Quaternary Benthic Foraminiferal Distribution in the Ross Sea, Antarctica, and Its Relationship to Oceanography.

This study focuses on Quaternary benthic foraminiferal distribution in the Ross Sea, and its relationship to oceanography and ice-shelf retreat. It is the first study of benthic foraminiferal distribution that takes the retreat history of the Ross Ice Shelf into account. This is also the first time foraminifera from a cold-water carbonate bank have been described. There are three foraminiferal faunas in the Ross Sea: Pleistocene carbonate-bank fauna, Modern-calcareous fauna, and Holocene agglutinated fauna. Numerically significant species in the carbonate-bank and Modern-calcareous faunas include Angulogerina earlandi, Cibicides lobatulus, Discorbis vilardeboana, Ehrenbergina glabra, Epistominella exigua, and Globocassidulina crassa . The carbonate-bank fauna has higher diversity and greater numerical abundance than the Modern-calcareous fauna. The agglutinated fauna, which is seen in Holocene sediments, contains Bathysiphon sp. A, Hormosinella ovicula, Miliammina earlandi, Textularia wiesneri, and Trochammina quadricamerata. The Modern-calcareous fauna is found where Warm Core Water upwells into the photic zone, causing an increase in phytoplankton productivity. The agglutinated fauna is found in water depths below the CCD and where Warm Core Water does not upwell in the photic zone. The carbonate-bank fauna probably formed during a period of increased upwelling in the northwestern Ross Sea. The utility of benthic foraminifera as a tool for distinguishing glacial environments is also tested. Ice-shelf proximal and distal environments could not be distinguished by benthic foraminiferal assemblages, which contained the agglutinated species Miliammina earlandi, reworked calcareous forms, and rare other agglutinated specimens. In addition, some samples with an abundant agglutinated assemblage were found in an open-water environment. This research also included a brief study of the distribution and formation of concentrically layered opaline spherules found in Antarctic sediments. These tiny spherules are found in association with calcareous foraminifera in the Ross and Weddell Seas and appear to form through precipitation as seasonal sea ice melts, causing freshwater to mix with saltwater, thus decreasing silica solubility in surface waters

Evolutionary rate of a gene affected by chromosomal position

AbstractGenes evolve at different rates depending on the strength of selective pressure to maintain their function. Chromosomal position can also have an influence [1,2]. The pseudoautosomal region (PAR) of mammalian sex chromosomes is a small region of sequence identity that is the site of an obligatory pairing and recombination event between the X and Y chromosomes during male meiosis [3–6]. During female meiosis, X chromosomes can pair and recombine along their entire length. Recombination in the PAR is therefore approximately 10 times greater in male meiosis compared with female meiosis [4–6]. The gene Fxy (also known as MID1[7]) spans the pseudoautosomal boundary (PAB) in the laboratory mouse (Mus musculus domesticus, C57BL/6) such that the 5′ three exons of the gene are located on the X chromosome but the seven exons encoding the carboxy-terminal two-thirds of the protein are located within the PAR and are therefore present on both the X and Y chromosomes [8]. In humans [7,9], the rat, and the wild mouse species Mus spretus, the gene is entirely X-unique. Here, we report that the rate of sequence divergence of the 3′ end of the Fxy gene is much higher (estimated at 170-fold higher for synonymous sites) when pseudoautosomal (present on both the X and Y chromosomes) than when X-unique. Thus, chromosomal position can directly affect the rate of evolution of a gene. This finding also provides support for the suggestion that regions of the genome with a high recombination frequency, such as the PAR, may have an intrinsically elevated rate of sequence divergence

Social Constructionism with a Twist of Pragmatism: A Suitable Cocktail for Information Systems Research

The Information Systems discipline is concerned with the identification, planning, development, implementation and management of information systems in organisations. Thus, it is in organisations that the events, happenings and stories of information systems are played out. Given this, the perspective that Information Systems researchers have of organisational reality is most important. This viewpoint affects and impacts upon researchers’ practice, from the identification and choice of the research question, right through the analysis of data to the writing up of the research. This paper explores a particular theoretical perspective on organisational reality. Social constructionism augmented by pragmatism, is described and explored in the paper, and the implications for research Information Systems are considered. It is argued in the paper that this theoretical orientation is particularly helpful in planning, conceptualising and executing relevant and practical research in the Information Systems discipline

Research partnerships across international contexts : a practice of unity or plurality?

This work was supported by Engineering and Physical Sciences Research Council [grant number EP/T025034/1].Partnership is not a benign practice; it is culturally and ethically loaded. The way in which partnerships are construed in international research determines its design, ethics and impacts. Despite this, and the growing assumption of partnership practice in our field, the concept has become increasingly abstract and the practice under-analysed. This article provides critical perspectives of current understandings of partnership in international development research from three angles: the motivations behind partnership working; an epistemological perspective in relation to epistemic justice and the agency of language; and finally, the systems that mediate partnerships, and the range of resources that guide them. Publisher PDFPeer reviewe

HOW DO ONLINE STUDENTS DIFFER FROM LECTURE STUDENTS?

This study has two primary objectives. First, we want to know how students who enroll in online classes differ from their peers in traditional lecture classes. Our second objective involves both exploring what factors influence performance among online students, as well as whether those factors differ for online and lecture students. Our comparisons are of two large sections of a course in computer programming for which almost the only difference was that one section consisted of on-campus lectures, and the other section was online. We find that online students do differ from lecture students in a number of important characteristics. However, when we examine class performance and course completion, we find that the factors which influence performance seem to have a stronger impact on lecture students, but we cannot reject the hypothesis that factor coefficients are the same for the two groups

Thyroid hormone and vitamin D regulate VGF expression and promoter activity

The Siberian hamster (Phodopus sungorus) survives winter by decreasing food intake and catabolizing abdominal fat reserves, resulting in a sustained, profound loss of body weight. Hypothalamic tanycytes are pivotal for this process. In these cells, short-winter photoperiods upregulate deiodinase 3, an enzyme that regulates thyroid hormone availability, and downregulate genes encoding components of retinoic acid (RA) uptake and signaling. The aim of the current studies was to identify mechanisms by which seasonal changes in thyroid hormone and RA signaling from tanycytes might ultimately regulate appetite and energy expenditure. proVGF is one of the most abundant peptides in the mammalian brain, and studies have suggested a role for VGF-derived peptides in the photoperiodic regulation of body weight in the Siberian hamster. In silico studies identified possible thyroid and vitamin D response elements in the VGF promoter. Using the human neuroblastoma SH-SY5Y cell line, we demonstrate that RA increases endogenous VG expression (P!0.05) and VGF promoter activity (P!0.0001). Similarly, treatment with 1,25-ihydroxyvitamin D3 increased endogenous VGF mRNA expression (P!0.05) and VGF promoter activity (P!0.0001),whereas triiodothyronine (T3) decreased both (P!0.01 and P!0.0001). Finally, intrahypothalamic administration of T3 blocked the short day-induced increase in VGF expression in the dorsomedial posterior arcuate nucleus of Siberian hamsters. Thus, we conclude that VGF expression is a likely target of photoperiod-induced changes in tanycyte-derived signals and is potentially a regulator of seasonal changes in appetite and energy expenditure