319 research outputs found
The Reciprocity Theory of Rights
David Rodin, Co-Director and Senior Research Fellow, ELAC, University of Oxford, provides a theoretical account of a central class of moral rights; their normative grounding, the conditions for their possession and forfeiture, and their moral stringency. He argues that interpersonal rights against harm and rights to assistance are best understood as arising from reciprocity relations between moral agents. This account has significant advantages compared with rivals such as the interest theory of rights. By explaining the differential enforceability of rights against harm and rights to assistance, the reciprocity theory helps to refute an argument made by Cecile Fabre that the poor may have a justification for engaging in war against the affluent to compel them to fulfil their duties of assistance to the poor
A study of the pre-translational regulation of follicle-stimulating hormone synthesis by gonadotrophin-releasing hormone and gonadal steroids
In adult male and female rats and mice, there was, generally, a good qualitative correlation between follicle-stimulating hormone (FSH) B mRNA levels and overall FSH synthesis (as reflected by pituitary and serum FSH), indicating the physiological significance of this pre-translational regulation. Oestradiol treatment from the time of operation attenuated the postovariectomy increase in FSH B mRNA in female rats and mice, while testosterone reduced FSH B mRNA levels in acutely orchidectomized males. There were no major differences between these species in the regulation of FSH B gene expression by gonadal steroids, but the results suggest a role for additional gonadal inhibitory factor(s) in this feedback regulation. In chronically castrated rats, oestradiol suppressed FSH B mRNA levels rapidly in females, but testosterone increased FSH B mRNA in males. This variability of response to testosterone may reflect interactions with other regulatory factors. Abolition of gonadotrophin-releasing hormone (GnRH) stimulation of the pituitary by GnRH antagonist or antiserum treatment, and gonadotroph desensitization using a GnRH agonist, prevented the increases in FSH B mRNA in orchidectomized rats and reduced FSH B mRNA levels in intact rats. Changes in overall FSH biosynthesis occurred in parallel. These observations suggest that FSH B gene expression is GnRH-dependent, that GnRH is the major releasing factor for FSH, and that modulation of GnRH secretion is the principal target for gonadal steroid negative feedback. For in vitro studies of gene regulation, two bovine FSH B genomic DNA clones were isolated and characterized. However, neither contained upstream sequences, the likely location of hormone response elements. Whilst there are differences in the gonadal regulation of FSH B and luteinizing hormone (LH) B genes, GnRH exerts parallel effects on LH B and FSH B mRNA levels, suggesting that it provides a common primary stimulus for the induction of both B-subunit genes in vivo
Strain-induced gauge and Rashba fields in ferroelectric Rashba lead chalcogenide PbX monolayers (X = S, Se, Te)
One of the exciting features of two-dimensional (2D) materials is their
electronic and optical tunability through strain engineering. Previously, we
found a class of 2D ferroelectric Rashba semiconductors PbX (X = S, Se, Te)
with tunable spin-orbital properties. In this work, based on our previous
tight-binding (TB) results, we derive an effective low-energy Hamiltonian
around the symmetry points that captures the effects of strain on the
electronic properties of PbX. We find that strains induce gauge fields which
shift the Rashba point and modify the Rashba parameter. This effect is
equivalent to the application of in-plane magnetic fields. The out-of-plane
strain, which is proportional to the electric polarization, is also shown to
modify the Rashba parameter. Overall, our theory connects strain and spin
splitting in ferroelectric Rashba materials, which will be important to
understand the strain-induced variations in local Rashba parameters that will
occur in practical applications
Spin-Orbit Dirac Fermions in 2D Systems
We propose a novel model for including spin-orbit interactions in buckled two
dimensional systems. Our results show that in such systems, intrinsic
spin-orbit coupling leads to a formation of Dirac cones, similar to Rashba
model. We explore the microscopic origins of this behaviour and confirm our
results using DFT calculations
Two-dimensional square buckled Rashba lead chalcogenides
We propose the lead sulphide (PbS) monolayer as a two-dimensional semiconductor with a large Rashba-like spin-orbit effect controlled by the out-of-plane buckling. The buckled PbS conduction band is found to possess Rashba-like dispersion and spin texture at the M and Î points, with large effective Rashba parameters of λâŒ5 eV Ă
and λâŒ1 eV Ă
, respectively. Using a tight-binding formalism, we show that the Rashba effect originates from the very large spin-orbit interaction and the hopping term that mixes the in-plane and out-of-plane p orbitals of Pb and S atoms. The latter, which depends on the buckling angle, can be controlled by applying strain to vary the spin texture as well as the Rashba parameter at Î and M. Our density functional theory results together with tight-binding formalism provide a unifying framework for designing Rashba monolayers and for manipulating their spin properties.P.Z.H., H.S.P., and D.K.C. acknowledge the support of the Physics and Mechanical Engineering Department at Boston University. P.Z.H. is grateful for the hospitality of the NUS Centre for Advanced 2D Materials and Graphene Research Centre where this work was initiated. D.K.C. acknowledges the hospitality of the Aspen Center for Physics, which is supported by the US National Science Foundation Grant No. PHY-1607611. A.S.R., A.C.,and A.H.C.N. acknowledge support by the National Research Foundation, Prime Minister Office, Singapore, under its Medium Sized Centre Programme and CRP award "Novel 2D materials with tailored properties: Beyond graphene" (Grant No. R-144-000295-281). (Physics and Mechanical Engineering Department at Boston University; PHY-1607611 - US National Science Foundation; R-144-000295-281 - National Research Foundation, Prime Minister Office, Singapore, under its Medium Sized Centre Programme and CRP award "Novel 2D materials with tailored properties: Beyond graphene")Published versio
A systematic review of treating recurrent head and neck cancer: a reintroduction of brachytherapy with or without surgery.
Purpose: To review brachytherapy use in recurrent head and neck carcinoma (RHNC) with focus on its efficacy and complication rates.
Material and methods: A literature search of PubMed, Ovid, Google Scholar, and Scopus was conducted from 1990 to 2017. Publications describing treatment of RHNC with brachytherapy with or without surgery were included. The focus of this review is on oncologic outcomes and the safety of brachytherapy in the recurrent setting.
Results: Thirty studies involving RHNC treatment with brachytherapy were reviewed. Brachytherapy as adjunctive treatment to surgical resection appears to be associated with an improved local regional control and overall survival, when compared with the published rates for re-irradiation utilizing external beam radiotherapy (RT) or brachytherapy alone. Safety data remains variable with different isotopes and dose rates with implantable brachytherapy demonstrating a tolerable side effect profile.
Conclusions: Although surgery remains a mainstay treatment for RHNC, intraoperative interstitial brachytherapy delivery as adjunctive therapy may improve the treatment outcome and may be associated with fewer complication rates as compared to reirradiation using external beam radiotherapy. Further investigations are required to elucidate the role of brachytherapy for RHNC
Factor structure of the Beck Hopelessness Scale in individuals with advanced cancer
Although the Beck Hopelessness Scale is often used with the seriously ill, its factor structure has been given relatively little consideration in this context. The factor structure of this scale was examined in a sample of 406 ambulatory patients with advanced lung or gastrointestinal cancer, using a sequential exploratory confirmatory factor analysis procedure. A two-factor model was consistent with the data: The first factor reflected a negative outlook and was labeled ânegative expectationsâ; the second factor identified a sense of resignation and was labeled âloss of motivation.â Implications regarding scoring of the scale in this population are discussed, as are implications of the two-factor structure for our understanding of hopelessness in individuals with advanced cancer.Social Sciences and Humanities Research Council (SSHRC
Species delimitation in lemurs: multiple genetic loci reveal low levels of species diversity in the genus Cheirogaleus
<p>Abstract</p> <p>Background</p> <p>Species are viewed as the fundamental unit in most subdisciplines of biology. To conservationists this unit represents the currency for global biodiversity assessments. Even though Madagascar belongs to one of the top eight biodiversity hotspots of the world, the taxonomy of its charismatic lemuriform primates is not stable. Within the last 25 years, the number of described lemur species has more than doubled, with many newly described species identified among the nocturnal and small-bodied cheirogaleids. Here, we characterize the diversity of the dwarf lemurs (genus <it>Cheirogaleus</it>) and assess the status of the seven described species, based on phylogenetic and population genetic analysis of mtDNA (<it>cytb </it>+ <it>cox2</it>) and three nuclear markers (<it>adora3</it>, <it>fiba </it>and <it>vWF</it>).</p> <p>Results</p> <p>This study identified three distinct evolutionary lineages within the genus <it>Cheirogaleus</it>. Population genetic cluster analyses revealed a further layer of population divergence with six distinct genotypic clusters.</p> <p>Conclusion</p> <p>Based on the general metapopulation lineage concept and multiple concordant data sets, we identify three exclusive groups of dwarf lemur populations that correspond to three of the seven named species: <it>C. major</it>, <it>C. medius </it>and <it>C. crossleyi</it>. These three species were found to be genealogically exclusive in both mtDNA and nDNA loci and are morphologically distinguishable. The molecular and morphometric data indicate that <it>C. adipicaudatus </it>and <it>C. ravus </it>are synonymous with <it>C. medius </it>and <it>C. major</it>, respectively. <it>Cheirogaleus sibreei </it>falls into the <it>C. medius </it>mtDNA clade, but in morphological analyses the membership is not clearly resolved. We do not have sufficient data to assess the status of <it>C. minusculus</it>. Although additional patterns of population differentiation are evident, there are no clear subdivisions that would warrant additional specific status. We propose that ecological and more geographic data should be collected to confirm these results.</p
Corrigendum: Life cycle assessment of a novel electrocatalytic process for the production of bulk chemical ethylene oxide from biogenic CO2
Life cycle assessment of a novel electrocatalytic process for the production of bulk chemical ethylene oxide from biogenic CO2
Carbon capture and utilization (CCU) technologies support future energy and climate transition goals by recycling carbon dioxide (CO2) emissions. The use of biogenic CO2 from renewable sources, is an avenue for the production of fully renewable products. Fossil-based materials can potentially be replaced in the long term while allowing for the use of so called âwasteâ streams. To foster the development of a circular economy more insights need to be gained on the life cycle impact of CCU technologies. This study analyzed a CCU process chain, with focus on the utilization of volatile renewable electricity and biogenic CO2. We performed a cradle-to-gate life cycle assessment, evaluating various environmental impact categories (CML 2001 methodology) and primary energy demand (PED) with GaBi LCA software by spheraÂź. The targeted olefin is ethylene oxide (C2H4O), which is a crucial intermediate chemical for the production of various synthetic materials, such as polyethylene terephthalate (PET). As functional unit, 1 kg ethylene oxide was chosen. In the novel process at first ethylene (C2H4) and hydrogen peroxide (H2O2) are produced from water and CO2via an electrocatalytic process (Power-to-X process). In a second step, the two intermediates are synthesized to ethylene oxide. The theoretical implementation of a medium-scale process under average European conditions was considered in 12 scenarios that differed in energy supply and CO2 source. Sensitivity analyses were conducted to evaluate the influence of the energy and resource efficiencies of the production steps. The process was compared to its fossil benchmark, an existing conventional EO production chain. Concerning the global warming potential (GWP), negative emissions of up to â0.5 kg CO2 eq./kg product were calculated under optimized process conditions regarding energy and conversion efficiency and using biogenic CO2. In contrast, the GWP exceeded the fossil benchmark when the European grid mix was applied. The PED of 87 MJ/kg product under optimized conditions is comparable to that of other Power-to-X processes, but is high compared to fossil-based ethylene oxide. Based on the results we conclude that the energy efficiency of the electrocatalytic cell and renewable energy as input are the main levers to achieve a low environmental impact
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