Flexible retinotopy: motion-dependent position coding in the visual cortex     

Whitney D  Goltz HC  Thomas CG  Gati JS  Menon RS  Goodale MA 《Science (New York, N.Y.)》2003,302(5646):878-881

Although the visual cortex is organized retinotopically, it is not clear whether the cortical representation of position necessarily reflects perceived position. Using functional magnetic resonance imaging (fMRI), we show that the retinotopic representation of a stationary object in the cortex was systematically shifted when visual motion was present in the scene. Whereas the object could appear shifted in the direction of the visual motion, the representation of the object in the visual cortex was always shifted in the opposite direction. The results show that the representation of position in the primary visual cortex, as revealed by fMRI, can be dissociated from perceived location.  相似文献   

Darwin and philosophers     

Herbert S 《Science (New York, N.Y.)》1979,204(4394):726-727

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High abrasion resistance with sparse mineralization: copper biomineral in worm jaws     

Lichtenegger HC  Schöberl T  Bartl MH  Waite H  Stucky GD 《Science (New York, N.Y.)》2002,298(5592):389-392

Biominerals are widely exploited to harden or stiffen tissues in living organisms, with calcium-, silicon-, and iron-based minerals being most common. In notable contrast, the jaws of the marine bloodworm Glycera dibranchiata contain the copper-based biomineral atacamite [Cu2(OH)3Cl]. Polycrystalline fibers are oriented with the outer contour of the jaw. Using nanoindentation, we show that the mineral has a structural role and enhances hardness and stiffness. Despite the low degree of mineralization, bloodworm jaws exhibit an extraordinary resistance to abrasion, significantly exceeding that of vertebrate dentin and approaching that of tooth enamel.  相似文献   

Removal of an intracoelomic hook via laparotomy in a sandbar shark (Carcharhinus plumbeus)     

Lécu A  Herbert R  Coulier L  Murray MJ 《Journal of zoo and wildlife medicine》2011,42(2):256-262

A twenty-one-year-old male sandbar shark (Carcharhinus plumbeus) demonstrated signs of chronic weight loss even though its appetite remained unchanged. In addition, the gradual development of a red, circular lesion on its ventral body was noted. After months without any significant changes, a ventral fistula appeared revealing the tip of a wire exposed within its center. The shark was immobilized via intramuscular remote injection through dartgun with etomidate; removed from its exhibit tank; and clinically examined with radiographic imaging, a cell blood count/serum chemistry evaluation, and the use of a metal detector along the body wall. A metallic hook was identified in the coelom about 10 cm cranial to the external fistula. The shark was transferred to an isolation pool for 1 mo. A second immobilization via immersion in eugenol was conducted in order to perform a celiotomy. The hook was located in a liver lobe and was surgically removed. After a prolonged recovery from anesthesia, the shark was released into its primary tank and recovered uneventfully, although some of the skin sutures sloughed prematurely.  相似文献   

Hydrogen ion input to the hubbard brook experimental forest,New Hampshire,during the last decade     

Gene E. Likens  F. Herbert Bormann  John S. Eaton  Robert S. Pierce  Noye M. Johnson 《Water, air, and soil pollution》1976,6(2-4):435-445

Being downwind of eastern and midwestern industrial centers, the Hubbard Brook Experimental Forest offers a prime location to monitor long-term trends in atmospheric chemistry. Continuous measurements of precipitation chemistry during the last 10 yr provide a measure of recent changes in precipitation inputs of H ion. The weighted average pH of precipitation during 1964–65 to 1973–74 was 4.14, with a minimum annual value of 4.03 in 1970–71 and a maximum annual value of 4.21 in 1973–74. The sum of all cations except H ion decreased from 51 μeq 1^?1 in 1964–65 to 23 μeq 1^?1 in 1973–74 providing a significant drop in neutralizing capacity during this period. Based upon regression analysis, the input in equivalents of H ion and nitrate increased by 1.4-fold and 2.3-fold respectively, from 1964–65 to 1973–74. Input of all other ions either decreased or showed no trend. Based upon a stoichiometric formation process in which a sea-salt, anionic component is subtracted from the total anions in precipitation, SO₄ ⁼, contribution to acidity dropped from 83% to 66%, whereas NO₃ ^? increased from 15% to 30% during 1964–65 to 1973–74. The increased annual input of H ion at Hubbard Brook during the past 10 yr is highly correlated with the increased input of nitrate in precipitation.  相似文献   

A prediction model of landslips     

Herbert Neuland 《CATENA》1976,3(2):215-230

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Using ground-penetrating radar to detect layers in a sandy field soil   总被引：1，自引：0，他引：1  

J. Boll  R. P. G. van Rijn  K. W. Weiler  J. A. Ewen  J. Daliparthy  S. J. Herbert  T. S. Steenhuis 《Geoderma》1996,70(2-4):117-132

Pollutant transport in sandy soils can be very complex due to the presence of coarse sand lenses. Water flows laterally over the coarse material and, subsequently, breakthrough occurs in concentrated pathways, called fingers. This (funneled) flow process is a form of preferential flow reducing solute travel time and degradation of organic chemicals.

In this paper, we test ground-penetrating radar (GPR) as a tool for detecting layers in the soil. Several GPR transects were established on a fine sandy loam soil throughout the growing season and subsequent fall period to find the best time to reveal layer structures. The effect of the spatially varying moisture content on the radar velocity was determined from actual measurements with soil samples and by using the Common Mid-Point (CMP) technique. The optimal time to find coarse layers with GPR in this soil was at the end of the fall season when the soil was wetted and evaporation had decreased. The depth of layers, as indicated by GPR, was highly sensitive to the soil moisture content and could be in error by as much as ±0.4 m on a depth scale of 1.5 to 2 m if an average propagation velocity was used. A satisfactory depth prediction of textural interfaces was obtained non-destructively by collecting data in both reflection and CMP mode.  相似文献   

Consistency and solubility changes in herring (Clupea harengus) light muscle homogenates as a function of pH     

Undeland I  Kelleher SD  Hultin HO  McClements J  Thongraung C 《Journal of agricultural and food chemistry》2003,51(14):3992-3998

Fish muscle proteins can be isolated from a variety of low-value raw materials by solubilization in either acid or base. If the consistency of the resulting solution is sufficiently low, it is possible to recover most of the solubilized proteins and remove most of the lipids by centrifugation. Lipid removal should greatly stabilize the isolated proteins. In a previous investigation into the use of herring for production of these protein isolates, it was observed that this species had particularly high consistency values when the proteins were solubilized. This study was undertaken to determine the consistencies obtained with herring light muscle tissue over the pH range covered by the two processes, from about pH 2.7 to 10.8. Protein solubility was compared to consistency of the resultant solutions. Maximum consistencies of the homogenates, approximately 220 and approximately 175 mPa.s, were obtained at pH values of approximately 3.5 and 10.5, respectively. Consistency began to increase approximately when solubilization began. Storage of homogenates at pH 2.7 decreased the consistency over a 10 min time period. The magnitude of the consistency peaks at both acid and alkaline pH values increased when using ice-stored as well as frozen-stored herring, especially in the acid range. Protein solubility at pH <4 and pH >/=10.8 slightly decreased after post-mortem storage of the herring muscle. It is suggested that the observed changes in consistency result from the expansion and solvation of protein aggregates which eventually dissociate into smaller units, perhaps even monomers.  相似文献   

The immune response of pigs to infection with the stomach worm Hyostrongylus rubidus (Hassall and Stiles, 1892): II. Multiple infections and reinfections in growing pigs and sows     

H.V. Smith  I.V. Herbert  A.J. Davis 《Veterinary parasitology》1976,1(4):337-344

Pigs given multiple infections of third stage Hyostrongylus ribidus larvae over a 10-day period produced detectable circulating agglutinins 2–3 days after the initial infection. Titres were neither higher nor more prolonged than those of pigs which received a single infection of larvae, although fluctuations in titres over a 30-day period were more marked.Pigs reinfected with a single dose of third stage larvae, however, showed a rapid initial decline in titre followed by a gradual increase to a level higher than that detected at primary infection. Biological manifestations of immunity such as a decreased parasite egg output and increased prepatent period were also seen. The host reaction to reinfection is regarded as an anamnestic response.  相似文献   

A new anthelmintic assay using rats infected with Trichostrongylus colubriformis.     

K A Gration  B F Bishop  M R Martin-Short  A Herbert 《Veterinary parasitology》1992,42(3-4):273-279

A new anthelmintic assay is described which uses immunosuppressed (60 ppm hydrocortisone acetate in diet) rats infected with the nematode Trichostrongylus colubriformis. Immunosuppressed rats were infected with 1500 T. colubriformis larvae, treated either orally or subcutaneously on Day 14 post-infection and necropsied 4 days after treatment. The worm counts in immunosuppressed control animals averaged 775 worms per rat. A range of benzimidazoles, levamisole hydrochloride, morantel tartrate, 22,23-dihydroavermectin B1a and alpha-milbemycin have been evaluated in the assay. The ED95 values obtained indicate that rats infected with T. colubriformis provide a highly predictive model for assaying the activity of experimental drugs in vivo prior to studies in ruminants.  相似文献