The water retention function for a model of soil structure with pore and solid fractal distributions     

N. R. A. Bird  E. Perrier  M. Rieu 《European Journal of Soil Science》2000,51(1):55-63

  相似文献   

Anti‐Mullerian Hormone Concentration and Antral Ovarian Follicle Population in Murrah Heifers Compared to Holstein and Gyr Kept Under the Same Management     

JM Baldrighi  MF Sá Filho  EOS Batista  RNVR Lopes  JA Visintin  PS Baruselli  MEOA Assumpção 《Reproduction in domestic animals》2014,49(6):1015-1020

This study was performed to evaluate plasma concentrations of anti‐Mullerian hormone (AMH) and the ovarian antral follicle population (AFP) in different genetic groups. Cyclic heifers (13 Bubalus bubalis [Murrah]; 15 Bos taurus [Holstein] and 10 Bos indicus [Gyr]) were maintained under the same management and were synchronized with two doses of 150 μg IM d‐cloprostenol administered 14 days apart. After the second d‐cloprostenol treatment, heifers had their ovaries scanned daily by ultrasound to define the day of ovulation. On the same day, the AFP was determined and a plasma sample was collected to measure AMH. Murrah heifers had less AFP (25.6 ± 2.1 follicles; p = 0.01) and plasma AMH concentration (0.18 ± 0.03 ng/ml; p < 0.001) than Gyr (60.0 ± 12.2 follicles and 0.60 ± 0.12 ng/ml of AMH); however, data were similar when compared to Holstein (35.9 ± 6.8 follicles and 0.24 ± 0.06 ng/ml of AMH) heifers. Regardless of genetic background, there was a positive relationship between the AFP and plasmatic AMH concentration (Murrah [r = 0.62; p < 0.01], Holstein [r = 0.66; p < 0.001] and Gyr [r = 0.88; p < 0.001]). Also, when heifers were classified according to high‐ or low‐AMH concentration based on the average within each genetic group, high‐AMH heifers had greater (p < 0.0001) AFP than low‐AMH heifers. In conclusion, both Murrah and Holstein heifers presented lower plasma AMH concentration and AFP when compared to Gyr.  相似文献   

Controlling Cotton's Insect Pests: A New System     

Adkisson PL  Niles GA  Walker JK  Bird LS  Scott HB 《Science (New York, N.Y.)》1982,216(4541):19-22

Cotton is more heavily treated with insecticides than any other crop in the United States. In southern Texas, this heavy treatment resulted in insecticide- resistant strains of major pests which almost destroyed the industry in the late 1960's and early 1970's. An integrated insect control program based on new short-season cotton varieties and traditional cultural practices has restored production in the area. The new system has been widely implemented because it produces greater net returns by reducing the use of insecticides, fertilizer, and irrigation.  相似文献   

A common fold mediates vertebrate defense and bacterial attack     

Rosado CJ  Buckle AM  Law RH  Butcher RE  Kan WT  Bird CH  Ung K  Browne KA  Baran K  Bashtannyk-Puhalovich TA  Faux NG  Wong W  Porter CJ  Pike RN  Ellisdon AM  Pearce MC  Bottomley SP  Emsley J  Smith AI  Rossjohn J  Hartland EL  Voskoboinik I  Trapani JA  Bird PI  Dunstone MA  Whisstock JC 《Science (New York, N.Y.)》2007,317(5844):1548-1551

Proteins containing membrane attack complex/perforin (MACPF) domains play important roles in vertebrate immunity, embryonic development, and neural-cell migration. In vertebrates, the ninth component of complement and perforin form oligomeric pores that lyse bacteria and kill virus-infected cells, respectively. However, the mechanism of MACPF function is unknown. We determined the crystal structure of a bacterial MACPF protein, Plu-MACPF from Photorhabdus luminescens, to 2.0 angstrom resolution. The MACPF domain reveals structural similarity with poreforming cholesterol-dependent cytolysins (CDCs) from Gram-positive bacteria. This suggests that lytic MACPF proteins may use a CDC-like mechanism to form pores and disrupt cell membranes. Sequence similarity between bacterial and vertebrate MACPF domains suggests that the fold of the CDCs, a family of proteins important for bacterial pathogenesis, is probably used by vertebrates for defense against infection.  相似文献   

Ulysses Radio Occultation Observations of the lo Plasma Torus During the Jupiter Encounter     

Bird MK  Asmar SW  Brenkle JP  Edenhofer P  Funke O  Pätzold M  Volland H 《Science (New York, N.Y.)》1992,257(5076):1531-1535

Radio signals from Ulysses were used to probe the lo plasma torus (IPT) shortly after the spacecraft's closest approach to Jupiter. The frequencies of the two downlinks at S-band (2.3 gigahertz) and X-band (8.4 gigahertz) were recorded, differenced, and integrated in order to derive the columnar electron density of the IPT. The measurements agree qualitatively with contemporary models of the IPT based on Voyager data, but significant differences are apparent as well. The overall level of the IPT electron density is approximately the same as the prediction, implying that the amount of gas (or plasma) injected from lo is similar to that observed during the Voyager era. On the other hand, the IPT seems to be less extended out of the centrifugal equator, implying a smaller plasma temperature than predicted.  相似文献   

Climatic change in tasmania inferred from a 1089-year tree-ring chronology of huon pine     

Cook E  Bird T  Peterson M  Barbetti M  Buckley B  D'Arrigo R  Francey R  Tans P 《Science (New York, N.Y.)》1991,253(5025):1266-1268

A climatically sensitive huon pine tree-ring chronology from western Tasmania allows inferences about Austral summer temperature change since A.D. 900. Since 1965, huon pine growth has been unusually rapid for trees that are in many cases over 700 years old. This growth increase correlates well with recent anomalous warming in Tasmania on the basis of instrumental records and supports claims that a climatic change, perhaps influenced by greenhouse gases, is in progress. Although this temperature increase exceeds any that are inferred to have occurred during the past 1089 years at this location, it has not yet clearly emerged from the natural background variability of climate in this part of the Southern Hemisphere.  相似文献   

Polarized gamma-ray emission from the crab     

Dean AJ  Clark DJ  Stephen JB  McBride VA  Bassani L  Bazzano A  Bird AJ  Hill AB  Shaw SE  Ubertini P 《Science (New York, N.Y.)》2008,321(5893):1183-1185

Pulsar systems accelerate particles to immense energies. The detailed functioning of these engines is still poorly understood, but polarization measurements of high-energy radiation may allow us to locate where the particles are accelerated. We have detected polarized gamma rays from the vicinity of the Crab pulsar using data from the spectrometer on the International Gamma-Ray Astrophysics Laboratory satellite. Our results show polarization with an electric vector aligned with the spin axis of the neutron star, demonstrating that a substantial fraction of the high-energy electrons responsible for the polarized photons are produced in a highly ordered structure close to the pulsar.  相似文献   

Auranofin improves overall survival when combined with standard of care in a pilot study involving dogs with osteosarcoma     

Liliana Endo‐Munoz  Tristram C. Bennett  Eleni Topkas  Sherry Y. Wu  Douglas H. Thamm  Laura Brockley  Maureen Cooper  Scott Sommerville  Maurine Thomson  Kathleen O'Connell  Amy Lane  Guy Bird  Anne Peaston  Nicholas Matigian  Rodney C. Straw  Nicholas A. Saunders 《Veterinary and comparative oncology》2020,18(2):206-213

Osteosarcoma is the most common paediatric primary bone malignancy. The major cause of death in osteosarcoma is drug‐resistant pulmonary metastasis. Previous studies have shown that thioredoxin reductase 2 is a driver of metastasis in osteosarcoma and can be inhibited by auranofin (AF). Moreover, studies have shown that AF significantly reduces pulmonary metastases in xenotransplant models. Here, we describe a phase I/II study of AF in canine osteosarcoma, a well‐recognized spontaneous model of human osteosarcoma. We performed a single‐arm multicentre pilot study of AF in combination with standard of care (SOC) (amputation + carboplatin). We recruited 40 dogs to the trial and used a historical SOC‐only control group (n = 26). Dogs >15 kg received 9 mg AF q3d PO and dogs <15 kg received 6 mg q3d. Follow‐up occurred over at least a 3‐year period. Auranofin plus SOC improved overall survival (OS) (P = .036) in all dogs treated. The improved outcome was attributable entirely to improved OS in male dogs (P = .009). At the time of writing, 10 dogs (25%) survive without measurable disease in the treatment group with survival times ranging between 806 and 1525 days. Our study shows that AF improves OS in male dogs when combined with SOC. Our findings have translational relevance for the management of canine and human osteosarcoma. Our data justify a larger multicentre phase 2 trial in dogs and a phase I/II trial in human patients with refractory disease at the time of initial surgery.  相似文献   

Administration of human chorionic gonadotropin to suckled beef cows before ovulation synchronization and fixed-time insemination: replacement of gonadotropin-releasing hormone with human chorionic gonadotropin     

Marquezini GH  Dahlen CR  Bird SL  Lamb GC 《Journal of animal science》2011,89(10):3030-3039

Two experiments were conducted to evaluate whether hCG administered 7 d before initiating the CO-Synch + controlled internal drug release (CIDR) ovulation synchronization protocol (Exp. 1 and 2), or replacing GnRH with hCG at the time of AI (Exp. 1), would improve fertility to a fixed-time AI (TAI) in suckled beef cows. In addition, the effects of hCG on follicle dynamics, corpus luteum development, and concentrations of progesterone (P4) were evaluated. In Exp. 1, cows were stratified by days postpartum, age, and parity and assigned randomly to a 2 × 2 factorial arrangement of 4 treatments: 1) cows received 100 μg of GnRH at CIDR insertion (d -7) and 25 mg of PGF(2α) at CIDR removal (d 0), followed in 64 to 68 h by a TAI plus a second injection of GnRH at TAI (CG; n = 29); 2) same as CG but the second injection of GnRH at the time of insemination was replaced by hCG (CH; n = 28); 3) same as CG, but cows received hCG 7 d (d -14) before CIDR insertion (HG; n = 28); and 4) same as HG, but cows received hCG 7 d (d -14) before CIDR insertion (HH; n = 29). Pregnancy rates were 52, 41, 59, and 38% for GG, GH, HG, and HH, respectively. Cows receiving hCG (39%) in place of GnRH at TAI tended (P = 0.06) to have poorer pregnancy rates than those receiving GnRH (56%). Pre-CO-Synch hCG treatment increased (P < 0.05) the percentage of cows with concentrations of P4 >1 ng/mL at d -7, increased (P < 0.02) concentration of P4 on d -7, and decreased (P < 0.001) the size of the dominant follicle on d 0 and 3, compared with cows not treated with hCG on d -14. In Exp. 2, cows were stratified based on days postpartum, BCS, breed type, and calf sex and then assigned to the CG (n = 102) or HG (n = 103) treatments. Overall pregnancy rates were 51%, but no differences in pregnancy rates were detected between treatments. Pre-CO-Synch hCG treatment increased (P < 0.05) the percentage of cows cycling on d -7 and increased (P < 0.05) concentrations of P4 on d -7 compared with pre-CO-Synch controls. Therefore, pretreatment induction of ovulation after hCG injection 7 d before initiation of CO-Synch + CIDR protocol failed to enhance pregnancy rates, but replacing GnRH with hCG at the time of AI may reduce pregnancy rates.  相似文献   

Research effort allocation and the conservation of restricted-range island bird species     

Ricardo F. de Lima  Jeremy P. Bird  Jos Barlow 《Biological conservation》2011,(1):627-632

Knowledge gap analyses can be useful to highlight imbalances in research and to improve the distribution of conservation research efforts. We used ISI’s Web of Knowledge (WoK) and BirdLife International’s library catalogue (BLI) to examine the allocation of research effort amongst the extinction-prone island restricted-range birds (RRSs, n = 1321) and the island endemic bird areas and secondary areas (EBAs, n = 108; SAs, n = 58) previously identified by BirdLife International. We found that the distribution of research effort was very uneven across both species and areas. Half of the number of outputs obtained from WoK referred to 3.1% of the island restricted-range bird species and to 4.8% of the endemic bird areas and secondary areas, whereas 52.2% of the species and 34.3% of the areas had no output. The global distribution of research had a strong spatial component, with a limited number of places receiving most of the research efforts (Hawaii, New Zealand, Central America), while many species rich areas were very poorly studied (South East Asia, South Pacific, most Atlantic islands). Research amongst the most threatened RRSs tended to be less biased, with these species having a higher probability of having at least one output from WoK than less threatened species. Given that threats to the conservation of biodiversity are often highly context-dependent, we advocate prioriting the study of poorly known species and regions. Finally, we integrate the knowledge gaps we identify with previously established conservation priorities, in order to prioritize for future conservation research on RRS, EBAs and SAs.  相似文献