Swirling Fluid Reduces the Bounce of Partially Filled Containers.

Certain spatial distributions of water inside partially filled containers can significantly reduce the bounce of the container. In experiments with containers filled to a volume fraction ϕ, we show that rotation offers control and high efficiency in setting such distributions and, consequently, in altering bounce markedly. High-speed imaging evidences the physics of the phenomenon and reveals a rich sequence of fluid-dynamics processes, which we translate into a model that captures our overall experimental findings.

Stability of a tilted granular monolayer: How many spheres can we pick before the collapse?

The triggering of avalanches is investigated using discrete element simulations for a process of random extraction of spheres. A monolayer, formed by identical spheres in a hexagonal configuration, is placed on a tilted plane surrounded by a small fence that sustains the spheres, mimicking the disposal of fruits in the market. Then, a random continuous extraction process of spheres is imposed until the collapse. For this simple numerical experiment, a phase diagram was obtained to visualize the occurrence of avalanches triggered by vacancies as a function of the tilting angle, system size, and friction coefficient. More importantly, a subzone was found where we can predict the critical number of extractions until the avalanche takes place. The prediction is made from an evolution model of the average coordination number based on statistical considerations. The theoretical prediction also gives a constant critical void fraction of spheres, which implies the system collapses at a critical packing fraction.

The effect of correlation and false negatives in pool testing strategies for COVID-19.

During the current COVID-19 pandemic, active testing has risen as a key component of many response strategies around the globe. Such strategies have a common denominator: the limited availability of diagnostic tests. In this context, pool testing strategies have emerged as a means to increase testing capacity. The efficiency gains obtained by using pool testing, derived from testing combined samples simultaneously, vary according to the spread of the SARS-CoV-2 virus in the population being tested. Motivated by the need for testing closed populations, such as long-term care facilities (LTCFs), where significant correlation in infections is expected, we develop a probabilistic model for settings where the test results are correlated, which we use to compute optimal pool sizes in the context of two-stage pool testing schemes. The proposed model incorporates the specificity and sensitivity of the test, which makes it possible to study the impact of these measures on both the expected number of tests required for diagnosing a population and the expected number and variance of false negatives. We use our experience implementing pool testing in LTCFs managed by SENAMA (Chile's National Service for the Elderly) to develop a simulation model of contagion dynamics inside LTCFs, which incorporates testing and quarantine policies implemented by SENAMA. We use this simulation to estimate the correlation of test results among collected samples when following SENAMA's testing guidelines. Our results show that correlation estimates are high in settings representative of LTCFs, which validates the use of the proposed model for incorporating correlation in determining optimal pool sizes for pool testing strategies. Generally, our results show that settings in which pool testing achieves efficiency gains, relative to individual testing, are likely to be found in practice. Moreover, the results show that incorporating correlation in the analysis of pool testing strategies both improves the expected efficiency and broadens the settings in which the technique is preferred over individual testing.

Triggering avalanches by transverse perturbations in a rotating drum.

We study the role of small-scale perturbations in the onset of avalanches in a rotating drum in the stick-slip regime. By vibrating the system along the axis of rotation with an amplitude orders of magnitude smaller than the particles' diameter, we found that the order parameter that properly describes the system is the kinetic energy. We also show that, for high enough frequencies, the onset of the avalanche is determined by the amplitude of the oscillation, contrary to previous studies that showed that either acceleration or velocity was the governing parameter. Finally, we present a theoretical model that explains the transition between the continuous and discrete avalanche regimes as a supercritical Hopf bifurcation.

Effect of added porosity on a novel porous Ti-Nb-Ta-Fe-Mn alloy exposed to simulated body fluid.

Porous titanium materials have gained interest as prosthesis materials due to their similar mechanical properties to the human bone, biocompatibility, and high corrosion resistance. The presence of pores in the metal matrix implies a decrease in the elastic modulus and an increase in the active area, perhaps improving the osseointegration. Corrosion resistance is a critical consideration as corrosion may lead not only to mechanical failure but also the release of ions and/or particles to the bloodstream. In this work, a novel Ti-Nb-Ta-Fe-Mn alloy with varying percentage of porosity (25, 31 and 37 v/v%) was exposed to simulated body fluid (SBF) at 37 °C and its corrosion resistance was investigated using electrochemical techniques and surface analysis as a function of exposure time. Open circuit potential and polarization curves revealed that the effect of porosity was mainly on the shift of the corrosion potential to more negative values with a slight increase in the anodic current. A passive range was also observed, which was not influenced either by increased exposure time or increased porosity. Therefore, a change in the surface specific area could have taken place during the exposure, which is not necessarily related to a corrosion process. Moreover, a typical porous electrode behavior was identified by electrochemical Impedance spectroscopy, without any significant change over time. No release of metal ions was detected by on line ICP-AES, either at the open circuit potential or upon polarizing the samples up to 2 V vs. SCE, whereas only traces elements (Fe and Mn 1 nmol/s cm2) were detected in the electrolyte accumulating all released ions during 30 days of exposure. Additionally, the surface analysis showed thickening of the oxide layer with exposure time. Therefore, the stability of the passive layer and low release of ions indicate that the porous alloys are suitable for further study as prosthesis materials.

Duplicación intestinal en la primera porción del duodeno en neonato / Intestinal Duplication in the First Portion of the Neonatal Duodenum

RESUMEN Se denomina duplicación intestinal a un grupo de malformaciones congénitas de la vía digestiva, de estructuras diverticulares, quísticas o tubulares, que presentan paredes de músculo liso como las del intestino y un revestimiento mucoso de tipo gastrointestinal. Se localiza en cualquier segmento del tubo digestivo, desde la boca hasta el ano. La zona más afectada es el íleon y constituye la causa más frecuente de masa abdominal en el periodo neonatal. El diagnóstico puede ser prenatal a través, de ecografía o resonancia. En el periodo posnatal es la clínica la que establece los indicios para realizar exámenes complementarios, que pueden ir desde ecografía hasta estudios con Tecnecio 99. En la porción duodenal esta enfermedad representa el 5 por ciento de todas las duplicaciones intestinales. La descripción de casos en la primera porción es excepcional, por lo que la consideramos para tener en cuenta como diagnóstico diferencial en las enfermedades tumorales neonatales de origen abdominal(AU)

ABSTRACT Intestinal duplication defines a group of congenital malformations of the digestive tract, of diverticular, cystic or tubular structures, which have smooth muscle walls such as those of the intestine and a gastrointestinal-type mucous lining. It is located in any segment of the digestive tract, from the mouth to the anus. The most affected area is the ileum, while the condition constitutes the most frequent cause of abdominal mass in the neonatal period. The diagnosis can be prenatal through either ultrasound or resonance. In the postnatal period, the clinical indications establish, based on the signs, whether complementary tests are required, which can range from ultrasound to studies with technetium-99. In the duodenal portion, this disease represents 5 percent of all intestinal duplications. The description of cases in the first portion is exceptional, which is the reason why we consider it as a differential diagnosis in neonatal tumor diseases of abdominal origin(AU)

Tumores Benignos de Ovario en la edad Pediátrica y Adolescencia / Benign Ovarian Tumors in Pediatric and Adolescence

Introducción: Los tumores ováricos son raros en la edad pediátrica y representan del 1 al 5% de los tumores infantiles. El objetivo del presente trabajo es conocer cuáles son los tumores de ovario más frecuentes en nuestro medio en niñas y adolescentes en un centro oncológico de la ciudad de Guayaquil-Ecuador. Métodos: El presente estudio es descriptivo y retrospectivo, en la que se realiza una revisión de registros de niñas y adolescentes con diagnóstico de tumores de ovario, en el Instituto Oncológico Nacional "Dr. Juan Tanca Marengo" en el período de enero 2015 a mayo del 2017. Las variables registradas fueron edad, diagnóstico ecográfico, diagnostico histopatológico, ovario afecto, características clínicas, salpingectomía, marcadores tumorales. Se utiliza estadística descriptiva. Resultados: Ingresaron al estudio 32 pacientes de 12.7 años promedio. El ovario más afectado fue el derecho con una relación 2.2: 1 y en 9 % fue bilateral. La histología reportada de los quistes serosos fueron el 21 % quiste folicular y 18.5 % por quiste lúteo. Los quistes simples representaron el 15.25 %, el cistoadenoma y el teratoma maduro con un 9 %, el quiste dermoide y le endometrioma con un 3 %. El dolor fue el síntoma más llamativo estado como síntoma único en 65.5 %. El 18.75 % terminó en anexectomía con ooforectomía por extensión del quiste, el 81.25 % solo requirió quistectomía. Conclusión: La histología reportada en esta serie de tumores benignos de ovario, los quistes serosos foliculares fueron los más prevalentes, seguidos de los quistes lúteos. El dolor pélvico fue el síntoma más llamativo. La mayoría de los casos requirieron quistectomía y el 19 % requirió adicionalmente ooforectomía.

Introduction: Ovarian tumors are rare in pediatric age and represent 1 to 5% of childhood tumors. The objective of this work is to know which are the most frequent ovarian tumors in our environment in girls and adolescents in an oncological center of the city of Guayaquil-Ecuador. Methods: The present study is descriptive and retrospective, in which a review of records of girls and adolescents diagnosed with ovarian tumors is performed, at the National Oncology Institute "Dr. Juan Tanca Marengo" in the period from January 2015 to May 2017. The variables recorded were age, ultrasound diagnosis, histopathological diagnosis, affected ovary, clinical characteristics, salpingectomy, tumor markers. Descriptive statistics are used. Results: 32 patients with an average age of 12.7 entered the study. The most affected ovary was the right one with a 2.2: 1 ratio and in 9% it was bilateral. The reported histology of serous cysts were 21% follicular cyst and 18.5% by luteal cyst. Simple cysts accounted for 15.25%, cystadenoma and mature teratoma with 9%, dermoid cyst and endometrioma with 3%. Pain was the most striking condition as a single symptom in 65.5%. 18.75% ended up in anexectomy with oophorectomy due to cyst extension, 81.25% only required a cystectomy. Conclusion: The histology reported in this series of benign ovarian tumors, follicular serous cysts were the most prevalent, followed by luteal cysts. Pelvic pain was the most striking symptom. The majority of cases required a cystectomy and 19% additionally required oophorectomy.

Linear Versus Nonlinear Acoustic Probing of Plasticity in Metals: A Quantitative Assessment.

The relative dislocation density of aluminum and copper samples is quantitatively measured using linear Resonant Ultrasound Spectroscopy (RUS). For each metallic group, four samples were prepared with different thermomechanical treatments in order to induce changes in their dislocation densities. The RUS results are compared with Nonlinear Resonant Ultrasound Spectroscopy (NRUS) as well as Second Harmonic Generation (SHG) measurements. NRUS has a higher sensitivity by a factor of two to six and SHG by 14⁻62%. The latter technique is, however, faster and simpler. As a main result, we obtain a quantitative relation between the changes in the nonlinear parameters and the dislocation density variations, which in a first approximation is a linear relation between these differences. We also present a simple theoretical expression that explains the better sensitivity to dislocation content of the nonlinear parameters with respect to the linear ones. X-Ray diffraction measurements, although intrusive and less accurate, support the acoustics results.

[Angiographic evaluation of high-risk treadmill scores in patients with unstable angina according to sex, age, or use of drugs with a negative chronotropic effect]. / Comparación angiográfica de los criterios e índices de alto riesgo para ergometría convencional en pacientes diagnosticados de angina inestable en función del sexo, la edad o el uso de fármacos bradicardizantes.

INTRODUCTION AND OBJECTIVES: The aim of the study is to determine whether age, sex, or the use of drugs with a negative chronotropic effect modifies the sensitivity, specificity, positive or negative predictive value, or positive or negative likelihood ratio of the high-risk criteria used in exercise testing as defined by the Spanish Society of Cardiology (SEC) and the American College of Cardiology/American Heart Association (ACC/AHA), the Duke treadmill score, the Veterans Affairs and West Virginia prognostic score, or the ST/Heart Rate Index at the time when left main coronary artery disease, three-vessel disease or two-vessel disease involving the proximal left anterior descending artery is detected by coronary angiography. METHODS: The study included a cohort of 469 consecutive patients aged 75 years who were admitted to hospital for unstable angina. All patients underwent exercise stress testing and coronary angiography. RESULTS: In all situations, the ACC/AHA high-risk criteria had the highest sensitivity, negative predictive value, and negative likelihood ratio, and the Duke Treadmill Score had the highest specificity and positive predictive value. The diagnostic accuracy of the other treadmill scores was affected by sex, age or the use of drugs with a negative chronotropic effect. CONCLUSIONS: The ACC/AHA high-risk criteria and Duke Treadmill Score provided useful additional information during the assessment of ST-segment depression. These measures could help improve the diagnostic accuracy of conventional ECG exercise testing in women, older individuals, and patients taking beta-blockers or non-dihydropyridine calcium antagonists.

Comparación angiográfica de los criterios e índices de alto riesgo para ergometría convencional en pacientes diagnosticados de angina inestable en función del sexo, la edad o el uso de fármacos bradicardizantes / Angiographic evaluation of high-risk treadmill scores in patients with unstable angina according to sex, age, or use of drugs with a negative chronotropic effect

Introducción y objetivos. El objetivo del estudio es evaluar si la edad, el sexo o la toma de fármacos bradicardizantes modifican la sensibilidad, la especificidad, el valor predictivo positivo y negativo y la razón de verosimilitud positiva y negativa del descenso del segmento ST, de los criterios de alto riesgo para ergometría convencional de la Sociedad Española de Cardiología (SEC) y del American College of Cardiology/American Heart Association (ACC/AHA), del índice de Duke, del índice pronóstico del Veterans Affairs y de West Virginia y del índice segmento ST/frecuencia cardiaca a la hora de detectar en la coronariografía: enfermedad del tronco común izquierdo, de 3 vasos o de 2 vasos con afección de la arteria descendente anterior proximal. Métodos. Se estudió a 469 pacientes con una edad ≤ 75 años, que ingresaron consecutivamente con el diagnóstico de angina inestable primaria, a los que se les practicó ergometría convencional pronóstica y cateterismo cardiaco. Resultados. Los criterios del ACC/AHA ofrecieron la mayor sensibilidad, valor predictivo negativo y razón de verosimilitud negativa en todos los casos. El índice de Duke presentó una mejor especificidad y valor predictivo positivo en todas las situaciones. El resto de escalas de riesgo vio afectado su rendimiento diagnóstico por el sexo, la edad o la toma de fármacos bradicardizantes. Conclusiones. Los criterios del ACC/AHA y el índice de Duke añadieron información relevante a la valoración aislada del descenso del segmento ST. Estas escalas podrían ser una herramienta útil a la hora de mejorar la rentabilidad diagnóstica de la prueba de esfuerzo convencional en mujeres, personas de más edad y pacientes con tratamiento con bloqueadores beta o antagonistas del cacio tipo no dihidropiridina (AU)

Introduction and objectives. The aim of the study is to determine whether age, sex, or the use of drugs with a negative chronotropic effect modifies the sensitivity, specificity, positive or negative predictive value, or positive or negative likelihood ratio of the high-risk criteria used in exercise testing as defined by the Spanish Society of Cardiology (SEC) and the American College of Cardiology/American Heart Association (ACC/AHA), the Duke treadmill score, the Veterans Affairs and West Virginia prognostic score, or the ST/Heart Rate Index at the time when left main coronary artery disease, three-vessel disease or two-vessel disease involving the proximal left anterior descending artery is detected by coronary angiography. Methods. The study included a cohort of 469 consecutive patients aged › 75 years who were admitted to hospital for unstable angina. All patients underwent exercise stress testing and coronary angiography. Results. In all situations, the ACC/AHA high-risk criteria had the highest sensitivity, negative predictive value, and negative likelihood ratio, and the Duke Treadmill Score had the highest specificity and positive predictive value. The diagnostic accuracy of the other treadmill scores was affected by sex, age or the use of drugs with a negative chronotropic effect. Conclusions. The ACC/AHA high-risk criteria and Duke Treadmill Score provided useful additional information during the assessment of ST-segment depression. These measures could help improve the diagnostic accuracy of conventional ECG exercise testing in women, older individuals, and patients taking beta-blockers or non-dihydropyridine calcium antagonists (AU)

A multicenter, randomized, masked, comparison trial of lucinactant, colfosceril palmitate, and beractant for the prevention of respiratory distress syndrome among very preterm infants.

BACKGROUND AND OBJECTIVE: Evidence suggests that synthetic surfactants consisting solely of phospholipids can be improved through the addition of peptides, such as sinapultide, that mimic the action of human surfactant protein-B (SP-B). A synthetic surfactant containing a mimic of SP-B may also reduce the potential risks associated with the use of animal-derived products. Our objective was to compare the efficacy and safety of a novel synthetic surfactant containing a functional SP-B mimic (lucinactant; Discovery Laboratories, Doylestown, PA) with those of a non-protein-containing synthetic surfactant (colfosceril palmitate; GlaxoSmithKline, Brentford, United Kingdom) and a bovine-derived surfactant (beractant; Abbott Laboratories, Abbott Park, IL) in the prevention of neonatal respiratory distress syndrome (RDS) and RDS-related death. METHODS: We assigned randomly (double-masked) 1294 very preterm infants, weighing 600 to 1250 g and of < or =32 weeks gestational age, to receive colfosceril palmitate (n = 509), lucinactant (n = 527), or beractant (n = 258) within 20 to 30 minutes after birth. Primary outcome measures were the rates of RDS at 24 hours and the rates of death related to RDS during the first 14 days after birth. All-cause mortality rates, bronchopulmonary dysplasia (BPD) rates, and rates of other complications of prematurity were prespecified secondary outcomes. Primary outcomes, air leaks, and causes of death were assigned by an independent, masked, adjudication committee with prespecified definitions. The study was monitored by an independent data safety monitoring board. RESULTS: Lucinactant reduced significantly the incidence of RDS at 24 hours, compared with colfosceril (39.1% vs 47.2%; odds ratio [OR]: 0.68; 95% confidence interval [CI]: 0.52-0.89). There was no significant difference in comparison with beractant (33.3%). However, lucinactant reduced significantly RDS-related mortality rates by 14 days of life, compared with both colfosceril (4.7% vs 9.4%; OR: 0.43; 95% CI: 0.25-0.73) and beractant (10.5%; OR: 0.35; 95% CI: 0.18-0.66). In addition, BPD at 36 weeks postmenstrual age was significantly less common with lucinactant than with colfosceril (40.2% vs 45.0%; OR: 0.75; 95% CI: 0.56-0.99), and the all-cause mortality rate at 36 weeks postmenstrual age was lower with lucinactant than with beractant (21% vs 26%; OR: 0.67; 95% CI: 0.45-1.00). CONCLUSIONS: Lucinactant is a more effective surfactant preparation than colfosceril palmitate for the prevention of RDS. In addition, lucinactant reduces the incidence of BPD, compared with colfosceril palmitate, and decreases RDS-related mortality rates, compared with beractant. Therefore, we conclude that lucinactant, the first of a new class of surfactants containing a functional protein analog of SP-B, is an effective therapeutic option for preterm infants at risk for RDS.

Myasthenia gravis and pregnancy: clinical implications and neonatal outcome.

BACKGROUND: The myasthenia gravis is twice as common in women as in men and frequently affects young women in the second and third decades of life, overlapping with the childbearing years. Generally, during pregnancy in one third of patients the disease exacerbates, whereas in two thirds it remains clinically unchanged. Complete remission can occur in some patients. METHODS: To describe the clinical course, delivery and neonatal outcome of 18 pregnant women with the diagnosis of myasthenia gravis. Retrospective chart review of pregnant patients with myasthenia gravis, followed at the National Institute of Perinatology in Mexico City over an 8-year period. Data was abstracted from the medical records on the clinical course during pregnancy, delivery and neonatal outcome. RESULTS: From January 1, 1996 to December 31, 2003 18 patients with myasthenia gravis were identified and included in the study. The mean +/- SD maternal age was 27.4 +/- 4.0 years. During pregnancy 2 women (11%) had an improvement in the clinical symptoms of myasthenia gravis, 7 women (39%) had clinical worsening of the condition of 9 other patients (50%) remained clinically unchanged. Nine patients delivered vaginally, 8 delivered by cesarean section and 1 pregnancy ended in fetal loss. Seventeen infants were born at mean +/- SD gestational age of 37.5 +/- 3.0 weeks and a mean birth weight of 2710 +/- 73 g. Only one infant presented with transient neonatal myasthenia gravis. No congenital anomalies were identified in any of the newborns. CONCLUSIONS: The clinical course of myasthenia gravis during pregnancy is variable, with a significant proportion of patients experiencing worsening of the clinical symptoms. However, neonatal transient myasthenia was uncommon in our patient population.

[Testicular necrosis caused by Fournier's gangrene: an exceptional case]. / Necrosis testicular por gangrena de Fournier: un caso excepcional.

OBJECTIVE: To report an uncommon case of Fournier's gangrene caused by a perforated retrocecal acute appendicitis that compromised the scrotum and testis. METHODS: Herein we describe a patient that was admitted for abdominal pain localized to the right lower flank and generalized virulent sepsis. RESULTS: Resection of the right inguinal cord and testis was performed. The outcome was poor and the patient died of multiorgan failure. CONCLUSIONS: Fournier's gangrene basically arises from anorectal and urological pathologies, although occasionally it may arise from an intraabdominal source, which should be ruled out especially when the abdominal examination shows interesting findings.