A Case Study in Testing Distributed Systems

This paper describes a case study in the testing of distributed systems. The software under test is a middleware system developed in Java. The full test lifecycle is examined including unit testing, integration testing, and system testing. Where possible, traditional tools and techniques are used to carry out the testing. One aspect where this is not possible is the testing of the low-level concurrency, which is often overlooked when testing commercial distributed systems, since the middleware or application server is already developed by a third-party and is assumed to operate correctly. This paper examines testing the middleware system itself, and therefore, a method for testing the concurrency properties of the system is used. The testing revealed a number of faults and design weaknesses, and showed that, with some adaptation, traditional tools and techniques go a long way in the testing of distributed applications

Tool Support for Testing Java Monitors

The Java programming language supports monitors. Monitor implementations, like other concurrent programs, are hard to test due to the inherent non-determinism. This paper presents the ConAn (Concurrency Analyser) tool for generating drivers for the testing of Java monitors. To obtain adequate controllability over the interactions between Java threads, the generated driver contains processes that are synchronized by a clock. The driver automatically executes the calls in the test sequence in the prescribed order and compares the outputs against the expected outputs specified in the test sequence. The method and tool are illustrated in detail on an asymmetric producer-consumer monitor, and their application to two other monitors is discussed

Playing the Admissions Game: Student Reactions to Increasing College Competition

Gaining entrance to a four-year college or university, particularly a selective institution, has become increasingly competitive over the last several decades. We document this phenomenon and show how it has varied across different parts of the student ability distribution and across region, with the most pronounced increases in competition being found among higher-ability students and in the Northeast. Additionally, we explore how the college preparatory behavior of high school seniors has changed in response to the growth in competition. We also discuss the theoretical implications of increased competition on longer-term measures of learning and achievement and attempt to test them empirically; the evidence and related literature, while limited, suggests little long-term benefit.

The interaction and orientation of Peptide KL4 in model membranes

We report on the orientation and location of synthetic pulmonary surfactant peptide KL4, (KLLLL)4K, in model lipid membranes. The partitioning depths of selectively deuterated leucine residues within KL4 were determined in DPPC:POPG (4:1) and POPC:POPG (4:1) bilayers by oriented neutron diffraction. These measurements were combined with an NMR-generated model of the peptide structure to determine the orientation and partitioning of the peptide at the lipid–water interface. The results demonstrate KL4 adopting an orientation that interacts with a single membrane leaflet. These observations are consistent with past 2H NMR and EPR studies (Antharam et al., 2009; Turner et al., 2014)

Digital technology and disease surveillance in the COVID-19 pandemic: A scoping review protocol

Introduction Infectious diseases pose a risk to public health, requiring efficient strategies for disease prevention. Digital health surveillance technologies provide new opportunities to enhance disease prevention, detection, tracking, reporting and analysis. However, in addition to concerns regarding the effectiveness of these technologies in meeting public health goals, there are also concerns regarding the ethics, legality, safety and sustainability of digital surveillance technologies. This scoping review examines the literature on digital surveillance for public health purposes during the COVID-19 pandemic to identify health-related applications of digital surveillance technologies, and to highlight discussions of the implications of these technologies. Methods and analysis The scoping review will be guided by the framework proposed by Arksey and O\u27Malley and the guidelines outlined by Colquhoun et al and Levac et al. We will search Medline (Ovid), PsycInfo, PubMed, Scopus, CINAHL (EBSCOhost), ACM Digital Library, Google Scholar and IEEE Explore for relevant studies published between December 2019 and December 2020. The review will also include grey literature. Data will be managed and analysed through an extraction table and thematic analysis. Ethics and dissemination Findings will be disseminated through traditional academic channels, as well as social media channels and research briefs and infographics. We will target our dissemination to provincial and federal public health organisations, as well as technology companies and community-based organisations managing the public response to the COVID-19 pandemic

The state of the Martian climate

60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes

Tim-3 expression defines a novel population of dysfunctional T cells with highly elevated frequencies in progressive HIV-1 infection

Progressive loss of T cell functionality is a hallmark of chronic infection with human immunodeficiency virus 1 (HIV-1). We have identified a novel population of dysfunctional T cells marked by surface expression of the glycoprotein Tim-3. The frequency of this population was increased in HIV-1–infected individuals to a mean of 49.4 ± SD 12.9% of CD8+ T cells expressing Tim-3 in HIV-1–infected chronic progressors versus 28.5 ± 6.8% in HIV-1–uninfected individuals. Levels of Tim-3 expression on T cells from HIV-1–infected inviduals correlated positively with HIV-1 viral load and CD38 expression and inversely with CD4+ T cell count. In progressive HIV-1 infection, Tim-3 expression was up-regulated on HIV-1–specific CD8+ T cells. Tim-3–expressing T cells failed to produce cytokine or proliferate in response to antigen and exhibited impaired Stat5, Erk1/2, and p38 signaling. Blocking the Tim-3 signaling pathway restored proliferation and enhanced cytokine production in HIV-1–specific T cells. Thus, Tim-3 represents a novel target for the therapeutic reversal of HIV-1–associated T cell dysfunction

Analysis of Pools of Targeted Salmonella Deletion Mutants Identifies Novel Genes Affecting Fitness during Competitive Infection in Mice

Pools of mutants of minimal complexity but maximal coverage of genes of interest facilitate screening for genes under selection in a particular environment. We constructed individual deletion mutants in 1,023 Salmonella enterica serovar Typhimurium genes, including almost all genes found in Salmonella but not in related genera. All mutations were confirmed simultaneously using a novel amplification strategy to produce labeled RNA from a T7 RNA polymerase promoter, introduced during the construction of each mutant, followed by hybridization of this labeled RNA to a Typhimurium genome tiling array. To demonstrate the ability to identify fitness phenotypes using our pool of mutants, the pool was subjected to selection by intraperitoneal injection into BALB/c mice and subsequent recovery from spleens. Changes in the representation of each mutant were monitored using T7 transcripts hybridized to a novel inexpensive minimal microarray. Among the top 120 statistically significant spleen colonization phenotypes, more than 40 were mutations in genes with no previously known role in this model. Fifteen phenotypes were tested using individual mutants in competitive assays of intraperitoneal infection in mice and eleven were confirmed, including the first two examples of attenuation for sRNA mutants in Salmonella. We refer to the method as Array-based analysis of cistrons under selection (ABACUS)