Analysis of specific heat anomalies of high-T c superconductors based on a two-carrier high-T c superconductor model

We investigate the specific heat properties of a high-T _c superconductor model, the “two-carrier model” which includes an electron-phonon interaction driven by lattice defects such as oxygen deficiencies in the otherwise conventional BCS superconductor. The normal state is identified as a two-carrier model system which is composed of two groups of charge carriers: the normal and the renormalized Bloch carriers. An enhanced normal-state electronic specific heat is obtained, and there is good agreement between theoretical predictions about the specific heat anomalies at and aboveT _c and experimental data.     

A 1.8-V distributed voltage-controlled oscillator module for 5.8-GHz ISM band

This letter presents the design and implementation of a 1.8-V 5.8-GHz distributed voltage-controlled oscillator module based on bipolar transistors. The oscillator delivered -2-dBm-output power with a current consumption of 11.5 mA. The tuning range achieved was 650 MHz. The measured phase noise was -100 dBc/Hz at 1-MHz offset. The circuit construction was simple and robust and no buffer amplifier was needed. The design can be used for 5.8-GHz ISM band wireless LAN applications.     

Ionic strength effect on the thermal unfolding of alpha-spectrin peptides

In previous work, we have shown that the ionic strength-mediated differences found for the hydrodynamic dimensions of the human erythrocyte spectrin are not caused by secondary structural changes, but are caused more probably by subtle changes in tertiary interactions (LaBrake, C. C., Wang, L., Keiderling, T. A., and Fung, L. W.-M. (1993) Biochemistry 32, 10296-10302.). The substructure of spectrin has been suggested to be composed largely of triple alpha-helical bundle structural domains in tandem. In the present study, we used fluorescence and circular dichroism methods to study ionic strength effects on intact spectrin dimers and on recombinant peptides of spectrin domains of different lengths. We observed little ionic strength effect on the thermal unfolding temperature, Tm, values in these systems. However, we found that ionic strength-induced cooperativity in the unfolding processes was similar for the spectrin dimer and for peptides with two or three domains, as measured by entropy changes (DeltaSm). Although single-domain peptides exhibited rather variable DeltaSm values, depending on the specific domain, they showed little salt effects on the DeltaSm values themselves. This suggests that spectrin undergoes subtle ionic strength-induced conformational changes, probably near the interdomain regions of the molecule. These conformational changes may be responsible for the observed hydrodynamic and unfolding properties in intact spectrin under different ionic strength conditions. We suggest that recombinant peptides of various lengths may serve as models for studying the structural flexibility in spectrin.     

Short-term effects of nicotine on bone and calciotropic hormones in adult female rats

Quantitative measurement of sound-induced discomfort and pain thresholds showed that migraineurs (n = 65) were significantly more sensitive than headache-free controls (n = 80), both during and outside attack (p < 0.0001). Patients tested with head pain had lower thresholds than those tested without pain (p < 0.01). Migraine with and without aura did not differ as to sound sensitivity. There were no significant differences in thresholds between the symptomatic and nonsymptomatic sides (p > or = 0.78). Patients with unilateral headache or pain of pulsating character were more sensitive than those with bilateral headache or pressing pain (p < 0.05). Phonophobia did not correlate significantly with duration, frequency, or severity of attacks. The main results were in accordance with a questionnaire study concerning subjective evaluation of sound sensitivity. Similarities between phonophobia and photophobia in migraine provide evidence that both phenomena share a common pathophysiological mechanism in this condition.     

Phase I trial of sequential high-dose chemotherapy with escalating dose paclitaxel, melphalan, and cyclophosphamide, thiotepa, and carboplatin with peripheral blood progenitor support in women with responding metastatic breast cancer

A single high-dose cycle of chemotherapy with stem cell support can produce disease-free survival of 15-20% for at least 3 years in women with responding stage IV breast cancer. North American Autologous Bone Marrow Transplant Registry data suggest that a complete response (CR) is the single most important prognostic factor associated with prolonged disease-free survival. Therefore, if sequential high-dose chemotherapy can increase the CR rate, then perhaps an increased proportion of patients will remain disease free. Women with at least a partial response (PR) to induction chemotherapy received three separate high-dose cycles of chemotherapy with peripheral blood progenitor support and granulocyte colony-stimulating factor. The first intensification was a dose escalation of paclitaxel (400-825 mg/ m2), the second intensification was melphalan (180 mg/m2), and the third intensification consisted of 6000 mg/m2 cyclophosphamide (1500 mg/m2/day), 500 mg/m2 thiotepa (125 mg/m2/day), and 800 mg/m2 carboplatin (200 mg/m2/day; CTCb). Thirty-six women were enrolled and 31 completed all three cycles. After the paclitaxel infusion most patients developed reversible predominantly sensory neuropathy. Of the 19 patients with measurable disease, 6 converted to CR, 7 converted to a PR* (the complete resolution of all soft tissue or visceral disease with sclerosis of prior lytic bone lesions), and 2 had a further PR for an overall response rate of 79%. Two patients had no further response and disease in two patients progressed, and thus they were taken off the study before CTCb. Seventy-eight percent are progression-free at a median follow-up of 14 months (range, 3-24+). Three sequential cycles of high-dose chemotherapy are feasible and were administered in this study with no mortality. Single agent paclitaxel at doses up to 825 mg/m2 were well tolerated with moderate reversible toxicity.     

Self-construal moderates age differences in social network characteristics.

In this study, the authors examined age differences in social network characteristics (SNC) among Hong Kong Chinese. The sample consisted of 596 Chinese adults, ranging from 18 to 91 years old. Age was positively associated with close social partners and negatively associated with peripheral social partners. For individuals who were more likely to define the self as interconnected with others (i.e., interdependent self-construal), increasing age was associated with a greater number of close social partners. The negative association between age and the number of peripheral social partners, well-documented in the Western literature, was found only among Chinese adults with lower interdependence but not among those with higher interdependence. These findings highlight the importance of examining the underlying mechanism rather than a particular pattern of SNC across cultures. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Is Tl2Ba2CuO6 a superconductor-metal array?

From structural analysis we have shown in a previous investigation that the series TlBa₂Ca _n Cu _n+1O_2n+5 and Tl₂Ba₂Ca _n Cu _n+1O_2n+6 are composed of superconductor-semiconductor arrays. In this paper, we demonstrate that the unit cell of the Tl₂Ba₂Ca _n Cu _n+1O_2n+6 series can further be viewed as composed of a composite block of superconductor-metal-semiconductor, where TlBa₂CuO₅ is the fundamental superconductor, TlO the metallic unit, and CaCuO₂ the semiconductor block. It is indicated that theT _c of Tl(2201) can be deduced from that of Tl(1201) based on Kresin's model of composite systems.     

Role of gender and vascular endothelium in rat aorta response to 17 beta-estradiol

Estrogen supplementation in postmenopausal women offers significant cardiovascular protection. The mechanism for this benefit is unclear but may be due to an interaction of estrogen with the blood vessel wall (vascular smooth muscle and endothelium). We examined the response of weight-matched female and male endothelium-intact and -denuded aortae to 17 beta-estradiol, its interaction with noradrenaline, and the effect of N-nitro-L-arginine. Estradiol produced relaxation responses that were significantly greater in female endothelium-intact preparations. This response was sensitive to N-nitro-L-arginine, while the response to 17 beta-estradiol in male endothelum-intact and both female and male endothelum-denuded preparations was resistant. Estradiol also inhibited contractions to noradrenaline, which was more pronounced in the female endothelium-intact aortic rings. These data imply that estradiol interacts preferentially with the female vascular endothelium, but there exists an endothelium-independent process that can also be activated in the male aorta. Further studies are warranted to elucidate these differential mechanisms.     

Comparison of tacrolimus absorption in transplant patients receiving continuous versus interrupted enteral nutritional feeding

1. The obese gene product leptin, secreted exclusively from adipocytes, was discovered to serve as a satiety factor and to play an important role in regulating body weight. In adults, the serum leptin level reportedly increases with the degree of obesity. Leptin receptors are expressed in various tissues, and recent in vitro studies suggest a role for leptin in haematopoiesis. 2. The present study was designed to clarify the relationship between serum leptin and body mass index, peripheral blood cell counts, serum cholesterol, high-density lipoprotein-cholesterol, insulin and cortisol levels in 299 Japanese male adolescents aged 15-16 years. 3. With simple linear correlation, log [serum leptin] showed a strong correlation with body mass index (r = 0.56), log [insulin] (r = 0.36) and leucocyte count (r = 0.22) (P < 0.001 for all). There were also correlations with systolic blood pressure, erythrocyte count, haematocrit and high-density lipoprotein-cholesterol (P < 0.01 for all). Even after adjustment for body mass index and log [insulin], log [leptin] correlated with leucocyte (P = 0.004) and erythrocyte (P = 0.057) counts. Stepwise multiple regression analyses revealed log [leptin] to correlate significantly with body mass index, log [insulin] and the leucocyte count (P < 0.005 for all, r2 = 0.399). 4. To our knowledge, this is the first clinical study to show the possible association of serum leptin level with blood cell counts, independent of body mass index and serum insulin. We conclude that these data further support a role for leptin in haematopoiesis.     

Signal and interference statistics of a CDMA system with feedbackpower control

Power control is essential in the use of direct-sequence code-division multiple-access (CDMA) techniques over fading radio channels. The paper investigates a feedback power control approach that allows power commands to be updated at a higher rate than the rate of multipath fading. The signal and interference statistics as received at the base stations after power control are obtained for a simulated CDMA system which includes multiple base stations with diversity receivers and a large number of power-controlled users continuously moving at various speeds. The authors show that often-used analyses based on perfect average power control lead to optimistic capacity results (by about 25%) because interference is underestimated by as much as 1 dB