Low-velocity collisions of centimeter-sized dust aggregates

Collisions between centimeter- to decimeter-sized dusty bodies are important to understand the mechanisms leading to the formation of planetesimals. We thus performed laboratory experiments to study the collisional behavior of dust aggregates in this size range at velocities below and around the fragmentation threshold. We developed two independent experimental setups with the same goal to study the effects of bouncing, fragmentation, and mass transfer in free particle-particle collisions. The first setup is an evacuated drop tower with a free-fall height of 1.5 m, providing us with 0.56 s of microgravity time so that we observed collisions with velocities between 8 mm/s and 2 m/s. The second setup is designed to study the effect of partial fragmentation (when only one of the two aggregates is destroyed) and mass transfer in more detail. It allows for the measurement of the accretion efficiency as the samples are safely recovered after the encounter. Our results are that for very low velocities we found bouncing as could be expected while the fragmentation velocity of 20 cm/s was significantly lower than expected. We present the critical energy for disruptive collisions Q*, which showed up to be at least two orders of magnitude lower than previous experiments in the literature. In the wide range between bouncing and disruptive collisions, only one of the samples fragmented in the encounter while the other gained mass. The accretion efficiency in the order of a few percent of the particle's mass is depending on the impact velocity and the sample porosity. Our results will have consequences for dust evolution models in protoplanetary disks as well as for the strength of large, porous planetesimal bodies

Neonatal-onset multisystem inflammatory disease responsive to interleukin-1 beta inhibition

BACKGROUND:Neonatal-onset multisystem inflammatory disease is characterized by fever, urticarial rash, aseptic meningitis, deforming arthropathy, hearing loss, and mental retardation. Many patients have mutations in the cold-induced autoinflammatory syndrome 1 (CIAS1) gene, encoding cryopyrin, a protein that regulates inflammation.METHODS:We selected 18 patients with neonatal-onset multisystem inflammatory disease (12 with identifiable CIAS1 mutations) to receive anakinra, an interleukin-1-receptor antagonist (1 to 2 mg per kilogram of body weight per day subcutaneously). In 11 patients, anakinra was withdrawn at three months until a flare occurred. The primary end points included changes in scores in a daily diary of symptoms, serum levels of amyloid A and C-reactive protein, and the erythrocyte sedimentation rate from baseline to month 3 and from month 3 until a disease flare.RESULTS:All 18 patients had a rapid response to anakinra, with disappearance of rash. Diary scores improved (P<0.001) and serum amyloid A (from a median of 174 mg to 8 mg per liter), C-reactive protein (from a median of 5.29 mg to 0.34 mg per deciliter), and the erythrocyte sedimentation rate decreased at month 3 (all P<0.001), and remained low at month 6. Magnetic resonance imaging showed improvement in cochlear and leptomeningeal lesions as compared with baseline. Withdrawal of anakinra uniformly resulted in relapse within days; retreatment led to rapid improvement. There were no drug-related serious adverse events.CONCLUSIONS:Daily injections of anakinra markedly improved clinical and laboratory manifestations in patients with neonatal-onset multisystem inflammatory disease, with or without CIAS1 mutations

Uma visão de alunos universitários sobre a relação de seus pais como casal

En una relación de pareja, sus integrantes comparten expectativas relacionadas con lo que vivieron y aprendieron en su familia de origen, de manera que la nueva familia reflejará patrones que los hijos reproducirán en un futuro. Si los hijos perciben relaciones de pareja adecuadas, retomarán estas mismas relaciones en la formación de su nueva familia; sin embargo, cuando esta relación se ve afectada por la separación, es probable que existan diferencias importantes en la percepción de los hijos. El objetivo del presente artículo fue analizar la percepción de universitarios respecto a la relación de sus padres como pareja dentro de la dinámica familiar, tomando en cuenta si sus padres vivían juntos o separados. Se utilizó una muestra intencional compuesta por 566 alumnos universitarios, de los cuales 345 eran mujeres y 221, hombres. Se aplicó el cuestionario Dinámica de la Familia Nuclear Mexicana de Vásquez et al. (2003), aunque solo se abordó el área "Los padres. Su dinámica cómo pareja". La diferencia estadística entre grupos se obtuvo a través de la prueba U de Mann-Whitney. Los resultados mostraron diferencias estadísticamente significativas entre la percepción de los universitarios con respecto a sus padres cuando viven juntos o cuando viven separados. Se concluyó que existen diferentes factores que afectan el funcionamiento de la dinámica familiar, los cuales influyen de manera diferencial en la percepción que puede tener cada miembro de la familia.When a couple starts a new family, both members share expectations based on what they have learned from their experience in their respective families of origin, in such a way that their offspring will repeat the same patterns in the future. If children perceive a healthy appropriate relationship between their parents, chances are that they too will have a good relationship when they start their own families. However, children will have a different perception when their parents go through a separation or divorce. Based on these facts, the aim of this article was to analyze university students' perception regarding their parents' relationship as a couple within their family environment, taking into consideration whether their parents lived together or separately. A target group comprised of 566 university students of which 345 were women and 221 were men participated in the study. The instrument used was the measurement questionnaire "Dinámica de la Familia Nuclear Mexicana" [The Mexican Family Dynamics] (Vásquez, et al., 2003). In this study the only area addressed was "Parents and their relationship as a couple". The statistical difference between groups was obtained using the Mann-Whitney U test. The results showed significant statistical differences between university students' perception of their parents depending on whether they live together or separately. A conclusion was reached on the existence of different factors that affect the family environment, which has a differential influence on each family member's perception.Em uma relação de casal, seus integrantes compartilham expectativas relacionadas com o que viveram e aprenderam em sua família de origem, de forma que a nova família refletirá padrões que os filhos reproduzirão no futuro. Se os filhos percebem relações de casal adequadas, retomarão essas mesmas relações na formação da sua nova família; no entanto, quando essa relação se vê afetada pela separação, é provável que existam diferenças importantes na percepção dos filhos. O objetivo do presente artigo foi analisar a percepção de universitários com respeito à relação de seus pais como casal dentro da dinâmica familiar, levando em consideração se seus pais viviam juntos ou separados. Utilizou-se uma amostra intencional composta por 566 alunos universitários, dos quais 345 eram mulheres e 221, homens. Aplicou-se o questionário Dinâmica da Família Nuclear Mexicana, de Vásquez et al. (2003), ainda que apenas a área "Os pais - sua dinâmica como casal" tenha sido abordada. A diferença estatística entre grupos foi obtida através do Teste U de Mann-Whitney. Os resultados mostraram diferenças estatisticamente significativas entre a percepção dos universitários com respeito a seus pais quando vivem juntos ou quando vivem separados. Concluiu-se que existem diferentes fatores que afetam o funcionamento da dinâmica familiar, os quais influenciam de maneira diferencial na percepção que cada membro da família pode ter

Adjusting to bodily change following stoma formation: a phenomenological study

Purpose: Scant research has been undertaken to explore in-depth the meaning of bodily change for individuals following stoma formation. The aim of this study was to understand the experience of living with a new stoma, with a focus on bodily change. Method: The study adopted a longitudinal phenomenological approach. Purposeful sampling was used to recruit twelve participants who had undergone faecal stoma-forming surgery. Indepth, unstructured interviews were conducted at three, nine and fifteen months following surgery. A five-stage framework facilitated iterative data analysis. Results: Stoma formation altered the taken-for-granted relationship individuals had with their bodies in terms of appearance, function and sensation, undermining the unity between body and self. Increasing familiarity with and perceived control over their stoma over time diminished awareness of their changed body, facilitating adaptation and self-acceptance. Conclusions: Stoma formation can undermine an individual’s sense of embodied self. A concept of embodiment is proposed to enable the experience of living with a new stoma to be understood as part of a wider process of re-establishing a unity between body, self and world. In defining a framework of care, individuals with a new stoma can be assisted to adapt to and accept a changed sense of embodied self

A Fluorescence-Based Method to Measure ADP/ATP Exchange of Recombinant Adenine Nucleotide Translocase in Liposomes

Several mitochondrial proteins, such as adenine nucleotide translocase (ANT), aspartate/glutamate carrier, dicarboxylate carrier, and uncoupling proteins 2 and 3, are suggested to have dual transport functions. While the transport of charge (protons and anions) is characterized by an alteration in membrane conductance, investigating substrate transport is challenging. Currently, mainly radioactively labeled substrates are used, which are very expensive and require stringent precautions during their preparation and use. We present and evaluate a fluorescence-based method using Magnesium Green (MgGrTM), a Mg2+-sensitive dye suitable for measurement in liposomes. Given the different binding affinities of Mg2+ for ATP and ADP, changes in their concentrations can be detected. We obtained an ADP/ATP exchange rate of 3.49 ± 0.41 mmol/min/g of recombinant ANT1 reconstituted into unilamellar liposomes, which is comparable to values measured in mitochondria and proteoliposomes using a radioactivity assay. ADP/ATP exchange calculated from MgGrTM fluorescence solely depends on the ANT1 content in liposomes and is inhibited by the ANT-specific inhibitors, bongkrekic acid and carboxyatractyloside. The application of MgGrTM to investigate ADP/ATP exchange rates contributes to our understanding of ANT function in mitochondria and paves the way for the design of other substrate transport assays

Compaction, cratering and collision frequency on chondritic parent objects

Calculamos el grado de compactación de un asteroide de 100 km de radio debido a un impacto con un asteroide pequeño para velocidades de impacto entre 3 y 5 km s−1. Calculamos el radio del cráter producto del impacto. Obtenemos además el número de impactos sobre el asteroide de 100 km de radio con toda la distribución de asteroides pequeños durante la edad del Sistema Solar.We calculate the compaction of an asteroid with radius 100 km due to an impact with a small asteroid for impact velocities between 3 and 5 km s−1. The crater formed on the target surface as a result of such an impact is calculated. The number of impacts on the target with the distribution of small asteroids during the age of the Solar System is computed.Fil: Parisi, Mirta Gabriela. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Beitz, E.. Technische Universitat Carolo Wilhelmina Zu Braunschweig.; AlemaniaFil: Blum, J.. Technische Universitat Carolo Wilhelmina Zu Braunschweig.; AlemaniaReunión anual de la Asociación Argentina de AstronomíaLa PlataArgentinaUniversidad Nacional de La Plata. Facultad de Ciencias Astronómicas y GeofísicasUniversidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plat

An archaeology of borders: qualitative political theory as a tool in addressing moral distance

Interviews, field observations and other qualitative methods increasingly are being used to inform the construction of arguments in normative political theory. This article works to demonstrate the strong salience of some kinds of qualitative material for cosmopolitan arguments to extend distributive boundaries. The incorporation of interviews and related qualitative material can make the moral claims of excluded others more vivid and possibly more difficult to dismiss by advocates of strong priority to compatriots in distributions. Further, it may help to promote the kind of perspective taking that has been associated with actually motivating a willingness to aid by individuals. Illustrative findings are presented from field work conducted for a normative project on global citizenship, including interviews with unauthorized immigrants and the analysis of artifacts left behind on heavily used migrant trails

Pentamidine Is Not a Permeant but a Nanomolar Inhibitor of the Trypanosoma brucei Aquaglyceroporin-2

The chemotherapeutic arsenal against human African trypanosomiasis, sleeping sickness, is limited and can cause severe, often fatal, side effects. One of the classic and most widely used drugs is pentamidine, an aromatic diamidine compound introduced in the 1940s. Recently, a genome-wide loss-of-function screen and a subsequently generated trypanosome knockout strain revealed a specific aquaglyceroporin, TbAQP2, to be required for high-affinity uptake of pentamidine. Yet, the underlying mechanism remained unclear. Here, we show that TbAQP2 is not a direct transporter for the di-basic, positively charged pentamidine. Even though one of the two common cation filters of aquaglyceroporins, i.e. the aromatic/arginine selectivity filter, is unconventional in TbAQP2, positively charged compounds are still excluded from passing the channel. We found, instead, that the unique selectivity filter layout renders pentamidine a nanomolar inhibitor of TbAQP2 glycerol permeability. Full, non-covalent inhibition of an aqua(glycero)porin in the nanomolar range has not been achieved before. The remarkable affinity derives from an electrostatic interaction with Asp265 and shielding from water as shown by structure-function evaluation and point mutation of Asp265. Exchange of the preceding Leu264 to arginine abolished pentamidine-binding and parasites expressing this mutant were pentamidine-resistant. Our results indicate that TbAQP2 is a high-affinity receptor for pentamidine. Taken together with localization of TbAQP2 in the flagellar pocket of bloodstream trypanosomes, we propose that pentamidine uptake is by endocytosis

High (but Not Low) Urinary Iodine Excretion Is Predicted by Iodine Excretion Levels from Five Years Ago

Background: It has not been investigated whether there are associations between urinary iodine (UI) excretion measurements some years apart, nor whether such an association remains after adjustment for nutritional habits. The aim of the present study was to investigate the relation between iodine-creatinine ratio (ICR) at two measuring points 5 years apart. Methods: Data from 2,659 individuals from the Study of Health in Pomerania were analyzed. Analysis of covariance and Poisson regressions were used to associate baseline with follow-up ICR. Results: Baseline ICR was associated with follow-up ICR. Particularly, baseline ICR >300 mu g/g was related to an ICR >300 mu g/g at follow-up (relative risk, RR: 2.20; p < 0.001). The association was stronger in males (RR: 2.64; p < 0.001) than in females (RR: 1.64; p = 0.007). In contrast, baseline ICR <100 mu g/g was only associated with an ICR <100 mu g/g at follow-up in males when considering unadjusted ICR. Conclusions: We detected only a weak correlation with respect to low ICR. Studies assessing iodine status in a population should take into account that an individual with a low UI excretion in one measurement is not necessarily permanently iodine deficient. On the other hand, current high ICR could have been predicted by high ICR 5 years ago. Copyright (C) 2011 S. Karger AG, Base