915 research outputs found
Coherent Ro-vibrational Revivals in a Thermal Molecular Ensemble
We report an experimental and theoretical study of the evolution of
vibrational coherence in a thermal ensemble of nitrogen molecules. Rotational
dephasing and rephasing of the vibrational coherence is detected by coherent
anti-Stokes Raman scattering. The existence of ro-vibrational coupling and the
discrete energy spectrum of the rotational bath lead to a whole new class of
full and fractional ro-vibrational revivals. Following the rich ro-vibrational
dynamics on a nanosecond time scale with sub-picosecond time resolution enables
us to determine the second-order ro-vibrational constant and assess
new possibilities of controlling decoherence.Comment: submitted at Physical Review
SCC: A Service Centered Calculus
We seek for a small set of primitives that might serve as a basis for formalising and programming service oriented applications over global computers. As an outcome of this study we introduce here SCC, a process calculus that features explicit notions of service definition, service invocation and session handling. Our proposal has been influenced by Orc, a programming model for structured orchestration of services, but the SCCâs session handling mechanism allows for the definition of structured interaction protocols, more complex than the basic request-response provided by Orc. We present syntax and operational semantics of SCC and a number of simple but nontrivial programming examples that demonstrate flexibility of the chosen set of primitives. A few encodings are also provided to relate our proposal with existing ones
The effect of signal acquisition and processing choices on ApEn values: Towards a âgold standardâ for distinguishing effort levels from isometric force records
Approximate Entropy (ApEn) is frequently used to identify changes in the complexity of isometric force records with ageing and disease. Different signal acquisition and processing parameters have been used, making comparison or confirmation of results difficult. This study determined the effect of sampling and parameter choices by examining changes in ApEn values across a range of submaximal isometric contractions of the First Dorsal Interosseus. Reducing the sample rate by decimation changed both the value and pattern of ApEn values dramatically. The pattern of ApEn values across the range of effort levels was not sensitive to the filter cut-off frequency, or the criterion used to extract the section of data for analysis. The complexity increased with increasing effort levels using a fixed ârâ value (which accounts for measurement noise) but decreased with increasing effort level when ârâ was set to 0.1 of the standard deviation of force. It is recommended isometric force records are sampled at frequencies >200 Hz, template length (âmâ) is set to 2, and 'r' set to measurement system noise or 0.1 SD depending on physiological process to be distinguished. It is demonstrated that changes in ApEn across effort levels are related to changes in force gradation strategy
Localization transition of random copolymers at interfaces
We consider adsorption of random copolymer chains onto an interface within
the model of Garel et al. Europhysics Letters 8, 9 (1989). By using the replica
method the adsorption of the copolymer at the interface is mapped onto the
problem of finding the ground state of a quantum mechanical Hamiltonian. To
study this ground state we introduce a novel variational principle for the
Green's function, which generalizes the well-known Rayleigh-Ritz method of
Quantum Mechanics to nonstationary states. Minimization with an appropriate
trial Green's function enables us to find the phase diagram for the
localization-delocalization transition for an ideal random copolymer at the
interface.Comment: 5 page
Why alternative teenagers self-harm: exploring the link between non-suicidal self-injury, attempted suicide and adolescent identity
Background:
The term âself-harmâ encompasses both attempted suicide and non-suicidal self-injury (NSSI). Specific adolescent subpopulations such as ethnic or sexual minorities, and more controversially, those who identify as âAlternativeâ (Goth, Emo) have been proposed as being more likely to self-harm, while other groups such as âJocksâ are linked with protective coping behaviours (for example exercise). NSSI has autonomic (it reduces negative emotions) and social (it communicates distress or facilitates group âbondingâ) functions. This study explores the links between such aspects of self-harm, primarily NSSI, and youth subculture.<p></p>
Methods:
An anonymous survey was carried out of 452 15 year old German school students. Measures included: identification with different youth cultures, i.e. Alternative (Goth, Emo, Punk), Nerd (academic) or Jock (athletic); social background, e.g. socioeconomic status; and experience of victimisation. Self-harm (suicide and NSSI) was assessed using Self-harm Behavior Questionnaire and the Functional Assessment of Self-Mutilation (FASM).<p></p>
Results:
An âAlternativeâ identity was directly (râââ0.3) and a âJockâ identity inversely (râââ-0.1) correlated with self-harm. âAlternativeâ teenagers self-injured more frequently (NSSI 45.5% vs. 18.8%), repeatedly self-injured, and were 4â8 times more likely to attempt suicide (even after adjusting for social background) than their non-Alternative peers. They were also more likely to self-injure for autonomic, communicative and social reasons than other adolescents.<p></p>
Conclusions:
About half of âAlternativeâ adolescentsâ self-injure, primarily to regulate emotions and communicate distress. However, a minority self-injure to reinforce their group identity, i.e. âTo feel more a part of a groupâ
Measurements of electron-proton elastic cross sections for
We report on precision measurements of the elastic cross section for
electron-proton scattering performed in Hall C at Jefferson Lab. The
measurements were made at 28 unique kinematic settings covering a range in
momentum transfer of 0.4 5.5 . These measurements
represent a significant contribution to the world's cross section data set in
the range where a large discrepancy currently exists between the ratio of
electric to magnetic proton form factors extracted from previous cross section
measurements and that recently measured via polarization transfer in Hall A at
Jefferson Lab.Comment: 17 pages, 18 figures; text added, some figures replace
Functional diversity and community assembly of river invertebrates show globally consistent responses to decreasing glacier cover
Global change threatens invertebrate biodiversity and its central role in numerous ecosystem functions and services. Functional trait analyses have been advocated to uncover global mechanisms behind biodiversity responses to environmental change, but the application of this approach for invertebrates is underdeveloped relative to other organism groups. From an evaluation of 363 records comprising >1.23 million invertebrates collected from rivers across nine biogeographic regions on three continents, consistent responses of community trait composition and diversity to replicated gradients of reduced glacier cover are demonstrated. After accounting for a systematic regional effect of latitude, the processes shaping river invertebrate functional diversity are globally consistent. Analyses nested within individual regions identified an increase in functional diversity as glacier cover decreases. Community assembly models demonstrated that dispersal limitation was the dominant process underlying these patterns, although environmental filtering was also evident in highly glacierized basins. These findings indicate that predictable mechanisms govern river invertebrate community responses to decreasing glacier cover globally.This work was funded by the following organisations: The UK Natural Environment Research
Council grants and studentships GR9/2913, NE/E003729/1, NE/E004539/1, NE/E004148/1,
20
NE/G523963/1, NER/S/A/2003/11192, and NE/L002574/1; the European Union
Environment and Climate Programme Arctic and Alpine Stream Ecosystem Research
(AASER) project (ENV-CT95-0164); EU-FP7 Assessing Climate impacts on the Quality and
quantity of WAter (ACQWA) project (212250); Icelandic Research Council (954890095,
954890096); University of Iceland Research Fund (GMG96, GMG97, GMG98), Wyoming
Center for Environmental Hydrology and Geophysics-National Science Foundation
(1208909); USA-Wyoming NASA Space Grant Faculty Research Initiation (#NNX10A095H);
USA-NSF Wyoming Epscor; Nationalpark Hohe Tauern, Austria; the Royal Society
(International Outgoing Grant 2006/R4); the Leverhulme Trust; the Universities of Leeds,
Birmingham, Iceland and Innsbruck; European Centre for Arctic Environmental Research
(ARCFAC): a Research Infrastructures Action of the European Community FP6 (026129-2008-
72); the Stelvio National Park (2000-2001); the Autonomous Province of Trento (HIGHEST
project, 2001-2004, del. PAT n. 1060/2001; VETTA project, 2003-2006, del. PAT n.
3402/2002); MUSE-Museo delle Scienze. We are grateful to Russell Taylor and Mike
Winterbourn at the University of Canterbury, NZ, who helped to collect NZ invertebrate data
and assisted with identification, and to Hakon Adalsteinsson who contributed to data
collection in Iceland. Many other people, too numerous to mention, assisted with fieldwork
at all of the study locations. The European Science Foundation sponsored an exploratory
âďžă´ďžă˛ď˝´ďžăŽ Wďžă。ăďžWS ăGďž;I。Wă´-fed rivers, hydroecology and climate change: current knowledge
and future network of monitoring sites (GLAC-HYDROECO-NETăśă ăď˝´;ă â;㲠エWďžS 。ďž
Birmingham, UK in September of 2013 where some of the ideas in this paper were first
discussedPeer Reviewe
Institutional creativity and pathologies of potential space: The modern university
This paper proposes the applicability of object relations psychoanalytic conceptions of dialogue (Ogden, 1986, 1993) to thinking about relationships and relational structures and their governance in universities. It proposes that: the qualities of dialogic relations in creative institutions are the proper index of creative productivity; that is of, as examples, âthinkingâ (Evans, 2004), âemotional learningâ (Salzberger-Wittenburg et al., 1983) or âcriticalityâ (Barnett, 1997); contemporary institutionsâ explicit preoccupation in assuring, monitoring and managing creative âdialogueâ can, in practice, pervert creative processes and thoughtful symbolic productivity, thus inhibiting studentsâ development and the quality of âthinking spaceâ for teaching and research. In this context the paper examines uncanny and perverse connections between Paulo Freireâs (1972) account of educational empowerment and dialogics (from his Pedagogy of the oppressed) to the consumerist (see, for example, Clarke & Vidler, 2005) rhetoric of student empowerment, as mediated by some strands of managerialism in contemporary higher education. The paper grounds its critique of current models of dialogue, feedback loops, audit and other mechanisms of accountability (Power, 1997; Strathern, 2000), in a close analysis of how creative thinking emerges. The paper discusses the failure to maintain a dialogic space in humanities and social science areas in particular, exploring psychoanalytic conceptions from Donald Winnicott (1971), Milner (1979), Thomas Ogden (1986) and Csikszentmihalyi (1997). Coleridgeâs ideas about imagination as the movement of thought between subjective and objective modes are discussed in terms of both intra- and inter-subjective relational modes of âdialogueâ, which are seen as subject to pathology in the pathologically structured psychosocial environment. Current patterns of institutional governance, by micromanaging dialogic spaces, curtail the ânaturalâ rhythms and temporalities of imagination by giving an over-emphasis to the moment of outcome, at the expense of holding the necessary vagaries of process in the institutional âmindâ. On the contrary, as this paper argues, creative thinking lies in sporadic emergences at the conjunction of object/(ive) outcome and through (thought) processes
- âŚ