8,206 research outputs found
The packing of granular polymer chains
Rigid particles pack into structures, such as sand dunes on the beach, whose
overall stability is determined by the average number of contacts between
particles. However, when packing spatially extended objects with flexible
shapes, additional concepts must be invoked to understand the stability of the
resulting structure. Here we study the disordered packing of chains constructed
out of flexibly-connected hard spheres. Using X-ray tomography, we find long
chains pack into a low-density structure whose mechanical rigidity is mainly
provided by the backbone. On compaction, randomly-oriented, semi-rigid loops
form along the chain, and the packing of chains can be understood as the
jamming of these elements. Finally we uncover close similarities between the
packing of chains and the glass transition in polymers.Comment: 11 pages, 4 figure
Quantum dense coding in multiparticle entangled states via local measurements
In this paper, we study quantum dense coding between two arbitrarily fixed
particles in a (N+2)-particle maximally-entangled states through introducing an
auxiliary qubit and carrying out local measurements. It is shown that the
transmitted classical information amount through such an entangled quantum
channel usually is less than two classical bits. However, the information
amount may reach two classical bits of information, and the classical
information capacity is independent of the number of the entangled particles in
the initial entangled state under certain conditions. The results offer deeper
insights to quantum dense coding via quantum channels of multi-particle
entangled states.Comment: 3 pages, no figur
A Method to Tackle First Order Differential Equations with Liouvillian Functions in the Solution - II
We present a semi-decision procedure to tackle first order differential
equations, with Liouvillian functions in the solution (LFOODEs). As in the case
of the Prelle-Singer procedure, this method is based on the knowledge of the
integrating factor structure.Comment: 11 pages, late
The missing group? Situating transnational contacts in defamilisation research
Defamilisation research is increasingly seen as an important component of studies of welfare and social work. It is concerned with people’s vulnerability to defamilisation risks, which are caused by insufficient opportunities for people to choose whether and how they participate in the family. Despite an increasing emphasis on defamilisation research, there has been insufficient attention given to how studies of transnational contacts contribute to defamilisation research. This article argues for the need to expand the scope of defamilisation research to incorporate the concept of ‘transnational contact-led strategies’ using evidence from focus groups with Chinese older people in the United Kingdom
Perfect State Transfer, Effective Gates and Entanglement Generation in Engineered Bosonic and Fermionic Networks
We show how to achieve perfect quantum state transfer and construct effective
two-qubit gates between distant sites in engineered bosonic and fermionic
networks. The Hamiltonian for the system can be determined by choosing an
eigenvalue spectrum satisfying a certain condition, which is shown to be both
sufficient and necessary in mirror-symmetrical networks. The natures of the
effective two-qubit gates depend on the exchange symmetry for fermions and
bosons. For fermionic networks, the gates are entangling (and thus universal
for quantum computation). For bosonic networks, though the gates are not
entangling, they allow two-way simultaneous communications. Protocols of
entanglement generation in both bosonic and fermionic engineered networks are
discussed.Comment: RevTeX4, 6 pages, 1 figure; replaced with a more general example and
clarified the sufficient and necessary condition for perfect state transfe
Characterization and Quantification of Isoprene-Derived Epoxydiols in Ambient Aerosol in the Southeastern United States
Isoprene-derived epoxydiols (IEPOX) are identified in ambient aerosol samples for the first time, together with other previously identified isoprene tracers (i.e., 2-methyltetrols, 2-methylglyceric acid, C5-alkenetriols, and organosulfate derivatives of 2-methyltetrols). Fine ambient aerosol collected in downtown Atlanta, GA and rural Yorkville, GA during the 2008 August Mini-Intensive Gas and Aerosol Study (AMIGAS) was analyzed using both gas chromatography/quadrupole mass spectrometry (GC/MS) and gas chromatography/time-of-flight mass spectrometry (GC/TOFMS) with prior trimethylsilylation. Mass concentrations of IEPOX ranged from ~1 to 24 ng m^(−3) in the aerosol collected from the two sites. Detection of particle-phase IEPOX in the AMIGAS samples supports recent laboratory results that gas-phase IEPOX produced from the photooxidation of isoprene under low-NO_x conditions is a key precursor of ambient isoprene secondary organic aerosol (SOA) formation. On average, the sum of the mass concentrations of IEPOX and the measured isoprene SOA tracers accounted for about 3% of the organic carbon, demonstrating the significance of isoprene oxidation to the formation of ambient aerosol in this region
Stillbirth and intrauterine fetal death: role of routine histological organ sampling to determine cause of death.
OBJECTIVES: Guidelines for the investigation of intrauterine death and sudden unexpected death in infancy (SUDI) recommend, based on expert opinion, autopsy procedures and tissue sampling strategies for histological analysis. Although stillbirth is much more common than SUDI, there have been no large-scale studies published which evaluate the usefulness of histological evaluation of specific organs in stillbirth for determining cause of death. Our aim was to evaluate the use of macroscopic and microscopic assessment of internal organs to determine cause of intrauterine death. METHODS: As part of a larger study evaluating several aspects of autopsy findings in intrauterine death, a dedicated database was used to collate antenatal and postmortem examination details for cases of intrauterine death examined between 2005 and 2013 at two tertiary specialist centers in London, UK. Histological findings for all organs were examined in relation to the final cause of death, as determined by objective criteria. RESULTS: Among 1064 intrauterine deaths, the majority (> 80%) of cases had internal organs that were normal on both macroscopic and microscopic examination. There was no case in which histological cardiac examination provided the cause of death when the macroscopic appearance of the heart was normal. Microscopic examination of lung tissue revealed 13 (1%) cases with histological abnormalities that provided the cause of death when the macroscopic appearance was normal, but there was only one (0.1%) case in which the diagnosis would not have been apparent on placental examination: a case of congenital cytomegalovirus infection. There was no case in which microscopic examination of macroscopically normal liver, kidneys, adrenals, spleen, thymus, intestines, pancreas, brain or thyroid provided the cause of death. CONCLUSION: In this large series of autopsies in cases of intrauterine death, only around 1% of cases demonstrated histological abnormalities which provided the cause of death when the internal organs appeared normal macroscopically. There was no case in which routine histological examination of most tissues provided diagnostically useful information that was not apparent from other examinations, such as placental pathology. There is little benefit, purely in terms of determining cause of death, in obtaining tissue from most macroscopically normal organs for routine histological examination
Spacetime Emergence and General Covariance Transmutation
Spacetime emergence refers to the notion that classical spacetime "emerges"
as an approximate macroscopic entity from a non-spatio-temporal structure
present in a more complete theory of interacting fundamental constituents. In
this article, we propose a novel mechanism involving the "soldering" of
internal and external spaces for the emergence of spacetime and the twin
transmutation of general covariance. In the context of string theory, this
mechanism points to a critical four dimensional spacetime background.Comment: 11 pages, v2: version to appear in MPL
Robust nodal superconductivity induced by isovalent doping in Ba(FeRu)As and BaFe(AsP)
We present the ultra-low-temperature heat transport study of iron-based
superconductors Ba(FeRu)As and
BaFe(AsP). For optimally doped
Ba(FeRu)As, a large residual linear term
at zero field and a dependence of are observed,
which provide strong evidences for nodes in the superconducting gap. This
result demonstrates that the isovalent Ru doping can also induce nodal
superconductivity, as P does in BaFe(AsP).
Furthermore, in underdoped Ba(FeRu)As and heavily
underdoped BaFe(AsP), manifests similar
nodal behavior, which shows the robustness of nodal superconductivity in the
underdoped regime and puts constraint on theoretical models.Comment: 5 pages, 4 figures - with two underdoped samples added, this paper
supersedes arXiv:1106.541
An Assessment of Risk of Iodine Deficiency Among Pregnant Women in Sarawak, Malaysia
Previous findings from a state-wide Iodine Deficiency Disorders (IDD) study among pregnant women (PW) in Sarawak indicated that PW are at risk of IDD and further assessment is needed. This paper describes the methodology used in conducting this study for an assessment of risk of iodine deficiency among pregnant women in Sarawak, Malaysia. A total of 30 maternal child health care clinics (MCHCs) were selected using probability proportional to population size (PPS) sampling technique. The PW sample size was calculated based on 95% confidence interval (CI), relative precision of 5%, design effect of 2, anticipated IDD prevalence of 65.0% and non-response rate of 20%. Thus, the total sample size required was 750 (25 respondents per selected MCHC). The WHO Expanded Programme on Immunization (EPI) surveys approach was used to randomly select the first respondent and subsequent respondents were chosen until the required number of PW was met. The required data were obtained through: face-to-face interviews (socio-demographic and food frequency questionnaire), clinical assessments (thyroid size, and hyper/hypothyroidism) and biochemical analysis (urine and blood serum). A total of 677 PW responded in the study with a response rate of 90.2%. Majority of the PW were at second gravida, aged 25-29 years old and of Malay ethnicity. The methodology used in this study was based on International guidelines which may provide state's estimates. All the necessary steps were taken into consideration to ensure valid and reliable findings on current iodine status among PW
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