A 2-4 keV multilayer mirrored channel for the NIF Dante system

During inertial confinement fusion experiments at the National Ignition Facility (NIF), a capsule filled with deuterium and tritium (DT) gas, surrounded by a DT ice layer and a high-density carbon ablator, is driven to the temperature and densities required to initiate fusion. In the indirect method, 2 MJ of NIF laser light heats the inside of a gold hohlraum to a radiation temperature of 300 eV; thermal x rays from the hohlraum interior couple to the capsule and create a central hotspot at tens of millions degrees Kelvin and a density of 100-200 g/cm³. During the laser interaction with the gold wall, m-band x rays are produced at ∼2.5 keV; these can penetrate into the capsule and preheat the ablator and DT fuel. Preheat can impact instability growth rates in the ablation front and at the fuel-ablator interface. Monitoring the hohlraum x-ray spectrum throughout the implosion is, therefore, critical; for this purpose, a Multilayer Mirror (MLM) with flat response in the 2-4 keV range has been installed in the NIF 37° Dante calorimeter. Precision engineering and x-ray calibration of components mean the channel will report 2-4 keV spectral power with an uncertainty of ±8.7%.

Gas scintillation mitigation in gas Cherenkov detectors for inertial confinement fusion (invited)

Gas Cherenkov detectors provide a time resolved measurement of the fusion burn in inertial confinement fusion experiments. The fusion rate delivers critical benchmark figures, such as burn width and bang time. Recent detector improvements pushed temporal resolution to 10 ps to make burn width measurements on igniting targets possible. First high temporal resolution measurements using CO₂ gas fills had a background signal with a long decay length (tail), which was caused by gas scintillation. This gas scintillation limits the ability of the detector to resolve short burn width and high frequency features in the fusion rate measurements. A thorough investigation of the cause of the tail and mitigation options for gas scintillation is presented here. As a near-term resolution, neon gas is being used to extract fusion burn histories. Paths forward for the next generation of gas Cherenkov detectors are identified including the usage of oxygen as a Cherenkov medium.

Hypomyelination and Congenital Cataract: Identification of a Novel likely pathogenic c.414+1G>A in FAM126A gene Variant

It is key to expand the differential diagnosis and consider possible genetic etiologies on a patient with congenital cataracts associated with clinical features, such as leukodystrophy or polyneuropathy.

Endocannabinoid Signaling for GABAergic-Microglia (Mis)Communication in the Brain Aging

The aging brain seems to be characterized by neuronal loss leading to cognitive decline and progressively worsening symptoms related to neurodegeneration. Also, pro-inflammatory states, if prolonged, may increase neuronal vulnerability via excessive activation of microglia and their pro-inflammatory by-products, which is seen as individuals increase in age. Consequently, microglial activity is tightly regulated by neuron-microglia communications. The endocannabinoid system (ECS) is emerging as a regulator of microglia and the neuronal-microglia communication system. Recently, it has been demonstrated that cannabinoid 1 (CB1) receptor signaling on GABAergic interneurons plays a crucial role in regulating microglial activity. Interestingly, if endocannabinoid signaling on GABAergic neurons are disturbed, the phenotypes mimic central nervous system insult models by activating microglia and leading to accelerated brain aging. Investigating the endocannabinoid receptors, ligands, and genetic deletions yields the potential to understand the communication system and mechanism by which the ECS regulates glial cells and aspects of aging. While there remains much to discover with the ECS, the information gathered and identified already could lead to the development of cell-specific therapeutic interventions that help in reducing the effects of age-related pro-inflammatory states and neurodegeneration.

The five line-of-sight neutron time-of-flight (nToF) suite on the National Ignition Facility (NIF)

Measurement of the neutron spectrum from inertial confinement fusion implosions is one of the primary diagnostics of implosion performance. Analysis of the spectrum gives access to quantities such as neutron yield, hot-spot velocity, apparent ion temperature, and compressed fuel ρr through measurement of the down-scatter ratio. On the National Ignition Facility, the neutron time-of-flight suite has been upgraded to include five independent, collimated lines of sight, each comprising a high dynamic range bibenzyl/diphenylacetylene-stilbene scintillator [R. Hatarik et al., Plasma Fusion Res. 9, 4404104 (2014)] and high-speed fused silica Cherenkov detectors [A. S. Moore et al., Rev. Sci. Instrum. 89, 10I120 (2018)].

Fluorescent biomarkers demonstrate prospects for spreadable vaccines to control disease transmission in wild bats

Vaccines that autonomously transfer among individuals have been proposed as a strategy to control infectious diseases within inaccessible wildlife populations. However, rates of vaccine spread and epidemiological efficacy in real-world systems remain elusive. Here, we investigate whether topical vaccines that transfer among individuals through social contacts can control vampire bat rabies-a medically and economically important zoonosis in Latin America. Field experiments in three Peruvian bat colonies, which used fluorescent biomarkers as a proxy for the bat-to-bat transfer and ingestion of an oral vaccine, revealed that vaccine transfer would increase population-level immunity up to 2.6 times beyond the same effort using conventional, non-spreadable vaccines. Mathematical models showed that observed levels of vaccine transfer would reduce the probability, size and duration of rabies outbreaks, even at low but realistically achievable levels of vaccine application. Models further predicted that existing vaccines provide substantial advantages over culling bats-the policy currently implemented in North, Central and South America. Linking field studies with biomarkers to mathematical models can inform how spreadable vaccines may combat pathogens of health and conservation concern before costly investments in vaccine design and testing.

Pulse dilation gas Cherenkov detector for ultra-fast gamma reaction history at the NIF (invited)

The Cherenkov mechanism used in Gas Cherenkov Detectors (GCDs) is exceptionally fast. However, the temporal resolution of GCDs, such as the Gamma Reaction History diagnostic at the National Ignition Facility (NIF), has been limited by the current state-of-the-art photomultiplier tube technology to ∼100 ps. The soon-to-be deployed Pulse Dilation Photomultiplier Tube (PD-PMT) at NIF will allow for temporal resolution comparable to that of the gas cell or ∼10 ps. Enhanced resolution will contribute to the quest for ignition in a crucial way through precision measurements of reaction history and ablator areal density (ρR) history, leading to better constrained models. Features such as onset of alpha heating, shock reverberations, and burn truncation due to dynamically evolving failure modes may become visible for the first time. Test measurements of the PD-PMT at Atomic Weapons Establishment confirmed that design goals have been met. The PD-PMT provides dilation factors of 2 to 40× in 6 increments. The GCD-3 recently deployed at the NIF has been modified for coupling to a PD-PMT and will soon be making ultrafast measurements.

Progress on next generation gamma-ray Cherenkov detectors for the National Ignition Facility

Fusion reaction history and ablator areal density measurements for Inertial Confinement Fusion experiments at the National Ignition Facility are currently conducted using the Gamma Reaction History diagnostic (GRH_6m). Future Gas Cherenkov Detectors (GCDs) will ultimately provide ∼100x more sensitivity, reduce the effective temporal response from ∼100 to ∼10 ps, and lower the energy threshold from 2.9 to 1.8 MeV, relative to GRH_6m. The first phase toward next generation GCDs consisted of inserting the existing coaxial GCD-3 detector into a reentrant well which puts it within 4 m of the implosion. Reaction history and ablator gamma measurement results from this Phase I are discussed here. These results demonstrate viability for the follow-on Phases of (II) the use of a revolutionary new pulse-dilation photomultiplier tube to improve the effective measurement bandwidth by >10x relative to current PMT technology; and (III) the design of a NIF-specific "Super" GCD which will be informed by the assessment of the radiation background environment within the well described here.

Would a two-stage N-removal be a suitable technology to implement at full scale the use of anammox for sewage treatment?

Sewage treatment with anammox could be implemented through a two-step reactor system, where the first reactor would be devoted to partial nitritation. A process design was sketched including control loops. The control strategy regulates the flow-rate of the rich ammonium sidestream produced after dewatering the digested sludge, to keep the ammonium concentration at a set point in the partial nitritation reactor by DOsing the SIde Stream (DOSIS). A second control loop manages the ammonium concentration set point based on the measurement of the total nitrogen in the partial nitritation reactor. A mathematical model was developed to assess the amount of sidestream required. Even in the case of a strong diurnal variability, simulations show how the control strategy is correctly performing, demonstrating the potential of the proposed technology.

[Surgical treatment of giant congenital melanocytic nevi: a change of aim]

OBJECTIVE

To review the surgical experience in Giant Congenital Melanocytic Nevi (GCMN).

MATERIAL AND METHODS

Review of GCMN cases consulting at the Department of Pediatric Surgery since 1994. Data registered were: year and age at 1st consultation, type of treatment, number of surgical procedures and complications, histology, central nervous system MRI and follow-up.

RESULTS

Eleven patients with GCMN > 10% of body surface consulted at ages ranging from newborn to 8 years. All of them had multiple surgical procedures (2-19), from nevus removal to only biopsies. Eight patients had tissue expansion, completed in 3 of them with skin grafts on dermal substitute. Six patients had complications: 4 expander extrusions, 5 infections, 3 flap necrosis and 1 dehiscence. In 6 children a total or subtotal resection of the nevus was achieved; in 2 the treatment was interrupted, remaining 20% and 50% of the initial nevus; three patients had not had nevus treatment. None of the patients presented cutaneous melanoma; one died from intracranial melanoma; another one has leptomeningeal melanosis. The first 4 patients underwent an average of 16 surgical procedures each, the last 7 patients only 5.

CONCLUSIONS

The aim of GCNM management has changed: GCNM treatment is now surgically conservative. Complete excision is now not the aim when technically unfeasible in few procedures; multiple surgical procedures with poor cosmetical results are not acceptable. The gravity is determined by CNS involvement.

Geochemical and environmental controls on the genesis of soluble efflorescent salts in coastal mine tailings deposits: a discussion based on reactive transport modeling

Water-soluble efflorescent salts often form on tailings in hyperarid climates. Their high solubility together with the high risk of human exposure to heavy metals such as Cu, Ni, Zn, etc., makes this occurrence a serious environmental problem. Understanding their formation (genesis) is therefore key to designing prevention and remediation strategies. A significant amount of these efflorescences has been described on the coastal area of Chañaral (Chile). There, highly soluble salts such as halite (NaCl) and eriochalcite (CuCl(2).2H(2)O) form on 4km(2) of marine shore tailings. Natural occurrence of eriochalcite is rare: its formation requires extreme environmental and geochemical conditions such as high evaporation rate and low relative air humidity, and continuous Cl and Cu supply from groundwater, etc. Its formation was examined by means of reactive transport modeling. A scenario is proposed involving sea water and subsequently a mixture of sea water/freshwater in the groundwater composition in the formation of these efflorescences. The strong competition from other halides (i.e. halite and silvite (KCl)) for the Cl may inhibit the precipitation of eriochalcite. Therefore, the Cl/Na ratio trend >1 is a key parameter in its formation. Cation-exchange between Na(+) and other major ions such as K(+), Ca(2+), Mg(2+) and Cu(2+) in the clay fraction of tailings is proposed to account for realistic Cl/Na ratios. With regard to preventing the formation of eriochalcite, a capillary barrier on the tailings surface is proposed as a suitable alternative. Its efficiency as a barrier is also tested by means of reactive transport models.

Competitive technology approaches for electronic hybridization detection in a microsystem with microfluidics for diagnosis genetic tests

This paper is presenting competitive technology alternatives for the electronic hybridization detection in a microsystem with microfluidics for diagnosis genetic tests that are carried out by two competitive research projects. The technologies developed are a photosensor, a capacitive sensor and an optical real-time affinity biosensor. The performance of those biosensors will be evaluated but also their manufacturability and cost will define the appropriateness of each one for industrialization and their integration on a microsystem for diagnosis genetic testing.

Estimation of recharge from floods in disconnected stream-aquifer systems

Stream-aquifer interaction has been the subject of much research for cases of good hydraulic connection (continuous saturated zone) between a river and an aquifer. Under these conditions, floods do not represent a very large net input to the aquifer because most of the water that enters the aquifer during the flood returns to the river when its stage recedes. The situation is different in disconnected stream-aquifer systems, where the streambed lies above the water level in the aquifer, thus preventing return flow from the aquifer. Under these conditions, floods may represent large, but hard to quantify, water inputs. Here, we present a methodology to estimate recharge from floods for disconnected stream-aquifer systems. Recharge is estimated as the product of a flood time function (dependent on the streamflow) and an unknown factor, which is obtained from calibrating a ground water flow model to aquifer heads. The approach can also benefit from concentration data, which can be very informative when river water concentrations vary over time. This methodology is applied to a field situation where recharge from river flooding is found to amount to nearly 15 million m(3)/year on the average, which represents 40% of the total aquifer inputs. Recharge from flooding helps explain major head recoveries, suggesting that basin water management programs should allow some floods to occur.

Model-based design of a control strategy for optimal start-up of a high-strength nitrification system

The objective of this study was to define an automatic control loop for the start-up of a high-strength nitrification system to achieve a rich nitrifying biomass from a poor nitrifying sludge by means of simulation tools. The used model considered the nitrification as a two-step model with substrate and non-competitive inhibitions. Two control strategies (on-off controller and proportional-integral (PI) controller) were designed, simulated and compared. The measured variable in the control loops was the sum of ammonium and nitrite concentrations in the effluent and the manipulated variable was the inflow. The objective in the optimisation of both controllers was to increase the inflow of the system as fast as possible without exceeding the maximum ammonium and nitrite concentrations allowed in the effluent. The optimised controllers parameters were used to simulate a 40 days start-up. The results obtained with both strategies were similar, although, the best strategy was the PI controller since it was less oscillatory and the biomass growth was slightly faster.

Phenol wastewater remediation: advanced oxidation processes coupled to a biological treatment

Nowadays, there are increasingly stringent regulations requiring more and more treatment of industrial effluents to generate product waters which could be easily reused or disposed of to the environment without any harmful effects. Therefore, different advanced oxidation processes were investigated as suitable precursors for the biological treatment of industrial effluents containing phenol. Wet air oxidation and Fenton process were tested batch wise, while catalytic wet air oxidation and H2O2-promoted catalytic wet air oxidation processes were studied in a trickle bed reactor, the last two using over activated carbon as catalyst. Effluent characterisation was made by means of substrate conversion (using high liquid performance chromatography), chemical oxygen demand and total organic carbon. Biodegradation parameters (i.e. maximum oxygen uptake rate and oxygen consumption) were obtained from respirometric tests using activated sludge from an urban biological wastewater treatment plant (WWTP). The main goal was to find the proper conditions in terms of biodegradability enhancement, so that these phenolic effluents could be successfully treated in an urban biological WWTP. Results show promising research ways for the development of efficient coupled processes for the treatment of wastewater containing toxic or biologically non-degradable compounds.

Feasibility of pegfilgrastim as haematopoietic support for dose-dense every-2-week adjuvant chemotherapy in breast cancer

18606

Background: Dose-dense sequential chemotherapy has been safety supported with Filgrastim (F). Pegfilgrastim (PEGF) is a pegylated recombinant human granulocyte colony-stimulating factor (G-CSF) that has a long half-life, a fact that facilitates a less frequent dosing. Its safety and efficacy has been established in 21- and 28-days schedules. Methods: We have performed a retrospective analysis of medical records of 2 cohort of patients (n=38) treated at our institution between December 2003 and November 2005. All patients received Adriamicin 60 mg/m2 plus Ciclophosphamide 600 mg/m2 q2w for 4 cycles followed by Paclitaxel 175 mg/m2 q2w for 4 cycles. As G-CSF support, in Cohort A (n=29) PEGF was administered 6 mg on day 2 of each cycle and in Cohort B (n=9) F days 3 to 10 at 5 μg/kg. The primary end point was to explore the feasibility and safety in terms of febrile neutropenia (FN) events, number of treatment delays (TD), incidence of neutropenia grade 3 (NPG3) and 4 (NPG4) and mean absolute neutrophil count (ANC) on day 14 of cycle 1 to 7 for both groups. Indirect comparisons have been performed. Results: Patients characteristics in both cohorts were well balanced, except for age in cohort A compared with cohort B (44,89 versus 52,5, p = 0,02). FN events and TD were increased in cohort B compared with cohort A (22% versus 0%, p=0.051, both comparisons). No statistically significant difference in number of episodes of NPG3 and NPG4 was observed. Median ANC on day 14 for each treatment cycle was significantly greater for Cohort A than Cohort B, except for cycle 6. Conclusions: PEGF is very safe and efficacy in patients treated with dose-dense sequential adjuvant chemotherapy for breast cancer. It could be even more efficient than F in preventing febrile neutropenia events.

[Table: see text]

Improving the start-up of an EBPR system using OUR to control the aerobic phase length: a simulation study

The enhanced biological phosphorus removal (EBPR) process is based on enriching the sludge with polyphosphate accumulating organisms (PAO) which are scarce in conventional non-EBPR wastewater treatment plant sludge. Hence, the start-up of EBPR systems (i.e. enriching the sludge with PAO) can be very slow and complex. A simulation study of a possible improvement of the start-up of an EBPR system in a sequencing batch reactor is presented in this work. The improvement is based on reducing the length of the aerobic phase so that it coincides with the depletion of orthophosphate from the medium. This improvement, though verified by simulation to be very successful, requires a good on-line orthophosphate sensor. To avoid this technical limitation, a link between oxygen uptake rate (OUR) measurements and orthophosphate presence is proposed. This link allows the control of the aerobic phase length with OUR as a measured variable and, consequently, a considerable improvement with respect to the conventional fixed aerobic phase length operation. An improvement of 95% in the ratio of PAO to heterotrophs and an increase of 30% in the final amount of PAO in sludge is achieved with this control strategy. The kinetic mod for simulations was a modification of the Activated Sludge Model 2d.

Observation and mathematical description of the acceleration phenomenon in batch respirograms associated with ammonium oxidation

Two-step nitrification models are generally calibrated using short-term respirometric batch experiments. Important discrepancies appear between model predictions and experimental observations just after the pulse addition since a fast transient in the OUR profile is experimentally observed. Acceleration of the OUR appears ongoing between the substrate addition and attainment of the maximum OUR value. Among the several phenomena that could contribute to this observation, the most probable cause is the limitation of reducing equivalents required for maximal ammonia monooxygenase activity at the time of substrate addition. Ignoring acceleration would result in large parameter estimation errors from respirometric batch experiments. This work proposes a simple methodology to successfully describe (not to explain) the acceleration phenomenon estimating only two parameters. This methodology consists of introducing a Gaussian-like expression in the model.

Limitations of ASM1 and ASM3: a comparison based on batch oxygen uptake rate profiles from different full-scale wastewater treatment plants

The two most popular models for the description of the biological COD removal are ASM1 and ASM3. However, some numerical inconsistencies arise when using these models to interpret the data obtained in short-term respirometric batch experiments. In this study, both models are fitted to four different respirometric batch profiles obtained with biomass from different WWTP. The parameter estimation results and the practical (local) identifiability are analysed, and the limitations of both models are discussed. The growth yield obtained by fitting ASM1 to the short-term respirometric batch profiles is higher than the default one, as well as the storage yield obtained by fitting ASM3 is lower than the default one. Based on these values, possible improvements to the modelling of the biological COD removal, such as the inclusion of simultaneous growth and storage on external substrate, are proposed.

Improving the biological nitrogen removal process in pharmaceutical wastewater treatment plants: a case study

The Biological Nitrogen Removal (BNR) process of some pharmaceutical wastewater treatment plants has important operational problems. This study shows that, in order to solve these problems, the design of industrial BNR processes should start by analysing three key parameters: the characteristics of the wastewater load, the determination of the maximum TKN removal rate and the detection of toxic or inhibitory compounds in the wastewater. A case study of this analysis in pharmaceutical wastewater is presented here. In this case, the conventional TKN analytical method does not make an accurate characterisation of the wastewater load because it measures a concentration of 100 mg TKN l(-1) whereas the real concentration, determined with a modified TKN analytical method, is 150-500 mg TKN l(-1). Also, the TKN removal of the treatment system is insufficient in some periods because it falls below legal requirements. This problem might be a consequence of the wrong characterisation of wastewater during the design process. The maximum TKN removal at 27 degrees C (24 mg N g VSS(-1) d(-1) or 197 mg N l(-1) d(-1)) was evaluated in a pilot-scale plant. This value is six times greater than the average NLR applied in the full-scale plant. Finally, some of the components of the wastewater, such as p-phenylenediamine, might have inhibitory or toxic effects on the biological process. P-phenylenediamine causes a large decrease in the nitrification rate. This effect was determined by respirometry. This methodology shows that the effect is mainly inhibitory with a contact time of 30 min and if the contact time is longer, 14 hours, a toxic effect is observed.

Biological nitrogen removal of high-strength ammonium industrial wastewater with two-sludge system

The biological nitrogen removal (BNR) process is the most common method for removing low quantities of ammonium from wastewater, but this is not the usual treatment for high-strength ammonium wastewater. The capacity to biologically remove the nitrogen content of a real industrial wastewater with a concentration of 5000 g N-NH(4)(+) L(-1) is demonstrated in this work. The experimental system used is based on a two-sludge system, with a nitrifying activated sludge and a denitrifying activated sludge. This system treated real industrial wastewater for 450 days, and during this period, it showed the capacity for oxidizing all the ammonium at average nitrification rates between 0.11 and 0.18 g N-NH(4)(+)g VSS(-1)d(-1). Two key process parameters were evaluated: the maximum nitrification rate (MNR) and the maximum denitrification rate (MDR). MNR was determined in continuous operation at three different temperatures: 15 degrees C, 20 degrees C and 25 degrees C, obtaining values of 0.10, 0.21 and 0.37 g N-NH(4)(+) g VSS(-1)d(-1), respectively. Complete denitrification was achieved using two different industrial carbon sources, one containing mainly ethanol and the other one methanol. The MDR reached with ethanol (0.64 g N-NO(x)(-) g VSS(-1)d(-1)) was about 6 times higher than the MDR reached with methanol (0.11g N-NO(x)(-)g VSS(-1)d(-1)).

Simultaneous Cerebral Aneurysms and Carotid Disease Should the Symptomatic Lesion always be the first to be Treated? A Case Report

SUMMARY

Simultaneous presentation of carotid stenosis and cerebral aneurysms is rare and it is conventionally accepted that symptomatic lesions need to be treated first. Our purpose was to describe our experience in managing patients who simultaneously presented significant carotid stenosis and cerebral aneurysm.

An off-line respirometric procedure to determine inhibition and toxicity of biodegradable compounds in biomass from an industrial WWTP

Determining whether a certain compound is toxic (or inhibitor) or not to a biomass of a WWTP is crucial in order to avoid WWTP malfunction. Respirometric techniques have been commonly used to assess the toxicity of a certain compound by evaluating the oxygen uptake rate (OUR) profile obtained when a pulse of substrate is added to endogenous biomass and comparing it with the OUR profile obtained when the pulse is a mixture of substrate and the possible toxic or inhibitor (PTI). However, when using this method with biodegradable compounds some difficulties arise because the PTI consumption implies oxygen consumption as well. In this study, a modified procedure for toxicity assessment using respirometry is developed which overcomes the difficulties caused by the toxic biodegradability. This procedure is based on the comparison of different respirograms obtained with pulses of control substrate before and after adding the PTI and with a pulse of PTI and control substrate together. Moreover, some examples are shown with p-phenylenediamine and phenol as an example of toxic and inhibitor for nitrifying biomass.

Effect of different operational parameters in the enhanced biological phosphorus removal process. Experimental design and results

The uncontrolled dumping of phosphorus into a water environment creates serious problems of eutrophication, affecting water quality and causing grave problems in the aquatic ecosystem. European legislation demands drastic reduction of phosphorus dissolved in wastewater. Enhanced Biological Phosphorus Removal (EBPR) is the current tendency in wastewater treatment. This biological process depends on a multiplicity of variables, but its three main factors are: influent COD/P ratio, anaerobic fraction and sludge retention time (SRT). The aim of this work is to statistically determine the effect of these three parameters in EBPR through a response surface methodology. The objective function that has been chosen is phosphorus removed per unit biomass formed. This function provides ample information on BPR, since the quantity of phosphorus removed depends on the accumulative capacity of the microorganisms present. Two levels were chosen for the SRT (5 and 10 days), two for the anaerobic fraction (0.1 and 0.2), and six for levels of the influent COD/P ratio (between 16 and 87). The experiments were undertaken at pilot scale (100 litres) with an A2/O configuration, with simultaneous nitrogen and phosphorous removaL The wastewater used is a synthetic mixture of complex sources of carbon and nitrogenwithout volatile fatty acids. The empirical model obtained indicates that the factor most influencing the EBPR process is the influent COD/P ratio, whilst the anaerobic fraction is that which has least influence. Additionally, there is an optimum in the influent COD/P ratio that is to be found between 41 and 48.

On the behavior of approaches to simulate reactive transport

Two families of approaches exist to simulate reactive transport in groundwater: The Direct Substitution Approach (DSA), based on Newton-Raphson and the Picard or Sequential Iteration Approach (SIA). We applied basic versions of both methods to several test cases and compared both computational demands and quality of the solution for varying grid size. Results showed that the behavior of the two approaches is sensitive to both grid size and chemistry. As a general rule, the DSA is more robust than the SIA, in the sense that its convergence is less sensitive to time step size (any approach will converge given a sufficiently small time step). Moreover, the DSA leads to a better simulation of sharp fronts, which can only be reproduced with fine grids after many iterations when the SIA is used. As a consequence, the DSA runs faster than SIA in chemically difficult cases (i.e., highly non-linear and/or very retarded), because the SIA may require very small time steps to converge. On the other hand, the size of the system of equations is much larger for the DSA than for the SIA, so that its CPU time and memory requirements tend to be less favorable with increasing grid size. As a result, the SIA may become faster than the DSA for very large, chemically simple problems. The use of an iterative linear solver for the DSA makes its CPU time less sensitive to grid size.

Teaching through clinical cases: a good method to study bioethics. Experience at the Lleida Faculty of Medicine

This paper summarises our experience in the teaching of bioethics during the final course in medicine at the Universitat de Lleida. Teaching has been based on the discussion of real clinical cases, the ethical implications of which have been extracted and presented by the professor, and analysed under his supervision. We present here the objectives, the programme and the course and evaluation methodology used, as well as the results of an inquiry carried out among the 55 students attending the course. The acceptance level was 92% and the attendance 95%. We believe the methodology used to be successful, since it makes possible the introduction of theoretical aspects of bioethics in order to solve actual cases, as well as encourage wide discussion. At the same time it emphasises that the students discover the values involved.

Massive fetomaternal hemorrhage: how long should children with good evolution be controlled? A case report

We report on a term infant with a severe fetomaternal hemorrhage that caused a serious anemia that was surmounted after several transfusions. After the initial complications, such as persistent pulmonary circulation, severe anemia and thrombocytopenia, the outcome was good. We discuss the importance of a long-term follow-up of affected children, as well as their mothers. No clear parameters for a real prognosis are available. A follow-up is needed in order to detect possible complications in neurological development.

Recurrent molecular abnormalities in type VII collagen in Southern Italian patients with recessive dystrophic epidermolysis bullosa

In this study we searched for mutations in the type VII collagen gene (COL7A1) in 10 families from Southern Italy with severe generalised recessive dystrophic epidermolysis bullosa using PCR amplification of genomic DNA, heteroduplex analysis and direct nucleotide sequencing. Our principal aim was to identify any recurrent mutations in COL7A1 that might facilitate future mutation detection strategies in this population. Three recurrent COL7A1 mutations were delineated in six of the 10 families: a frameshift mutation in exon 4, 497insA, was detected in three affected individuals from three families, a deletion mutation at the acceptor splice site of intron 114/exon 115, 8441-14del21, was found in five patients in three of the families, and an intron 49 acceptor splice site mutation, 4783-1 G-to-A, was identified in three subjects in two families (GenBank accession no, L02870). Haplotype analyses showed evidence for propagation of common ancestral mutant COL7A1 alleles for each of these recurrent mutations. These results contribute significantly to understanding the nature of COL7A1 pathology in patients from Southern Italy and in designing future approaches to mutation detection.

Microsurgical reconstruction of the Achilles tendon with a fascia lata flap

A case of total reconstruction of the Achilles tendon is reported. A compound free musculocutaneous unit of fascia lata was used to supply the absent tendon and soft tissues, achieving excellent cosmetic and functional results. This technique is suggested as an alternative for combating infection, providing soft-tissue cover, and bridging the gap in the tendon.

[Evaluation of serum adenosine deaminase as a prognostic marker in the treatment of human immunodeficiency virus infection with zidovudine]

BACKGROUND

Adenosine deaminase (ADA) is a key enzyme in cellular immunity. It catalyses the reaction 2'deoxyadenosine to 2'deoxiinosine, a critical step in the production of essential metabolites for the synthesis of nucleic acids. Its main physiological activity occurs in T cells of lymphoid tissue. The advanced HIV infection is characterized by a severe and progressive cellular immunity compromise. Partial positive results have been obtained with Zidovudine (AZT), a drug which Serum adenosine deaminase has been proposed as a useful marker for the assessment of the therapy response in these patients.

METHODS

Serum ADA activity was determined in patients infected with HIV in stage II, before and after four months of therapy with AZT, regarding variations in its activity with improvements in biological parameters--CD4 and CD8 lymphocytes.

RESULTS

Patients infected with HIV showed a significant increase in ADA activity compared with patients in the control group: 21.6 +/- 5.4 vs. 10.4 +/- 2.3 U/l (p < 0.001). Therapy with AZT decreased ADA activity: 21.6 +/- 5.4 vs. 15.2 +/- 4.3 U/l (p < 0.001) and correlated with an increase in CD4 counts: 187 +/- 105 vs. 353 +/- 145/mm3 (p < 0.001) and in CD4/CD8 ratio: 0.188 +/- 0.10 vs. 0.382 +/- 0.18 (p < 0.001).

CONCLUSIONS

The detection of a decrease in ADA correlates significantly with a favourable outcome in immunological parameters in individuals infected with HIV in stage II of disease treated with AZT.

[Depression of the mononuclear phagocyte system caused by high doses of narcotics]

We evaluated in human monocytes the effect of high doses of alfentanyl on the expression of vimentin filaments, the phagocytic activity and the membrane display of HLA-DR molecules in the subjects undergoing surgery. The study was performed on 30 patients, ASAI-II. The patients received 100 mcg/kg i.v. of Alfentanil and the maintenance of anaesthesia was made with Alfentanil (2-3 mcg/kg/min.). The patients were randomized in two groups. The patients were ventilated with N2O:O2 (1:1) (Group I) or air: O2 (1:1) (Group II). After surgery, all patients of the Group II received Naloxone (0.2-0.4 mg). Central venous blood samples were obtained before induction, one and two hours after induction of anaesthesia and at the end of surgery. Separation of monocytes was performed according to Boyum technique. CD35 and HLA-DR molecules and vimentin filaments were studied by indirect immunofluorescence method using monoclonal antibodies. Percentage of positive cells were read with a cytofluorometer. The phagocytic function of monocytes was determined by ingestion of latex particles. Cortisol and ACTH plasma levels were determined by RIA. High doses of Alfentanyl depress phagocytic function and membrane display of CD35 and HLA-DR molecules in monocyte and induce marked changes in the organization of vimentin filaments in these cells in patients undergoing surgery. This monocytic depression was more marked in the patients ventilated with N2O. In our results there was uninhibition of ACTH and cortisol plasma levels responses to surgical stress by Alfentanil administration. Since the effects of Alfentanil were reversed by Naloxone, an opioid receptor mechanism seems to mediate these events.