Sum rules and interlayer conductivity of high-Tc cuprates     

DN Basov  SI Woods  AS Katz  EJ Singley  RC Dynes  M Xu  DG Hinks  CC Homes  M Strongin 《Science (New York, N.Y.)》1999,283(5398):49-52

Analysis of the interlayer infrared conductivity of cuprate high-transition temperature superconductors reveals an anomalously large energy scale extending up to midinfrared frequencies that can be attributed to formation of the superconducting condensate. This unusual effect is observed in a va- riety of materials, including Tl2Ba2CuO6+x, La2-xSrxCuO4, and YBa2Cu3O6.6, which show an incoherent interlayer response in the normal state. Midinfrared range condensation was examined in the context of sum rules that can be formulated for the complex conductivity. One possible interpretation of these experiments is in terms of a kinetic energy change associated with the superconducting transition.  相似文献   

The Current State of Solar Modeling     

J Christensen-Dalsgaard  W Dappen  SV Ajukov  ER Anderson  HM Antia  S Basu  VA Baturin  G Berthomieu  B Chaboyer  SM Chitre  AN Cox  P Demarque  J Donatowicz  WA Dziembowski  M Gabriel  DO Gough  DB Guenther  JA Guzik  JW Harvey  F Hill  G Houdek  CA Iglesias  AG Kosovichev  JW Leibacher  P Morel  CR Proffitt  J Provost  J Reiter  EJ Rhodes  FJ Rogers  IW Roxburgh  MJ Thompson  RK Ulrich 《Science (New York, N.Y.)》1996,272(5266):1286-1292

Data from the Global Oscillation Network Group (GONG) project and other helioseismic experiments provide a test for models of stellar interiors and for the thermodynamic and radiative properties, on which the models depend, of matter under the extreme conditions found in the sun. Current models are in agreement with the helioseismic inferences, which suggests, for example, that the disagreement between the predicted and observed fluxes of neutrinos from the sun is not caused by errors in the models. However, the GONG data reveal subtle errors in the models, such as an excess in sound speed just beneath the convection zone. These discrepancies indicate effects that have so far not been correctly accounted for; for example, it is plausible that the sound-speed differences reflect weak mixing in stellar interiors, of potential importance to the overall evolution of stars and ultimately to estimates of the age of the galaxy based on stellar evolution calculations.  相似文献   

THE HEALING OF SEGMENTAL BONE DEFECTS, INDUCED BY RECOMBINANT HUMAN BONE MORPHOGENETIC PROTEIN (rhBMP-2): A RADIOGRAPHIC, HISTOLOGICAL, AND BIOMECHANICAL STUDY IN RATS     

AW Yasko  JM Lane  EJ Fellinger  V. Rosen  JM Wozney  EA Wang 《Veterinary surgery : VS》1993,22(1):10-10

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Probing cold dense nuclear matter     

Subedi R  Shneor R  Monaghan P  Anderson BD  Aniol K  Annand J  Arrington J  Benaoum H  Benmokhtar F  Boeglin W  Chen JP  Choi S  Cisbani E  Craver B  Frullani S  Garibaldi F  Gilad S  Gilman R  Glamazdin O  Hansen JO  Higinbotham DW  Holmstrom T  Ibrahim H  Igarashi R  de Jager CW  Jans E  Jiang X  Kaufman LJ  Kelleher A  Kolarkar A  Kumbartzki G  Lerose JJ  Lindgren R  Liyanage N  Margaziotis DJ  Markowitz P  Marrone S  Mazouz M  Meekins D  Michaels R  Moffit B  Perdrisat CF  Piasetzky E  Potokar M  Punjabi V  Qiang Y  Reinhold J  Ron G 《Science (New York, N.Y.)》2008,320(5882):1476-1478

The protons and neutrons in a nucleus can form strongly correlated nucleon pairs. Scattering experiments, in which a proton is knocked out of the nucleus with high-momentum transfer and high missing momentum, show that in carbon-12 the neutron-proton pairs are nearly 20 times as prevalent as proton-proton pairs and, by inference, neutron-neutron pairs. This difference between the types of pairs is due to the nature of the strong force and has implications for understanding cold dense nuclear systems such as neutron stars.  相似文献   

Climate Change During the Last Deglaciation in Antarctica   总被引：1，自引：0，他引：1  

PA Mayewski  MS Twickler  SI Whitlow  LD Meeker  Q Yang  J Thomas  K Kreutz  PM Grootes  DL Morse  EJ Steig  ED Waddington  ES Saltzman  P Whung  KC Taylor 《Science (New York, N.Y.)》1996,272(5268):1636-1638

Greenland ice core records provide clear evidence of rapid changes in climate in a variety of climate indicators. In this work, rapid climate change events in the Northern and Southern hemispheres are compared on the basis of an examination of changes in atmospheric circulation developed from two ice cores. High-resolution glaciochemical series, covering the period 10,000 to 16,000 years ago, from a central Greenland ice core and a new site in east Antarctica display similar variability. These findings suggest that rapid climate change events occur more frequently in Antarctica than previously demonstrated.  相似文献   

Rapid Variations in Atmospheric Methane Concentration During the Past 110,000 Years     

EJ Brook  T Sowers  J Orchardo 《Science (New York, N.Y.)》1996,273(5278):1087-1091

A methane record from the GISP2 ice core reveals that millennial-scale variations in atmospheric methane concentration characterized much of the past 110,00 years. As previously observed in a shorter record from central Greenland, abrupt concentration shifts of about 50 to 300 parts per billion by volume were coeval with most of the interstadial warming events (better known as Dansgaard-Oeschger events) recorded in the GISP2 ice core throughout the last glacial period. The magnitude of the rapid concentration shifts varied on a longer time scale in a manner consistent with variations in Northern Hemisphere summer insolation, which suggests that insolation may have modulated the effects of interstadial climate change on the terrestrial biosphere.  相似文献   

Histopathological,Immunohistochemical, Lectinhistochemical and Molecular Findings in Spontaneous Bovine Abortions by Campylobacter fetus     

EL Morrell  CG Barbeito  CA Odeón  EJ Gimeno  CM Campero 《Reproduction in domestic animals》2011,46(2):309-315

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Follicle Wave Growth in Cattle   总被引：1，自引：0，他引：1  

M Mihm  MA Crowe  PG Knight  EJ Austin 《Reproduction in domestic animals》2002,37(4):191-200

Ovarian follicle growth in cattle culminates in the selection of a single dominant follicle which attains the ability for final maturation and ovulation once or twice during the luteal phase and at the end of the oestrous cycle, as well as during other reproductive states. This review will describe in detail the first follicle wave of the cycle leading to selection of the first wave dominant follicle, indicating the specific gonadotrophin dependencies of cohort and dominant follicles, and relating follicle fate to steroidogenesis. As a differential gonadotrophin response of growing antral follicles during the follies‐stimulating hormone (FSH) decline may determine which follicle becomes selected, first wave follicles are also characterized in relation to intrafollicular growth factors, which may modify the gonadotrophin response, such as inhibins and members of the insulin‐like growth factor (IGF) family. Subsequently, the follicular control of the transient FSH rise and decline so crucial to dominant follicle selection will be discussed. It is concluded that successful hormonal manipulation of follicle wave growth and dominant follicle selection will depend on our detailed understanding of the gonadotrophin requirements of differentiating wave follicles.  相似文献   

Low levels of antibacterial drug resistance expressed by Gram-negative bacteria isolated from poultry carcasses in New Zealand     

EJ Pleydell  L Rogers  E Kwan  NP French 《New Zealand veterinary journal》2013,61(5):229-236

Abstract

AIM: To provide baseline data on the levels and patterns of antibacterial drug resistance expressed by Gram-negative bacteria isolated from poultry carcasses in New Zealand.

METHODS: Between July and December 2006, isolates of Escherichia coli (n=407) and Salmonella spp. (n=3) originating from carcass-rinse samples were submitted by testing laboratories affiliated to five major poultry processing plants. Isolates of Campylobacter jejuni (n=193) originating from retail poultry carcasses in 2005–2006 were retrieved from the Massey University archives. All isolates underwent disc diffusion susceptibility testing against panels of 12 (Enterobacteriaceae) and six (Campylobacter spp.) antibacterial drugs. Cephalothin-resistance in isolates of E. coli was confirmed using ETest strips, and confirmation of the resistance phenotypes for a subset of C. jejuni isolates used microbroth dilution assays. Patterns within the resistance phenotypes of the isolates were investigated using hierarchical clustering, and logistic regression modelling.

RESULTS: The majority of isolates (71.5% E. coli, 99% C. jejuni, and all three Salmonella spp. isolates) were fully susceptible to the drugs that were tested. Four (1%) E. coli isolates showed resistance to three or more drugs. The proportions of susceptible E. coli differed between the five processing plants. Resistances were detected in E. coli isolates, using disc diffusion to cephalothin (18.2%), ampicillin (4.4%), tetracycline (4.4%) and gentamicin (1.5%). There was an association between cephalothin-resistant isolates of E. coli and decreased susceptibility to gentamicin. Using ETests to ascertain the minimum inhibitory concentrations (MIC) of E. coli for cephalothin gave inconsistent results. One of 193 C. jejuni isolates was resistant to erythromycin, and microbroth dilution assays confirmed that this panel of C. jejuni was generally susceptible to antibacterial drugs.

CONCLUSIONS: The levels of resistance shown by Gram-negative bacteria isolated from chicken carcasses in New Zealand are among the lowest reported around the world. No resistance to extended-spectrum cephalosporin drugs was detected in E. coli, suggesting that CTX-M and AmpC beta-lactamases are rare or absent. Salmonella spp. are rarely isolated from poultry carcasses during routine testing in New Zealand, and the isolates identified during this study were fully susceptible to the drugs tested. A panel of C. jejuni isolates originating from retail poultry carcasses were susceptible to first-line and second-line antibacterial drugs. The use of cephalothin as a marker of resistance to first-generation cephalosporins may not be appropriate for non-type-specific E. coli of animal origin.  相似文献   

Circadian polymorphisms associated with affective disorders     

Daniel F Kripke  Caroline M Nievergelt  EJ Joo  Tatyana Shekhtman  John R Kelsoe 《Journal of circadian rhythms》2009,7(1):2-10

Background  

Clinical symptoms of affective disorders, their response to light treatment, and sensitivity to other circadian interventions indicate that the circadian system has a role in mood disorders. Possibly the mechanisms involve circadian seasonal and photoperiodic mechanisms. Since genetic susceptibilities contribute a strong component to affective disorders, we explored whether circadian gene polymorphisms were associated with affective disorders in four complementary studies.  相似文献