Magnetic microwire probes for the magnetic rod interfacial stress rheometer.

The magnetic needle interfacial shear rheometer is a valuable tool for the study of the mechanical properties of thin fluid films or monolayers. However, it is difficult to differentiate the interfacial and subphase contributions to the drag on the needle. In principle, the problem can be addressed by decreasing the needle diameter, which decreases the bulk contribution while the interfacial contribution remains essentially the same. Here we show the results obtained when using a new type of needle, that of magnetic microwires with diameter approximately 10 times thinner than for commercial needles. We show that the lower inertia of the microwires calls for a new calibration procedure. We propose such a new calibration procedure based on the flow field solution around the needle introduced in refs 1 and 2. By measuring thin silicone oil films with well-controlled interfacial viscosities as well as eicosanol (C20) and pentadecanoic acid (PDA, C15) Langmuir monolayers, we show that the new calibration method works well for standard needles as well as for the microwire probes. Moreover, we show that the analysis of the force terms contributing to the force on the needle helps to ascertain whether the measurements obtained are reliable for given surface shear viscosity values. We also show that the microwire probes have at least a 10-fold-lower resolution limit, allowing one to measure interfacial viscosities as low as 10(-7) N·m/s.

Aggregation and disaggregation dynamics of sedimented and charged superparamagnetic micro-particles in water suspension.

This article presents results on the aggregation and disaggregation kinetics on a 1 µm diameter charged superparamagnetic particles dispersed in water under a constant uniaxial magnetic field in experiments with salt (KCl) added to the suspension in order to observe the behaviour of the system when the electrical properties of the particles have been screened. These particles have an electric charge and are confined between two separated 100 µm thick quartz windows, and sediment near the charged bottom wall. The electrostatic interactions that take place in this experimental setup may affect the micro-structure and colloidal stability of the suspension and thus, the dynamics of aggregation and disaggregation.

Electrostatic and hydrodynamics effects in a sedimented magnetorheological suspension.

We present experimental results on the equilibrium microstructure of a sedimented magnetorheological suspension, namely, an aqueous suspension of micron-sized superparamagnetic particles. We develop a study of the electrical interactions on the suspension by processing video-microscopy images of the sedimented particles. We calculate the pair distribution function, g(r), which yields the electrostatic pair potential u(r), showing an anomalous attractive interaction for distances on the order of twice the particle diameter, with characteristic parameters whose values show a dependence with the two-dimensional concentration of particles. The repulsive body of the potential is adjusted to a DLVO expression in order to calculate the Debye screening length and the effective surface charge density. Influence of confinement and variations on the Boltzmann sedimentation profile because of the electrostatic interactions appear to be essential for the interpretation of experimental results.

Morphological, rheological and mechanical characterization of polypropylene nanocomposite blends.

In the present work, the effectiveness of styrene/ethylene-butylene/styrene rubbers grafted with maleic anhydride (MA) and a metallocene polyethylene (mPE) as toughening materials in binary and ternary blends with polypropylene and its nanocomposite as continuous phases was evaluated in terms of transmission electron microscopy (TEM), scanning electron microscopy (SEM), oscillatory shear flow and dynamic mechanical thermal analysis (DMA). The flexural modulus and heat distortion temperature values were determined as well. A metallocene polyethylene and a polyamide-6 were used as dispersed phases in these binary and ternary blends produced via melt blending in a corotating twin-screw extruder. Results showed that the compatibilized blends prepared without clay are tougher than those prepared with the nanocomposite of PP as the matrix phase and no significant changes in shear viscosity, melt elasticity, flexural or storage moduli and heat distortion temperature values were observed between them. However, the binary blend with a nanocomposite of PP as matrix and metallocene polyethylene phase exhibited better toughness, lower shear viscosity, flexural modulus, and heat distortion temperature values than that prepared with polyamide-6 as dispersed phase. These results are related to the degree of clay dispersion in the PP and to the type of morphology developed in the different blends.

[Preliminary results of the Spanish Society of Nephrology multicenter study of quality performance measures: hemodialysis outcomes can be improved]. / Resultados del proyecto de mejora de la calidad de la asistencia en hemodiálisis: estudio multicéntrico de indicadores de calidad de la Sociedad Española de Nefrología (SEN).

INTRODUCTION: The Spanish Society of Nephrology "Quality in Nephrology Working Group" (QNWG) was created in 2002. The aims of this group are the identification, diffusion, implementation and consolidation of a systematic, objective and comprehensive set of quality performance measures (QPMs) to help along the improvement of patient care and outcomes on hemodialysis, by means of strategies of feedback and benchmarking, and the design of quality improvement projects. The objective of this study is to present the preliminary results of a set of quality performance measures obtained in a group of Spanish hemodialysis centers, as well as to evaluate the repercussion of the application of the aforementioned thecniques on the observed results. METHODS: During 2007 a total of 28 hemodialysis units participated in the study; 2516 patients were evaluated. A specific software was designed and used to facilitate the calculation of CPMs in each unit. The clinical indicators used refered to dialysis adequacy; anemia; mineral metabolisme; nutrition; viral infections; vascular access; mortality, morbidity (number and days of hospital admissions); and renal transplant. Every three months each center received its own data and its comparison with the rest of the group. RESULTS: Except for hemoglobin levels we observed a global improvement. The percentage of centers reaching the stablished standards defined by the QNWG passed from 65% to 90,9% for Kt/V Daugirdas II (> 1,3 in > that 80% of the patients); from 71,4 % to 77,2 % for PTH (> 30 % of patients with serum PTH between 150 and 300 pg/ml); and from 42,8 % to 63,5 % for phosphate (> 75 % of patients with a serum phsphate < 5,5 mg/dl). More than 50% of centers showed an improvement in their final results as compared with their own initial results in all analyzed CPMs. Those centers that did not obtained an improvement in their results started the study with better percentages of acomplishment than those that showed a significant improvement in QPMs. (80,6+/-15,4 versus 71,8+/-16,6 respectively; p<0,001) CONCLUSIONS: We are starting to make progresses in our knowledge of clinical results in our hemodialysis units, although there is still a long way to go over. To monitor and share CPMs results within hemodialysis centers might help to improve their results as well as to reduce intecenters variability.

Scaling in the aggregation dynamics of a magnetorheological fluid.

We present experimental results on the aggregation dynamics of a magnetorheological fluid, namely, an aqueous suspension of micrometer-sized superparamagnetic particles, under the action of a constant uniaxial magnetic field using video microscopy and image analysis. We find a scaling behavior in several variables describing the aggregation kinetics. The data agree well with the Family-Vicsek scaling ansatz for diffusion-limited cluster-cluster aggregation. The kinetic exponents z and z' are obtained from the temporal evolution of the mean cluster size S(t) and the number of clusters N(t), respectively. The crossover exponent Delta is calculated in two ways: first, from the initial slope of the scaling function; second, from the evolution of the nonaggregated particles, n1(t). We report on results of Brownian two-dimensional dynamics simulations and compare the results with the experiments. Finally, we discuss the differences obtained between the kinetic exponents in terms of the variation in the crossover exponent and relate this behavior to the physical interpretation of the crossover exponent.

Pedestrian collective motion in competitive room evacuation.

When a sizable number of people evacuate a room, if the door is not large enough, an accumulation of pedestrians in front of the exit may take place. This is the cause of emerging collective phenomena where the density is believed to be the key variable determining the pedestrian dynamics. Here, we show that when sustained contact among the individuals exists, density is not enough to describe the evacuation, and propose that at least another variable -such as the kinetic stress- is required. We recorded evacuation drills with different degrees of competitiveness where the individuals are allowed to moderately push each other in their way out. We obtain the density, velocity and kinetic stress fields over time, showing that competitiveness strongly affects them and evidencing patterns which have been never observed in previous (low pressure) evacuation experiments. For the highest competitiveness scenario, we detect the development of sudden collective motions. These movements are related to a notable increase of the kinetic stress and a reduction of the velocity towards the door, but do not depend on the density.

Risk factors associated with sarcopenia in elderly persons in military Hospital Central de la Defensa «Gómez Ulla»

Antecedents and objectives: Sarcopenia is a syndrome characterized by the progressive and generalized decrease in skeletal muscle mass, strength and decreased physical performance. Associated factors are age, diet, sedentary lifestyle and chronic diseases. Very few studies have been conducted on the epidemiology of sarcopenia in hospitalized elderly. The objective of the study was to describe the prevalence of sarcopenia and identify the associated factors among elderly patients hospitalized in Madrid, Spain.Material y Methods:A cross-sectional study was conducted at the Hospital Central de la Defensa “Gómez Ulla” during the period from March to September 2018. 295 patients with ages greater than or equal to 65 participated. Sarcopenia was defined according to the EWGSOP2 criterion measuring muscle mass, muscle strength and functionality.Results:The prevalence of sarcopenia was 28.5% (95% CI 23.3-33.7), without significant differences between men and women. The Body Mass Index, hospital stay, alcohol consumption, smoke, physical activity, frequency of physical activity and strength of muscle mass, muscle strenght and funcionality presented an association with the sarcopenia.Conclusions:The prevalence was higher than other studies. The body mass index was significantly higher in subjects with sarcopenia. A higher proportion of smoking was found in subjects without sarcopenia. Likewise, an association was found between physical exercise and a lower prevalence of sarcopenia. (AU)

Antecedentes y objetivos: La sarcopenia es un síndrome caracterizado por la disminución progresiva y generalizada de la masa muscular esquelética, la fuerza y ​​la disminución del rendimiento físico. Los factores asociados son la edad, la dieta, el sedentarismo y las enfermedades crónicas. Se han realizado muy pocos estudios sobre la epidemiología de la sarcopenia en ancianos hospitalizados. El objetivo del estudio fue describir la prevalencia de sarcopenia e identificar los factores asociados entre pacientes ancianos hospitalizados en Madrid, España.Material y Métodos:Se realizó un estudio transversal en el Hospital Central de la Defensa «Gómez Ulla» durante el periodo de marzo a septiembre de 2018. Participaron 295 pacientes con edades mayores o iguales a 65 años. La sarcopenia se definió según el criterio EWGSOP2 que mide la masa muscular, la fuerza muscular y la funcionalidad.Resultados:La prevalencia de sarcopenia fue del 28,5 % (IC 95 % 23,3-33,7), sin diferencias significativas entre hombres y mujeres. El índice de masa corporal, estancia hospitalaria, consumo de alcohol, tabaquismo, actividad física, frecuencia de actividad física y fuerza de masa muscular, fuerza muscular y funcionalidad presentaron asociación con sarcopenia.Conclusiones:La prevalencia fue superior a otros estudios. El índice de masa corporal fue significativamente mayor en sujetos con sarcopenia. Se encontró una mayor proporción de fumadores en sujetos sin sarcopenia. Asimismo, se encontró asociación entre el ejercicio físico y una menor prevalencia de sarcopenia. (AU)

Jamming during the discharge of granular matter from a silo.

In this work, we present an experimental study of the jamming that stops the free flow of grains from a silo discharging by gravity. When the outlet size is not much bigger than the beads, granular material jams the outlet of the container due to the formation of an arch. Statistical data from the number of grains fallen between consecutive jams are presented. The information that they provide can help one to understand the jamming phenomenon. As the ratio between the size of the orifice and the size of the beads is increased, the probability that an arch blocks the outlet decreases. We show here that there is a power-law divergence of the mean avalanche size for a finite critical radius. Beyond this critical radius, no jamming can occur and the flow is never stopped. The dependence of the arch formation on the shape and the material of the grains has been explored. It has been found that the material properties of the grains do not affect the arch formation probability. On the contrary, the shape of the grains deeply influences it. A simple model to interpret the results is also discussed.

Impact of HLA antibodies on transplant glomerulopathy.

The influence of humoral rejection on the development of chronic allograft nephropathy (CAN) is controversial, especially in relation to transplant glomerulopathy. The aim of our study was to analyse the influence of anti-HLA antibodies on the development of transplant glomerulopathy (cg0, cg1, cg2, and cg3; Banff'97). We selected all renal transplants patients from 1975 to 2003 who had a functioning graft for at least 6 months and a clinically indicated graft biopsy with CAN and chronic glomerular changes (case group). We studied the presence of anti-HLA antibodies (Ab) in the last serum taken while the graft was functioning and divided them into three groups according to the severity of glomerular lesions. We also selected 52 contemporary and comparable cases without transplant glomerulopathy (control group). A total of 77 case had transplant glomerulopathy: 39 cg1, 29 cg2, and 9 cg3. Pretransplant Ab titers and number of previous blood transfusions were higher among the subgroup with the most severe glomerulopathy. Patients who developed posttransplant anti-HLA Ab more frequently showed transplant glomerulopathy. Serum creatinine and proteinuria were higher among cases with chronic glomerulopathy, and more grafts were lost in that group. Thus, the presence of HLA-Ab is a key factor in the development of transplant glomerulopathy and chronic allograft rejection.

Flow and clogging of a sheep herd passing through a bottleneck.

We present an experimental study of a flock passing through a narrow door. Video monitoring of daily routines in a farm has enabled us to collect a sizable amount of data. By measuring the time lapse between the passage of consecutive animals, some features of the flow regime can be assessed. A quantitative definition of clogging is demonstrated based on the passage time statistics. These display broad tails, which can be fitted by power laws with a relatively large exponent. On the other hand, the distribution of burst sizes robustly evidences exponential behavior. Finally, borrowing concepts from granular physics and statistical mechanics, we evaluate the effect of increasing the door size and the performance of an obstacle placed in front of it. The success of these techniques opens new possibilities regarding their eventual extension to the management of human crowds.

Differences in anti-CREG antibody formation between transplanted and nontransplanted renal patients.

BACKGROUND: The aim of this study was investigation of the HLA-I cross-reactive group (CREG)-specific antibodies (Abs) in sera from patients with a failed renal transplant and from nontransplanted patients. METHODS: A total of 5292 sera from 570 patients awaiting kidney transplantation were screened for the presence of HLA-I CREG-specific Abs. Patients who had never received a transplant (group A), and those with a previous transplant and Abs either not related (group B) or related to donor specificities (group C) were studied. A further division was made for Abs directed against specificities either included in (intra-CREG) or not included in patients' HLA-CREG (extra-CREG). RESULTS: Twelve of 24 (50%) Abs produced in response to mismatched donor HLA specificities after a failed graft were intra-CREG Abs, compared to 7 of 39 (18%) Abs that were not transplant-related. CONCLUSIONS: Renal grafts showed a stronger immunogenicity than other sources of allosensitization. Our data also suggest that CREG matching may not be useful for renal allocation.

Association of leukemia and pregnancy: clinical and obstetric aspects.

The association of leukemia and pregnancy is not common. We have analyzed the hematologic and obstetric problems occurring in 10 pregnant leukemic patients, 7 with acute leukemia and 3 with chronic myeloid leukemia. One patient died in the fifth month of pregnancy with a nonviable fetus. There was one premature twin birth with both fetuses dead. The other fetuses were viable, although there was one premature birth and three fetuses had below-normal birth weights. No bleeding complications were observed during delivery. Three patients had infections during puerperium. This article discusses the possible influences and relations between leukemia and pregnancy, based on our observations and on data in the literature.

25 Hz electromagnetic field exposure has no effect on cell cycle distribution and apoptosis in U-937 and HCA-2/1cch cells.

It is reported that exposure to 50 Hz extremely low-frequency electromagnetic field (ELF-EMF) can produce apoptosis and small variations in cell cycle distribution on different cell lines. In order to study the effect of ELF-EMF on tumoral cells in vitro, two cell lines (U-937, from a histiocytic lymphoma, and HCA-2/1cch, from a human colon adenocarcinoma) were exposed to 25 Hz, 1.5 mT, for 2 h and 45 min. Cell cycle distribution, apoptosis (spontaneous and dexamethasone-induced) and cell growth were evaluated. Neither significant alteration in cell cycle phases nor induction of apoptosis was observed. Nevertheless, the relative cell number was found to decrease to 55.84+/-7.35% (p <0.05, Student's t-test) for HCA-2/1cch cells after exposure to EMF in the presence of dexamethasone. The presence of dexamethasone during the EMF exposure could probably produce a decrease in the cell growth of this cell line.

[Prevention of acute graft versus host disease using 3 prophylactic schemes]. / Prevención de la enfermedad injerto contra huésped aguda con tres esquemas profilácticos diferentes.

During 7 years 81 patients received an allogeneic bone marrow transplant (BMT) for several diseases. The prevention of graft-versus-host disease (GVHD) was undertaken with methotrexate (MTX), MTX plus antilymphocytic gammaglobulin plus prednisone (MTX + ALT + P), and elimination of the T-lymphocytes of the donor's bone marrow with the monoclonal antibody CAMPATH-1. The actuarial survival of the patients who did not develop GVHD was significantly better than that of those who developed grade II-IV GVHD: 56% [95% confidence interval (CI) 39-71%] versus 10% (95% CI 3-25%) (p less than 0.0001). However, actuarial survival was similar in each of the three groups: MTX 35%, MTX + ALT + P 38%, and CAMPATH-1 43%. The incidence of GVH disease, when the sex of the donor and the receptor were different, was significantly higher than in cases where the donor and the receptor had the same sex: 45% (95% CI 31-58%) vs 15% (95% CI 8-28%) (p less than 0.005). By contrast, significant differences were not found between the three groups in the incidence of GVHD: MTX 36%, MTX + ALT + P 34%, and CAMPATH-1 20%. In patients with leukemia, a higher number of relapses occurred in the MTX group, because a higher number of patients in second or third complete remission (CR) or with active disease underwent transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)

[Spleno-gonadal fusion: a clinical case]. / Fusión espleno-gonadal: caso clínico.

The presence of splenic tissue in the scrotum, creating a spleno-gonadal fusion, is a very rare condition within benign intra-scrotal tumours. Accidental discovery in a 68 year-old male following histopathological study allows us to make a few considerations and review the literature.

[Cefotaxime treatment of osteomyelitis of the foot in the diabetic]. / Cefotaxima en el tratamiento de las osteomielitis en el pie del diabético.

Osteomyelitis at the base of an ulcer the foot of diabetic patient is a serious complication usually produced because of the patient's neglect, and entailing difficulties in diagnosis and treatment. Several factors (neurological and vascular ...) favor the onset of the initial ulcer and its evolution, the ulcer subsequently converting into the main door for soft tissue infection with extension to the contiguous bone, with a bad prognosis. Cefotaxime is a 3rd generation cephalosporin, active against coccus gram positive and the majority of aerobic gram negative bacillus. This antibiotic was used in 25 diabetic patients with osteomyelitis at a dosage of 2 gr. IV a/d, during at least 30 days, adding metronidazole when anaerobic bacteria were isolated. The number of patients cured were 21 (84%), one improvement (4%), one resistant (4%) and two relapses (8%). There were no secondary effects.

[Rheumatic diseases. A three-year retrospective study at an internal medicine service]. / Doenças reumáticas. Estudo retrospectivo de três anos num serviço de medicina interna.

In order to assess the weight of Rheumatic Diseases, the Authors retrospectively studied 117 patients admitted to the Internal Medicine Service of the Faro District Hospital over a 3 year period (1989-1991). The selection criterion comprised the final rheumatological diagnosis. The diseases were arranged in nosological groups according to the Classification of Rheumatic Diseases of the American Rheumatism Association. The relative frequency, in totality and by nosological groups, and other variables, were determined. The relative frequency was of 4.2%. The mean age was 52.9 years. The distribution in age groups showed 2 peaks in the sixth and seventh decades. Females were more often affected (61%). The mean time of internment was 22.3 days. The proportional mortality reached 6.8%. Diffuse Connective Tissue Diseases were the most frequently found (42.7%) and among these Rheumatoid Arthritis and Systemic Lupus Erythematous were the most prevailing.