2,622 research outputs found
3D Virtual Worlds and the Metaverse: Current Status and Future Possibilities
Moving from a set of independent virtual worlds to an integrated network of 3D virtual worlds or Metaverse rests on progress in four areas: immersive realism, ubiquity of access and identity, interoperability, and scalability. For each area, the current status and needed developments in order to achieve a functional Metaverse are described. Factors that support the formation of a viable Metaverse, such as institutional and popular interest and ongoing improvements in hardware performance, and factors that constrain the achievement of this goal, including limits in computational methods and unrealized collaboration among virtual world stakeholders and developers, are also considered
Left of bang interventions in trauma : ethical implications for military medical prophylaxis
Advances in medical capability should be accompanied by discussion of their ethical implications. In the military medical context there is a growing interest in developing prophylactic interventions that will mitigate the effects of trauma and improve survival. The ethics of this novel capability are currently unexplored. This paper describes the concept of trauma prophylaxis (Left Of Bang Interventions in Trauma) and outlines some of the ethical issues that need to be considered, including within concept development, research and implementation. Trauma prophylaxis can be divided into interventions that do not (type 1) and those that do (type 2) have medical enhancement as an unintended side effect of their prophylactic action. We conclude that type 1 interventions have much in common with established military medical prophylaxis, and the potentially enhancing qualities of type 2 interventions raise different issues. We welcome further debate on both interventions
Feather growth rate and mass in nearctic passerines with variablemigratory behavior and molt pattern
Bird species vary greatly in the duration of their annual complete feather molt. However, such variation is not well documented
in birds from many biogeographic areas, which restricts our understanding of the diversification of molt strategies. Recent research has revealed
that molt duration can be estimated in passerines from ptilochronology-based measurements of the growth rate of their tail feathers. We used
this approach to explore how molt duration varied in 98 Nearctic species that have different migratory strategies and molt patterns. As previously
documented for Palearctic species, migration was associated with a shortening of molt duration among species that molted during summer on
their breeding range. However, molts of winter-molting migratory species were as long as those of summer-molting sedentary species, which
suggests that winter molt also allows Nearctic migrants to avoid the temporal constraints experienced during summer. Our results also suggest
that migratory species that undergo a stopover molt within the Mexican monsoon region have the shortest molt duration among all Nearctic
passerines. Interestingly, and contrary to expectations from a potential tradeoff between molt duration and feather quality, observed variation
in feather growth rate was positively correlated with differences in tail feather mass, which may be caused by differences among groups in the
availability of resources for molting. We encourage the use of similar approaches to study the variation in molt duration in other geographic areas
where knowledge of the evolution of molt is limited.
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Effect of oil palm sustainability certification on deforestation and fire in Indonesia.
Many major corporations and countries have made commitments to purchase or produce only "sustainable" palm oil, a commodity responsible for substantial tropical forest loss. Sustainability certification is the tool most used to fulfill these procurement policies, and around 20% of global palm oil production was certified by the Roundtable on Sustainable Palm Oil (RSPO) in 2017. However, the effect of certification on deforestation in oil palm plantations remains unclear. Here, we use a comprehensive dataset of RSPO-certified and noncertified oil palm plantations (∼188,000 km2) in Indonesia, the leading producer of palm oil, as well as annual remotely sensed metrics of tree cover loss and fire occurrence, to evaluate the impact of certification on deforestation and fire from 2001 to 2015. While forest loss and fire continued after RSPO certification, certified palm oil was associated with reduced deforestation. Certification lowered deforestation by 33% from a counterfactual of 9.8 to 6.6% y-1 Nevertheless, most plantations contained little residual forest when they received certification. As a result, by 2015, certified areas held less than 1% of forests remaining within Indonesian oil palm plantations. Moreover, certification had no causal impact on forest loss in peatlands or active fire detection rates. Broader adoption of certification in forested regions, strict requirements to avoid all peat, and routine monitoring of clearly defined forest cover loss in certified and RSPO member-held plantations appear necessary if the RSPO is to yield conservation and climate benefits from reductions in tropical deforestation
Spectroscopic Observations of Convective Patterns in the Atmospheres of Metal-Poor Stars
Convective line asymmetries in the optical spectrum of two metal-poor stars,
Gmb1830 and HD140283, are compared to those observed for solar metallicity
stars. The line bisectors of the most metal-poor star, the subgiant HD140283,
show a significantly larger velocity span that the expectations for a
solar-metallicity star of the same spectral type and luminosity class. The
enhanced line asymmetries are interpreted as the signature of the lower metal
content, and therefore opacity, in the convective photospheric patterns. These
findings point out the importance of three-dimensional convective velocity
fields in the interpretation of the observed line asymmetries in metal-poor
stars, and in particular, urge for caution when deriving isotopic ratios from
observed line shapes and shifts using one-dimensional model atmospheres.
The mean line bisector of the photospheric atomic lines is compared with
those measured for the strong Mg I b1 and b2 features. The upper part of the
bisectors are similar, and assuming they overlap, the bottom end of the
stronger lines, which are formed higher in the atmosphere, goes much further to
the red. This is in agreement with the expected decreasing of the convective
blue-shifts in upper atmospheric layers, and compatible with the high velocity
redshifts observed in the chromosphere, transition region, and corona of
late-type stars.Comment: 27 pages, LaTeX; 10 Figures (14 PostScript files); to be published in
The Astrophysical Journa
The large-scale shock in the cluster of galaxies Hydra A
We analyzed a deep XMM-Newton observation of the cluster of galaxies Hydra A,
focusing on the large-scale shock discovered as a surface brightness
discontinuity in Chandra images. The shock front can be seen both in the
pressure map and in temperature profiles in several sectors. The Mach numbers
determined from the temperature jumps are in good agreement with the Mach
numbers derived from EPIC/pn surface brightness profiles and previously from
Chandra data and are consistent with M~1.3. The estimated shock age in the
different sectors using a spherically symmetric point explosion model ranges
between 130 and 230 Myr and the outburst energy between 1.5 and 3e61 ergs. The
shape of the shock seen in the pressure map can be approximated with an ellipse
centered 70 kpc towards the NE from the cluster center. We aimed to develop a
better model that can explain the offset between the shock center and the AGN
and give a consistent result on the shock age and energy. To this end, we
performed 3D hydrodynamical simulations in which the shock is produced by a
symmetrical pair of AGN jets launched in a spherical galaxy cluster. As an
explanation of the observed offset of the shock center, we consider large-scale
bulk flows in the intracluster medium. The simulation successfully reproduces
the size, ellipticity, and average Mach number of the observed shock front. The
predicted age of the shock is 160 Myr and the total input energy 3e61 erg. Both
values are within the range determined by the spherically symmetric model.
Matching the observed 70 kpc offset of the shock ellipse from the cluster
center requires large-scale coherent motions with a high velocity of 670 km/s.
We discuss the feasibility of this scenario and offer alternative ways to
produce the offset and to further improve the simulation.Comment: 14 pages, accepted for publication in A&A, minor revision compared to
previous versio
The effect of rituximab therapy on immunoglobulin levels in patients with multisystem autoimmune disease.
BACKGROUND: Rituximab is a B cell depleting anti-CD20 monoclonal antibody. CD20 is not expressed on mature plasma cells and accordingly rituximab does not have immediate effects on immunoglobulin levels. However, after rituximab some patients develop hypogammaglobulinaemia. METHODS: We performed a single centre retrospective review of 177 patients with multisystem autoimmune disease receiving rituximab between 2002 and 2010. The incidence, severity and complications of hypogammaglobulinaemia were investigated. RESULTS: Median rituximab dose was 6 g (1-20.2) and total follow-up was 8012 patient-months. At first rituximab, the proportion of patients with IgG <6 g/L was 13% and remained stable at 17% at 24 months and 14% at 60 months. Following rituximab, 61/177 patients (34%) had IgG <6 g/L for at least three consecutive months, of whom 7/177 (4%) had IgG <3 g/L. Low immunoglobulin levels were associated with higher glucocorticoid doses during follow up and there was a trend for median IgG levels to fall after ≥ 6 g rituximab. 45/115 (39%) with IgG ≥ 6 g/L versus 26/62 (42%) with IgG <6 g/L experienced severe infections (p=0.750). 6/177 patients (3%) received intravenous immunoglobulin replacement therapy, all with IgG <5 g/L and recurrent infection. CONCLUSIONS: In multi-system autoimmune disease, prior cyclophosphamide exposure and glucocorticoid therapy but not cumulative rituximab dose was associated with an increased incidence of hypogammaglobulinaemia. Severe infections were common but were not associated with immunoglobulin levels. Repeat dose rituximab therapy appears safe with judicious monitoring
A qualitative study of stakeholders' perspectives on the social network service environment
Over two billion people are using the Internet at present, assisted by the mediating activities of software agents which deal with the diversity and complexity of information. There are, however, ethical issues due to the monitoring-and-surveillance, data mining and autonomous nature of software agents. Considering the context, this study aims to comprehend stakeholders' perspectives on the social network service environment in order to identify the main considerations for the design of software agents in social network services in the near future. Twenty-one stakeholders, belonging to three key stakeholder groups, were recruited using a purposive sampling strategy for unstandardised semi-structured e-mail interviews. The interview data were analysed using a qualitative content analysis method. It was possible to identify three main considerations for the design of software agents in social network services, which were classified into the following categories: comprehensive understanding of users' perception of privacy, user type recognition algorithms for software agent development and existing software agents enhancement
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Psychosocial Challenges Facing Women Living with HIV During the Perinatal Period in Rural Uganda
The complexities of navigating pregnancy while living with HIV predispose women to additional stress. Finding ways to minimize psychosocial challenges during the perinatal period may maximize the well-being of mothers living with HIV and their children. The goal of this study was to explore psychosocial challenges experienced by women living with HIV (WLWH) during pregnancy and the postpartum.
We conducted individual in-depth interviews with 20 WLWH recruited from an HIV treatment cohort study in Mbarara, Uganda as part of a larger study exploring perinatal depression. We conducted content analyses to identify themes related to challenges of WLWH during pregnancy and the postpartum. Participants had a median age of 33 years [IQR: 28± 35], a median of 3 living children [IQR: 2±5], and 95% had achieved HIV-RNA suppression. Challenges were organized around the following themes: HIV -related stigma from health professionals, HIV status disclosure dilemma, unintended pregnancy and intimate partner violence, HIV and environmental structural barriers and distress and fear related to maternal and child health. Stigma centered on discrimination by health care professionals and personal shame associated with being pregnant as a WLWH. This led to difficulty engaging in HIV care, particularly when coupled with structural barriers, such as lack of transportation to clinic. Participants experienced intimate partner violence and lacked support from their partners and family members. Distress and fear about the health and uncertainty about the future of the unborn baby due to maternal deteriorating physical health was common. The perinatal period is a time of stress for WLWH. Challenges experienced by WLWH may compromise successful engagement in HIV care and may reduce quality of life for women and their children. Strategies aimed at alleviating the challenges of WLWH should involve the larger structural environment including partners, family and community member as well as policy makers, funders and program implementers to work together for the common cause. These consolidated efforts may not only lower the risk of psychological distress but has potential to create long lasting solutions to benefit the wider community
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