1,334 research outputs found
Ricci Collineations of the Bianchi Types I and III, and Kantowski-Sachs Spacetimes
Ricci collineations of the Bianchi types I and III, and Kantowski-Sachs
space- times are classified according to their Ricci collineation vector (RCV)
field of the form (i)-(iv) one component of is nonzero, (v)-(x)
two components of are nonzero, and (xi)-(xiv) three components of
are nonzero. Their relation with isometries of the space-times is
established. In case (v), when , some metrics are found under
the time transformation, in which some of these metrics are known, and the
other ones new. Finally, the family of contracted Ricci collineations (CRC) are
presented.Comment: 21 Pages, LaTeX, no figures, accepted for publication in the
International Journal of Modern Physics
High-order harmonic generation from Rydberg states at fixed Keldysh parameter
Because the commonly adopted viewpoint that the Keldysh parameter
determines the dynamical regime in strong field physics has long been
demonstrated to be misleading, one can ask what happens as relevant physical
parameters, such as laser intensity and frequency, are varied while is
kept fixed. We present results from our one- and fully three-dimensional
quantum simulations of high-order harmonic generation (HHG) from various bound
states of hydrogen with up to 40, where the laser intensities and the
frequencies are scaled from those for in order to maintain a fixed
Keldysh parameter for all . We find that as we increase
while keeping fixed, the position of the cut-off scales in well
defined manner. Moreover, a secondary plateau forms with a new cut-off,
splitting the HHG plateau into two regions. First of these sub-plateaus is
composed of lower harmonics, and has a higher yield than the second one. The
latter extends up to the semiclassical cut-off. We find that this
structure is universal, and the HHG spectra look the same for all
when plotted as a function of the scaled harmonic order. We investigate the
-, - and momentum distributions to elucidate the physical mechanism
leading to this universal structure
Phase-dependent interference fringes in the wavelength scaling of harmonic efficiency
We describe phase-dependent wavelength scaling of high-order harmonic
generation efficiency driven by ultra-short laser fields in the mid-infrared.
We employ both numerical solution of the time-dependent Schr\"{o}dinger
equation and the Strong Field Approximation to analyze the fine-scale
oscillations in the harmonic yield in the context of channel-closing effects.
We show, by varying the carrier-envelope phase, that the amplitude of these
oscillations depend strongly on the number of returning electron trajectories.
Furthermore, the peak positions of the oscillations vary significantly as a
function of the carrier-envelope phase. Owing to its practical applications, we
also study the wavelength dependence of harmonic yield in the "single-cycle"
limit, and observe a smooth variation in the wavelength scaling originating
from the vanishing fine-scale oscillations.Comment: 5 pages, 4 figure
Turkish version of impact on family scale: a study of reliability and validity
<p>Abstract</p> <p>Background</p> <p>Although there is a considerably high prevalence of developmental disorders in Turkey there are not many assessment tools related to evaluating the impact of these children on their family. The aim of this study was to determine the validity and reliability of the Turkish version of the Impact on Family Scale (IPFAM), a health related quality of life measurement to be utilized in clinical trials, health care services, research and evaluation.</p> <p>Methods</p> <p>Caregivers of 85 children with developmental disabilities answered the questionnaire and 65 of them answered it twice with a one week interval. The reliability of the measurement was assessed by Cronbach's alpha coefficient, and with intraclass correlation coefficient (ICC) for test-retest reliability. Construct validity was assessed by calculating the correlation between total impact score of IPFAM, WeeFIM and the physiotherapists' evaluation via Visual Analogue Scale (VAS) to determine the child's disability.</p> <p>Results</p> <p>Test-retest reliability was found to be ICC = 0.953 for total impact, 0.843 for financial support, 0.940 for general impact, 0.871 for disruption of social relations and 0.787 for coping. Internal consistency was tested using Cronbach's alpha and was found to be 0.902 for total impact of IPFAM. For construct validity the correlation between total impact score of IPFAM and WeeFIM was r = -0,532 (p < 0.001) and the correlation between total impact score of IPFAM and the physiotherapist's evaluation was r = 0.519 (p < 0.001).</p> <p>Conclusion</p> <p>The Turkish version of IPFAM was found to be a reliable and valid instrument for assessing the impact of developmental disorders of the child on the family.</p
Oral manifestations in a boy with X-linked reticulate pigmentary disorder
X-linked reticulate pigmentary disorder (XLPDR) is a rare, multi-systemic disease with only a limited number of families described in the literature. XLPDR has a genetic origin and the gene has been mapped to Zp22p21. Dental features resemble those of hypohidrotic ectodermal dysplasia. A case of a 3-years-old boy is described
CEP-Controlled Molecular Dissociation by Ultrashort Chirped Laser Pulses
We demonstrate and characterize that a carrier-envelope-phase
(CEP)-controlled ultrashortchirped field is an efficient and robust mechanism
to modify the dissociation dynamics of molecularhydrogen. Different
dissociation pathways are collectively induced and their interference
contributeto the kinetic energy release spectra. Chirping is able to
efficiently manipulate the interferencesof different dissociation pathways. We
demonstrate a linear relationship between chirp and CEP-dependence,
dissociation as well as directional electron localization
Oral manifestation of Goltz-Gorlin syndrome in a young girl
Introduction
Focal dermal hypoplasia (Goltz-Gorlin syndrome) is a multi-system disorder characterized by involvement of skin, skeletal system, eyes and face. It is caused by loss-of-function mutations in the PORCN gene. We report the case of a young female, focusing on the dental features.
Aim
To describe the oral manifestation of a rare disorder that resembles ectodermal dysplasia (ED).
Case report
Clinical, radiological and genetic findings revealed common features of Goltz-Gorlin syndrome and pure ED. Oro-dental characteristics of the patient mostly corresponded to those described in the literature. However, previously unreported oro-dental findings such as taurodontism, peg-shaped teeth and microdontia are considered unusual for Goltz-Gorlin syndrome, but similar to the dental features of hypohidrotic ED. Clinical characterization of the patient by a multidisciplinary approach is described and a comprehensive review of the literature is presented
- …