A counter-example for the Bezout equation in the Hardy classH p

Leff ₁,f ₂ be bounded holomorphic functions in the unit disc of the complex plane ℂ. Using a recent result of S. Treil about estimates in the corona theorem, we strengthen a counterexample given by Amar, Bruna and Nicolau to the existence of functionsg ₁,g ₂ in the Hardy spaceH ^p ( ) verifying the Bezout equationf ₁ g ₁+f ₂ g ₂=1.     

Extraction and transport of chromium(VI) through a bulk liquid membrane containing triphenylphosphine

The solvent extraction of chromium(VI) in chloroform, dichloromethane, dichloroethane and its transport through a chloroformic bulk liquid membrane from sulphuric acid solutions with the neutral extractant triphenylphosphine (TPP) were studied. It was highlighted that the TPP extractant is an interesting complexing and efficient carrier for transport of chromium(VI) as [(HTPP)HCr2O7] complex from a 2M sulphuric acid solutions. It has a high ability to concentrate the chromium(VI) in the receiving phase according to the Donnan equilibrium. The co-extraction and the co-transport of sulphuric acid is very low and has no effect on the transport efficiency. The transport rate depends mainly on the initial concentration of the extractant.     

Visualizing flow vortices inside a single levitated drop

The internal flow dynamics in single liquid drops, kept in place through levitation by a counterflowing continuous fluid phase in a suitably designed glass cell, is investigated by PFG NMR techniques. The positional stability of the drops was confirmed from series of one-dimensional profiles and was found to be below the spatial resolution of the experiment. Velocity distribution functions (propagators) along all three coordinates were obtained and demonstrated the long-time stability of the internal dynamics in terms of the velocity magnitudes occurring in the systems. Finally, velocity imaging was applied to visualize the internal vortex patterns in the drops either as projections onto different planes or within thin slices of selected orientations. Two different fluid systems were investigated in order to cover the principal cases of rigid and mobile interfaces. Different fast velocity imaging techniques were employed for monitoring the vastly differing velocity ranges of both cases, and the high sensitivity of the internal three-dimensional motion to the cell geometry is demonstrated.     

A role of melanin-concentrating hormone producing neurons in the central regulation of paradoxical sleep

Background

Peptidergic neurons containing the melanin-concentrating hormone (MCH) and the hypocretins (or orexins) are intermingled in the zona incerta, perifornical nucleus and lateral hypothalamic area. Both types of neurons have been implicated in the integrated regulation of energy homeostasis and body weight. Hypocretin neurons have also been involved in sleep-wake regulation and narcolepsy. We therefore sought to determine whether hypocretin and MCH neurons express Fos in association with enhanced paradoxical sleep (PS or REM sleep) during the rebound following PS deprivation. Next, we compared the effect of MCH and NaCl intracerebroventricular (ICV) administrations on sleep stage quantities to further determine whether MCH neurons play an active role in PS regulation.

Results

Here we show that the MCH but not the hypocretin neurons are strongly active during PS, evidenced through combined hypocretin, MCH, and Fos immunostainings in three groups of rats (PS Control, PS Deprived and PS Recovery rats). Further, we show that ICV administration of MCH induces a dose-dependant increase in PS (up to 200%) and slow wave sleep (up to 70%) quantities.

Conclusion

These results indicate that MCH is a powerful hypnogenic factor. MCH neurons might play a key role in the state of PS via their widespread projections in the central nervous system.

     

The broadband social acoustic signaling behavior of spinner and spotted dolphins

Efforts to study the social acoustic signaling behavior of delphinids have traditionally been restricted to audio-range (<20 kHz) analyses. To explore the occurrence of communication signals at ultrasonic frequencies, broadband recordings of whistles and burst pulses were obtained from two commonly studied species of delphinids, the Hawaiian spinner dolphin (Stenella longirostris) and the Atlantic spotted dolphin (Stenella frontalis). Signals were quantitatively analyzed to establish their full bandwidth, to identify distinguishing characteristics between each species, and to determine how often they occur beyond the range of human hearing. Fundamental whistle contours were found to extend beyond 20 kHz only rarely among spotted dolphins, but with some regularity in spinner dolphins. Harmonics were present in the majority of whistles and varied considerably in their number, occurrence, and amplitude. Many whistles had harmonics that extended past 50 kHz and some reached as high as 100 kHz. The relative amplitude of harmonics and the high hearing sensitivity of dolphins to equivalent frequencies suggest that harmonics are biologically relevant spectral features. The burst pulses of both species were found to be predominantly ultrasonic, often with little or no energy below 20 kHz. The findings presented reveal that the social signals produced by spinner and spotted dolphins span the full range of their hearing sensitivity, are spectrally quite varied, and in the case of burst pulses are probably produced more frequently than reported by audio-range analyses.     

Sugar-cellulose composites V. The mechanism of fiber strengthening by cell wall incorporation of sugars

The incorporation of sucrose or some other disaccharides (cellobiose, -lactose or trehalose) into the cell wall of pulp fibers increases the tearing resistance of the resultant sugar-containing paper relative to that of its sugar-free counterpart, but only when the fiber is well-refined. Maltose and -lactose do not exhibit this effect. By the use of a high cellulose pulp the increase is shown not to be due to the presence of hemicelluloses. Differential scanning calorimetry indicates that the interaction between the sucrose molecules and the cellulosic fibers changes and becomes more uniform as the fibers are refined. Although the azo dye Congo red bonds strongly with cellulose the analogous reaction with disaccharides and cyclodextrins, established spectrophotometrically, could not be used to predict the physical outcome of the interactions with added disaccharides or cyclodextrins. From a consideration of the stereochemistry of the impregnant disaccharides the augmentation of the fiber strength is attributed to the interlamellar hydrogen bonding of impregnant molecules having hydroxy endgroups in the cis conformation and separated by about 10Å. The incorporation of cyclodextrins further demonstrates that the conformation and the separation distance between the OH groups located in the interlamellar sugar molecule play an important role in strengthening the sugar-impregnated fiber and in augmenting the tearing resistance of sugar-containing papers.     

On a hierarchy of models for electrical conduction in biological tissues

In this paper we derive a hierarchy of models for electrical conduction in a biological tissue, which is represented by a periodic array of period ε of conducting phases surrounded by dielectric shells of thickness εη included in a conductive matrix. Such a hierarchy will be obtained from the Maxwell equations by means of a concentration process η → 0, followed by a homogenization limit with respect to ε. These models are then compared with regard to their physical meaning and mathematical issues. Copyright © 2005 John Wiley & Sons, Ltd.     

Trends in labor efficiency among American hospital markets

The health care sector is one of the most labor intensive sectors of the economy. As a major player in health service delivery, hospitals must closely examine their largest cost — labor expenses. This study evaluates trends in the efficiency of health care labor among urban hospital markets. More specifically, it assesses the hypothesis that technological changes and market and regulatory pressures have increased aggregate labor efficiency. Using data envelopment analysis (DEA), this study evaluates labor efficiency in 1989 and 1993 in 298 metropolitan statistical areas (MSAs) with two or more hospitals. Results of this study suggest that between 1989 and 1993, hospital markets generally demonstrated higher labor inefficiencies. The U.S. health care system could save approximately $16.6 billion in 1993 by eliminating hospitals' excessive use of health care provider labor.