4,286 research outputs found
p-Wave stabilization of three-dimensional Bose-Fermi solitons
We explore bright soliton solutions of ultracold Bose-Fermi gases, showing
that the presence of p-wave interactions can remove the usual collapse
instability and support stable soliton solutions that are global energy minima.
A variational model that incorporates the relevant s- and p-wave interactions
in the system is established analytically and solved numerically to probe the
dependencies of the solitons on key experimental parameters. Under attractive
s-wave interactions, bright solitons exist only as meta-stable states
susceptible to collapse. Remarkably, the presence of repulsive p-wave
interactions alleviates this collapse instability. This dramatically widens the
range of experimentally-achievable soliton solutions and indicates greatly
enhanced robustness. While we focus specifically on the boson-fermion pairing
of 87Rb and 40K, the stabilization inferred by repulsive p-wave interactions
should apply to the wider remit of ultracold Bose-Fermi mixtures.Comment: 9 pages, 6 figure
Performance management: Outsourcing and behavioural dynamics
Empirical research captured information from a multinational EU leader in the financial services sector during the early stage of outsourcing IT services and an action inquiry methodology surfaced the embedded web of meanings relating to changes and effects on working relationships. The results identified the importance of addressing strategic performance issues and inter/intra relationships between parent company team members and their outsource counterparts. Conclusions indicate that behavioural issues such as psychological contracts within inter/intra work groups, power and trust are highly significant managerial performance issues when perceiving the success or failure of an outsourcing strategy, such that they potentially outweigh economic factors and corporate performance imperatives specified in the service level agreement
Discovery of a large and bright bow shock nebula associated with low mass X-ray binary SAX J1712.6-3739
In a multiwavelength program dedicated to identifying optical counterparts of
faint persistent X-ray sources in the Galactic Bulge, we find an accurate X-ray
position of SAX J1712.6-3739 through Chandra observations, and discover its
faint optical counterpart using our data from EFOSC2 on the ESO 3.6m telescope.
We find this source to be a highly extincted neutron star LMXB with blue
optical colours. We serendipitously discover a relatively bright and large bow
shock shaped nebula in our deep narrowband H alpha imaging, most likely
associated with the X-ray binary. A nebula like this has never been observed
before in association with a LMXB, and as such provides a unique laboratory to
study the energetics of accretion and jets. We put forward different models to
explain the possible ways the LMXB may form this nebulosity, and outline how
they can be confirmed observationally.Comment: Accepted for publication in MNRAS-Letters; 5 pages, 4 figures, 2
tables. Quality of figure 2 downgraded because of arXiv file size limit
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'Not at the diagnosis point': Dealing with contradiction in autism assessment teams
Social science literature has documented how the concept of diagnosis can be seen as an interactive process, imbued with uncertainty and contradiction, which undermines a straightforward notion of diagnosis as a way to identify underlying biological problems that cause disease. We contribute to this body of work by examining the process of resolving contradiction in autism diagnosis for adults and adolescents. Autism is a useful case study as diagnosis can be a complex and protracted process due to the heterogeneity of symptoms and the necessity to interpret behaviours that may be ambiguous. We audio-recorded and transcribed 18 specialist clinical assessment meetings in four teams in England, covering 88 cases in two adult, one child and one adolescent (14+) setting. We undertook a qualitative analysis of discursive processes and narrative case-building structure utilised by clinicians to counteract contradiction. We identified a three-part interactional pattern which allows clinicians to forward evidence for and against a diagnosis, facilitates their collaborative decision-making process and enables them to build a plausible narrative which accounts for the diagnostic decision. Pragmatism was found to operate as a strategy to help assign diagnosis within a condition which, diagnostically, is permeated by uncertainty and contradiction. Resolution of contradiction from different aspects of the assessment serves to create a narratively-coherent, intelligible clinical entity that is autism
Near-Infrared Mapping and Physical Properties of the Dwarf-Planet Ceres
We study the physical characteristics (shape, dimensions, spin axis
direction, albedo maps, mineralogy) of the dwarf-planet Ceres based on
high-angular resolution near-infrared observations. We analyze adaptive optics
J/H/K imaging observations of Ceres performed at Keck II Observatory in
September 2002 with an equivalent spatial resolution of ~50 km. The spectral
behavior of the main geological features present on Ceres is compared with
laboratory samples. Ceres' shape can be described by an oblate spheroid (a = b
= 479.7 +/- 2.3 km, c = 444.4 +/- 2.1 km) with EQJ2000.0 spin vector
coordinates RA = 288 +/- 5 deg. and DEC = +66 +/- 5 deg. Ceres sidereal period
is measured to be 9.0741 +/- 0.0001 h. We image surface features with diameters
in the 50-180 km range and an albedo contrast of ~6% with respect to the
average Ceres albedo. The spectral behavior of the brightest regions on Ceres
is consistent with phyllosilicates and carbonate compounds. Darker isolated
regions could be related to the presence of frost.Comment: 11 pages, 8 Postscript figures, Accepted for publication in A&
The Cognitive Atlas: Toward a Knowledge Foundation for Cognitive Neuroscience
Cognitive neuroscience aims to map mental processes onto brain function, which begs the question of what “mental processes” exist and how they relate to the tasks that are used to manipulate and measure them. This topic has been addressed informally in prior work, but we propose that cumulative progress in cognitive neuroscience requires a more systematic approach to representing the mental entities that are being mapped to brain function and the tasks used to manipulate and measure mental processes. We describe a new open collaborative project that aims to provide a knowledge base for cognitive neuroscience, called the Cognitive Atlas (accessible online at http://www.cognitiveatlas.org), and outline how this project has the potential to drive novel discoveries about both mind and brain
Making things happen : a model of proactive motivation
Being proactive is about making things happen, anticipating and preventing problems, and seizing opportunities. It involves self-initiated efforts to bring about change in the work environment and/or oneself to achieve a different future. The authors develop existing perspectives on this topic by identifying proactivity as a goal-driven process involving both the setting of a proactive goal (proactive goal generation) and striving to achieve that proactive goal (proactive goal striving). The authors identify a range of proactive goals that individuals can pursue in organizations. These vary on two dimensions: the future they aim to bring about (achieving a better personal fit within one’s work environment, improving the organization’s internal functioning, or enhancing the organization’s strategic fit with its environment) and whether the self or situation is being changed. The authors then identify “can do,” “reason to,” and “energized to” motivational states that prompt proactive goal generation and sustain goal striving. Can do motivation arises from perceptions of self-efficacy, control, and (low) cost. Reason to motivation relates to why someone is proactive, including reasons flowing from intrinsic, integrated, and identified motivation. Energized to motivation refers to activated positive affective states that prompt proactive goal processes. The authors suggest more distal antecedents, including individual differences (e.g., personality, values, knowledge and ability) as well as contextual variations in leadership, work design, and interpersonal climate, that influence the proactive motivational states and thereby boost or inhibit proactive goal processes. Finally, the authors summarize priorities for future researc
Impaired postprandial skeletal muscle vascular responses to a mixed meal challenge in normoglycaemic people with a parent with type 2 diabetes
Aims/hypothesis: Microvascular blood flow (MBF) increases in skeletal muscle postprandially to aid in glucose delivery and uptake in muscle. This vascular action is impaired in individuals who are obese or have type 2 diabetes. Whether MBF is impaired in normoglycaemic people at risk of type 2 diabetes is unknown. We aimed to determine whether apparently healthy people at risk of type 2 diabetes display impaired skeletal muscle microvascular responses to a mixed-nutrient meal.
Methods: In this cross-sectional study, participants with no family history of type 2 diabetes (FH-) for two generations (n = 18), participants with a positive family history of type 2 diabetes (FH+; i.e. a parent with type 2 diabetes; n = 16) and those with type 2 diabetes (n = 12) underwent a mixed meal challenge (MMC). Metabolic responses (blood glucose, plasma insulin and indirect calorimetry) were measured before and during the MMC. Skeletal muscle large artery haemodynamics (2D and Doppler ultrasound, and Mobil-O-graph) and microvascular responses (contrast-enhanced ultrasound) were measured at baseline and 1 h post MMC.
Results: Despite normal blood glucose concentrations, FH+ individuals displayed impaired metabolic flexibility (reduced ability to switch from fat to carbohydrate oxidation vs FH-; p \u3c 0.05) during the MMC. The MMC increased forearm muscle microvascular blood volume in both the FH- (1.3-fold, p \u3c 0.01) and FH+ (1.3-fold, p \u3c 0.05) groups but not in participants with type 2 diabetes. However, the MMC increased MBF (1.9-fold, p \u3c 0.01), brachial artery diameter (1.1-fold, p \u3c 0.01) and brachial artery blood flow (1.7-fold, p \u3c 0.001) and reduced vascular resistance (0.7-fold, p \u3c 0.001) only in FH- participants, with these changes being absent in FH+ and type 2 diabetes. Participants with type 2 diabetes displayed significantly higher vascular stiffness (p \u3c 0.001) compared with those in the FH- and FH+ groups; however, vascular stiffness did not change during the MMC in any participant group.
Conclusions/interpretation: Normoglycaemic FH+ participants display impaired postprandial skeletal muscle macro- and microvascular responses, suggesting that poor vascular responses to a meal may contribute to their increased risk of type 2 diabetes. We conclude that vascular insulin resistance may be an early precursor to type 2 diabetes in humans, which can be revealed using an MMC
Electromagnetic Fluctuations during Fast Reconnection in a Laboratory Plasma
Clear evidence for a positive correlation is established between the
magnitude of magnetic fluctuations in the lower-hybrid frequency range and
enhancement of reconnection rates in a well-controlled laboratory plasma. The
fluctuations belong to the right-hand polarized whistler wave branch,
propagating obliquely to the reconnecting magnetic field, with a phase velocity
comparable to the relative drift velocity between electrons and ions. The short
coherence length and large variation along the propagation direction indicate
their strongly nonlinear nature in three dimensions.Comment: 4 pages, 6 figures, submitted to Phys. Rev. Let
Towards a Post-Graduate Level Curriculum for Biodiversity Informatics. Perspectives from the Global Biodiversity Information Facility (GBIF) Community
Biodiversity informatics is a new and evolving field, requiring efforts to develop capacity and a curriculum for this field of science. The main objective was to summarise the level of activity and the efforts towards developing biodiversity informatics curricula, for work-based training and/or academic teaching at universities, taking place within the Global Biodiversity Information Facility (GBIF) countries and its associated network. A survey approach was used to identify existing capacities and resources within the network. Most of GBIF Nodes survey respondents (80%) are engaged in onsite training activities, with a focus on work-based professionals, mostly researchers, policy-makers and students. Training topics include data mobilisation, digitisation, management, publishing, analysis and use, to enable the accessibility of analogue and digital biological data that currently reside as scattered datasets. An initial assessment of academic teaching activities highlighted that countries in most regions, to varying degrees, were already engaged in the conceptualisation, development and/or implementation of formal academic programmes in biodiversity informatics, including programmes in Benin, Colombia, Costa Rica, Finland, France, India, Norway, South Africa, Sweden, Taiwan and Togo. Digital e-learning platforms were an important tool to help build capacity in many countries. In terms of the potential in the Nodes network, 60% expressed willingness to be recruited or commissioned for capacity enhancement purposes. Contributions and activities of various country nodes across the network have been highlighted and a working curriculum framework has been defined. © 2021. Parker-Allie F et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are creditedPeer reviewe
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