1,939 research outputs found
Relativistic quantum measurement
Does the measurement of a quantum system necessarily break Lorentz
invariance? We present a simple model of a detector that measures the spacetime
localization of a relativistic particle in a Lorentz invariant manner. The
detector does not select a preferred Lorentz frame as a Newton-Wigner
measurement would do. The result indicates that there exists a Lorentz
invariant notion of quantum measurement and sheds light on the issue of the
localization of a relativistic particle. The framework considered is that of
single-particle mechanics as opposed to field theory. The result may be taken
as support for the interpretation postulate of the spacetime-states formulation
of single-particle quantum theory.Comment: 9 pages, no figures: Revision: references adde
A programmable two-qubit quantum processor in silicon
With qubit measurement and control fidelities above the threshold of
fault-tolerance, much attention is moving towards the daunting task of scaling
up the number of physical qubits to the large numbers needed for fault tolerant
quantum computing. Here, quantum dot based spin qubits may offer significant
advantages due to their potential for high densities, all-electrical operation,
and integration onto an industrial platform. In this system, the
initialisation, readout, single- and two-qubit gates have been demonstrated in
various qubit representations. However, as seen with other small scale quantum
computer demonstrations, combining these elements leads to new challenges
involving qubit crosstalk, state leakage, calibration, and control hardware
which provide invaluable insight towards scaling up. Here we address these
challenges and demonstrate a programmable two-qubit quantum processor in
silicon by performing both the Deutsch-Josza and the Grover search algorithms.
In addition, we characterise the entanglement in our processor through quantum
state tomography of Bell states measuring state fidelities between 85-89% and
concurrences between 73-80%. These results pave the way for larger scale
quantum computers using spins confined to quantum dots
Attitudes of students from south-east and east Asian countries to slaughter and transport of livestock
Attitudes to animals have been extensively studied for people in developed countries, but not for those in developing countries. The attitudes of prospective stakeholders in the livestock sectors in south-east and east Asia toward transport and slaughter were examined by surveying university students studying veterinary medicine and animal science in Malaysia, Thailand, China and Vietnam, with a total of 739 students taking part. Students had greater acceptability of transport than slaughter issues for livestock, and female students found most transport and slaughter issues of greater concern than male students. Veterinary students were more accepting of several issues than animal science students, in particular killing animals that were injured or ill. Religion had a major effect on attitudes. Muslim students found using animals that died naturally for products least acceptable. Compared to them, Hindu students were less accepting of killing injured or ill animals and Buddhist students less accepting of euthanasing healthy pets. Students with more experience of pets were less accepting of both transport and slaughter issues. It is concluded that concern was exhibited by future stakeholders in the SE and E Asian livestock industries for slaughter and, to a lesser extent, transport issues, although attitudes were influenced by their religion, gender and experience of pet-keeping
Integrated processing of sugarcane bagasse : arabinoxylan extraction integrated with ethanol production.
The authors gratefully acknowledge the funding for âProject POC02_NOV 14 Campbellâ from the Lignocellulosic Biorefinery Network (LBNet), funded by the Biotechnology and Biological Sciences Research Council (BBSRC).A proof-of-concept project compared extraction of arabinoxylans (AX) from sugarcane bagasse and wheat bran via alkaline hydrogen peroxide followed by enzyme-assisted extraction with combinations of feruloyl esterases and a xylanase. Bagasse contains comparable amounts of AX to wheat bran, but with a much lower arabinoxylan substitution on the xylan backbone (A:X ratio of around 0.2 compared with 0.6 for wheat bran), hence offering AX products with distinctive functionality and potential end uses. In the current work, bagasse released its AX more readily than wheat bran, and released a wider range of molecular weights. Use of feruloyl esterase and xylanase enzymes on their own or following alkaline peroxide extraction did not enhance AX release substantially; however, the xylanase appeared to be effective at reducing the size of AX molecules, and there is scope to optimise the effects of enzymes to produce specific AX product fractions. As bagasse frequently arises within the context of bioethanol production, integration of AX extraction with ethanol production could allow economic production of a portfolio of AX products, as has been demonstrated in principle for AX co-production in a wheat ethanol plant.PostprintPeer reviewe
Competitive nationalism:state, class, and the forms of capital in devolved Scotland
Devolved government in Scotland actively reconstitutes the unequal conditions of social class reproduction. Recognition of state-led class reconstitution draws upon the social theory of Bourdieu. Our analysis of social class in devolved Scotland revisits theories that examine the state as a `power container'. A range of state-enabling powers regulate the legal, economic, social, and cultural containers of class relations as specific forms of what Bourdieu called economic, social, and cultural `capital'. The preconditions of class reproduction are structured in direct ways by the Scottish state as a wealth container but also, more indirectly, as a cultural container and a social container. Competitive nationalism in the devolved Scottish state enacts neoliberal policies as a class- specific worldview but, at the same time, discursively frames society as a panclass national fraternity in terms of distinctive Scottish values of welfare nationalism. Nationalism is able to express this ambiguity in symbolic ways in which the partisan language of social class cannot
Individual, unit and vocal clan level identity cues in sperm whale codas
Fieldwork was supported by Discovery and Equipment grants to H.W. from the Natural Sciences and Engineering Research Council of Canada (NSERC) and the Whale and Dolphin Conservation Society. S.G. and L.R. were supported by the Marine Alliance for Science and Technology for Scotland (MASTs) pooling initiative and their support is gratefully acknowledged. MASTs is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions. S.G. was also supported by an NSERC Postgraduate Scholarship (PGS-M), an NSERC Canadian Graduate Scholarship (CGS-D), the Izaak Killam Memorial Scholarship, the Patrick F. Lett Fund, the Dalhousieâs Presidents Award, and an FNU fellowship for the Danish Council for Independent Research from the Ministry of Higher Education and Science supplemented by a Sapere Aude Research Talent Award.The âsocial complexity hypothesisâ suggests that complex social structure is a driver of diversity in animal communication systems. Sperm whales have a hierarchically structured society in which the largest affiliative structures, the vocal clans, are marked on ocean-basin scales by culturally transmitted dialects of acoustic signals known as âcodasâ. We examined variation in coda repertoires among both individual whales and social unitsâthe basic element of sperm whale societyâusing data from nine Caribbean social units across six years. Codas were assigned to individuals using photo-identification and acoustic size measurement, and we calculated similarity between repertoires using both continuous and categorical methods. We identified 21 coda types. Two of those (â1+1+3â and â5R1â) made up 65% of the codas recorded, were shared across all units and have dominated repertoires in this population for at least 30 years. Individuals appear to differ in the way they produce â5R1â but not â1+1+3â coda. Units use distinct 4-click coda types which contribute to making unit repertoires distinctive. Our results support the social complexity hypothesis in a marine species as different patterns of variation between coda types suggest divergent functions, perhaps representing selection for identity signals at several levels of social structure.Publisher PDFPeer reviewe
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Mothers behaving badly: chaotic hedonism and the crisis of neoliberal social reproduction
This article focuses on the significance of the plethora of representations of mothers âbehaving badlyâ in contemporary anglophone media texts, including the films Bad Moms, Fun Mom Dinner and Bad Momâs Christmas, the book and online cartoons Hurrah for Gin and the recent TV comedy dramas Motherland, The Let Down and Catastrophe. All these media texts include representations of, first, mothers in the midst of highly chaotic everyday spaces where any smooth routine of domesticity is conspicuous by its absence; and second, mothers behaving hedonistically, usually through drinking and partying, behaviour that is more conventionally associated with men or women without children. After identifying the social type of the mother behaving badly (MBB), the article locates and analyses it in relation to several different social and cultural contexts. These contexts are: a neoliberal crisis in social reproduction marked by inequality and overwork; the continual if contested role of women as âfoundation parentsâ; and the negotiation of longer-term discourses of female hedonism. The title gestures towards a popular British sitcom of the 1990s, Men Behaving Badly, which popularized the idea of the ânew ladâ; and this article suggests that the new ladâs counterpart, the ladette, is mutating into the mother behaving badly, or the âlad momâ. Asking what work this figure does now, in a later neoliberal context, it argues that the mother behaving badly is simultaneously indicative of a widening and liberating range of maternal subject positions and symptomatic of a profound contemporary crisis in social reproduction. By focusing on the classed and racialised dynamics of the MBB â by examining who exactly is permitted to be hedonistic, and how â and by considering the MBBâs limited and partial imagining of progressive social change, the article concludes by emphasizing the urgency of creating more connections between such discourses and âparents behaving politicallyâ
Photofission of heavy nuclei at energies up to 4 GeV
Total photofission cross sections for 238U, 235U, 233U, 237Np, 232Th, and
natPb have been measured simultaneously, using tagged photons in the energy
range Egamma=0.17-3.84 GeV. This was the first experiment performed using the
Photon Tagging Facility in Hall B at Jefferson Lab. Our results show that the
photofission cross section for 238U relative to that for 237Np is about 80%,
implying the presence of important processes that compete with fission. We also
observe that the relative photofission cross sections do not depend strongly on
the incident photon energy over this entire energy range. If we assume that for
237Np the photofission probability is equal to unity, we observe a significant
shadowing effect starting below 1.5 GeV.Comment: 4 pages of RevTex, 6 postscript figures, Submitted to Phys. Rev. Let
Time resolution of the plastic scintillator strips with matrix photomultiplier readout for J-PET tomograph
Recent tests of a single module of the Jagiellonian Positron Emission
Tomography system (J-PET) consisting of 30 cm long plastic scintillator strips
have proven its applicability for the detection of annihilation quanta (0.511
MeV) with a coincidence resolving time (CRT) of 0.266 ns. The achieved
resolution is almost by a factor of two better with respect to the current
TOF-PET detectors and it can still be improved since, as it is shown in this
article, the intrinsic limit of time resolution for the determination of time
of the interaction of 0.511 MeV gamma quanta in plastic scintillators is much
lower. As the major point of the article, a method allowing to record
timestamps of several photons, at two ends of the scintillator strip, by means
of matrix of silicon photomultipliers (SiPM) is introduced. As a result of
simulations, conducted with the number of SiPM varying from 4 to 42, it is
shown that the improvement of timing resolution saturates with the growing
number of photomultipliers, and that the 2 x 5 configuration at two ends
allowing to read twenty timestamps, constitutes an optimal solution. The
conducted simulations accounted for the emission time distribution, photon
transport and absorption inside the scintillator, as well as quantum efficiency
and transit time spread of photosensors, and were checked based on the
experimental results. Application of the 2 x 5 matrix of SiPM allows for
achieving the coincidence resolving time in positron emission tomography of
0.170 ns for 15 cm axial field-of-view (AFOV) and 0.365 ns
for 100 cm AFOV. The results open perspectives for construction of a
cost-effective TOF-PET scanner with significantly better TOF resolution and
larger AFOV with respect to the current TOF-PET modalities.Comment: To be published in Phys. Med. Biol. (26 pages, 17 figures
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