2,334 research outputs found
Resonant backward scattering of light by a two-side-open subwavelength metallic slit
The backward scattering of TM-polarized light by a two-side-open
subwavelength slit in a metal film is analyzed. We show that the reflection
coefficient versus wavelength possesses a Fabry-Perot-like dependence that is
similar to the anomalous behavior of transmission reported in the study [Y.
Takakura, Phys. Rev. Lett. \textbf{86}, 5601 (2001)]. The open slit totally
reflects the light at the near-to-resonance wavelengths. In addition, we show
that the interference of incident and resonantly backward-scattered light
produces in the near-field diffraction zone a spatially localized wave whose
intensity is 10-10 times greater than the incident wave, but one order of
magnitude smaller than the intra-cavity intensity. The amplitude and phase of
the resonant wave at the slit entrance and exit are different from that of a
Fabry-Perot cavity.Comment: 5 figure
A systematic review of interpersonal processes and their measurement within experience sampling studies of self-injurious thoughts and behaviours
Self-injurious thoughts and behaviours (SITBs) are a leading cause of death, and interpersonal processes (IPs) appear to play a role in SITBs. This systematic review synthesises the literature on IPs and SITBs in daily life and addresses four critical questions: (1) Which IPs have been assessed and how, (2) What is the relationship between IPs and SITBs in daily life?, (3) Do daily-life fluctuations in IPs differ between individuals with and without SITBs?, and (4) Do IPs relate differently to self-injurious thoughts than behaviours? Our review followed PRISMA guidelines and eligible literature was screened until 29 August 2023. We identified 52 Experience Sampling studies (34.62% daily-diary studies) of which most focused on IPs from suicide theories (e.g., thwarted belongingness) but largely used inconsistent operationalizations. Results from 35 studies investigating within-person associations were mixed. Based on 24 studies, whether individuals with and without SITBs differ in their interpersonal experiences remains unclear. Four studies have investigated whether IPs relate to the transition from thoughts to behaviours, but temporal models are needed to draw firm conclusions. Studies investigating IPs and SITBs in daily life are largely inconclusive. Psychometrically validated measures are warranted, and future daily-life studies would benefit from drawing on ideation-to-action frameworks
Enhanced transmission versus localization of a light pulse by a subwavelength metal slit: Can the pulse have both characteristics?
The existence of resonant enhanced transmission and collimation of light
waves by subwavelength slits in metal films [for example, see T.W. Ebbesen et
al., Nature (London) 391, 667 (1998) and H.J. Lezec et al., Science, 297, 820
(2002)] leads to the basic question: Can a light be enhanced and simultaneously
localized in space and time by a subwavelength slit? To address this question,
the spatial distribution of the energy flux of an ultrashort (femtosecond)
wave-packet diffracted by a subwavelength (nanometer-size) slit was analyzed by
using the conventional approach based on the Neerhoff and Mur solution of
Maxwell's equations. The results show that a light can be enhanced by orders of
magnitude and simultaneously localized in the near-field diffraction zone at
the nm- and fs-scales. Possible applications in nanophotonics are discussed.Comment: 5 figure
Single and vertically coupled type II quantum dots in a perpendicular magnetic field: exciton groundstate properties
The properties of an exciton in a type II quantum dot are studied under the
influence of a perpendicular applied magnetic field. The dot is modelled by a
quantum disk with radius , thickness and the electron is confined in the
disk, whereas the hole is located in the barrier. The exciton energy and
wavefunctions are calculated using a Hartree-Fock mesh method. We distinguish
two different regimes, namely (the hole is located at the radial
boundary of the disk) and (the hole is located above and below the
disk), for which angular momentum transitions are predicted with
increasing magnetic field. We also considered a system of two vertically
coupled dots where now an extra parameter is introduced, namely the interdot
distance . For each and for a sufficient large magnetic field,
the ground state becomes spontaneous symmetry broken in which the electron and
the hole move towards one of the dots. This transition is induced by the
Coulomb interaction and leads to a magnetic field induced dipole moment. No
such symmetry broken ground states are found for a single dot (and for three
vertically coupled symmetric quantum disks). For a system of two vertically
coupled truncated cones, which is asymmetric from the start, we still find
angular momentum transitions. For a symmetric system of three vertically
coupled quantum disks, the system resembles for small the pillar-like
regime of a single dot, where the hole tends to stay at the radial boundary,
which induces angular momentum transitions with increasing magnetic field. For
larger the hole can sit between the disks and the state
remains the groundstate for the whole -region.Comment: 11 pages, 16 figure
Resumption of Attention Deficit Hyperactivity Disorder medication in early adulthood: findings from a UK primary care prescribing study
This is the author accepted manuscript. The final version is available from Springer via the DOI in this record.This study aimed to examine resumption of Attention Deficit Hyperactivity Disorder (ADHD)
prescriptions in early adulthood in young people whose ADHD prescriptions stopped in adolescence.
Whilst prescribing studies indicate that the proportion of those with ADHD stopping treatment in late
adolescence remains in excess of the proportion expected to be symptom free, very few studies have
examined patterns of resumption amongst young adults previously prescribed medication.
Primary care records from the UK Clinical Practice Research Datalink from 2008 to 2013 were used
to examine the outcome of resumption of ADHD prescriptions from age 20 years in a sample of cases
with ADHD whose prescriptions stopped aged 14-18. A Cox regression model was fitted to explore
variables that could theoretically be associated with resumption of prescriptions.
Of 1,440 cases, 109 (7.6%) had their ADHD prescriptions resumed. Characteristics associated with an
increased probability of resumption included female gender, learning disability, referral to adult
mental health services, and prescription of antipsychotic medication.
In this study, only a small proportion of adolescents who stopped ADHD medication subsequently
resumed their prescriptions in primary care. Those that did resume were a more complex group. As
many vulnerable individuals with ongoing ADHD symptoms may not have the resources required to
surmount the barriers to re-enter services, the implication is that not all those who could benefit from
resuming medication are able to do so. The findings raise questions around whether current care
models are flexible enough and whether primary care are adequately supported in managing this
group
Neurological Symptom Improvement After Re-Irradiation in Patients With Diffuse Intrinsic Pontine Glioma: A Retrospective Analysis of the SIOP-E-HGG/DIPG Project
Adolescent; Diffuse intrinsic pontine glioma; RadiotherapyAdolescente; Glioma pontino intrĂnseco difuso; RadioterapiaAdolescent; Glioma pontĂ intrĂnsec difĂșs; RadioterĂ piaPurpose: The aim of this study is to investigate the spectrum of neurological triad improvement in patients with diffuse intrinsic pontine glioma (DIPG) treated by re-irradiation (re-RT) at first progression.
Methods: We carried out a re-analysis of the SIOP-E retrospective DIPG cohort by investigating the clinical benefits after re-RT with a focus on the neurological triad (cranial nerve deficits, ataxia, and long tract signs). Patients were categorized as ârespondingâ or ânon-respondingâ to re-RT. To assess the interdependence between patientsâ characteristics and clinical benefits, we used a chi-square or Fisherâs exact test. Survival according to clinical response to re-RT was calculated by the KaplanâMeier method.
Results: As earlier reported, 77% (n = 24/31) of patients had any clinical benefit after re-RT. Among 25/31 well-documented patients, 44% (n = 11/25) had improvement in cranial nerve palsies, 40% (n = 10/25) had improvement in long-tract signs, and 44% (11/25) had improvement in cerebellar signs. Clinical benefits were observed in at least 1, 2, or 3 out of 3 symptoms of the DIPG triad, in 64%, 40%, and 24%, respectively. Patients irradiated with a dose â„20 Gy versus <20 Gy may improve slightly better with regard to ataxia (67% versus 23%; p-value = 0.028). The survival from the start of re-RT to death was not different between responding and non-responding DIPG patients (p-value = 0.871).
Conclusion: A median re-irradiation dose of 20 Gy provides a neurological benefit in two-thirds of patients with an improvement of at least one symptom of the triad. DIPG patients receiving â„20 Gy appear to improve slightly better with regard to ataxia; however, we need more data to determine whether dose escalation up to 30 Gy provides additional benefits.This work was supported in part by Deutsche Kinderkrebsstiftung
A Composite Chiral Pair of Rotational Bands in the odd-A Nucleus 135Nd
High-spin states in 135Nd were populated with the 110Pd(30Si,5n)135Nd
reaction at a 30Si bombarding energy of 133 MeV. Two Delta(I)=1 bands with
close excitation energies and the same parity were observed. These bands are
directly linked by Delta(I)=1 and Delta(I)=2 transitions. The chiral nature of
these two bands is confirmed by comparison with three-dimensional tilted axis
cranking calculations. This is the first observation of a three-quasiparticle
chiral structure and established the primarily geometric nature of this
phenomenon.Comment: 10 pages, 5 figures (1 in color), 1 table, submitted to Physics
Review Letters, written in REVTEX4 forma
The RMS Charge Radius of the Proton and Zemach Moments
On the basis of recent precise measurements of the electric form factor of
the proton, the Zemach moments, needed as input parameters for the
determination of the proton rms radius from the measurement of the Lamb shift
in muonic hydrogen, are calculated. It turns out that the new moments give an
uncertainty as large as the presently stated error of the recent Lamb shift
measurement of Pohl et al.. De Rujula's idea of a large Zemach moment in order
to reconcile the five standard deviation discrepancy between the muonic Lamb
shift determination and the result of electronic experiments is shown to be in
clear contradiction with experiment. Alternative explanations are touched upon.Comment: 6 pages, 4 figures, final version includes discussion of systematic
and numerical error
New empirical fits to the proton electromagnetic form factors
Recent measurements of the ratio of the elastic electromagnetic form factors
of the proton, G_Ep/G_Mp, using the polarization transfer technique at
Jefferson Lab show that this ratio decreases dramatically with increasing Q^2,
in contradiction to previous measurements using the Rosenbluth separation
technique. Using this new high quality data as a constraint, we have reanalyzed
most of the world e-p elastic cross section data. In this paper, we present a
new empirical fit to the reanalyzed data for the proton elastic magnetic form
factor in the region 0 < Q^2 < 30 GeV^2. As well, we present an empirical fit
to the proton electromagnetic form factor ratio, G_Ep/G_Mp, which is valid in
the region 0.1 < Q^2 < 6 GeV^2
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