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"Powell, Brent A"
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Collection care
by
Powell, Brent A
in
Antiquities
,
Antiquities -- Collection and preservation -- Handbooks, manuals, etc
,
Antiquities--Collection and preservation
2015,2016
Collection Care: An Illustrated Handbook for the Care and Handling of Cultural Objects provides a solid overview of basic collection care procedures and policies. The topics covered address the decision making criteria and risk assessment solutions involved in the best practices for handling art and artifacts. Technical subjects will cover proven techniques, materials, equipment and address problem solving assessment and current solutions. The comprehensive overview of staff responsibilities, relationships and training will bring the book to a conclusion of addressing the unison of all profess.
Immunological imprinting of humoral immunity to SARS-CoV-2 in children
2023
Omicron variants of SARS-CoV-2 are globally dominant and infection rates are very high in children. We measure immune responses following Omicron BA.1/2 infection in children aged 6-14 years and relate this to prior and subsequent SARS-CoV-2 infection or vaccination. Primary Omicron infection elicits a weak antibody response with poor functional neutralizing antibodies. Subsequent Omicron reinfection or COVID-19 vaccination elicits increased antibody titres with broad neutralisation of Omicron subvariants. Prior pre-Omicron SARS-CoV-2 virus infection or vaccination primes for robust antibody responses following Omicron infection but these remain primarily focussed against ancestral variants. Primary Omicron infection thus elicits a weak antibody response in children which is boosted after reinfection or vaccination. Cellular responses are robust and broadly equivalent in all groups, providing protection against severe disease irrespective of SARS-CoV-2 variant. Immunological imprinting is likely to act as an important determinant of long-term humoral immunity, the future clinical importance of which is unknown.
The immune responses to SARS CoV-2 infection in children are less well understood than in adults. Here the authors characterise immune responses to newer omicron lineages and relate these to previous infection with earlier lineages of SARS-CoV-2, implicating a reduced immunogenicity from omicron variants and imprinting from previous virus strains.
Journal Article
Hepatic stellate cells control liver zonation, size and functions via R-spondin 3
2025
Hepatic stellate cells (HSCs) have a central pathogenetic role in the development of liver fibrosis. However, their fibrosis-independent and homeostatic functions remain poorly understood
1
,
2
,
3
,
4
–
5
. Here we demonstrate that genetic depletion of HSCs changes WNT activity and zonation of hepatocytes, leading to marked alterations in liver regeneration, cytochrome P450 metabolism and injury. We identify R-spondin 3 (RSPO3), an HSC-enriched modulator of WNT signalling, as responsible for these hepatocyte-regulatory effects of HSCs. HSC-selective deletion of
Rspo3
phenocopies the effects of HSC depletion on hepatocyte gene expression, zonation, liver size, regeneration and cytochrome P450-mediated detoxification, and exacerbates alcohol-associated and metabolic dysfunction-associated steatotic liver disease.
RSPO3
expression decreases with HSC activation and is inversely associated with outcomes in patients with alcohol-associated and metabolic dysfunction-associated steatotic liver disease. These protective and hepatocyte-regulating functions of HSCs via RSPO3 resemble the R-spondin-expressing stromal niche in other organs and should be integrated into current therapeutic concepts.
Hepatic stellate cells regulate hepatocyte functions via R-spondin 3.
Journal Article
Secondary attack rates in primary and secondary school bubbles following a confirmed case: Active, prospective national surveillance, November to December 2020, England
2022
Following the full re-opening of schools in England and emergence of the SARS-CoV-2 Alpha variant, we investigated the risk of SARS-CoV-2 infection in students and staff who were contacts of a confirmed case in a school bubble (school groupings with limited interactions), along with their household members.
Primary and secondary school bubbles were recruited into sKIDsBUBBLE after being sent home to self-isolate following a confirmed case of COVID-19 in the bubble. Bubble participants and their household members were sent home-testing kits comprising nasal swabs for RT-PCR testing and whole genome sequencing, and oral fluid swabs for SARS-CoV-2 antibodies.
During November-December 2020, 14 bubbles were recruited from 7 schools, including 269 bubble contacts (248 students, 21 staff) and 823 household contacts (524 adults, 299 children). The secondary attack rate was 10.0% (6/60) in primary and 3.9% (4/102) in secondary school students, compared to 6.3% (1/16) and 0% (0/1) among staff, respectively. The incidence rate for household contacts of primary school students was 6.6% (12/183) and 3.7% (1/27) for household contacts of primary school staff. In secondary schools, this was 3.5% (11/317) and 0% (0/1), respectively. Household contacts were more likely to test positive if their bubble contact tested positive although there were new infections among household contacts of uninfected bubble contacts.
Compared to other institutional settings, the overall risk of secondary infection in school bubbles and their household contacts was low. Our findings are important for developing evidence-based infection prevention guidelines for educational settings.
Journal Article
Thermal imaging in plant and ecosystem ecology: applications and challenges
by
Still, Christopher
,
Helliker, Brent
,
Kim, Youngil
in
Air temperature
,
Biogeochemistry
,
Cameras
2019
Temperature is a primary environmental control on ecological systems and processes at a range of spatial and temporal scales. The surface temperature of organisms is often more relevant for ecological processes than air temperature, which is much more commonly measured. Surface temperature influences—and is influenced by—a range of biological, physical, and chemical processes, providing a unique view of temperature effects on ecosystem function. Furthermore, surface temperatures vary markedly over a range of temporal and spatial scales and may diverge from air temperature by 40°C or more. Surface temperature measurements have been challenging due to sensor and computational limitations but are now feasible at high spatial and temporal resolutions using thermal imaging. Thus, significant advances in our understanding of plant and ecosystem thermal regimes and their functional consequences are now possible. Thermal measurements may be used to address many ecological questions, such as the thermal controls on plant and ecosystem metabolism and the impact of heat waves and drought. Further advances in this area will require interdisciplinary collaborations among practitioners in fields ranging from physiology to ecosystem ecology to remote sensing and geospatial analysis. In this overview, we demonstrate the feasibility, utility, and potential of thermal imaging for measuring vegetation surface temperatures across a range of scales and from measurement, analysis, and synthesis perspectives.
Journal Article
Parents’ and teachers’ attitudes to and experiences of the implementation of COVID-19 preventive measures in primary and secondary schools following reopening of schools in autumn 2020: a descriptive cross-sectional survey
2022
ObjectiveTo assess implementation and ease of implementation of control measures in schools as reported by staff and parents.DesignA descriptive cross-sectional survey.SettingStaff and parents/guardians of the 132 primary schools and 19 secondary schools participating in COVID-19 surveillance in school kids (sKIDs and sKIDsPLUS Studies).Main outcome measurePrevalence of control measures implemented in schools in autumn 2020, parental and staff perception of ease of implementation.ResultsIn total, 56 of 151 (37%) schools participated in this study, with 1953 parents and 986 staff members completing the questionnaire. Most common measures implemented by schools included regular hand cleaning for students (52 of 56, 93%) and staff (70 of 73, 96%), as reported by parents and staff, respectively, and was among the easiest to implement at all times for students (57%) and even more so, for staff (78%). Maintaining 2-metre distancing was less commonly reported for students (24%–51%) as it was for staff (81%–84%), but was one of the most difficult to follow at all times for students (25%) and staff (16%) alike. Some measures were more commonly reported by primary school compared to secondary school parents, including keeping students within the same small groups (28 of 41, 68% vs 8 of 15, 53%), ensuring the same teacher for classes (29 of 41, 71% vs 6 of 15, 40%). On the other hand, wearing a face covering while at school was reported by three-quarters of secondary school parents compared with only parents of 4 of 41 (10%) primary schools. Other measures such as student temperature checks (5%–13%) and advising staff work from home if otherwise healthy (7%–15%) were rarely reported.ConclusionsVariable implementation of infection control measures was reported, with some easier to implement (hand hygiene) than others (physical distancing).
Journal Article
Subcellular Metabolite and Lipid Analysis of Xenopus laevis Eggs by LAESI Mass Spectrometry
2014
Xenopus laevis eggs are used as a biological model system for studying fertilization and early embryonic development in vertebrates. Most methods used for their molecular analysis require elaborate sample preparation including separate protocols for the water soluble and lipid components. In this study, laser ablation electrospray ionization (LAESI), an ambient ionization technique, was used for direct mass spectrometric analysis of X. laevis eggs and early stage embryos up to five cleavage cycles. Single unfertilized and fertilized eggs, their animal and vegetal poles, and embryos through the 32-cell stage were analyzed. Fifty two small metabolite ions, including glutathione, GABA and amino acids, as well as numerous lipids including 14 fatty acids, 13 lysophosphatidylcholines, 36 phosphatidylcholines and 29 triacylglycerols were putatively identified. Additionally, some proteins, for example thymosin β4 (Xen), were also detected. On the subcellular level, the lipid profiles were found to differ between the animal and vegetal poles of the eggs. Radial profiling revealed profound compositional differences between the jelly coat vitelline/plasma membrane and egg cytoplasm. Changes in the metabolic profile of the egg following fertilization, e.g., the decline of polyamine content with the development of the embryo were observed using LAESI-MS. This approach enables the exploration of metabolic and lipid changes during the early stages of embryogenesis.
Journal Article
A microbial ecosystem beneath the West Antarctic ice sheet
by
Achberger, Amanda M.
,
Priscu, John C.
,
Barbante, Carlo
in
45/23
,
631/158/855
,
Antarctic Regions
2014
There has been active debate over microbial life in Antarctic subglacial lakes owing to a paucity of direct observations from beneath the ice sheet and concerns about contamination in the samples that do exist; here the authors present the first geomicrobiological description of pristine water and surficial sediments from Subglacial Lake Whillans, and show that the lake water contains a diverse microbial community, many members of which are closely related to chemolithoautotrophic bacteria and archaea.
Abundant microbes in subglacial Lake Whillans
Whether there is microbial life in subglacial lakes in the Antarctic has been a matter of controversy, as early results were compromised when it was discovered that contamination may have occurred during drilling. Discovered less than a decade ago using satellite data, Lake Whillans lies beneath some 800 metres of ice on the lower portion of the Whillans Ice Stream (WIS) in West Antarctica and is part of an extensive and evolving subglacial drainage network. In the first study to sample Antarctic subglacial waters directly, analysis of sediments obtained by the WISSARD drilling program shows that Lake Whillans' water contains more than 3,900 different types of bacteria and archaea, including one closely related to the nitrite oxidizing betaproteobacterium '
Candidatus
Nitrotoga arctica', which comprised 13% of the sequence data. The lake waters contain a diverse range of metabolically active microorganisms, many of which seem to gain nutrients from the melting ice and from the rock and sediment beneath the ice.
Liquid water has been known to occur beneath the Antarctic ice sheet for more than 40 years
1
, but only recently have these subglacial aqueous environments been recognized as microbial ecosystems that may influence biogeochemical transformations on a global scale
2
,
3
,
4
. Here we present the first geomicrobiological description of water and surficial sediments obtained from direct sampling of a subglacial Antarctic lake. Subglacial Lake Whillans (SLW) lies beneath approximately 800 m of ice on the lower portion of the Whillans Ice Stream (WIS) in West Antarctica and is part of an extensive and evolving subglacial drainage network
5
. The water column of SLW contained metabolically active microorganisms and was derived primarily from glacial ice melt with solute sources from lithogenic weathering and a minor seawater component. Heterotrophic and autotrophic production data together with small subunit ribosomal RNA gene sequencing and biogeochemical data indicate that SLW is a chemosynthetically driven ecosystem inhabited by a diverse assemblage of bacteria and archaea. Our results confirm that aquatic environments beneath the Antarctic ice sheet support viable microbial ecosystems, corroborating previous reports suggesting that they contain globally relevant pools of carbon and microbes
2
,
4
that can mobilize elements from the lithosphere
6
and influence Southern Ocean geochemical and biological systems
7
.
Journal Article
When a Tree Dies in the Forest
by
Grote, Rüdiger
,
Camarero, Jesus Julio
,
Gessler, Arthur
in
Abiotic stress
,
Analysis
,
Biogeochemistry
2016
Drought- and heat-driven tree mortality, along with associated insect outbreaks, have been observed globally in recent decades and are expected to increase in future climates. Despite its potential to profoundly alter ecosystem carbon and water cycles, how tree mortality scales up to ecosystem functions and fluxes is uncertain. We describe a framework for this scaling where the effects of mortality are a function of the mortality attributes, such as spatial clustering and functional role of the trees killed, and ecosystem properties, such as productivity and diversity. We draw upon remote-sensing data and ecosystem flux data to illustrate this framework and place climate-driven tree mortality in the context of other major disturbances. We find that emerging evidence suggests that climate-driven tree mortality impacts may be relatively small and recovery times are remarkably fast (~ 4 years for net ecosystem production). We review the key processes in ecosystem models necessary to simulate the effects of mortality on ecosystem fluxes and highlight key research gaps in modeling. Overall, our results highlight the key axes of variation needed for better monitoring and modeling of the impacts of tree mortality and provide a foundation for including climate-driven tree mortality in a disturbance framework.
Journal Article