Compression of an elastic roller between two rigid plates

A closed solution - exact within two-dimensional linear elastostatics - is deduced for the problem appropriate to the compression of an elastic circular cylinder between two smooth, flat and parallel, rigid plates. The boundary displacements obtained for the cylinder involve elliptic integrals, whereas its stress field is given in terms of elementary functions exclusively. The results found for the distribution of the contact pressure and for the width of the contact zone are compared with the corresponding predictions of Hertz's approximate theory, for which elementary corrections are determined by asymptotic means. Analogous corrections are established for a previously available approximate estimate of the diametral compression undergone by the roller, which remains indeterminate in the Hertz treatment of this two-dimensional contact problem

Positive and negative tissue-specific signaling by a nematode epidermal growth factor receptor

The major determinants of receptor tissue tyrosine kinase (RTK) signaling specificity have been proposed to be Src homology 2 (SH2) binding sites, phosphotyrosine-containing oligopeptides in the cytoplasmic domain of the receptor. The Caenorhabditis elegans epidermal growth factor receptor homologue LET-23 has multiple functions during development and has eight potential SH2-binding sites in a region carboxyl terminal to its kinase domain. By analyzing transgenic nematodes for three distinct LET-23 functions, we show that six of eight potential sites function in vivo and that they are required for most, but not all, of LET-23 activity. A single site is necessary and sufficient to promote wild-type fertility. Three other sites activate the RAS pathway and are involved only in viability and vulval differentiation. A fifth site is promiscuous and can mediate all three LET-23 functions. An additional site mediates tissue-specific negative regulation. Putative SH2 binding sites are thus key effectors of both cell-specific and negative regulation in an intact organism. We suggest two distinct mechanisms for tissue-specific RTK-mediated signaling. A positive mechanism would promote RTK function through effectors present only in certain cell types. A negative mechanism would inhibit RTK function through tissue-specific negative regulators

“Robbing Peter to Pay Paul”: Economic and Cultural Explanations for How Lower-Income Families Manage Debt

This article builds upon classic economic perspectives of financial behavior by applying the narrative identity perspective of cultural sociology to explain how lower-income families respond to indebtedness. Drawing on in-depth qualitative interviews with 194 lower-income household heads, we show that debt management strategies are influenced by a desire to promote a financially responsible, self-sufficient social identity. Families are reluctant to ask for assistance when faced with economic hardship because it undermines this identity. Because the need to pay on debts is less acute than the need to pay for regular monthly expenses like rent or groceries, debts receive a lower priority in the monthly budget and families typically juggle their debts in private rather than turning to social networks for assistance. In some cases, however, debts take on special meanings and are handled differently. Respondents prioritize debts when they perceive payment as affirming a self-sufficient or upwardly mobile identity, but they reject and ignore debts they view as unfair or unjust. Because the private coping strategies families employ trap them in costly cycles of indebtedness and hinder future mobility prospects, debt management strategies are consequential for long-term financial well-being

The lin-3/let-23 pathway mediates inductive signalling during male spicule development in Caenorhabditis elegans

During Caenorhabditis elegans male spicule development, four pairs of precursor cells respond to multiple positional cues and establish a pattern of fates that correlates with relative anterior-posterior cell position. One of the extracellular cues is provided by the F and U cells, which promote anterior fates. We show that the genes in the lin-3/let-23 signalling pathway required for hermaphrodite vulval induction also mediate this F/U signal. Reduction-of-function mutations in lin-3, let-23, sem-5, let-60 or lin-45 disrupt the fate of anterior cells. Likewise, activation of the pathway with ubiquitously produced signal results in posterior cells inappropriately adopting the anterior fates even in the absence of F and U. We have further used this genetic pathway to begin to understand how multiple positional cues are integrated to specify cell fate. We demonstrate that lin-15 acts in spicule development as it does in vulval induction, as a negative regulator of let-23 receptor activity. A second extracellular cue, from Y.p, also acts antagonistically to the lin-3/let-23 pathway. However, this signal is apparently integrated into the lin-3/let-23 pathway at some step after lin-45 raf and is thus functionally distinct from lin-15. We have also investigated the role of lin-12 in forming the anterior/posterior pattern of fates. A lin-12 gain-of-function defect is masked by redundant positional information from F and U

Plasma neuronal specific enolase : a potential stage diagnostic marker in human African trypanosomiasis

© The Author 2014. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene. All rights reserved. For permissions, please e-mail: [email protected]. Funding: This work was supported through grants from the Wellcome Trust [082786] and Foundation for Innovative New Diagnostics.Peer reviewedPublisher PD

Cracking the Code: An Empirical Analysis of Consumer Bankruptcy Outcomes

Chapter 13 is a cornerstone of the bankruptcy system. Its legal requirements strike a balance between the rehabilitation of debtors through keeping assets and reducing debt, and the repayment of creditors over a period of years. Despite the accolades from policymakers, the hard truth is that the majority of the half-million families each year that seek refuge in chapter 13 bankruptcy will not achieve the debt relief of a discharge. Prior research found that those who drop out of bankruptcy quickly endure the serious financial struggles that they had before bankruptcy—now even worse off for having spent thousands of dollars to seek help. Despite the profound inefficiency of chapter 13 bankruptcy, we previously did not know what differentiates those who succeed in chapter 13 from those who fail. This article is the first study to use a national random sample to predict which debtors obtain a discharge of debt. Using sophisticated statistical techniques that allow us to control for unobservable or unmeasurable effects at the local level, we identify the factors that make completing chapter 13 bankruptcy more likely. We find, among other robust effects, that blacks are more than twice as unlikely to receive debt relief than non-blacks, that those without an attorney have extremely low odds compared to those who hire an attorney, and that families with children fare worse. We also find that the local variations in bankruptcy practice that have been deemed “best practices” do not correlate with higher rates of bankruptcy completion. We discuss the implications of our findings for the millions of families who struggle to repay their debts in bankruptcy, and suggest concrete fixes to increase the efficacy of the consumer bankruptcy system. This article upsets the debate about bankruptcy reform and will help shape policy and practice in upcoming decades

Focus–specific clinical profiles in human African trypanosomiasis caused by <i>Trypanosoma brucei rhodesiense</i>

&lt;p&gt;&lt;b&gt;Background:&lt;/b&gt; Diverse clinical features have been reported in human African trypanosomiasis (HAT) foci caused by &lt;i&gt;Trypanosoma brucei rhodesiense&lt;/i&gt; (&lt;i&gt;T.b.rhodesiense&lt;/i&gt;) giving rise to the hypothesis that HAT manifests as a chronic disease in South-East African countries and increased in virulence towards the North. Such variation in disease severity suggests there are differences in host susceptibility to trypanosome infection and/or genetic variation in trypanosome virulence. Our molecular tools allow us to study the role of host and parasite genotypes, but obtaining matched extensive clinical data from a large cohort of HAT patients has previously proved problematic.&lt;/p&gt; &lt;p&gt;&lt;b&gt;Methods/Principal Findings:&lt;/b&gt; We present a retrospective cohort study providing detailed clinical profiles of 275 HAT patients recruited in two northern foci (Uganda) and one southern focus (Malawi) in East Africa. Characteristic clinical signs and symptoms of &lt;i&gt;T.b.rhodesiense&lt;/i&gt; infection were recorded and the degree of neurological dysfunction determined on admission. Clinical observations were mapped by patient estimated post-infection time. We have identified common presenting symptoms in &lt;i&gt;T.b.rhodesiense&lt;/i&gt; infection; however, marked differences in disease progression and severity were identified between foci. HAT was characterised as a chronic haemo-lymphatic stage infection in Malawi, and as an acute disease with marked neurological impairment in Uganda. Within Uganda, a more rapid progression to meningo-encephaltic stage of infection was observed in one focus (Soroti) where HAT was characterised by early onset neurodysfunction; however, severe neuropathology was more frequently observed in patients in a second focus (Tororo).&lt;/p&gt; &lt;p&gt;&lt;b&gt;Conclusions/Significance:&lt;/b&gt; We have established focus-specific HAT clinical phenotypes showing dramatic variations in disease severity and rate of stage progression both between northern and southern East African foci and between Ugandan foci. Understanding the contribution of host and parasite factors in causing such clinical diversity in &lt;i&gt;T.b.rhodesiense&lt;/i&gt; HAT has much relevance for both improvement of disease management and the identification of new drug therapy.&lt;/p&gt

Hans Döllgast, post-war reconstruction and modern architecture

The works of post-war reconstruction in Munich by the German architect Hans Döllgast (1891-1974) have become a reference point for interpretative modern architectural responses to damaged heritage. In the context of Berlin’s museum restorations of the past 15 years, leading designers from David Chipperfield to Roger Diener have paid tribute to Döllgast’s inspirational restitution of the Alte Pinakothek art museum in Munich in the 1950s. This article revisits Döllgast’s contribution to reconstruction by drawing on a wider corpus of his writings. Döllgast’s critical attitude to modernism is examined not as a quirk but rather as a key to his distinct achievements in reconstruction. Unlike existing accounts, the article focuses on cross-cutting themes in Döllgast’s approach rather than approaching his work by case studies. It challenges the tendency to over-privilege the iconography of ruination in Döllgast and draws attention to his underlying interest in continuity in modern architecture

Inflating Fat Bubbles in Clusters of Galaxies by Precessing Massive Slow Jets

We conduct hydrodynamical numerical simulations and find that precessing massive slow jets can inflate fat bubbles, i.e., more or less spherical bubbles, that are attached to the center of clusters of galaxies. To inflate a fat bubble the jet should precess fast. The precessing angle $\theta$ should be large, or change over a large range $0 \le \theta \le \theta_{\max} \sim 30-70 ^\circ$ (depending also on other parameters), where $\theta=0$ is the symmetry axis. The constraints on the velocity and mass outflow rate are similar to those on wide jets to inflate fat bubbles. The velocity should be v_j \sim 10^4 \kms, and the mass loss rate of the two jets should be 2 \dot M_j \simeq 1-50 \dot M_\odot \yr^{-1} . These results, and our results from a previous paper dealing with slow wide jets, support the claim that a large fraction of the feedback heating in cooling flow clusters and in the processes of galaxy formation is done by slow massive jets.Comment: Accepted for publication in MNRA

The no-core shell model with general radial bases

Calculations in the ab initio no-core shell model (NCSM) have conventionally been carried out using the harmonic-oscillator many-body basis. However, the rapid falloff (Gaussian asymptotics) of the oscillator functions at large radius makes them poorly suited for the description of the asymptotic properties of the nuclear wavefunction. We establish the foundations for carrying out no-core configuration interaction (NCCI) calculations using a basis built from general radial functions and discuss some of the considerations which enter into using such a basis. In particular, we consider the Coulomb-Sturmian basis, which provides a complete set of functions with a realistic (exponential) radial falloff.Comment: 7 pages, 3 figures; presented at Horizons on Innovative Theories, Experiments, and Supercomputing in Nuclear Physics 2012, New Orleans, Louisiana, June 4-7, 2012; submitted to J. Phys. Conf. Se