Predatory Dinosaurs from the Sahara and Late Cretaceous Faunal Differentiation

Late Cretaceous (Cenomanian) fossils discovered in the Kem Kem region of Morocco include large predatory dinosaurs that inhabited Africa as it drifted into geographic isolation. One, represented by a skull approximately 1.6 meters in length, is an advanced allosauroid referable to the African genus Carcharodontosaurus. Another, represented by a partial skeleton with slender proportions, is a new basal coelurosaur closely resembling the Egyptian genus Bahariasaurus. Comparisons with Cretaceous theropods from other continents reveal a previously unrecognized global radiation of carcharodontosaurid predators. Substantial geographic differentiation of dinosaurian faunas in response to continental drift appears to have arisen abruptly at the beginning of the Late Cretaceous.     

Radioactive elements on Mercury's surface from MESSENGER: implications for the planet's formation and evolution

The MESSENGER Gamma-Ray Spectrometer measured the average surface abundances of the radioactive elements potassium (K, 1150 ± 220 parts per million), thorium (Th, 220 ± 60 parts per billion), and uranium (U, 90 ± 20 parts per billion) in Mercury's northern hemisphere. The abundance of the moderately volatile element K, relative to Th and U, is inconsistent with physical models for the formation of Mercury requiring extreme heating of the planet or its precursor materials, and supports formation from volatile-containing material comparable to chondritic meteorites. Abundances of K, Th, and U indicate that internal heat production has declined substantially since Mercury's formation, consistent with widespread volcanism shortly after the end of late heavy bombardment 3.8 billion years ago and limited, isolated volcanic activity since.     

Searching the world wide Web

The coverage and recency of the major World Wide Web search engines was analyzed, yielding some surprising results. The coverage of any one engine is significantly limited: No single engine indexes more than about one-third of the "indexable Web," the coverage of the six engines investigated varies by an order of magnitude, and combining the results of the six engines yields about 3.5 times as many documents on average as compared with the results from only one engine. Analysis of the overlap between pairs of engines gives an estimated lower bound on the size of the indexable Web of 320 million pages.     

Analysis of airborne particles sampled in the southern Appalachian mountains

Over 3 yr of particulate measurements were made at two high elevation sites in the southern Appalachian Mountains of Tennessee and Virginia. Both dichotomous samplers and filter packs were used to obtain day and night, week-long samples for subsequent elemental and ionic analysis. Total No _inf3 ^sup? (HNO₃ + No _in3 ^sup? ) and SO _inf4 ^sup2? averaged, respectively, 1.1 and 5.0 µg m^?3 at Look Rock, Tennessee and 2.0 and 6.4 µg m^?3 at Whitetop Mountain, Virginia. At Whitetop Mountain, the spring and summer seasons had the highest average SO _inf4 ^sup2? concentrations. Seasonally, total N03 varied little. The diurnal variation of elements and SO _inf4 ^sup2? was small. Only total NO _inf3 ^sup? varied substantially with highest values during the day. The fine fraction (particle diameter < 2.5 µm) accounted for about 67% of the total mass. Fine mass and elemental concentrations were generally higher at Look Rock. The elements comprising the principal mass fraction of the coarse samples (2.5 gm < particle diameter < 10 to 15 µm) were of crustal origin (e.g., Al, Si, Ca, Fe) while the element comprising the principal mass fraction of the fine samples (i.e., S) was of manmade origin. Cluster analysis identified two groups of elements at Whitetop Mountain. These groups, in both the coarse and fine fraction, were associate with a soil and an automobile emission component. At Look Rock, only a soil component was obvious.     

The effect of turbulence on the light environment of alfalfa

The properties of sunflecks in alfalfa canopies and their relationship to turbulence were quantified from measurements of light fluctuations and winds. Winds were measured above the canopy at 10 Hz, while light was measured at rates as high as 27 Hz inside the canopy. Power spectral analyses were used to determine the importance of various time scales of light fluctuations. Under all wind conditions a prominent spectral peak ranging from 1 to 2 Hz was observed for photosynthetically active radiation (PAR) in the canopy at LAI of 1.7. As mean winds increased from 1 to 7 ms⁻¹, the peak broadened and large increases were observed in the contribution of higher frequencies up to 10 Hz. The slope of spectral densities of PAR at the higher frequencies exhibited a linear relationship with the friction velocity or intensity of turbulence above the canopy. This implies that certain properties of sunflecks may be evaluated from measured properties of turbulence.The most prominent peaks in the PAR power spectra are likely due to stalk waving, which is triggered by gusts or turbulent structures. The strong damping effects of plants on the resonant interactions, as well as leaf flutter, account for the broad, flat peak under windy conditions. The frequency of leaf flutter is considered to be the main factor governing the slope of the linear portion of the PAR spectrum.     

Diurnal migration and responses to simulated rainfall in desert soil microarthropods and nematodes

Diurnal patterns of microarthropod abundance in surface leaf litter were related to its moisture content. Leaf litter moisture was nearly 7% by weight at 0800h but fell to less than 1% by mid-day. Oribatid and tydeid mites moved into litter in the early morning and back into the soil before mid-day. There were no significant differences in numbers of nematodes in litter or soil and 78–98% of the nematodes were anhydrobiotic (coiled) in soil and litter at all times sampled.Following simulated rainfall there were fewer microarthropods in litter at mid-day in the absence of marked decreases in soil and litter moisture content. During drying, there were gradual reductions in numbers and species diversity of litter microarthropods. Nematode numbers did not change as litter dried. Anhydrobiotic nematodes in the soil increased from 14% on day 1 to 85% on day 4. Between 24 and 36 h after simulated rainfall, the proportion of anhydrobiotic litter nematodes increased from 35 to 80%,.Within 1 h after simulated rainfall, there were marked increases in numbers and diversity of microarthropods in surface litter. No collembolans were extracted from dry litter controls but the wet litter was dominated by isotomid, sminthurid and onychiurid collembolans. There were increases in numbers and diversity of oribatid, tydeid and gamasid mites in the wet surface litter within l h after wetting compared to controls.     

Effect of Dietary Phospholipids on the Choline Requirement ofLitopenaeus vannamei Juveniles

An 8-wk feeding trial was conducted with a 3 ± 4 factorial design for evaluating the nutritional relationship between phospholipids (lecithin at 0, 1.5% or 3% of diet) and choline chloride (0, 1,000, 2,000, or 4,000 mg/kg diet) in juvenile Litopenaeus vannamei . In addition, diets with five graded levels of choline chloride (0, 500, 1,000, 2,000, and 4,000 mg/kg) without supplemental phospholipids or cholesterol were fed for determining the dietary choline requirement. Overall survival was 99% with no difference among the dietary treatments. The choline requirement was estimated to be 871 mg/kg diet without dietary phospholipids. No choline requirement was evident when lecithin was provided at 1.5% and 3% of diet. Shrimp growth significantly increased with incremental dietary phospholipids regardless of choline chloride level. These results indicate that lecithin could effectively provide choline. Conversely, synthesis of phospholipids from choline could not meet the phospholipids requirement of shrimp. Both dietary lecithin and choline chloride supplementation reduced lipid in shrimp muscle. However, only lecithin supplementation increased lipid in hepatopancreas, and dietary choline chloride decreased the level of other phospholipids (except phosphatidylcholine) in shrimp muscle.     

Integrated tick and tick-borne disease control trials in crossbred dairy cattle in Malawi

Summary Crossbred dairy heifers on a farm in an East Coast fever (ECF) endemic area in Malawi were immunised againstTheileria parva, Anaplasma spp.,Babesia bigemina, Babesia bovis andCowdria ruminantium. They were treated at infrequent intervals with chlorfenvinphos to limit infestation with adult ticks, without providing complete tick control. In one trial, which tested a threshold dipping regimen, 20 heifers were dipped only once in 6 months to control a flush ofBoophilus microplus. Unimmunised controls showed serological evidence of exposure toT. parva andB. bigemina, and one died of ECF, but there were no incidents of tick-borne disease in the immunised group. In a second trial, which tested a strategic dipping regimen, 107 animals were dipped 9 times over a 6 month period. Despite heavy challenge byB. bovis and moderate challenge byB. bigemina andAnaplasma spp, demonstrated serologically, there was only a single clinical case of babesiosis. The observations provide encouragement for the introduction of integrated tick and tick-borne disease control programmes in improved cattle in ECF endemic areas.

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Sistemas Integrados De Control De Garrapatas Y Enfermedades Transmitidas Por Garrapatas En Ganado Vacuno Lechero Cruzado En Malawi

Resumen Se inmunizaron terneras lecheras cruzadas frente aTheileria parva, Anaplasma spp.,Babesia bigemina, Babesia bovis yCowdria ruminantium. El experimento se realizó en una granja situada en una zona de Malawi en la que la fiebre de la costa este es endémica. Los animales se trataron de forma infrecuente con clorfenvinfos para limitar la carga de garrapatas adultas, pero no se llevó a cabo ningún programa completo de control de garrapatas. El primer ensayo tuvo como objetivo determinar la frecuencia minima de baños antigarrapata. Un total de 20 terneras recibieron un único baño a lo largo de 6 meses para controlar un aumento en la carga deBoophilus microplus. Los animales control que no habían sido inmunizados mostraron evidencia serológica de exposición aTheileria parva y uno de ellos murió de fiebre de la costa este. Sin embargo, en el grupo de animales inmunizados no se detectó ningún caso de enfermedad transmitida por garrapatas. El segundo experimento tuvo como objetivo comprobar la eficacia de un programa estratégico de baños antigarrapata. Un total de 107 animales fueron bañados 9 veces a lo largo de 6 meses. Si bien se demostró serológicamente una fuerte infestación porBabesia bovis y una infestación moderada porB. bigemina yAnaplasma spp, ningún animal enfermó de babesiosis. Estas observaciones sugieren la conveniencia de introducir programas de control integrados de garrapatas y enfermedades transmitidas por garrapatas en ganado vacuno mejorado en zonas donde la fiebre de la costa este es endémica.

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Experience De Lutte Integree Contre Les Tiques Et Leurs Maladies Chez Le Betail Hybride Laitier Au Malawi

Résumé Des génisses hybrides productrices de lait furent immunisées contreTheileria parva, Anaplasma spp.Babesia bigemina, Babesia bovis etCowdria ruminantium dans une ferme située dans une région à East Coast fever (ECF). Elles furent traitées à intervalles irréguliers avec du chlorfenvinphos pour limiter l'infestation des tiques adultes, mais sans pourvoir un contrôle complet sur les tiques. Pendant une expérience, qui testa le seuil limite du lavage avec des acaricides, 20 génisses furent lavées une seule fois en 6 mois pour maîtriser l'infestation parBoophilus microplus. Les contrôles, non immunisés, montrèrent des preuves sérolôgiques d'exposition àTheileria parva etBabesia bigemina, et une genisse mourut d'ECF, mais aucun problème de maladie liée aux tiques ne fut observé dans le groupe immunisé. Lors d'une seconde expérience, testant une approche stratégique du lavage avec acaricide, 107 animaux furent lavés neuf fois en six mois. Malgré une infection importante parB. bovis et modérée parB. bigemina etAnaplasma spp., prouvée par étude sérologique, il n'y eut qu'un cas de babésiose. Les observations encouragent l'introduction de programmes de contrôle des tiques et de leurs maladies associées pour améliorer le bétail dans les zones endémiques à ECF.

     

A serological comparison of complement fixation reactions using Brucella abortus and B. melitensis antigens in B. abortus infected cattle

Brucella abortus and B. melitensis antigens were used in parallel on the National Standard Brucella abortus antiserum and on field sera coming from cattle where practically exclusively B. abortus biotypes 1 and 2 have been isolated over the last 11 years. With the National Standard serum the titres to B. melitensis were consistently lower than those to B. abortus antigen. Most were 1 dilution (twofold) lower. Although a similar trend was seen with the field sera, there were 7/346 sera which had twofold or higher titres to B. melitensis antigen. Although this may be due to the vagaries of the test it also warrants closer investigation of the animals concerned to see whether M-antigen predominant Brucella biotypes are possibly present. The use of the dual antigens could identify herds which are infected only with A-antigen predominant brucellae but would not be reliable for classifying individual animals.