental and maxillofacial trauma in College of Medical Sciences, Teaching Hospital, Bharatpur, Nepal was carried out to assess the causes of trauma and the relationship between the injuries to the Patient's Age, Gender, Type, Site of injury and the Influence of Alcohol from June 1, 2008 to May 31, 2011. Files of 1986 trauma patients were reviewed. Maxillofacial or dental injuries were observed in 269 (13.54%) of the trauma patients, caused by road traffic accidents 173 (64.3%), fall injury 43 (16.0%), physical assault 25 (9.3%), animal attack 9 (3.3%) and sport injury 19 (7.1%) Men were hospitalized almost three times more than women, most common site of injury was dentoalveolar fracture 79(29.37%) young people were at greater risk. The most frequent age of trauma was 15-29 years (51.7%). DOI: http://dx.doi.org/10.3126/jcmsn.v7i3.6702 Journal of College of Medical Sciences-Nepal, 2011, Vol-7, No-3, 11-16  

Enteric fever with severe pancytopenia in a four year girl

Typhoid fever and paratyphoid fever (also known as enteric fever) are severe systemic illnesses caused by salmonella typhi and S. paratyphi respectively. Enteric fever is prevalent in developing countries including Nepal, where it still remains as a major health problem. There have been reports of pancytopenia with enteric fever which has been attributed to mechanisms like bone marrow suppression, infection associated hemophagocytic syndrome and disseminated intravascular coagulation. We report here a case of severe pancytopenia in enteric fever as a result of bone marrow suppression due to systemic infection. Keywords: enteric fever, pancytopenia, bone marrow suppression

Fiber-optic bronchoscopy: seven-year experience at Nepal Medical College Teaching Hospital

Fiber-optic bronchoscopy is a safe and useful diagnostic and therapeutic tool for the management of the pulmonary diseases. The purpose of this study was to find out the demographic profiles, indications, bronchoscopic findings, and diagnoses of the patients who underwent bronchoscopic examination. Retrospective analysis of 231 consecutive bronchoscopies done in Nepal Medical College Teaching Hospital over the period of seven years (January 2003 to January 2010) was done. The commonest indication was radiological opacity (90.2%), followed by diffuse pulmonary infiltrates (4.3%). Cough was the commonest presenting symptom seen in 89.8% of the patients. 79.7% of the patients were smokers and the history of smoking among the patients diagnosed to have lung cancer was 94%. The commonest bronchoscopic finding was endobronchial growth (47.8%). Histopathological examination revealed malignancy in 53.8% of the patients, of which small cell lung cancer was 22.8% and non small cell lung cancer 77.2%. Even when growth was not visualized on bronchoscopy, biopsies attempted from the segments with radiological abnormality established the diagnosis of malignancy in 10.16%, pulmonary tuberculosis in 5.1% and Sarcoidosis in 2.2% of the cases.

Enteric fever with severe pancytopenia in a four year girl

Typhoid fever and paratyphoid fever (also known as enteric fever) are severe systemic illnesses caused by salmonella typhi and S. paratyphi respectively. Enteric fever is prevalent in developing countries including Nepal, where it still remains as a major health problem. There have been reports of pancytopenia with enteric fever which has been attributed to mechanisms like bone marrow suppression, infection associated hemophagocytic syndrome and disseminated intravascular coagulation. We report here a case of severe pancytopenia in enteric fever as a result of bone marrow suppression due to systemic infection.

A novel modification of a bone repositioning device and a new technique for reestablishing facial contours after mandibular resection surgery

A novel modification of a bone repositioning device previously published by the same authors is introduced. A flexible tube to define the intersegmental bony relationship is filled with light-cured resin. It solidifies following exposure to strong visible light for about 1 min. This technique can be used for bone positioning after mandibular resection surgery and during positioning of the proximal segment after sagittal split ramus osteotomy. The authors also propose a simple method for determining the contour of the reconstructed mandible to regain the original shape and form. The advantage of this technique is its simplicity and flexibility compared with other methods of bone positioning during mandibular segmental surgery.

Intraoperative surgical clearance confirmation of tongue carcinomas using ultrasound

OBJECTIVES

The existence of tumour cells on the surgical margin can be shown in frozen sections. However, there has been no method to obtain information about surgical clearance intraoperatively. We propose a simple method to confirm the surgical clearance of tongue carcinomas during surgery.

METHODS

Just after the resection of a tumour in a conventional manner, the resected fresh specimen was immersed in a gelatine solution, maintaining its original shape and orientation, and refrigerated for solidification of the gelatine. Then ultrasound observation of the gelatine-embedded specimen was performed from the surface of the gelatine.

RESULTS

Very fine images could be obtained easily and without any specialist skills.

CONCLUSIONS

With this method, the operator can easily obtain information about surgical clearance during the operation.

Characterization and susceptibility patterns of clinically important Enterococcus species in eastern Nepal

Life threatening infections caused by enterococcus species with multidrug resistance has emerged as a threat to medical care in the present era. This study was conducted to characterize enterococcus species isolated from different clinical samples and to detect the pattern of susceptibility to some of the commonly used antibiotics in B.P Koirala Institute of Health Sciences (BPKIHS), a tertiary care hospital in eastern Nepal. Clinical samples submitted to the microbiology unit of Central Laboratory Service (CLS) for culture and sensitivity during March 2002 - February 2003 was analyzed. Enterococcus species were identified by colony characteristics, gram staining and relevant biochemical tests. Antibiotic susceptibility test was done by the Kirby Bauer disc diffusion technique. Of 50 Enterococcus species isolated, E. faecalis was the predominant isolate (48.0%) followed by E. faecium (32.0%) and E. avium (20.0%). Eighty-eight percent of E. faecalis showed sensitivity to cephotaxime and 87.0% to vancomycin. Multiple drug resistance was observed most commonly in E. faecium. Seventeen percent of E. faecium were resistant to vancomycin and 63.0% to ciprofloxacin and 44.0% to ampicillin. On the contrary E. avium rarely showed resistance to the antimicrobials tested including vancomycin. Enterococcal infections are common nowadays specially in hospitalized patients. Inappropriate use of antibiotics in clinical practice and poultry should be discouraged to prevent the emergence of multidrug resistant species.

A simple method for bone positioning of mandibular segments

A simple bone-positioning technique is reported, using a combination of bone plates and a flexible tube filled with acrylic polymer. The flexible tube is solidified by injection of acrylic monomer. This technique is applicable for bone positioning after mandibular resection as well as positioning of the proximal segment after sagittal split ramus osteotomy. This technique has the advantages of greater simplicity and flexibility compared to previously reported methods of bone positioning.

Morphological change of the micelle of poly(styrene)-b-poly(2-vinylpyridine)-b-poly(ethylene oxide) induced by binding of sodium dodecyl sulfate

Morphological change of a micelle of poly(styrene)-b-poly(2-vinylpyridine)-b-poly(ethylene oxide) (PS-PVP-PEO) polymer was induced by binding sodium dodecyl sulfate (SDS) to the PVP block in acidic aqueous solutions. The change in the size of SDS/PS-PVP-PEO complexes was detected by dynamic light scattering measurements and atomic force microscopy, and the binding of SDS was confirmed by zeta-potential measurements. When the micelle was free from SDS in acidic aqueous solutions, the hydrodynamic diameter of the micelle was 216 nm, reflecting the extended conformation of the PVP block due to the repulsion between protonated pyridine units. As the cationic PVP block was electrically neutralized with anionic SDS, the diameter was gradually reduced concomitant with the decrease in zeta-potential and finally reached 175 nm when the PVP block was completely neutralized. The decrease in the diameter shows the morphological change of the PVP block from extended to shrunken forms. Further addition of SDS did not cause the changes of the diameter nor zeta-potential. This indicates that SDS was not bound to the PS-PVP-PEO polymer after the PVP block was fully neutralized and that the hydrophobic binding of SDS to the polymer was negligible due to the low concentration of SDS.