New observations regarding deterministic, time reversible thermostats and Gauss's principle of least constraint

Deterministic thermostats are frequently employed in non-equilibrium molecular dynamics simulations in order to remove the heat produced irreversibly over the course of such simulations. The simplest thermostat is the Gaussian thermostat, which satisfies Gauss's principle of least constraint and fixes the peculiar kinetic energy. There are of course infinitely many ways to thermostat systems, e.g. by fixing $\sum\limits_i{|{p_i}|^{\mu + 1}}$. In the present paper we provide, for the first time, convincing arguments as to why the conventional Gaussian isokinetic thermostat ($\mu=1$) is unique in this class. We show that this thermostat minimizes the phase space compression and is the only thermostat for which the conjugate pairing rule (CPR) holds. Moreover it is shown that for finite sized systems in the absence of an applied dissipative field, all other thermostats ($\mu=1$) perform work on the system in the same manner as a dissipative field while simultaneously removing the dissipative heat so generated. All other thermostats ($\mu=1$) are thus auto-dissipative. Among all $\mu$-thermostats, only the $\mu=1$ Gaussian thermostat permits an equilibrium state.Comment: 27 pages including 10 figures; submitted for publication Journal of Chemical Physic

Discourse and identity in a corpus of lesbian erotica

This article uses corpus linguistic methodologies to explore representations of lesbian desires and identities in a corpus of lesbian erotica from the 1980s and 1990s. We provide a critical examination of the ways in which “lesbian gender,” power, and desire are represented, (re-)produced, and enacted, often in ways that challenge hegemonic discourses of gender and sexuality. By examining word frequencies and collocations, we critically analyze some of the themes, processes, and patterns of representation in the texts. Although rooted in linguistics, we hope this article provides an accessible, interdisciplinary, and timely contribution toward developing understandings of discursive practices surrounding gender and sexuality

Analysis of surface tris (2,3-dibromopropyl) phosphate on chlorobutyl rubber SCAPE suits

Tris (2,30-dibromopropyl) phosphate was used to confer flame retardant properties on butyl rubber formulations used in protective clothing such as the self-contained atmospheric protective ensembles (SCAPE suits) worn at Kennedy Space Center in support of Apollo, Skylab, and Apollo-Soyuz missions since 1966. Because tris (2,3-dibromopropyl) phosphate is mutagenic, surface concentrations of the compound in SCAPE suits were investigated as were as potential methods of removing or isolating it. Analytical procedures for determining surface concentrations of the tris compound on non-porous materials are described. Soap-and-water washing is the most efficient method of removing the compound from fabricated SCAPE suits and unused material

New Records of Fishes in the Northwestern Gulf of Mexico, with Notes on Some Rare Species

Based on submersible, SCUBA, and trawl collections 14 new fish records are reported for the northwestern Gulf of Mexico. In addition the distribution of eight rare species are discussed in detail

Secondary School Students Knowledge, Attitude and Practices Towards Water Pollution in Riverine Area of Ondo State

Water pollution has been a major problem facing people living in riverine area all over Nigeria. This has become life threaten to majority of people living in the area as well as visitors to the area. A descriptive action research design was adopted foe the study and 3 instruments were developed for the collection of data. The population of the study comprises of all secondary school students in riverine area of Ondo State while 200 respondents were randomly selected from 10 schools 5 on the land and 5 on water. The questionnaire titled Environmental knowledge scale (EKS) Environmental Attitude scale (EAS) AND Environmental practice scale (EPS) were used to collect data for the study. Data generated were analyzed using descriptive statistics of mean, and standard deviation. The finding from the study shows that though participants are aware of actions that can pollute water, yet their attitude towards water pollution is negative

Wave-induced H2S flux sustains a chemoautotrophic symbiosis

Symbioses involving sulfur‐oxidizing bacteria and invertebrate hosts require a source of reduced sulfur, a source of O2, and transport mechanisms that ensure them a supply of both. We investigated these mechanisms using the symbiosis between the sessile ciliate Zoothamnium niveum (Hemprich and Ehrenberg 1831) and bacteria living on its surface. The stalked colonies of Z. niveum grow on peat walls around the openings of centimeter‐scale conduits created when mangrove rootlets decompose. Using in situ, time‐series measurements with fast‐responding amperometric microelectrodes, we found that the conduits were charged with H2S by diffusion from the decaying rootlets during periods of low boundary‐layer flow speed. During these times, the feeding current of the zooids transported oxygenated seawater from outside the peat wall toward the ectobiotic bacteria. During periods of high flow speed, H2S‐rich seawater from the conduits was drawn along the colonies and over the bacteria. We conclude that this symbiosis exploits a combination of two transport mechanisms: (1) venting of H2S‐rich seawater due to pulsating boundary‐layer current over ciliate groups and (2) the continuous and rapid feeding current generated by the host’s cilia. This discovery raises the possibility that other systems in which pockets of decay are exposed to pulsating flow could support similar symbioses

Streptococcus mutans Levels and Biotypes in Egyptian and Saudi Arabian Students During the First Months of Residency in the United States

Several studies indicated that serotype/biotype c strains are the most common on a global basis, but that regional differences may occur relative to other serotype/biotypes. Of particular interest is the observation that individuals residing in the Middle East have higher incidences of serotype e and d strains relative to their levels in American citizens. This could reflect exposure to different Streptococcus mutans serotypes during the period in which the teeth are colonized, or might reflect other factors local to the region, such as diet. The purpose of the present study was to observe Egyptian and Saudi Arabian students during the first four months after their arrival in the United States, in order to determine whether this change in habitat affected the levels and biotypes of S. mutans. The results of this study showed that biotype c strains were the most prevalent in saliva and plaque of these Egyptians and Saudi Arabian students, followed by biotype e and biotype d. There was a drop in the number of S. mutans in the saliva and the proportions of S. mutans in the plaque after two months of residence in the United States, followed by a significant increase after four months of residence. This increase was most noticeable in subjects who had a higher number of decayed surfaces. In these subjects, the percentage of S. mutans in pooled occlusal plaque increased significantly, from 6.1 to 13.2%.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66894/2/10.1177_00220345840630011201.pd

Theory of Mind Performance in Younger and Older Adults with Elevated Autistic Traits

Little is known about the impact of aging with Autism Spectrum Disorder on theory of mind (ToM). While ToM difficulties appear to abate with age in older autistic populations, this has yet to be explored in the Broad Autism Phenotype (BAP). The current study examined ToM performance among younger (n = 49, aged 18–46) and older adults (n = 47, aged 60–91) who were classified as on the BAP (younger n = 18; older n = 21) or not (younger n = 31; older n = 26) using the BAP Questionnaire. ToM was assessed using the ecologically valid Strange Stories Film Task (SSFT) and the dynamic Happé–Frith Triangle Animations task (TA). A 2 × 2 analysis of variance examined the effects of autistic traits (BAP vs. non‐BAP) and age (young vs. old). For both SSFT and TA, results showed autistic trait main effects on task performance (non‐BAP > BAP). Age main effects were observed for some but not all metrics on TA (younger better than older), with no differences in SSFT. An interaction of autistic traits and age was observed in TA Intentionality, with younger non‐BAP and younger BAP performing similarly but older non‐BAP performing better than older BAP. Results show that younger and older adults with elevated autistic traits show poorer ToM performance. Despite ToM difficulties being common in later life in the general population, this effect was not observed when using a ToM task designed to reflect real‐world scenarios. However, results suggest that autistic traits and age could interact to increase risk for poor ToM performance in older adults who endorse elevated autistic traits

A social network analysis of actors involved in wild pig (\u3ci\u3eSus scrofa\u3c/i\u3e) management in Missouri

Wild pigs (Sus scrofa) cause significant damage to agriculture and native ecosystems and can transmit diseases to animals and people. Management responses designed to reduce population numbers are needed to mitigate these threats. Identifying networks of key actors, including the ways in which they interact, is valuable for purposes of better understanding opportunities or constraints that generate or impede effective management responses. The goal of our study was to understand the network of organizations, and the personnel working within them, that were active in wild pig management, research, or policy initiatives in Missouri during 2018–2020 by 1) identifying individuals and organizations involved in the network, 2) investigating the attributes of relevant personnel, 3) determining the structural patterns of the network, and 4) examining how the network structure could be optimized to improve communication and collaboration efforts. Results from a social network analysis identified 150 personnel affiliated with 26 organizations actively working on wild pig issues in Missouri. The network was largely homogenous based on respondents\u27 attributes, had low density, and was relatively fragmented, small, decentralized with few ties per node, and separated with few brokers. We emphasize the importance of understanding the strengths and weaknesses of a network\u27s structure in facilitating effective collective action to manage wild pigs