5,682 research outputs found
Raman scattering from fractals. Simulation on large structures by the method of moments
We have employed the method of spectral moments to study the density of
vibrational states and the Raman coupling coefficient of large 2- and 3-
dimensional percolators at threshold and at higher concentration. We first
discuss the over-and under-flow problems of the procedure which arise when
-like in the present case- it is necessary to calculate a few thousand moments.
Then we report on the numerical results; these show that different scattering
mechanisms, all {\it a priori} equally probable in real systems, produce
largely different coupling coefficients with different frequency dependence.
Our results are compared with existing scaling theories of Raman scattering.
The situation that emerges is complex; on the one hand, there is indication
that the existing theory is not satisfactory; on the other hand, the
simulations above threshold show that in this case the coupling coefficients
have very little resemblance, if any, with the same quantities at threshold.Comment: 26 pages, RevTex, 8 figures available on reques
The equality implications of being a migrant in Britain.
Researching the equality implications of being a migrant in Britain is hampered by imprecise definitions of what a migrant is and by a lack of data on many equality groups (groups which share a common attribute in respect of age, disability, gender, race, religion or belief, or sexual orientation, as defined by the Equality Act 2006). The literature and evidence on inequalities tends to be more abundant on gender and race but remains focused on ethnic minority categories rather than on migrants as such. While the foreign-born population in the UK has increased from four to six million over the last decade, people arrive via different routes and with varying intentions. Much recent debate on the benefits and pressures resulting from immigration has been provoked by the large numbers of arrivals from Eastern Europe since 2004, but they, like other migrants from the European Union (EU), have freedom of movement guaranteed by EU Directives. Although they have to register or obtain authorisation to work legally (and 766,000 had registered by the end of 2007), there are few
reliable statistics on their presence in specific areas or in the UK as a whole. Other migrants from outside the EU also come to the UK to work (about 200,000 in 2006)
or study (309,000 in 2006). A number of migrants, estimated at between 310,000 and 570,000, are believed to be living in the country without formal immigration authorisation. In 2007, the largest group of those born abroad was from India
(553,300), followed by those from Poland (423,300). There are significant differences in terms of gender and age between different national groups, comprising recent and
established migrants, and in their experiences of employment and access to services. This heterogeneity makes policymaking based on averages or an assumed homogeneity meaningless or even dangerous
New migrants in England and their needs.
This research was commissioned in 2007 and maps new migrant communities in the UK.
It includes a report, anecdotal information from stakeholder interviews and 11 locality studies which summarises and explain all available data sets
Impact of bisphenol A (BPA) on early embryo development in the marine mussel Mytilus galloprovincialis: Effects on gene transcription.
Bisphenol A (BPA), a monomer used in plastic manufacturing, is weakly estrogenic and a potential endocrine disruptor in mammals. Although it degrades quickly, it is pseudo-persistent in the environment because of continual inputs, with reported concentrations in aquatic environments between 0.0005 and 12 \u3bcg/L. BPA represents a potential concern for aquatic ecosystems, as shown by its reproductive and developmental effects in aquatic vertebrates. In invertebrates, endocrine-related effects of BPA were observed in different species and experimental conditions, with often conflicting results, indicating that the sensitivity to this compound can vary considerably among related taxa. In the marine mussel Mytilus galloprovincialis BPA was recently shown to affect early development at environmental concentrations. In this work, the possible effects of BPA on mussel embryos were investigated at the molecular level by evaluating transcription of 13 genes, selected on the basis of their biological functions in adult mussels. Gene expression was first evaluated in trocophorae and D-veligers (24 and 48 h post fertilization) grown in physiological conditions, in comparison with unfertilized eggs. Basal expressions showed a general up-regulation during development, with distinct transcript levels in trocophorae and D-veligers. Exposure of fertilized eggs to BPA (10 \u3bcg/L) induced a general upregulation at 24 h pf, followed by down regulation at 48 h pf. Mytilus Estrogen Receptors, serotonin receptor and genes involved in biomineralization (Carbonic Anydrase and Extrapallial Protein) were the most affected by BPA exposure. At 48 h pf, changes in gene expression were associated with irregularities in shell formation, as shown by scanning electron microscopy (SEM), indicating that the formation of the first shelled embryo, a key step in mussel development, represents a sensitive target for BPA. Similar results were obtained with the natural estrogen 17\u3b2-estradiol. The results demonstrate that BPA and E2 can affect Mytilus early development through dysregulation of gene transcription
Hint for axial-vector contact interactions in the data on e+e- -> e+e-(gamma) at centre-of-mass energies 192-208 GeV
For the first time the experiments ALEPH, DELPHI, L3 and OPAL have presented
preliminary results for fermion-pair production in e+e- collisions on the full
data set above the Z pole. A combined analysis of the Bhabha scattering
measurements is performed to search for effects of contact interactions. In the
case of two axial-vector (AA) currents the best fit to the data is 2.6 standard
deviations away from the Standard Model expectation, corresponding to an energy
scale TeV for contact interactions. For other
models no statistically significant deviations are observed, and the data are
used to set lower limits at 95 % confidence level on the contact interaction
scales ranging from 8.2 to 21.3 TeV, depending on the helicity structure.Comment: 6 pages, 1 table, 3 figure
Phenotypical and molecular changes induced by carbamazepine and propranolol on larval stages of Mytilus galloprovincialis
The possible impact of carbamazepine (CBZ) and propranolol (PROP), two widespread pharmaceuticals in the aquatic environment, were investigated on morphology and gene transcription of early larvae of Mytilus galloprovincialis. Pharmaceuticals were first tested in a wide concentration range (from 0.01 to 1000 a) through the 48-hpf embryotoxicity assay. The results showed that both compounds significantly affected embryo development from environmental concentrations. Although similar EC50 were obtained, (congruent to 1 mu g/L) CBZ induced a progressive increase in embryo malformations, whereas PROP apparently showed greater impacts in terms of arrested development and embryo mortality at higher concentrations (>10 mu g/L). Transcriptional analyses of 17 genes involved in different physiological functions in mussels and/or in their response to environmental contaminants, were performed at 24 and 48 h pf at two selected concentrations of CBZ and PROP (0.01 and 1 mu g/L). Both compounds induced down-regulation of shell-specific and neuroendocrine related transcripts, while distinct effects were observed on antioxidant, lysosomal, and immune-related transcripts, also depending on the larval stage investigated. The results demonstrate that CBZ and PROP can affect development and gene transcription in mussel early larvae at environmental concentrations. (C) 2019 Elsevier Ltd. All rights reserved
Precision Physics at LEP
1 - Introduction
2 - Small-Angle Bhabha Scattering and the Luminosity Measurement
3 - Z^0 Physics
4 - Fits to Precision Data
5 - Physics at LEP2
6 - ConclusionsComment: Review paper to appear in the RIVISTA DEL NUOVO CIMENTO; 160 pages,
LateX, 70 eps figures include
Child abuse and dental neglect: the dental team's role in identification and prevention
Health, education and social services are placing increasing emphasis on preventing abuse and neglect by early intervention to support families where children and young people may be at risk. Dental hygienist and dental assistants, like all other health professionals, can have a part in recognizing and preventing children from those who would cause them harm. They should be aware of the warning signs, recognizing what to consider as abuse or dental neglect and know how to deal with these young patients, and to fulfil their legal and ethical obligation to report suspected cases. The purpose of this report is to review the oral and dental aspects of child abuse and dental neglect thus helping the dental team in detecting such conditions. In particular, this report addresses the evaluation of bite marks as well as perioral and intraoral injuries, infections, early childhood caries and diseases that may be indicative of child abuse or neglect. Emphasis is placed on an appropriate protocol to follow in the dental practice to best treat and protect children who may have suffered abuse, helping the team in the diagnosis and documentation
Two-Loop Bhabha Scattering in QED
In the context of pure QED, we obtain analytic expressions for the
contributions to the Bhabha scattering differential cross section at order
alpha^4 which originate from the interference of two-loop photonic vertices
with tree-level diagrams and from the interference of one-loop photonic
diagrams amongst themselves. The ultraviolet renormalization is carried out.
The IR-divergent soft-photon emission corrections are evaluated and added to
the virtual cross section. The cross section obtained in this manner is valid
for on-shell electrons and positrons of finite mass, and for arbitrary values
of the center of mass energy and momentum transfer. We provide the expansion of
our results in powers of the electron mass, and we compare them with the
corresponding expansion of the complete order alpha^4 photonic cross section,
recently obtained in hep-ph/0501120. As a by-product, we obtain the
contribution to the Bhabha scattering differential cross section of the
interference of the two-loop photonic boxes with the tree-level diagrams, up to
terms suppressed by positive powers of the electron mass. We evaluate
numerically the various contributions to the cross section, paying particular
attention to the comparison between exact and expanded results.Comment: 35 pages, 18 figure
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