Magnetic Field and Plasma Observations at Mars: Initial Results of the Mars Global Surveyor Mission   总被引：2，自引：0，他引：2  

MH Acu?a  JEP Connerney  P Wasilewski  RP Lin  KA Anderson  CW Carlson  J McFadden  DW Curtis  D Mitchell  H Reme  C Mazelle  JA Sauvaud  C d'Uston  A Cros  JL Medale  SJ Bauer  P Cloutier  M Mayhew  D Winterhalter  NF Ness 《Science (New York, N.Y.)》1998,279(5357):1676-1680

The magnetometer and electron reflectometer investigation (MAG/ER) on the Mars Global Surveyor spacecraft has obtained magnetic field and plasma observations throughout the near-Mars environment, from beyond the influence of Mars to just above the surface (at an altitude of approximately 100 kilometers). The solar wind interaction with Mars is in many ways similar to that at Venus and at an active comet, that is, primarily an ionospheric-atmospheric interaction. No significant planetary magnetic field of global scale has been detected to date (<2 x 10(21) Gauss-cubic centimeter), but here the discovery of multiple magnetic anomalies of small spatial scale in the crust of Mars is reported.  相似文献   

The structure of the upper atmosphere of mars: In situ accelerometer measurements from mars global surveyor   总被引：1，自引：0，他引：1  

GM Keating  SW Bougher  RW Zurek  RH Tolson  GJ Cancro  SN Noll  JS Parker  TJ Schellenberg  RW Shane  BL Wilkerson  JR Murphy  JL Hollingsworth  RM Haberle  M Joshi  JC Pearl  BJ Conrath  MD Smith  RT Clancy  RC Blanchard  RG Wilmoth  DF Rault  TZ Martin  DT Lyons  PB Esposito  MD Johnston  al et 《Science (New York, N.Y.)》1998,279(5357):1672-1676

The Mars Global Surveyor (MGS) z-axis accelerometer has obtained over 200 vertical structures of thermospheric density, temperature, and pressure, ranging from 110 to 170 kilometers, compared to only three previous such vertical structures. In November 1997, a regional dust storm in the Southern Hemisphere triggered an unexpectedly large thermospheric response at mid-northern latitudes, increasing the altitude of thermospheric pressure surfaces there by as much as 8 kilometers and indicating a strong global thermospheric response to a regional dust storm. Throughout the MGS mission, thermospheric density bulges have been detected on opposite sides of the planet near 90 degreesE and 90 degreesW, in the vicinity of maximum terrain heights. This wave 2 pattern may be caused by topographically-forced planetary waves propagating up from the lower atmosphere.  相似文献   

Effects of parasitism and of supplementing ewes with methyl methionine hydroxy analogue on the wool production of their lambs as adults     

JL WHEELER  AJ WILLIAMS  WH SOUTHCOTT 《Australian veterinary journal》1988,65(11):358-359

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Oral Newcastle disease vaccination with V4 virus in chickens: comparison with other routes   总被引：3，自引：0，他引：3  

PB SPRADBROW  JL SAMUEL 《Australian veterinary journal》1991,68(3):114-115

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Workshop studies with monoclonal antibodies identifying a novel porcine differentiation antigen, SWC9     

J. Dominguez  A. Ezquerra  F. Alonso  R. Bullido  K. McCullough  A. Summerfield  A. Bianchi  R. J. Zwart  Y. B. Kim  F. Blecha  S. Eicher  M. P. Murtaugh  M. Pampusch  K. Burger 《Veterinary immunology and immunopathology》1998,60(3-4):343-349

Two monoclonal antibodies (mAb) within cluster M4 of the myeloid section of the Second International Swine CD Workshop, C4 (No. 144) and PM18-7 (No. 192), showed reactivity with thymocytes and among cells of myelomonocytic origin with mature macrophages but not with monocytes and granulocytes. Both mAb recognize a protein showing two bands of 205 kDa and 130 kDa under both reducing and non-reducing conditions. Although epitope mapping with these mAb could not be performed, this cluster received the SWC9 designation.  相似文献   

Bovine babesiosis in dual purpose calves in the state of Yucatan,Mexico     

Ramirez  G.T.  Jones  T.W.  Brown  C.G.D.  Dominguez  J.L.D.  Honhold  N. 《Tropical animal health and production》1998,30(1):45-52

Thirty-eight dual purpose calves in the 3 agricultural zones of the state of Yucatan, Mexico were monitored for antibodies to Babesia bovis and B. bigemina from close to birth up to 12 months of age.The results showed that infection with both parasites is widespread throughout the 3 zones. Many of the animals had produced antibody to both parasites by 6 months of age indicating high transmission rates resulting in enzootic stability for both parasites.Any changes to agricultural practices in the state that could affect disease stability through either reduction in numbers of tick vectors or the introduction of susceptible adults will have to be accompanied with measures such as vaccination to limit losses due to clinical babesiosis.  相似文献   

Prevalence of anti-T. canis antibodies in stray dogs in Mexico City     

Martínez-Barbabosa I  Quiroz MG  González LA  Cárdenas EM  Edubiel AA  Juárez JL  Gaona E 《Veterinary parasitology》2008,153(3-4):270-276

Toxocara canis is a common intestinal helminth found in dogs. In humans, it is a cause of Visceral Larva Migrans (VLM), a zoonosis rarely studied in Mexico. The aim of this study is to examine, by means of the indirect haemaglutination test (IHAT), the prevalence of antibodies of T. canis in the serum of stray dogs in Mexico City. METHODS AND MATERIALS: 141 stray dog serum samples from three different districts of the city were analyzed: Iztacalco (49), Iztapalapa (49) and Coyoacan (43). In each location three study groups were formed. Group I with 35 dogs (less than a year old), Group II with 91 dogs (ages 1相似文献   

Effect of different mini‐volume colloid centrifugation configurations on flow cytometrically sorted sperm recovery efficiency and quality using a computer‐assisted semen analyzer          下载免费PDF全文

LB Ferré  JL Chitwood  C Fresno  HH Ortega  ME Kjelland  PJ Ross 《Reproduction in domestic animals》2018,53(1):26-33

Straws of sex‐sorted sperm are usually packaged at a low concentration (e.g., ~2.1 × 10⁶ sperm/ml) and cost significantly more than unsorted conventional semen from the same sire. In order to maximize the efficiency of using sex‐sorted sperm under in vitro fertilization conditions, the selection of an appropriate sperm separation technique is essential. In this study, the effect of using different silane‐coated silica colloid dilutions and layering configurations during centrifugation of sex‐sorted sperm was examined over an extended period of incubation time. Sperm recovery and viability after centrifugation using the colloid separation technique were measured along with several sperm motility parameters using CASA. For this purpose, frozen and thawed sex‐sorted sperm samples were centrifuged using mini‐volume single‐layer (40%, 60% and 80%) and mini‐volume two‐layer (45%/90%, 40%/80% and 30%/60%) separation configurations using PureSperm^®. A single layer of 40% PureSperm^® recovered significantly more sex‐sorted sperm (78.07% ± 2.28%) followed by a single layer of 80% PureSperm^® (68.43% ± 2.33%). The lowest sperm recovery was obtained using a two‐layer PureSperm^® dilution of 45%/90% (47.57% ± 2.33%). Single‐layer centrifugation recovered more sorted sperm (68.67% ± 1.74%) than two layer (53.74% ± 1.74%) (p < .0001). A single layer of 80% PureSperm^® exhibited the highest sorted sperm viability (72.01% ± 2.90%) after centrifugation (p < .05). The mini‐volume single layer of 80% PureSperm^® was determined to be an effective alternative to a two‐layer centrifugation configuration for sex‐sorted sperm selection. In addition, single‐layer colloid dilution of 80% performed either as well as or significantly outperformed the other treatments, as well as the control, with regard to motility (MOT) for all time periods of analysis.  相似文献   

Foregut fermentation in the hoatzin, a neotropical leaf-eating bird     

Grajal A  Strahl SD  Parra R  Gloria Dominguez M  Neher A 《Science (New York, N.Y.)》1989,245(4923):1236-1238

The only known case of an avian digestive system with active foregut fermentation is reported for the hoatzin (Opisthocomus hoazin), one of the world's few obligate folivorous (leaf-eating) birds. Hoatzins are one of the smallest endotherms with this form of digestion. Foregut fermentation in a flying bird may be explained by increased digestive efficiency by selection of highly fermentable and extremely patchy resources, coupled with microbial nutritional products and secondary compound detoxification. This unexpected digestive system gives a new perspective to the understanding of size limitations of vertebrate herbivores and to the evolution of foregut fermentation.  相似文献   

Sediment imbalances and flooding risk in European deltas and estuaries     

Albert Rovira  Rhoda Ballinger  Carles Ibáñez  Paul Parker  M. Dolores Dominguez  Xavier Simon  Andrzej Lewandowski  Boris Hochfeld  Marian Tudor  Liesbeth Vernaeve 《Journal of Soils and Sediments》2014,14(8):1493-1512

Purpose

We analysed the status of current water and sediment management practices in six deltas and estuaries, which were part of the European DELTANET, INTERREG-funded network.

Materials and methods

These systems—the Danube, Ebro and Vistula deltas and the Elbe, Minho and Severn estuaries—represent different geographic regions of Europe. This enables comparison between the sites’ approaches to common coastal issues, notably those associated with sediment budgets, contamination and flood risk. Based on documentary analysis, workshop events and expert discussion, we employ a simple classification scheme to distinguish between levels of risk from these aspects.

Results

We suggest that flood risk is the most significant risk, followed by upstream sediment retention and sediment aggradation. Chemical contamination, though less severe, is not unimportant. Key management issues include a lack of environmental quality standards for sediment and suspended particulate matter, as well as the limited deployment of monitoring programmes, regular sediment sampling and associated chemical analyses.

Conclusions

These include both general and specific recommendations. Within these, the limited scope of integrated plans that aim for sustainability of the respective systems is highlighted. It is suggested that these do not challenge traditional, classical engineering approaches sufficiently. Nor do they address the origin of many environmental problems, especially those which are closely linked to short-term political and economic priorities.  相似文献