The ecology of early man in southern Africa

It is not possible at present to demonstrate hominid occupation of southern Africa prior to the middle or late Pliocene, perhaps 3 million years ago. It may be the case that much, if not most, of the subcontinent was in fact uninhabited before that. The earliest hominid known to have lived in southern Africa is Australopithecus africanus. It was apparently replaced by Homo (?evolved into Homo) by 2 million years ago, at approximately the same time as A. robustus is first recorded locally. Homo and A. robustus then coexisted until perhaps 1 million years ago, after which Homo survived alone. There is no solid evidence that either of the southern African australopithecines made tools or accumulated bones. In fact, at the known sites, it now seems more likely that the bones, including those of the australopithecines themselves, were accumulated by carnivores. The known archeological record of southern Africa begins 2 million to 1.5 million years ago and the oldest stone tools may belong to the Oldowan Industry. Far better documentation exists for the succeeding Acheulean Industrial Complex, which was present in southern Africa almost certainly before 1 million years ago and persisted with modifications probably until sometime between 300,000 and 130,000 years ago. Although it is known that Acheulean peoples made handaxes, cleavers, and other stone tools, very little else is known about the activities of Acheuleans in southern Africa. Far more is known about their Middle and Later Stone Age successors. Southern African MSA peoples were perhaps among the earliest anywhere to take systematic advantage of aquatic resources for their subsistence, although they apparently did so far less effectively than did the LSA peoples who followed them. There are also contrasts between the ways in which MSA and LSA peoples dealt with terrestrial prey and between the contents of MSA and LSA artifact assemblages. The LSA peoples, for example, seem to have made much more extensive use of bone as a raw material, and they were the first to manufacture articles that are clearly interpretable as ornaments or art objects. From an evolutionary perspective, the LSA may represent a quantum advance over the MSA, perhaps correlated with the replacement of an archaic human physical type by the modem one. However, this must remain only a working hypothesis until much more is learned about the earliest LSA, dating to 35,000 to 40,000 years ago or more, and until there are adequate samples of well-provenienced MSA and early LSA physical remains. The later LSA, postdating 20,000 to 18,000 years ago, is reasonably well known. Later LSA peoples were probably at least partly responsible for the extinction of several large mammals in southern Africa about 10,000 years ago. By that date or shortly thereafter, at least some LSA peoples established basic hunting-gathering adaptations, which continued until the introduction and spread of agriculture and pastoralism, beginning roughly 2000 years ago. Thereafter, hunters and gatherers became progressively restricted in numbers and distribution, such that today only a very few exist, restricted to some of the most marginal environments of the subcontinent. It remains a major goal of southern African archeology to shed more light on the evolution and operation of hunting-gathering cultures during the vast time span when they covered all of southern Africa.     

Genetic and fossil evidence for the origin of modern humans

The origin of living Homo sapiens has once again been the subject of much debate. Genetic data on present human population relationships and data from the Pleistocene fossil hominid record are used to compare two contrasting models for the origin of modern humans. Both genetics and paleontology support a recent African origin for modern humans rather than a long period of multiregional evolution accompanied by gene flow.     

The ginsberg experiment: modern and prehistoric evidence of a bone-flaking technology

The discovery of butchered and modified bones of extinct Pleistocene fauna from Old Crow Flats, Yukon Territory, and the Dutton and Selby sites, Colorado, provides some of the earliest evidence for man in the New World. However, the significance of these discoveries rests entirely on the ability to determine whether these remains were modified by man. The results of experiments of elephant butchering, bone fracturing, and bone tool manufacturing support the hypothesis that these modified bones can be used to identify the presence of cultural activities.     

Ages for the Middle Stone Age of southern Africa: implications for human behavior and dispersal

The expansion of modern human populations in Africa 80,000 to 60,000 years ago and their initial exodus out of Africa have been tentatively linked to two phases of technological and behavioral innovation within the Middle Stone Age of southern Africa-the Still Bay and Howieson's Poort industries-that are associated with early evidence for symbols and personal ornaments. Establishing the correct sequence of events, however, has been hampered by inadequate chronologies. We report ages for nine sites from varied climatic and ecological zones across southern Africa that show that both industries were short-lived (5000 years or less), separated by about 7000 years, and coeval with genetic estimates of population expansion and exit times. Comparison with climatic records shows that these bursts of innovative behavior cannot be explained by environmental factors alone.     

现代教育技术在教学中的应用初探--以"计算机文化基础"课程为例

本文通过对计算机文化基础课程教学特点的分析，论述了现代教育技术在计算机文化基础课程教学中作为演示工具、交流工具、资源环境的一些应用体会。     

Milk for humans: Evolving perceptions of an all-time mother science

Milk is the most nourishing natural biofluid and almost an ideal functional food for humans of all ages. The objective of this review article is to delineate global nutritional and health implications of main live-stock dairy products for optimum postmodern life quality. Milk bioactives contribute considerably to meeting nutrient requirements while offering potentials to reduce risks of cancers, traumas and metabolic disorders. Milk functions beyond its nutritive worth. Cow milk intake by lactating mothers enriches breast milk ??-lactoglobulin and ovalbumin. Milk intake leads to more standard body frame structure and bone health. Milk immunoglobulins act against Enterotoxigenic Escherichia coli. Casomorphins, immunostimulating peptides, and ACE-inhibitory peptides modulate the gut nutrient assimilation. Whey proteins are insulinotropic and medium chain fatty acids improve insulin action. Peptides along with calcium may reduce blood pressure and cholesterol. Milk improves folate availability, and reduces homocysteinemia and heart infarcts. Ewe milk is richer than cow milk in riboflavin, thiamine, niacin, pantothenic acid, vitamin B₆, vitamin B₁₂ and biotin. Goat milk has less ??-s-1-casein, ??-carotene, agglutinin; and is lower in citric acid, Na, Fe, S, Zn, Mo, ribonuclease, alkaline phosphatase, lipase, xanthine oxidase, N-acetylneuraminic acid, orotic acid, pyridoxine, folate, vitamin B₁₂, and vitamin C than cow milk. Goat milk is richer in Ca, K, Mg, P, Cl, Mn, vitamins A and D, nicotinic acid, choline, inositol, medium-chain FA, small diameter fat globules than cow milk. Goat milk is a suitable substitute in allergies, and with low orotic acid might prevent fatty liver. Lysozyme-rich milk has been produced with transgenic dairy goats to prevent intestinal disorders in infants. Donkey and horse milks are considered optimal substitutes for human and cow milk in minimizing allergies and hyperlipidemia related complexities. Effective education and data dissemination are the ongoing obligations for unbiased milk science to be adequately perceived and applied by postmodern human populations.     

Tricyclic antidepressants: evidence for an intraneuronal site of action

Desipramine, a tricyclic antidepressant drug, almost completely prevents the accumulation of tritiated norepinephrine by sympathetic neurons of the rat heart after the injection of a tracer dose of the labeled amine. However, desipramine does not alter the accumulation of norepinephrine after the injection of a large dose of the neurohormone. Despite the failure of desipramine to block the neuronal uptake of norepinephrine, it still prevents exogenous norepinephrine from displacing the endogenous neurohormone (previously labeled with H(3)-norepinephrine) from intraneuronal storage sites.     

早籼稻天禾1号的选育、特征特性及栽培要点

天禾1号系金华市天禾生物技术研究所与金华三才种业公司用金恢88作母本,浙3作父本进行杂交后经辐射选育的早籼稻新品种.该品种属中熟偏迟早籼,株型较紧凑,着粒密度高,穗型较大,产量高,抗性强,米质优良.谷粒圆形,长宽比小,整精米率高,总淀粉含量、直链淀粉含量和蛋白质含量较高,适宜加工味精、米粉、红曲、红曲色素、啤酒及饲料加工用粮等多种用途.2004年3月通过浙江省农作物品种审定委员会审定.适宜在金华、衢州及类似地区推广种植.     

美国西部重要害虫摩门螽斯病原真菌的研究

The Mormon cricket (MC),Anabrus simplex (Orthoptera:Tettigoniidae),has a long and negative history with agriculture in the western states of the USA where MC often migrates in large groups and causes significant damage to forage plants and cultivated crops.In this review, virulence to MC of isolates of the insect-pathogenic fungus Metarhizium anisopliae varieties acridum and anisopliae were compared in an effort to identify isolates with promise for use as MC biological control agents.All of the isolates tested induced 100% or nearly 100% mortality by six days post application of the fungal conidia.Searches for new Metarhizium isolates with high heat and UV-B tolerance included isolation fungi from field-caught MC and grasshopper after they died in the laboratory and culturing fungi from soil samples collected from numerous western USA sites.The survey was preceded by development of a dodine based selective medium that,at 0.002% active ingredient,permitted growth of M.anisopliae var.acridum,but inhibited most contaminating fungi.The M.anisopliae var.acridum isolates examined to date have much higher tolerance to heat and UV-B irradiation than M.anisopliae var.anisopliae isolates,and this may be critical to successful field applications.The variety acridum has not yet been found in the USA,so our search for such isolates continues.Several new M.anisopliae var.anisopliae and Beauveria spp.were found,and the Metarhizium isolates are being characterized as to stress tolerance and virulence to insects.Characterization includes comparisons of new and pre-existing Metarhizium isolates by amplified fragment-length polymorphism (AFLP) analysis.Finally, experiments on MC developmental biology were conducted to gather data needed to develop a degree day model and to establish laboratory colonies of MC.     

Infusion of 2-deoxy-D-glucose into the hepatic-portal system causes eating: evidence for peripheral glucoreceptors

Injections of 2-deoxyglucose into the hepatic-portal system of normal rabbits increased eating to a greater extent and with shorter latency than comparable injections of 2-deoxyglucose into the jugular vein or into the hepaticportal circulation of the vagotomized rabbit. These differences suggest the existence of vagally mediated peripheral glucoreceptors important in the initiation of food intake.     

Fauna of Catal Hüyük: evidence for early cattle domestication in Anatolia

Analysis of the remains of cattle from Catal Hüyük indicates that cattle were domesticated in Anatolia by 5800 B.C., and strongly suggests that they were probably domestic at least 500 years earlier. This is the earliest known evidence for the domestication of cattle in the Near East.     

Reactivation of an inactive human X chromosome: evidence for X inactivation by DNA methylation

A mouse-human somatic cell hybrid clone, deficient in hypoxanthine-guanine phosphoribosyltransferase (HPRT) and containing a structurally normal inactive human X chromosome, was isolated. The hybrid cells were treated with 5-azacytidine and tested for the reactivation and expression of human X-linked genes. The frequency of HPRT-positives clones after 5-azacytidine treatment was 1000-fold greater than that observed in untreated hybrid cells. Fourteen independent HPRT-positive clones were isolated and analyzed for the expression of human X markers. Isoelectric focusing showed that the HPRT expressed in these clones is human. One of the 14 clones expressed human glucose-6-phosphate dehydrogenase and another expressed human phosphoglycerate kinase. Since 5-azacytidine treatment results in hypomethylation of DNA, DNA methylation may be a mechanism of human X chromosome inactivation.     

文学作品的福柯式阅读-以《拾橡子的男孩》为例

时下,学界对福柯的关注主要集中在他的一些颠覆性话语上面,却较少关注作为他思想精髓的认识论和方法论。本文以英国作家R.杰弗里斯的短篇小说《拾橡子的男孩》为例,尝试运用福柯的话语分析方法解读文学作品,力图建立一种新的阅读模式,以期克服文学批评中形而上学的泛滥。     

Probing chemical reactions: evidence for exploration of an excited potential energy surface at thermal energies

The reaction K + NaBr --> KBr + Na is probed during the reactive collision by a continuous wave laser tuned to frequencies not resonant with excitation in either reagents or products. Transient [K..Br..Na] absorbs a laser photon giving [K..Br..Na](*), which can decompose to Na(*) + KBr. Emission from excited Na(*) at the sodium D lines provides direct evidence of laser absorption during the reaction. Different excitation spectra were observed, depending on which sodium D line was monitored. This difference is explicable if, in the absence of the laser, the reaction flux partially bifurcates to a second potential energy surface during the reaction.     

The composition of phobos: evidence for carbonaceous chondrite surface from spectral analysis

A reflectance spectrum of Phobos (from 200 to 1100 nanometers) has been compiled from the Mariner 9 ultraviolet spectrometer, Viking lander imaging, and ground-based photometric data. The reflectance of the martian satellite is approximately constant at 5 percent from 1100 to 400 nanometers but drops sharply below 400 nanometers, reaching a value of 1 percent at 200 nanometers. The spectral albedo of Phobos bears a striking resemblance to that of asteroids (1) Ceres and (2) Pallas. Comparison of the reflectance spectra of asteroids with those of meteorites has shown that the spectral signature of Ceres is indicative of a carbonaceous chondritic composition. A physical explanation of how the compositional information is imposed on the reflectance spectrum is given. On the basis of a good match between the reflectance spectra of Phobos and Ceres and the extensive research that has been done to infer the composition of Ceres, it seems reasonable to believe that the surface composition of Phobos is similar to that of carbonaceous chondrites. This suggestion is consistent with the recently determined low density of Mars's inner satellite. Our result and recent Viking noble gas measurements suggest different modes of origin for Mars and Phobos.