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Showing papers by "Tulane University published in 1992"


Journal ArticleDOI
TL;DR: A simple analytic representation of the correlation energy for a uniform electron gas, as a function of density parameter and relative spin polarization \ensuremath{\zeta}, which confirms the practical accuracy of the VWN and PZ representations and eliminates some minor problems.
Abstract: We propose a simple analytic representation of the correlation energy ${\mathrm{\ensuremath{\varepsilon}}}_{\mathit{c}}$ for a uniform electron gas, as a function of density parameter ${\mathit{r}}_{\mathit{s}}$ and relative spin polarization \ensuremath{\zeta}. Within the random-phase approximation (RPA), this representation allows for the ${\mathit{r}}_{\mathit{s}}^{\mathrm{\ensuremath{-}}3/4}$ behavior as ${\mathit{r}}_{\mathit{s}}$\ensuremath{\rightarrow}\ensuremath{\infty}. Close agreement with numerical RPA values for ${\mathrm{\ensuremath{\varepsilon}}}_{\mathit{c}}$(${\mathit{r}}_{\mathit{s}}$,0), ${\mathrm{\ensuremath{\varepsilon}}}_{\mathit{c}}$(${\mathit{r}}_{\mathit{s}}$,1), and the spin stiffness ${\mathrm{\ensuremath{\alpha}}}_{\mathit{c}}$(${\mathit{r}}_{\mathit{s}}$)=${\mathrm{\ensuremath{\partial}}}^{2}$${\mathrm{\ensuremath{\varepsilon}}}_{\mathit{c}}$(${\mathit{r}}_{\mathit{s}}$, \ensuremath{\zeta}=0)/\ensuremath{\delta}${\mathrm{\ensuremath{\zeta}}}^{2}$, and recovery of the correct ${\mathit{r}}_{\mathit{s}}$ln${\mathit{r}}_{\mathit{s}}$ term for ${\mathit{r}}_{\mathit{s}}$\ensuremath{\rightarrow}0, indicate the appropriateness of the chosen analytic form. Beyond RPA, different parameters for the same analytic form are found by fitting to the Green's-function Monte Carlo data of Ceperley and Alder [Phys. Rev. Lett. 45, 566 (1980)], taking into account data uncertainties that have been ignored in earlier fits by Vosko, Wilk, and Nusair (VWN) [Can. J. Phys. 58, 1200 (1980)] or by Perdew and Zunger (PZ) [Phys. Rev. B 23, 5048 (1981)]. While we confirm the practical accuracy of the VWN and PZ representations, we eliminate some minor problems with these forms. We study the \ensuremath{\zeta}-dependent coefficients in the high- and low-density expansions, and the ${\mathit{r}}_{\mathit{s}}$-dependent spin susceptibility. We also present a conjecture for the exact low-density limit. The correlation potential ${\mathrm{\ensuremath{\mu}}}_{\mathit{c}}^{\mathrm{\ensuremath{\sigma}}}$(${\mathit{r}}_{\mathit{s}}$,\ensuremath{\zeta}) is evaluated for use in self-consistent density-functional calculations.

21,353 citations


Journal ArticleDOI
TL;DR: A way is found to visualize and understand the nonlocality of exchange and correlation, its origins, and its physical effects as well as significant interconfigurational and interterm errors remain.
Abstract: Generalized gradient approximations (GGA's) seek to improve upon the accuracy of the local-spin-density (LSD) approximation in electronic-structure calculations. Perdew and Wang have developed a GGA based on real-space cutoff of the spurious long-range components of the second-order gradient expansion for the exchange-correlation hole. We have found that this density functional performs well in numerical tests for a variety of systems: (1) Total energies of 30 atoms are highly accurate. (2) Ionization energies and electron affinities are improved in a statistical sense, although significant interconfigurational and interterm errors remain. (3) Accurate atomization energies are found for seven hydrocarbon molecules, with a rms error per bond of 0.1 eV, compared with 0.7 eV for the LSD approximation and 2.4 eV for the Hartree-Fock approximation. (4) For atoms and molecules, there is a cancellation of error between density functionals for exchange and correlation, which is most striking whenever the Hartree-Fock result is furthest from experiment. (5) The surprising LSD underestimation of the lattice constants of Li and Na by 3--4 % is corrected, and the magnetic ground state of solid Fe is restored. (6) The work function, surface energy (neglecting the long-range contribution), and curvature energy of a metallic surface are all slightly reduced in comparison with LSD. Taking account of the positive long-range contribution, we find surface and curvature energies in good agreement with experimental or exact values. Finally, a way is found to visualize and understand the nonlocality of exchange and correlation, its origins, and its physical effects.

17,848 citations


Journal ArticleDOI
TL;DR: An analytic representation of g\ifmmode\bar\else\textasciimacron\fi{} (and hence g) in real space for a uniform electron gas with density parameter ${\mathit{r}$ and spin polarization \ensuremath{\zeta}.
Abstract: The pair-distribution function g describes physical correlations between electrons, while its average g\ifmmode\bar\else\textasciimacron\fi{} over coupling constant generates the exchange-correlation energy. The former is found from the latter by g=(1-${\mathit{a}}_{0}$\ensuremath{\partial}/\ensuremath{\partial}${\mathit{a}}_{0}$)g\ifmmode\bar\else\textasciimacron\fi{}, where ${\mathit{a}}_{0}$ is the Bohr radius. We present an analytic representation of g\ifmmode\bar\else\textasciimacron\fi{} (and hence g) in real space for a uniform electron gas with density parameter ${\mathit{r}}_{\mathit{s}}$ and spin polarization \ensuremath{\zeta}. This expression has the following attractive features: (1) The exchange-only contribution is treated exactly, apart from oscillations we prefer to ignore. (2) The correlation contribution is correct in the high-density (${\mathit{r}}_{\mathit{s}}$\ensuremath{\rightarrow}0) and nonoscillatory long-range (R\ensuremath{\rightarrow}\ensuremath{\infty}) limits. (3) The value and cusp are properly described in the short-range (R\ensuremath{\rightarrow}0) limit. (4) The normalization and energy integrals are respected. The result is found to agree with the pair-distribution function g from Ceperley's quantum Monte Carlo calculation. Estimates are also given for the separate contributions from parallel and antiparallel spin correlations, and for the long-range oscillations at a high finite density.

689 citations


Journal ArticleDOI
TL;DR: The results link antemortem risk factors to the development of atherosclerotic lesions and emphasize the need for preventive cardiology in early life.
Abstract: Race and sex differences in aorta and coronary atherosclerotic lesions were studied in 150 persons aged 6 to 30 years. The intimal surface involvement with aorta fatty streaks was extensive, 0 to 71%, and greater in blacks than in whites (32 vs 20%, p

600 citations


Journal ArticleDOI
Akira Arimura1
TL;DR: Immunohistochemical study indicated that PACAP containing neural fibers are present throughout the brain, including both internal and external zones of the median eminence, in the hypothalamus and the supraoptic nucleus in various species.

458 citations


Journal ArticleDOI
TL;DR: In this article, the backpropagation algorithm is extended to complex domain back-propagations, which can be used to train neural networks for which the inputs, weights, activation functions, and outputs are complex-valued.
Abstract: The backpropagation algorithm is extended to complex domain backpropagation (CDBP) which can be used to train neural networks for which the inputs, weights, activation functions, and outputs are complex-valued Previous derivations of CDBP were necessarily admitting activation functions that have singularities, which is highly undesirable In the derivation, CDBP is derived so that that it accommodates classes of suitable activation functions One such function is found and the circuit implementation of the corresponding neuron is given CDBP hardware circuits can be used to process sinusoidal signals all at the same frequency (phasors) >

353 citations


Journal ArticleDOI
TL;DR: The ability of experts to reliably evaluate the optic disc within themselves is confirmed and the need for developing standardized methods for interobserver evaluation of the optic Disc in glaucoma is emphasized.

315 citations


Journal ArticleDOI
TL;DR: The reaction rate in skin test-positive patients was significantly higher than in those with negative skin tests, demonstrating the positive predictive value of positive tests to both major and minor determinants.
Abstract: Background. — A history (or lack thereof) of penicillin allergy is known to be unreliable in predicting reactions on subsequent administration of the drug. This study tests the usefulness of four penicillin allergen skin tests in the prediction of IgE-mediated reactions subsequent to administration of penicillin. Methods. — Eight centers cooperated in the National Institute of Allergy and Infectious Diseases trial of the predictive value of skin testing with major and minor penicillin derivatives. Hospitalized adults were tested with a major determinant (octa-benzylpenicilloyl-octalysine) and a minor determinant mixture and its components (potassium benzylpenicillin, benzylpenicilloate, and benzylpenicilloyl-N-propylamine). Patients then received a therapeutic course of penicillin and were observed, for 48 hours, for adverse reactions compatible with an IgE-mediated immediate or accelerated allergy. Results.— Among 726 history-positive patients, 566 with negative skin tests received penicillin and only seven (1.2%) had possibly IgE-mediated reactions. Among 600 history-negative patients, 568 with negative skin tests received penicillin and none had a reaction. Only nine of the 167 positive skin test reactors received a penicillin agent and then usually by cautious incremental dosing. Two (22%) of these nine patients had reactions compatible with IgE-mediated immediate or accelerated penicillin allergy; both were positive to the two determinants. Conclusions.— These data corroborate previous data about the negative predictive value of negative skin tests to these materials. The reaction rate in skin test—positive patients was significantly higher than in those with negative skin tests, demonstrating the positive predictive value of positive tests to both major and minor determinants. The number of patients positive only to the major determinant or only to the minor determinant mix was too small to draw conclusions about the positive predictive value of either reagent alone. ( Arch Intern Med. 1992;152:1025-1032)

305 citations


Journal ArticleDOI
TL;DR: Three methods of recording information from focus groups onto paper, as well as three techniques for condensing hours of free-flowing discussion into a readable article that accurately reflects the main points of the focus group discussions are outlined.
Abstract: Focus groups are widely used in the field of public health as a quick, low-cost means of obtaining information from selected groups in the target population for programmatic purposes. Much has been written about techniques for conducting focus groups, but there is limited practical information on systematic analysis of the results. The current article outlines three methods of recording information from focus groups onto paper, as well as three techniques for condensing hours of free-flowing discussion into a readable article that accurately reflects the main points of the focus group discussions. The value of using microcomputers in organizing the focus group information is also discussed.

291 citations


Journal ArticleDOI
TL;DR: demonstrating a beneficial effect of the HA coating at all time periods is believed to be due to the use of paired comparisons, which allow assessment of subtle differences that might otherwise have been obscured by normal biological variability.
Abstract: The effect of a plasma-sprayed hydroxylapatite (HA) coating on the degree of bone ingrowth and interface shear attachment strength was investigated using a canine femoral transcortical implant model. Cylindrical implants were fabricated by sintering spherical Co-Cr-Mo particles 500-710 microns in diameter; the nominal implant dimensions were 5.95 +/- 0.05 mm diameter by 18 mm in length. One half of each implant was coated with hydroxylapatite, 25-30 microns in thickness, by a plasma-spray technique. Using strict aseptic technique, the implants were placed through both femoral cortices into defects approximately 0.05 mm undersized. After 2, 4, 6, 8, 12, 18, 26, and 52 weeks, the implants were harvested and subjected to mechanical pullout testing and undecalcified histologic evaluation. The application of the HA coating to porous implants enhanced both the amount of bone ingrowth and the interface attachment strength at all time periods. These differences were statistically significant for the percent of bone ingrowth at the 4-, 6-, 12-, 18-, 26-, and 52-week time periods, and interface shear strength values were significantly different at the 6-, 8-, 12-, 18-, and 26-week time periods. The rate of development of interface strength and bone ingrowth was also more rapid for the HA-coated implants. No evidence of any disruption, mechanical failure, or biologic resorption of the HA coating was observed. The results of the present study--demonstrating a beneficial effect of the HA coating at all time periods--are believed to be due to the use of paired comparisons, which allow assessment of subtle differences that might otherwise have been obscured by normal biological variability.

283 citations


Journal ArticleDOI
TL;DR: Three-dimensional finite element models of a partially edentulated human mandible were generated to calculate the mechanical response to simulated isometric biting and mastication loads and showed that a model with over 30,000 degrees of freedom was required to obtain analysis accuracy.

Journal ArticleDOI
TL;DR: Recordings from granule cells in hippocampal slices removed from rats 1-4 months after kainate treatment suggest that new local excitatory circuits may be suppressed normally, and then emerge functionally when synaptic inhibition is blocked, and suggest that after repeated seizures and excitotoxic damage in the hippocampus, synaptic reorganization of the mossy fibers is consistently associated with normal responses.

Journal ArticleDOI
TL;DR: Analysis of patients with a history of systemic allergic reactions to either honeybee or yellow jacket stings during VIT concluded that results obtained from studies on the allergy to one Hymenoptera venom cannot be extrapolated to allergies to other Hymanoptera venoms.
Abstract: Venom immunotherapy (VIT) for Hymenoptera allergy is accepted as safe and effective. However, widely varying success rates and frequencies of side effects are reported. Differences between various Hymenoptera species could account for these diverging results. We therefore analyzed 205 patients with a history of systemic allergic reactions to either honeybee (148 patients) or yellow jacket stings (57 patients) during VIT. All patients had a positive skin test to the respective venom before VIT, were monitored for side effects of VIT, and submitted to a sting challenge while they were receiving VIT. Patients with honeybee-venom allergy had a higher sensitivity in both skin tests (p less than 0.05) and RAST (p less than 0.001) than patients with yellow jacket-venom allergy. They developed systemic side effects to VIT injections significantly more often (41% versus 25%; p less than 0.01) and also reacted more frequently to the sting challenge (23% versus 9%; p less than 0.01) than patients with yellow jacket-venom allergy. We conclude that results obtained from studies on the allergy to one Hymenoptera venom cannot be extrapolated to allergies to other Hymenoptera venoms.

Journal ArticleDOI
TL;DR: The results of two investigations of leader characteristics and behaviors associated with extraordinary performance are reported in this paper, which emphasize the importance of professional development opportunities for followers and suggest that specific leader behaviors, rather than personality, inspire followers to higher levels of performance.
Abstract: The results of two investigations of leader characteristics and behaviors associated with extraordinary performance are reported. In a quantitative exploration using Bass's Multifactor Leadership Questionnaire, educators associated leader effectiveness with charisma and intellectual stimulation. Problems are noted with the operational definition of charisma. In a separate investigation, narratives describing educational leaders perceived to be extraordinary were analyzed to determine more specific leader behaviors and characteristics that followers ascribe to those leaders. The qualitative results emphasize the importance of professional development opportunities for followers and suggest that specific leader behaviors, rather than personality, inspire followers to higher levels of performance.

Journal ArticleDOI
TL;DR: The distribution of PACAP-immunoreactive nerve cell bodies and nerve fibers in the gut wall suggests their involvement in the regulation of both motor and secretory activities.

Journal ArticleDOI
TL;DR: Several systems adopting this approach to encode general knowledge in an expressive language, then dynamically construct a decision model for each particular situation or problem instance are developed.
Abstract: In recent years there has been a growing interest among AI researchers in probabilistic and decision modelling, spurred by significant advances in representation and computation with network modelling formalisms. In applying these techniques to decision support tasks, fixed network models have proven to be inadequately expressive when a broad range of situations must be handled. Hence many researchers have sought to combine the strengths of flexible knowledge representation languages with the normative status and well-understood computational properties of decision-modelling formalisms and algorithms. One approach is to encode general knowledge in an expressive language, then dynamically construct a decision model for each particular situation or problem instance. We have developed several systems adopting this approach, which illustrate a variety of interesting techniques and design issues.

Journal ArticleDOI
TL;DR: In this article, confirmatory factor analyses of a priori models of psychological climate were conducted with data collected from 18,457 sales personnel in 567 stores in five regions of a national retail organization.
Abstract: Confirmatory factor analyses of a priori models of psychological climate were conducted with data collected from 18,457 sales personnel in 567 stores in five regions of a national retail organization. The results provide good support for viewing employee work-climate perceptions as composed of two higher order factors—concern for employees and concern for customers. These higher order factors are posited to reflect employees' cognitive appraisals of the behavior of agents toward (a) employees' well-being in the organization's internal environment and (b) the well-being of other organizational constituencies or stakeholders (e.g., customers) in the task environment, respectively. The implications of a multiple-stakeholder perspective for extending notions of psychological climate are discussed. Recently, James and James (1989) proposed that work-climate perceptions represent valuations or cognitive appraisals of environmental attributes in terms of their acquired meaning and significance to the individual. From James and James's perspective, "Valuation appears to be the key to such cognitive appraisals in asmuch as (a) values serve as standards for assessing welfare (Locke, 1976), where welfare is denned in terms of a sense of well-being. . . and (b) valuation provides appraisals of the degree to which these standards are represented in environmental attributes" (James & James, 1989, pp. 739-740). James and James viewed valuations or cognitive appraisals as "emotional cognitions" because they are hypothesized to reflect the subjective meanings that, in combination with perceived physiological arousal, help to label emotion and to determine the direction and intensity of the experience and the emotion. Drawing from the work of Lazarus (1982,1984) and Lazarus and Folkman (1984), James and James (1989) further proposed that all emotionally relevant cognitions reflect a single higher order factor comprising the degree to which the environment is perceived as personally beneficial or detrimental to one's wellbeing. Results of James and James's confirmatory factor analyses on four diverse samples supported a hierarchical factor

Journal ArticleDOI
TL;DR: The results of the present study suggest a significant and widespread occurrence of both DF and DP in dust mite sensitive people with asthma, and extracts of both mite species should be considered for diagnostic tests and immunotherapy.
Abstract: The density and species prevalence of dust mites were determined at various times over a 5-year-period in 252 homes of dust mite sensitive people with asthma who lived in eight geographic areas of the United States (Cincinnati, Ohio; New Orleans, La.; Memphis, Tenn.; Galveston, Texas; Greenville, N.C.; Delray Beach, Fla.; San Diego and Los Angeles, Calif.). The most common dust mites found in the homes were Dermatophagoides farinae (DF), D. pteronyssinus (DP), Euroglyphus maynei (EM), and Blomia tropicalis. All homes in all locations contained Dermatophagoides spp. mites, but few homes were populated exclusively by either DF or DP alone. Most homes (81.7%) were coinhabitated by both DF and DP. In coinhabited homes one species was predominant and usually made up at least 75% of the total mite population. Prevalence of the dominant or only species present varied between homes within a geographic area. EM occurred in significant numbers in 35.7% of homes in New Orleans, Memphis, Galveston, Delray Beach, and San Diego. Blomia tropicalis occurred in these same cities but in low densities. For all dust samples, only 13 homes of the 252 sampled had 100 or fewer mites/gm dust, which is considered to be the threshold for sensitivity. Most homes had average mite densities of 500 or more mites/gm dust. The results of the present study suggest a significant and widespread occurrence of both DF and DP. Therefore extracts of both mite species should be considered for diagnostic tests and immunotherapy. Significant levels of EM were present in some areas. Thus sensitivity to EM should be considered in these areas.

Journal ArticleDOI
TL;DR: In this paper, the authors applied the Data Envelopment Analysis (DEA) to a sample of public (government-owned) and not-for-profit hospitals operating in Michigan in 1982.

Journal ArticleDOI
TL;DR: A variety of techniques have been used to deliver antigens to the gut-associated lymphoid tissues in an attempt to initiate production of specific secretory immunoglobulin A for protection against pathogens that colonize or cross mucosal surfaces to initiate infection.
Abstract: A variety of techniques, including the use of live oral vaccines, have been used to deliver antigens to the gut-associated lymphoid tissues in an attempt to initiate production of specific secretory immunoglobulin A for protection against pathogens that colonize or cross mucosal surfaces to initiate infection. A number of attenuated Salmonella mutants are able to interact with the lymphoid tissues in the Peyer9s patches but are not able to cause systemic disease. Some of these mutants are effective as live vaccines (i.e., able to protect against infection with the virulent Salmonella parent) and are candidates for use as carriers for virulence determinants of other mucosal pathogens. This has been shown to be an effective means of stimulating significant levels of specific mucosal secretory immunoglobulin A directed against the carrier strains and against a variety of heterologous antigens and has been shown to stimulate production of serum antibodies and cell-mediated responses as well. This review examines the history of this mechanism of vaccine delivery and summarizes the most recent applications of this evolving technology. This is a technique for vaccine delivery with significant potential for influencing the management of infectious diseases on a large scale. It can be used not only for vaccines against enteric bacterial pathogens but also for vaccines against a variety of other bacteria, viruses, and parasites. The results obtained to date are encouraging, and there is great potential for development of safe, effective, affordable vaccines.


Journal ArticleDOI
Hahn Shik Lee1
TL;DR: In this article, the authors developed testing procedures for cointegration and seasonal co-integration for nonstationary time series which have unit roots at seasonal frequencies as well as at the zero frequency.

Journal ArticleDOI
F B Cogswell1
TL;DR: A latent stage for PlasModium spp.
Abstract: Although the phenomenon of malarial relapse was known to the ancients, the mechanism has only recently been explained satisfactorily. The long-held hypothesis of a tissue "cycle" in primate malaria as a cause of relapse did not fit clinical and experimental observations. A latent stage for Plasmodium spp. in the liver, for which there is now extensive morphological and experimental confirmation, best explains both the relapse phenomenon and the long prepatent periods seen with some strains of Plasmodium vivax. These latent stages (hypnozoites) have been detected in three relapsing malarias and have been found to persist in the liver as uninucleate parasites for up to 229 days after sporozoite inoculation. They have been found in in vitro cultures of two species of Plasmodium, and their ultrastructure has been partially described.

Journal ArticleDOI
TL;DR: It is suggested that qualitatively different mechanisms may be responsible for the elevated intrarenal angiotensin I and Ang II levels during the initial and maintenance phases of renal hypertension.
Abstract: Renal tissue angiotensin I (Ang I) and II (Ang II) content and angiotensin converting enzyme activity were assessed in both kidneys during initial (7 days) and maintenance (25 days) phases of two-kidney, one clip hypertension in rats. At 7 and 25 days, systolic arterial pressure was 146 +/- 2 and 170 +/- 7 mm Hg, respectively. After 7 days, Ang I content of clipped kidneys was 64% and 70% higher (p < 0.001) than in nonclipped and sham-operated kidneys, respectively, when compared with levels in kidneys from sham-operated rats. In kidneys harvested 25 days after clipping one renal artery, Ang I and Ang II contents in clipped kidneys were increased 102% and 24% (p < 0.01), respectively. Ang II content was also 32% higher in nonclipped kidneys. Angiotensin converting enzyme activity in nonclipped kidneys was greater (p < 0.05) than that in either clipped (46% higher) or sham-operated kidneys (57% higher). Plasma Ang I and Ang II levels were elevated at 7 days but were not different at 25 days in clipped rats. These results demonstrate a dissociation between intrarenal and circulating levels of Ang I and Ang II and suggest that qualitatively different mechanisms may be responsible for the elevated intrarenal Ang II levels during the initial and maintenance phases of renal hypertension.

Journal ArticleDOI
R.P. Dickey, Terry T. Olar1, David N. Curole1, S.N. Taylor1, Phillip H. Rye1 
TL;DR: The endometrial pattern and thickness was analysed prospectively on the day of administration of human chorionic gonadotrophin in 200 in-vitro fertilization (IVF), gamete intra-Fallopian transfer (GIFT) and tubal embryo transfer (TET) cycles and was positively correlated with oestradiol levels.
Abstract: The endometrial pattern and thickness was analysed prospectively on the day of administration of human chorionic gonadotrophin (HCG) in 200 in-vitro fertilization (IVF), gamete intra-Fallopian transfer (GIFT) and tubal embryo transfer (TET) cycles. Increasing maturity of the endometrial pattern was positively correlated with oestradiol levels (r = 0.20; P = 0.005), number of mature eggs (r = 0.13; P less than 0.05) and the number of top quality embryos (r = 0.40; P less than 0.001). The endometrial thickness was positively correlated with the number of follicles greater than or equal to 15 mm (r = 0.15; P less than 0.02) and the cycle day on which HCG was administered (r = 0.14; P less than 0.03). It was unaffected by the dose of human menopausal gonadotrophin and was negatively correlated with the use of clomiphene citrate (r = 0.40; P less than 0.001). Fecundity was increased for IVF when the endometrial thickness was greater than or equal to 9 mm (P less than 0.05) and for GIFT and TET when a Type C triple-line endometrial pattern was present (P less than 0.05). Biochemical pregnancies for the combined methods increased from 2.5% of all pregnancies when the endometrial thickness was 9-13 mm, to 27.8% when the thickness was less than 9 mm or greater than 13 mm (P less than 0.01). Biochemical pregnancies occurred in 67% of IVF pregnancies when the endometrial thickness was greater than or equal to 3 mm.(ABSTRACT TRUNCATED AT 250 WORDS)

Journal ArticleDOI
TL;DR: Shelter and Street Night (S-Night) was the recent effort by the U.S. Bureau of the Census to include selected components of the nation's homeless population in the 1990 decennial count as discussed by the authors.
Abstract: Shelter and Street Night (S-Night) was the recent effort by the U.S. Bureau of the Census to include selected components of the nation's homeless population in the 1990 decennial count. Teams of investigators in five cities (New York, Chicago, Los Angeles, Phoenix, and New Orleans) were contracted by the Census Bureau's Center for Survey Methods Research to assist in assessing various aspects of the S-Night enumeration. Each team compiled independent shelter lists that were compared against the Bureau's lists and also undertook experiments to assess the reliability of the enumeration effort. This introductory statement reviews the design features, methods, findings, and recommendations that were common to all five studies presented in a special issue focused on counting the homeless.


Journal ArticleDOI
TL;DR: This study was designed to improve and validate methods for the accurate and consistent quantitation of angiotensin (ANG) I and II levels in rat kidney and to determine the effects on renal ANG I andII of changes in dietary sodium intake and ANG-converting enzyme (ACE) inhibition.
Abstract: This study was designed to improve and validate methods for the accurate and consistent quantitation of angiotensin (ANG) I and II levels in rat kidney and to determine the effects on renal ANG I and II of changes in dietary sodium intake and ANG-converting enzyme (ACE) inhibition. Kidneys from pentobarbital-anesthetized rats were rapidly removed and homogenized in methanol before extraction and purification of ANG peptides by solid-phase extraction and high-performance liquid chromatography (HPLC). Recoveries of 125I-ANG I and II were greater than 80%. Reversed-phase HPLC of the partially purified methanol extract showed that greater than 75% of the ANG I- and greater than 82% of the ANG II-like immunoreactivity coeluted with ANG I and II, respectively. Dietary sodium deprivation (0.003 meq/g) and excess (1.34 meq/g) for 7 days significantly (P less than 0.01) increased and decreased renal ANG I (296 +/- 30 and 82.6 +/- 15.8 vs. 161 +/- 18 fmol/g) and ANG II (216 +/- 16 and 45.6 +/- 11.8 vs. 98 +/- 16 fmol/g) contents, respectively. Plasma ANG I and II levels showed similar changes. ACE activity was significantly upregulated by sodium deprivation in both kidney (44% increase) and plasma (30% increase). In rats fed normal chow, infusion of enalaprilat for 1 h abolished plasma ACE activity but decreased renal ACE activity by only 58%. ACE inhibition increased renal and plasma ANG I levels 2.8- and 12-fold, respectively, and decreased renal and plasma ANG II levels 75-78%.(ABSTRACT TRUNCATED AT 250 WORDS)

Journal Article
TL;DR: The overproduction of IL-6 by affected scleroderma fibroblasts in the lesions may play a significant role in the pathogenesis of PSS and may profoundly influence the course of the disease.
Abstract: Fibroblasts were cultured from affected skin sites of patients with progressive systemic sclerosis (PSS), from unaffected skin sites of the same patients, and from a healthy donor. The concentration of interleukin 6 (IL-6) in culture medium conditioned by the growth of early passage cells was determined by radioimmunoassay and by quantitative bioassay. Results demonstrated that fibroblasts from affected PSS skin produce from 6 to 30-fold higher levels of biologically active IL-6 compared to unaffected and control cells. In contrast, serum IL-6 concentrations in 6 of 8 patients examined were not significantly different from healthy donors. Serum IL-6 levels were elevated 2 to 3-fold in 2 of 8 patients examined. Thus, the overproduction of IL-6 by affected scleroderma fibroblasts does not necessarily correlate with a systemic increase in IL-6, but may increase its concentration locally. In view of its biological activities, including stimulation of antibody production and T cell activation, the overproduction of IL-6 by PSS fibroblasts in the lesions may play a significant role in the pathogenesis of PSS and may profoundly influence the course of the disease.

Journal ArticleDOI
TL;DR: The rates of photo-induced electron transfer (ET) in a series of donor-acceptor molecules (4,4'-R 2 -2,2'-bipyridine) were studied by photolysis/transient absorbance techniques.
Abstract: The rates of photoinduced electron transfer (ET) in a series of donor-acceptor molecules (4,4'-R 2 -2,2'-bipyridine) 2 Ru(1-(4-CH 3 -2,2'-bipyridine-4'-yl-(CH 2 ) n )-4,4'-bipyridinediium-1'-R') 4+ (R=H, CH 3 ; R'=CH 3 , CH 2 CN; n=1, 2) were studied by picosecond flash photolysis/transient absorbance techniques. The rate of intramolecular forward ET (MLCT quenching) in acetonitrile varied with -ΔG o according to classical Marcus theory for n=2, but not for n=1