663 research outputs found
Systematic child abuse incidents in a childrenâs residential home in Hong Kong: regulatory and criminal law reform proposals
Purpose â The paper aims to recommend legal and regulatory reforms to better prevent child abuse in childcare institutions in Hong Kong. Design/methodology/approach â A summary of investigation report and news reports are referred to in describing the abuse incidents which occurred in a childrenâs residential home. Routine Activity Theory (RAT) is used as the framework for identifying the causes. Local and overseas legislation, regulations, case law, and policies are analysed to provide recommendations for reforms. Findings â There are systematic failures such as workload issues, inadequate supervision, and the absence of continuing professional development (CPD) that contributed to the incidents. The regulations governing the operation of childcare centres and criminal laws against child abuse are long overdue for an update in Hong Kong. On the institutional side, this paper recommends enacting regulations that mandate CPD, lower the staff-to-child ratio, and strengthen the Social Welfare Departmentâs (SWD) supervisory powers over childcare centres. From the criminal law perspective, it is recommended that âreasonable chastisementâ be abolished as a defence of corporal punishment, and that there be new offences for failure to report suspected child abuse incidents and causing or allowing the death/serious harm of a child. Originality/value â The child abuse incidents, occurring in a childcare institution, have drawn wide public concern. Reform is required to protect vulnerable children and regain public confidence
Planar Octilinear Drawings with One Bend Per Edge
In octilinear drawings of planar graphs, every edge is drawn as an
alternating sequence of horizontal, vertical and diagonal ()
line-segments. In this paper, we study octilinear drawings of low edge
complexity, i.e., with few bends per edge. A -planar graph is a planar graph
in which each vertex has degree less or equal to . In particular, we prove
that every 4-planar graph admits a planar octilinear drawing with at most one
bend per edge on an integer grid of size . For 5-planar
graphs, we prove that one bend per edge still suffices in order to construct
planar octilinear drawings, but in super-polynomial area. However, for 6-planar
graphs we give a class of graphs whose planar octilinear drawings require at
least two bends per edge
Higgs-Boson Production Associated with a Single Bottom Quark in Supersymmetric QCD
Due to the enhancement of the couplings between Higgs boson and bottom quarks
in the minimal sypersymmetric standard model (MSSM), the cross section of the
process pp(p\bar{p}) \to h^0b(h^0\bar{b})+X at hadron colliders can be
considerably enhanced. We investigated the production of Higgs boson associated
with a single high-p_T bottom quark via subprocess bg(\bar{b}g) \to
h^0b(h^0\bar{b}) at hadron colliders including the next-to-leading order (NLO)
QCD corrections in MSSM. We find that the NLO QCD correction in the MSSM
reaches 50%-70% at the LHC and 60%-85% at the Fermilab Tevatron in our chosen
parameter space.Comment: accepted by Phys. Rev.
Relativistic close coupling calculations for photoionization and recombination of Ne-like Fe XVII
Relativistic and channel coupling effects in photoionization and unified
electronic recombination of Fe XVII are demonstrated with an extensive 60-level
close coupling calculation using the Breit-Pauli R-matrix method.
Photoionization and (e + ion) recombination calculations are carried out for
the total and the level-specific cross sections, including the ground and
several hundred excited bound levels of Fe XVII (up to fine structure levels
with n = 10). The unified (e + ion) recombination calculations for (e + Fe
XVIII --> Fe XVII) include both the non-resonant and resonant recombination
(`radiative' and `dielectronic recombination' -- RR and DR). The low-energy and
the high energy cross sections are compared from: (i) a 3-level calculation
with 2s^2p^5 (^2P^o_{1/2,3/2}) and 2s2p^6 (^2S_{1/2}), and (ii) the first
60-level calculation with \Delta n > 0 coupled channels with spectroscopic
2s^2p^5, 2s2p^6, 2s^22p^4 3s, 3p, 3d, configurations, and a number of
correlation configurations. Strong channel coupling effects are demonstrated
throughout the energy ranges considered, in particular via giant
photoexcitation-of-core (PEC) resonances due to L-M shell dipole transition
arrays 2p^5 --> 2p^4 3s, 3d in Fe XIII that enhance effective cross sections by
orders of magnitude. Comparison is made with previous theoretical and
experimental works on photoionization and recombination that considered the
relatively small low-energy region (i), and the weaker \Delta n = 0 couplings.
While the 3-level results are inadequate, the present 60-level results should
provide reasonably complete and accurate datasets for both photoionization and
(e + ion) recombination of Fe~XVII in laboratory and astrophysical plasmas.Comment: 19 pages, 8 figures, Phys. Rev. A (submitted
Modelling of strain effects in manganite films
Thickness dependence and strain effects in films of
perovskites are analyzed in the colossal magnetoresistance regime. The
calculations are based on a generalization of a variational approach previously
proposed for the study of manganite bulk. It is found that a reduction in the
thickness of the film causes a decrease of critical temperature and
magnetization, and an increase of resistivity at low temperatures. The strain
is introduced through the modifications of in-plane and out-of-plane electron
hopping amplitudes due to substrate-induced distortions of the film unit cell.
The strain effects on the transition temperature and transport properties are
in good agreement with experimental data only if the dependence of the hopping
matrix elements on the bond angle is properly taken into account.
Finally variations of the electron-phonon coupling linked to the presence of
strain turn out important in influencing the balance of coexisting phases in
the filmComment: 7 figures. To be published on Physical Review
Time-integrated luminosity recorded by the BABAR detector at the PEP-II e+e- collider
This article is the Preprint version of the final published artcile which can be accessed at the link below.We describe a measurement of the time-integrated luminosity of the data collected by the BABAR experiment at the PEP-II asymmetric-energy e+e- collider at the Ï(4S), Ï(3S), and Ï(2S) resonances and in a continuum region below each resonance. We measure the time-integrated luminosity by counting e+e-âe+e- and (for the Ï(4S) only) e+e-âÎŒ+ÎŒ- candidate events, allowing additional photons in the final state. We use data-corrected simulation to determine the cross-sections and reconstruction efficiencies for these processes, as well as the major backgrounds. Due to the large cross-sections of e+e-âe+e- and e+e-âÎŒ+ÎŒ-, the statistical uncertainties of the measurement are substantially smaller than the systematic uncertainties. The dominant systematic uncertainties are due to observed differences between data and simulation, as well as uncertainties on the cross-sections. For data collected on the Ï(3S) and Ï(2S) resonances, an additional uncertainty arises due to Ïâe+e-X background. For data collected off the Ï resonances, we estimate an additional uncertainty due to time dependent efficiency variations, which can affect the short off-resonance runs. The relative uncertainties on the luminosities of the on-resonance (off-resonance) samples are 0.43% (0.43%) for the Ï(4S), 0.58% (0.72%) for the Ï(3S), and 0.68% (0.88%) for the Ï(2S).This work is supported by the US Department of Energy and National Science Foundation, the Natural Sciences and Engineering Research Council (Canada), the Commissariat Ă lâEnergie Atomique and Institut National de Physique NuclĂ©aire et de Physiquedes Particules (France), the Bundesministerium fĂŒr Bildung und Forschung and Deutsche Forschungsgemeinschaft (Germany), the Istituto Nazionale di Fisica Nucleare (Italy), the Foundation for Fundamental Research on Matter (The Netherlands), the Research Council of Norway, the Ministry of Education and Science of the Russian Federation, Ministerio de Ciencia e InnovaciĂłn (Spain), and the Science and Technology Facilities Council (United Kingdom). Individuals have received support from the Marie-Curie IEF program (European Union) and the A.P. Sloan Foundation (USA)
Measurement of the p-pbar -> Wgamma + X cross section at sqrt(s) = 1.96 TeV and WWgamma anomalous coupling limits
The WWgamma triple gauge boson coupling parameters are studied using p-pbar
-> l nu gamma + X (l = e,mu) events at sqrt(s) = 1.96 TeV. The data were
collected with the DO detector from an integrated luminosity of 162 pb^{-1}
delivered by the Fermilab Tevatron Collider. The cross section times branching
fraction for p-pbar -> W(gamma) + X -> l nu gamma + X with E_T^{gamma} > 8 GeV
and Delta R_{l gamma} > 0.7 is 14.8 +/- 1.6 (stat) +/- 1.0 (syst) +/- 1.0 (lum)
pb. The one-dimensional 95% confidence level limits on anomalous couplings are
-0.88 < Delta kappa_{gamma} < 0.96 and -0.20 < lambda_{gamma} < 0.20.Comment: Submitted to Phys. Rev. D Rapid Communication
Defect-mediated ferromagnetism in ZnO:Mn nanorods
In this work, the structural, chemical and magnetic properties of ZnO:Mn nanorods were investigated. Firstly, well-aligned ZnO nanorods with their long axis parallel to the crystalline c-axis were successfully grown by the vapor phase transport technique on Si substrates coated with a ZnO buffer layer. Mn metal was then diffused into these nanorods at different temperatures in vacuum. From SEM results, ZnO:Mn nanorods were observed to have diameters of ~100 nm and lengths of 4 ”m. XPS analysis showed that the Mn dopant substituted into the ZnO matrix with a valence state of +2. Magnetic measurements performed at room temperature revealed that undoped ZnO nanorods exhibit ferromagnetic behavior which may be related to oxygen vacancy defect-mediated d0 ferromagnetism. ZnO:Mn samples were seen to show an excess room temperature ferromagnetism that is attributed to the presence of oxygen vacancy defects forming bound magnetic polarons involving Mn
CP Violation in Top Quark Pair Production at Hadron Colliders
CP violating effects in top quark pair production at the future 2 TeV Tevatron and 14 TeV LHC colliders are investigated. We study three
kinds of CP violating sources:the supersymmetric CP-odd phase of the stop
trilinear soft breaking term: , the CP-odd parameter in two-Higgs
doublet extensions of the standard model(2HDM), and the model-independent top
quark chromoelectric dipole moment(CEDM), respectively. Optimal observables as
well as simple observables are used. We find that it is possible to observe CP
violating effects from in top quark pair production at the 2 TeV
Tevatron with integrated luminosity when GeV. If the experimental systematic errors are sufficient small, the LHC
with can put a limit of order on the phase
and the CP-odd parameter in 2HDM by using optimal observables. The
CEDM of the top quark can be measured to an accuracy of at
the Tevatron and few at the LHC.Comment: 28 pages,3 figures, 38 ref
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