3,578 research outputs found

    Thermodynamic Bethe Ansatz for N = 1 Supersymmetric Theories

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    We study a series of N ⁣= ⁣1N\!=\!1 supersymmetric integrable particle theories in d=1+1d=1+1 dimensions. These theories are represented as integrable perturbations of specific N ⁣= ⁣1N\!=\!1 superconformal field theories. Starting from the conjectured SS-matrices for these theories, we develop the Thermodynamic Bethe Ansatz (TBA), where we use that the 2-particle SS-matrices satisfy a free fermion condition. Our analysis proves a conjecture by E.~Melzer, who proposed that these N ⁣= ⁣1N\!=\!1 supersymmetric TBA systems are ``folded'' versions of N ⁣= ⁣2N\!=\!2 supersymmetric TBA systems that were first studied by P.~Fendley and K.~Intriligator.Comment: 24 pages, Revte

    Reactivity effects in video-based classroom research: an investigation using teacher and student questionnaires as well as teacher eye-tracking

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    One prominent problem of conducting observational assessments of teaching quality is the possibility of reactivity effects. To date, the issue of reactivity has received limited empirical attention. The present study, therefore, investigated reactivity in 447 students from 24 classes as well as their 12 teachers. We compared reactivity during lessons that were video-recorded with those that were not: according to t‑test analyses of teacher ratings and MIMIC analyses of student ratings, no significant differences emerged in teaching quality or teaching practices. Significant differences were found in teacher and student emotions, as well as in student cognition and behavior. Supplementary eye-tracking analyses indicated reactivity depleted after 1 min 20 s. The results are discussed with respect to their relevance for future video studies on classroom instruction

    Quenched charmonium spectrum on anisotropic lattices

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    We present the results of quenched charmonium spectrum for S- and P-states, obtained by a relativistic heavy quark method on anisotropic lattices. Simulations are carried out using the standard plaquette gauge action and a meanfield-improved clover quark action at at1=3a_t^{-1} = 3--6 GeV with the renormalized anisotropy fixed to ξas/at=3\xi \equiv a_s/a_t =3. We study the scaling of our fine and hyperfine mass splittings, and compare with previous results.Comment: Lattice 2000 (Heavy Quark Physics), 4 pages, 6 eps figures, LaTeX(espcrc2.sty

    A descriptive analysis of child-relevant systematic reviews in the Cochrane Database of Systematic Reviews

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    <p>Abstract</p> <p>Background</p> <p>Systematic reviews (SRs) are considered an important tool for decision-making. There has been no recent comprehensive identification or description of child-relevant SRs. A description of existing child-relevant SRs would help to identify the extent of available child-relevant evidence available in SRs and gaps in the evidence base where SRs are required. The objective of this study was to describe child-relevant SRs from the Cochrane Database of Systematic Reviews (CDSR, Issue 2, 2009).</p> <p>Methods</p> <p>SRs were assessed for relevance using pre-defined criteria. Data were extracted and entered into an electronic form. Univariate analyses were performed to describe the SRs overall and by topic area.</p> <p>Results</p> <p>The search yielded 1666 SRs; 793 met the inclusion criteria. 38% of SRs were last assessed as up-to-date prior to 2007. Corresponding authors were most often from the UK (41%). Most SRs (59%) examined pharmacological interventions. 53% had at least one external source of funding. SRs included a median of 7 studies (IQR 3, 15) and 679 participants (IQR 179, 2833). Of all studies, 48% included only children, and 27% only adults. 94% of studies were published in peer-reviewed journals. Primary outcomes were specified in 72% of SRs. Allocation concealment and the Jadad scale were used in 97% and 25% of SRs, respectively. Adults and children were analyzed separately in 12% of SRs and as a subgroup analysis in 14%. Publication bias was assessed in only 14% of SRs. A meta-analysis was conducted in 68% of SRs with a median of 5 trials (IQR 3, 9) each. Variations in these characteristics were observed across topic areas.</p> <p>Conclusions</p> <p>We described the methodological characteristics and rigour of child-relevant reviews in the CDSR. Many SRs are not up-to-date according to Cochrane criteria. Our study describes variation in conduct and reporting across SRs and reveals clinicians' ability to access child-specific data.</p

    Magnetoresistance, specific heat and magnetocaloric effect of equiatomic rare-earth transition-metal magnesium compounds

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    We present a study of the magnetoresistance, the specific heat and the magnetocaloric effect of equiatomic RETRETMg intermetallics with RE=LaRE = {\rm La}, Eu, Gd, Yb and T=AgT = {\rm Ag}, Au and of GdAuIn. Depending on the composition these compounds are paramagnetic (RE=LaRE = {\rm La}, Yb) or they order either ferro- or antiferromagnetically with transition temperatures ranging from about 13 to 81 K. All of them are metallic, but the resistivity varies over 3 orders of magnitude. The magnetic order causes a strong decrease of the resistivity and around the ordering temperature we find pronounced magnetoresistance effects. The magnetic ordering also leads to well-defined anomalies in the specific heat. An analysis of the entropy change leads to the conclusions that generally the magnetic transition can be described by an ordering of localized S=7/2S=7/2 moments arising from the half-filled 4f74f^7 shells of Eu2+^{2+} or Gd3+^{3+}. However, for GdAgMg we find clear evidence for two phase transitions indicating that the magnetic ordering sets in partially below about 125 K and is completed via an almost first-order transition at 39 K. The magnetocaloric effect is weak for the antiferromagnets and rather pronounced for the ferromagnets for low magnetic fields around the zero-field Curie temperature.Comment: 12 pages, 7 figures include

    Scattering and Thermodynamics of Fractionally-Charged Supersymmetric Solitons

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    We show that there are solitons with fractional fermion number in integrable NN=2 supersymmetric models. We obtain the soliton S-matrix for the minimal, NN=2 supersymmetric theory perturbed in the least relevant chiral primary field, the Φ(1,3)\Phi _{(1,3)} superfield. The perturbed theory has a nice Landau-Ginzburg description with a Chebyshev polynomial superpotential. We show that the S-matrix is a tensor product of an associated ordinary ADEADE minimal model S-matrix with a supersymmetric part. We calculate the ground-state energy in these theories and in the analogous NN=1 case and SU(2)SU(2) coset models. In all cases, the ultraviolet limit is in agreement with the conformal field theory.Comment: 27 page

    The Eruption from a Sigmoidal Solar Active Region on 2005 May 13

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    This paper presents a multiwavelength study of the M8.0 flare and its associated fast halo CME that originated from a bipolar active region NOAA 10759 on 2005 May 13. The source active region has a conspicuous sigmoid structure at TRACE 171 A channel as well as in the SXI soft X-ray images, and we mainly concern ourselves with the detailed process of the sigmoid eruption as evidenced by the multiwavelength data ranging from Halpha, WL, EUV/UV, radio, and hard X-rays (HXRs). The most important finding is that the flare brightening starts in the core of the active region earlier than that of the rising motion of the flux rope. This timing clearly addresses one of the main issues in the magnetic eruption onset of sigmoid, namely, whether the eruption is initiated by an internal tether-cutting to allow the flux rope to rise upward or a flux rope rises due to a loss of equilibrium to later induce tether cutting below it. Our high time cadence SXI and Halpha data shows that the first scenario is relevant to this eruption. As other major findings, we have the RHESSI HXR images showing a change of the HXR source from a confined footpoint structure to an elongated ribbon-like structure after the flare maximum, which we relate to the sigmoid-to-arcade evolution. Radio dynamic spectrum shows a type II precursor that occurred at the time of expansion of the sigmoid and a drifting pulsating structure in the flare rising phase in HXR. Finally type II and III bursts are seen at the time of maximum HXR emission, simultaneous with the maximum reconnection rate derived from the flare ribbon motion in UV. We interpret these various observed properties with the runaway tether-cutting model proposed by Moore et al. in 2001.Comment: 10 pages, 10 figures, The Astrophysical Journal, accepted July, 200

    Разработка технологии утилизации отходов птицеводства в кормовую добавку

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    В статье рассматриваются проблемы утилизации перо-пухового сырья птицефабрик в высокобелковые корма и кормовые продукты для сельскохозяйственных животных и птиц. Представлена актуальность и приоритет разработки данного направления в развития нашей страны. Показана рациональность применения перо-пуховых отходов в качестве источника белковых веществ в рационах сельскохозяйственных животных и птиц. Рассмотрена модель структуры главного белка пера - кератина. Предложена технологическая схема производства биопрепарата на основе культур промышленных непатогенных микроорганизмов: Bacillus pumilus SAFR-032, Microbacterium terregens AC1180, Bacillus fastidiosus B11090, Arthrobacter globiformis AC1529, Streptomyces olivocinereus AC1169, Acinetobacter sp. B3905 для утилизации кератинсодержащих отходов, а также технологические этапы производства кормовой добавки из перо-пуховых отходов с применением разработанного биопрепарата.In the annotation the problems of perception of disposing feather-down raw poultry farms in high-protein forage and fodder products for agricultural animals and birds are considered in the article. The urgency and priority of developing this direction in the development of our country is presented. It shows a rational application of down-feather waste as a source of proteins in the diet of farm animals and birds. A model of the structure of the main protein of the pen - keratin is considered. Bioproduct proposed technological production scheme based on industrial crops nonpathogenic microorganisms: Bacillus pumilus SAFR-032, Microbacterium terregens AC1180, Bacillus fastidiosus B11090, Arthrobacter globiformis AC1529, Streptomyces olivocinereus AC1169, Acinetobacter sp. B3905 keratin-waste for recycling, as well as the technological stages of production of the feed additive of the pen-feather waste developed using a biological product

    A Contribution of the Trivial Connection to Jones Polynomial and Witten's Invariant of 3d Manifolds I

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    We use the Chern-Simons quantum field theory in order to prove a recently conjectured limitation on the 1/K expansion of the Jones polynomial of a knot and its relation to the Alexander polynomial. This limitation allows us to derive a surgery formula for the loop corrections to the contribution of the trivial connection to Witten's invariant. The 2-loop part of this formula coincides with Walker's surgery formula for Casson-Walker invariant. This proves a conjecture that Casson-Walker invariant is a 2-loop correction to the trivial connection contribution to Witten's invariant of a rational homology sphere. A contribution of the trivial connection to Witten's invariant of a manifold with nontrivial rational homology is calculated for the case of Seifert manifolds.Comment: 28 page
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