Inorganic Carbon Chemistry In East Antarctic Coastal Polynyas

Polynyas are large areas of open water or reduced sea ice coverage that persistently form in polar environments and often experience enhanced rates of physical, chemical, and biological processes that impact ocean dynamics on local to global scales. Polynyas that form adjacent to the coast, known as coastal polynyas, play an important role in the global carbon cycle by regulating the exchange of CO2 between the ocean and atmosphere in the high latitudes. Because of their importance to the global carbon cycle, there is a particular interest to better characterize CO2 system processes in Antarctic coastal polynyas. In this study, the inorganic carbon chemistry in three East Antarctic coastal polynyas - the Dalton Polynya, the Mertz Polynya, and the Ninnis Polynya - is investigated using a combination of ship-board water column and underway observations, remote sensing products, and model outputs. The first biogeochemical observations in the Dalton Polynya are presented, and the physical and biological controls on total dissolved inorganic carbon (TCO2) are examined. Despite the evidence of TCO2 depletion due to biological production, the surface waters of the Dalton Polynya were a weak net source of CO2 to the atmosphere during the summer survey. Satellite estimates of sea surface chlorophyll a concentration suggest that the shipboard observations were made prior to the peak of the productive season and are more likely representative of the transition between spring and summer. Compared to coastal polynyas, the rates of net community production and air-sea CO2 exchange in the Dalton polynya were relatively small

A Continental Shelf Pump for CO2 on the Adélie Land Coast, East Antarctica

We quantify the transport of inorganic carbon from the continental shelf to the deep ocean in Dense Shelf Water (DSW) from the Mertz and Ninnis Polynyas along the Adélie Land coast in East Antarctica. For this purpose, observations of total dissolved inorganic carbon (TCO2) from two summer hydrographic surveys in 2015 and 2017 were paired with DSW volume transport estimates derived from a coupled ocean‐sea ice‐ice shelf model to examine the fate of inorganic carbon in DSW from Adélie Land. Transports indicate a net outflow of 227 ± 115 Tg C yr−1 with DSW in the postglacial calving configuration of the Mertz Polynya. The greatest outflow of inorganic carbon from the shelf region was delivered through the northern boundary across the Adélie and Mertz Sills, with an additional transport westward from the Mertz Polynya. Inorganic carbon in DSW is derived primarily from inflowing TCO2‐rich modified Circumpolar Deep Water; local processes (biological productivity, air‐sea exchange of CO2, and the addition of brine during sea ice formation) make much smaller contributions. This study proposes that DSW export serves as a continental shelf pump for CO2 and is a pathway to sequester inorganic carbon from the shallow Antarctic continental shelf to the abyssal ocean, removing CO2 from atmospheric exchange on the time scale of centuries

Navigating Gender at Sea

Fieldwork, including work done at sea, is a key component of many geoscientists' careers. Recent studies have highlighted the pervasive harassment faced by women and LGBTQ+ people during fieldwork. However, transgender and gender diverse (TGD) scientists face obstacles which have not yet been thoroughly examined. We fill this gap by sharing our experiences as TGD people. We have experienced sexual harassment, misconduct, privacy issues, and legal and medical struggles as we conduct seagoing work. In this work, we provide recommendations for individuals, cruise leaders, and institutions for making seagoing work safer for our communities

Relatively Low HIV Infection Rates in Rural Uganda, but with High Potential for a Rise: A Cohort Study in Kayunga District, Uganda

BACKGROUND: Few studies have been conducted in Uganda to identify and quantify the determinants of HIV-1 infection. We report results from a community-based cohort study, whose primary objectives were to determine HIV-1 prevalence, incidence, and determinants of these infections, among other objectives. METHODOLOGY: Consenting volunteers from the rural district of Kayunga in Uganda aged 15-49 years were enrolled between March and July 2006. Participants were evaluated every six months. A questionnaire that collected information on behavioral and other HIV-1 risk factors was administered, and a blood sample obtained for laboratory analysis at each study visit. PRINCIPAL FINDINGS: HIV-1 prevalence among the 2025 participants was 9.9% (95% CI = 8.6%-11.2%). By the end of 12 months of follow-up, 1689.7 person-years had been accumulated, with a median follow-up time of 11.97 months. Thirteen HIV-1 incident cases were detected giving an annual HIV-1 incidence of 0.77% (95% CI = 0.35-1.19). Prevalence of HSV-2 infection was 57% and was strongly associated with prevalent HIV-1 infection (adjusted Odds Ratio = 3.9, 95% CI = 2.50-6.17); as well as incident HIV-1 infection (adjusted Rate Ratio (RR) = 8.7, 95% CI = 1.11-67.2). The single most important behavioral characteristic associated with incident HIV infection was the number of times in the past 6 months, a participant had sex with person(s) they suspected/knew were having sex with others; attaining statistical significance at 10 times and higher (adjusted RR = 6.3, 95% CI = 1.73-23.1). By the end of 12 months of follow-up, 259 participants (13%) were lost to follow-up, 13 (0.6%) had died, and 2 (0.1%) had withdrawn consent. CONCLUSIONS: Despite relatively low HIV-1 incidence observed in this community, prevalence remains relatively high. In the presence of high prevalence of HSV-2 infection and the behavioral characteristic of having sex with more than one partner, there is potential for increase in HIV-1 incidence

The STF2p Hydrophilin from Saccharomyces cerevisiae Is Required for Dehydration Stress Tolerance

The yeast Saccharomyces cerevisiae is able to overcome cell dehydration; cell metabolic activity is arrested during this period but restarts after rehydration. The yeast genes encoding hydrophilin proteins were characterised to determine their roles in the dehydration-resistant phenotype, and STF2p was found to be a hydrophilin that is essential for survival after the desiccation-rehydration process. Deletion of STF2 promotes the production of reactive oxygen species and apoptotic cell death during stress conditions, whereas the overexpression of STF2, whose gene product localises to the cytoplasm, results in a reduction in ROS production upon oxidative stress as the result of the antioxidant capacity of the STF2p protein

The database of the PREDICTS (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems) project

K

Comparison of histological delineations of medial temporal lobe cortices by four independent neuroanatomy laboratories

The medial temporal lobe (MTL) cortex, located adjacent to the hippocampus, is crucial for memory and prone to the accumulation of certain neuropathologies such as Alzheimer's disease neurofibrillary tau tangles. The MTL cortex is composed of several subregions which differ in their functional and cytoarchitectonic features. As neuroanatomical schools rely on different cytoarchitectonic definitions of these subregions, it is unclear to what extent their delineations of MTL cortex subregions overlap. Here, we provide an overview of cytoarchitectonic definitions of the entorhinal and parahippocampal cortices as well as Brodmann areas (BA) 35 and 36, as provided by four neuroanatomists from different laboratories, aiming to identify the rationale for overlapping and diverging delineations. Nissl-stained series were acquired from the temporal lobes of three human specimens (two right and one left hemisphere). Slices (50 μm thick) were prepared perpendicular to the long axis of the hippocampus spanning the entire longitudinal extent of the MTL cortex. Four neuroanatomists annotated MTL cortex subregions on digitized slices spaced 5 mm apart (pixel size 0.4 μm at 20× magnification). Parcellations, terminology, and border placement were compared among neuroanatomists. Cytoarchitectonic features of each subregion are described in detail. Qualitative analysis of the annotations showed higher agreement in the definitions of the entorhinal cortex and BA35, while the definitions of BA36 and the parahippocampal cortex exhibited less overlap among neuroanatomists. The degree of overlap of cytoarchitectonic definitions was partially reflected in the neuroanatomists' agreement on the respective delineations. Lower agreement in annotations was observed in transitional zones between structures where seminal cytoarchitectonic features are expressed less saliently. The results highlight that definitions and parcellations of the MTL cortex differ among neuroanatomical schools and thereby increase understanding of why these differences may arise. This work sets a crucial foundation to further advance anatomically-informed neuroimaging research on the human MTL cortex

Consequences of a large-scale fragmentation experiment for Neotropical bats : disentangling the relative importance of local and landscape-scale effects

Context Habitat loss, fragmentation and degradation are widespread drivers of biodiversity decline. Understanding how habitat quality interacts with landscape context, and how they jointly affect species in human-modified landscapes, is of great importance for informing conservation and management. Objectives We used a whole-ecosystem manipulation experiment in the Brazilian Amazon to investigate the relative roles of local and landscape attributes in affecting bat assemblages at an interior-edge-matrix disturbance gradient. Methods We surveyed bats in 39 sites, comprising continuous forest (CF), fragments, forest edges and intervening secondary regrowth. For each site, we assessed vegetation structure (local-scale variable) and, for five focal scales, quantified habitat amount and four landscape configuration metrics. Results Smaller fragments, edges and regrowth sites had fewer species and higher levels of dominance than CF. Regardless of the landscape scale analysed, species richness and evenness were mostly related to the amount of forest cover. Vegetation structure and configurational metrics were important predictors of abundance, whereby the magnitude and direction of response to configurational metrics were scale-dependent. Responses were ensemble-specific with local-scale vegetation structure being more important for frugivorous than for gleaning animalivorous bats. Conclusions Our study indicates that scale-sensitive measures of landscape structure are needed for a more comprehensive understanding of the effects of fragmentation on tropical biota. Although forest fragments and regrowth habitats can be of conservation significance for tropical bats our results further emphasize that primary forest is of irreplaceable value, underlining that their conservation can only be achieved by the preservation of large expanses of pristine habitat