Chirp filtering in the fractional Fourier Domain

Cataloged from PDF version of article.In the Wigner domain of a one-dimensional function, a certain chirp term represents a rotated line delta function. On the other hand, a fractional Fourier transform (FRT) can be associated with a rotation of the Wigner-distribution function by an angle connected with the FRT order. Thus with the FRT tool a chirp and a delta function can be transformed one into the other. Taking the chirp as additive noise, the FRT is used for filtering the line delta function in the appropriate fractional Fourier domain. Experimental filtering results for a Gaussian input function, which is modulated by an additive chirp noise, are shown. Excellent agreement between experiments and computer simulations is achieved

Fractional Fourier Transform- Simulations and experimental results

Cataloged from PDF version of article.Recently two optical interpretations of the fractional Fourier transform operator were introduced. We address implementation issues of the fractional-Fourier-transform operation. We show that the original bulk-optics configuration for performing the fractional-Fourier-transform operation 3J. Opt. Soc. Am. A 10, 2181 1199324 provides a scaled output using a fixed lens. For obtaining a non-scaled output, an asymmetrical setup is suggested and tested. For comparison, computer simulations were performed. A good agreement between computer simulations and experimental results was obtained

Anamorphic Fractional Fourier Transforming--Optical Implementation and Applications

Cataloged from PDF version of article.An additional degree of freedom is introduced to fractional-Fourier-transform systems by use of anamorphic optics. A different fractional Fourier order along the orthogonal principal directions is performed. A laboratory experimental system shows preliminary results that demonstrate the proposed theory. Applications such as anamorphic fractional correlation and multiplexing in fractional domains are briefly suggested. (C) 1995 Optical Society of Americ

Electrophysiological Evidence of Attentional Biases in Social Anxiety Disorder

Background: Previous studies investigating attentional biases in social anxiety disorder (SAD) have yielded mixed results. Recent event-related potential (ERP) studies using the dot-probe paradigm in non-anxious participants have shown that the P1 component is sensitive to visuospatial attention towards emotional faces. We used a dot-probe task in conjunction with high-density ERPs and source localization to investigate attentional biases in SAD. Method: Twelve SAD and 15 control participants performed a modified dot-probe task using angry–neutral and happy–neutral face pairs. The P1 component elicited by face pairs was analyzed to test the hypothesis that SAD participants would display early hypervigilance to threat-related cues. The P1 component to probes replacing angry, happy or neutral faces was used to evaluate whether SAD participants show either sustained hypervigilance or decreased visual processing of threat-related cues at later processing stages. Results: Compared to controls, SAD participants showed relatively (a) potentiated P1 amplitudes and fusiform gyrus (FG) activation to angry–neutral versus happy–neutral face pairs; (b) decreased P1 amplitudes to probes replacing emotional (angry and happy) versus neutral faces; and (c) higher sensitivity (d′) to probes following angry–neutral versus happy–neutral face pairs. SAD participants also showed significantly shorter reaction times (RTs) to probes replacing angry versus happy faces, but no group differences emerged for RT. Conclusions: The results provide electrophysiological support for early hypervigilance to angry faces in SAD with involvement of the FG, and reduced visual processing of emotionally salient locations at later stages of information processing, which might be a manifestation of attentional avoidance.Psycholog

Kinetic temperatures toward X1/X2 orbit interceptions regions and Giant Molecular Loops in the Galactic center region

Context: It is well known that the kinetic temperatures, Tkin, of the molecular clouds in the Galactic center region are higher than in typical disk clouds. However, the Tkin of the molecular complexes found at higher latitudes towards the giant molecular loops in the central region of the Galaxy is so far unknown. The gas of these high latitude molecular clouds (hereafter referred to as halo clouds) is located in a region where the gas in the disk may interact with the gas in the halo in the Galactic center region. Aims: To derive Tkin in the molecular clouds at high latitude and understand the physical process responsible for the heating of the molecular gas both in the Central Molecular Zone (the concentration of molecular gas in the inner 500 pc) and in the giant molecular loops. Methods: We measured the metastable inversion transitions of NH3 from (1,1) to (6,6) toward six positions selected throughout the Galactic central disk and halo. We used rotational diagrams and large velocity gradient modeling to estimate the kinetic temperatures toward all the sources. We also observed other molecules like SiO, HNCO, CS, C34S, C18O, and 13CO, to derive the densities and to trace different physical processes (shocks, photodissociation, dense gas) expected to dominate the heating of the molecular gas. Results: We derive for the first time Tkin of the high latitude clouds interacting with the disk in the Galactic center region. We find high rotational temperatures in all the observed positions. We derive two kinetic temperature components (150 K and 40 K) for the positions in the Central Molecular Zone, and only the warm kinetic temperature component for the clouds toward the giant molecular loops. The fractional abundances derived from the different molecules suggest that shocks provide the main heating mechanism throughout the Galactic center, also at high latitudesComment: accepted for publication in A&A 06/09/201

Scheduling with Sequencing Flexibility *

This study examines the effects of sequencing flexibility on the performance of rules used to schedule operations in manufacturing systems. The findings show that taking advantage of even low levels of sequencing flexibility in the set of operations required to do a job results in substantial improvement in the performance of scheduling rules with respect to mean flowtime. Differences in the mean flowtime measure for various rules also diminish significantly with increasing sequencing flexibility. Performance improvements additionally result for such due-date related performance measures as mean tardiness and the proportion of jobs tardy. At high levels of sequencing flexibility, some nonparametric scheduling rules outperform the shortest processing time rule in terms of the mean flowtime criterion. Rules based on job due dates also outperform rules based on operation milestones in terms of tardiness related criteria at high levels of sequencing flexibility. The implications of these findings for the design of manufacturing systems and product design are noted.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73893/1/j.1540-5915.1993.tb00477.x.pd

Distances of the TeV SNR complex CTB 37 towards the Galactic Bar

Three supernova remnants form the CTB 37 complex: CTB 37A (G348.5+0.1, associated with the TeV $\gamma$-ray source HESS J1714-385), CTB 37B (G348.7+0.3, associated with HESS J1713-381 and the magnetar CXOU J171405.7.381031), and G348.5-0.0. We use 21 cm HI absorption measurements to constrain the kinematic distances to these SNRs, which have not previously been determined well. We revise the kinematic distance for CTB 37A to be in the range 6.3 to 9.5 kpc (previously $\sim$11.3 kpc) because it is beyond the near 3-kpc arm and in front of the far side of the CO cloud at -145 km s$^{-1}$ towards $l$=348.5. G348.5-0.0 has a HI column density (N$_{HI}$ $\sim6.1\times10^{21}$ cm$^{-2}$) lower than CTB 37A (\sim7.1\time10^{21} cm$^{-2}$). Also, G348.5-0.0 does not have the major absorption feature at -107 km s$^{-1}$ that CTB 37A shows. This is caused by the near 3-kpc arm, so G348.5-0.0 is at a distance of $\le$ 6.3 kpc. CTB 37B is at a distance of $\sim$13.2 kpc (previously 5 to 9 kpc) based on: 1) it has an absorption feature at -10$\pm$5 km s$^{-1}$ from the far 3-kpc arm, so CTB 37B is behind it; 2) there is absorption at -30 km s$^{-1}$ but not at -26 km s$^{-1}$, which yields the distance value; 3) the HI column density towards CTB 37B ($\sim8.3\times10^{21}$ cm$^{-2}$) is larger than CTB 37A. In summary, CTB 37A, CTB 37B and G348.5+0.0 are all at different distances and are only by chance nearby each other on the sky. In addition, we conclude that CTB 37 A and B are not associated with the historical Supernova AD 393.Comment: 6 pages, 3 figs. Accepted by MNRA

Neuroactive steroids in depression and anxiety disorders: Clinical studies

Certain neuroactive steroids modulate ligand-gated ion channels via non-genomic mechanisms. Especially 3 alpha-reduced pregnane steroids are potent positive allosteric modulators of the gamma-aminobutyric acid type A (GABA(A)) receptor. During major depression, there is a disequilibrium of 3 alpha-reduced neuroactive steroids, which is corrected by clinically effective pharmacological treatment. To investigate whether these alterations are a general principle of successful antidepressant treatment, we studied the impact of nonpharmacological treatment options on neuroactive steroid concentrations during major depression. Neither partial sleep deprivation, transcranial magnetic stimulation, nor electroconvulsive therapy affected neuroactive steroid levels irrespectively of the response to these treatments. These studies suggest that the changes in neuroactive steroid concentrations observed after antidepressant pharmacotherapy more likely reflect distinct pharmacological properties of antidepressants rather than the clinical response. In patients with panic disorder, changes in neuroactive steroid composition have been observed opposite to those seen in depression. However, during experimentally induced panic induction either with cholecystokinine-tetrapeptide or sodium lactate, there was a pronounced decline in the concentrations of 3 alpha-reduced neuroactive steroids in patients with panic disorder, which might result in a decreased GABAergic tone. In contrast, no changes in neuroactive steroid concentrations could be observed in healthy controls with the exception of 3 alpha,5 alpha-tetrahydrodeoxycorticosterone. The modulation of GABA(A) receptors by neuroactive steroids might contribute to the pathophysiology of depression and anxiety disorders and might offer new targets for the development of novel anxiolytic compounds. Copyright (c) 2006 S. Karger AG, Basel

Inequalities in health care use and expenditures: empirical data from eight developing countries and countries in transition

This paper summarizes eight country studies of inequality in the health sector. The analyses use household data to examine the distribution of service use and health expenditures. Each study divides the population into "income" quintiles, estimated using consumption expenditures. The studies measure inequality in the use of and spending on health services. Richer groups are found to have a higher probability of obtaining care when sick, to be more likely to be seen by a doctor, and to have a higher probability of receiving medicines when they are ill, than the poorer groups. The richer also spend more in absolute terms on care. In several instances there are unexpected findings. There is no consistent pattern in the use of private providers. Richer households do not devote a consistently higher percentage of their consumption expenditures to health care. The analyses indicate that intuition concerning inequalities could result in misguided decisions. It would thus be worthwhile to measure inequality to inform policy-making. Additional research could be performed using a common methodology for the collection of data and applying more sophisticated analytical techniques. These analyses could be used to measure the impact of health policy changes on inequality