Late pleistocene vegetation and degree of pluvial climatic change in the chihuahuan desert

Eight Pleistocene wood rat middens at elevations of 1200, 880, and 600 meters in the Chihuahuan Desert contain abundant macrofossils of pinyon pine, juniper, shrubby liveoak, and Opuntia, together with smaller quantities of Agave lecheguilla and other xerophytes of existing desert vegetation, which in dicate a xerophilous woodland vegetation in the lowlands, as much as 800 meters below existing woodland, during the Wisconsin pluvial. Ten radiocarbon dates show ages that range from 11,560 to 14,800 and 16,250 to 20,000 years, and to more than 40,000 years. Absence of most mesophytic montane species in deposits as high as 1200 meters indicates a lack of equivalent downward dis placement for the ponderosa pine zone or other zones of montane vegetation. Uneven stocking of isolated peaks in the Chihuahuan Desert province with montane species suggests that long-distance transport of propagules, rather than former continuity, may account for the disjunct distributions of many species.     

Winter dormancy in sea turtles: independent discovery and exploitation in the gulf of california by two local cultures

Documentation is reported for sea turtles overwintering on the sea bottom. Seri Indians have traditionally hunted nonmigrating dormant green turtles (Chelonia mydas) along the bottom of the Infiernillo Channel in the Gulf of California. Mexican fishermen independently discovered dormant turtles during winter 1972-1973, and with new hunting technologies are rapidly decimating these unusual stocks.     

Mineral source and transport in waters of the gulf of Mexico and Caribbean sea

Mineral particles suspended in the Gulf of Mexico and Caribbean Sea were analyzed in relation to clay mineral distributions in bottom sediments, to sedimentation processes active in the region, and to the prevailing currents. Circulation in the upper layers of water flowing from the Caribbean, carrying a micaceous-rich mineral assemblage, has exercised an influence on mineral transport into the Gulf of Mexico, different from the montmorillonite-rich load delivered by the Mississippi River. Particulate matter, suspended in North Atlantic water and Amazon River discharge, enters the Caribbean through the Lesser Antilles and contributes to the detrital mineral content of Caribbean water, as does that carried by the wind.     

Isotopic composition and origin of the red sea and salton sea geothermal brines

Abstract. Deuterium and oxygen-18 measurements show that the Red Sea and Salton Sea brines are the results of a single process, the leaching of sediments by surface water circulating downward to a geothermal reservoir. The Salton Sea brine is derived from local precipitation but the Red Sea brine originates 1000 kilometers south of its basin, on the shallow sill which controls the circulation of the Red Sea. On this sill sea water penetrates a thick evaporite sequence to a depth of 2000 meters, and, driven by its increased density relative to sea water, flows northward to emerge in the brine-filled deeps.     

Laminated diatomaceous sediments from the guaymas basin slope (central gulf of california): 250,000-year climate record

During Deep Sea Drilling Project-International Program of Ocean Drilling leg 64, December 1978 to January 1979, the initial test of the Deep Sea Drilling Project's hydraulic piston corer obtained an almost undisturbed section from a 152-meter hole into the sediments of the oxygen minimum zone at a depth of 655 meters along the Guaymas slope in the central Gulf of California. The section records variations in climate, productivity, and circulation for more than 250,000 years of Late Pleistocene to Holocene history with recordings of seasonal variations in these parameters in the laminated sections.     

Galaxies and the Universe: Properties of the universe are revealed by the rotation of galaxies and their distribution in space

A brief review is given of what the study of galaxies has taught us about properties of the universe. It is assumed that the universe started from a general "explosion," and that the general expansion observed today, as well as the 3 degrees K blackbody radiation, are consequences of this explosion. The present average density in the universe is probably close to the critical value of 10(-29) g/cm(3). Only about 3 percent of this is contained in galaxies; the rest consists probably of intergalactic gas at a temperature between 10(5) and 10(6) degrees K. Observations in our own galaxy indicate that this intergalactic gas is still flowing into it.     

Continental breakup by a leaky transform: the gulf of elat (aqaba)

The floor of the Gulf of Elat consists of five distinct deeps. Its structure is controlled by faulting which has produced rhomb-shaped grabens. The gulf is a newly formed plate boundary between Arabia and Sinai.     

Diagenesis of carbonate sediments: interaction of magnesium in sea water with mineral grains

Samples of natural fine-grained carbonate sediment from Florida Bay, Florida, undergo mole-for-mole cation exchange with aqueous solutions of MgCl(2) and CaCl(2) in the laboratory. The exchange reaction, which involves the surface of the grains of sediment, can be essentially described by a simple mass action-law equation. Enrichment of Mg++ beyond the amounts found within particle interiors should take place on the surface of CaCo(3) sediments immersed in sea water; it may be on both exchangeable and unexchangeable sites.     

玉米高光谱及其红边特征分析

通过大田和室内试验,测定了玉米冠层、完全展开倒一、三叶在不同发育期的反射光谱及叶片的叶绿素、类胡萝卜素含量。结果表明,随发育期推迟,冠层反射率在可见光范围内降低,在近红外区域增高;冠层光谱的红边具有“双峰”现象,红边位置λrad随发育期推迟呈“红移”现象,而红边幅值Dλred和红边面积Sred“红移”和“蓝移”现象;叶面积指数、地上生物量和鲜叶重与冠层λred、Dλred、Sred显著相关,叶片叶绿素和类胡萝卜素含量与其λred、Dλred、Sred也显著相关。     

A unique symbiosis in the gut of tropical herbivorous surgeonfish (acanthuridae: teleostei) from the red sea

Herbivorous surgeonfish (Acanthurus species) in the Red Sea harbor gut symbionts that include bacteria, trichomonadid flagellates, and a peculiar putative protist that attains densities of 20,000 to 100,000 cells per milliliter of gut contents. The structure, mode of reproduction, and within-gut distribution of the latter are described. This may be the first report of an organism of this type and the first evidence of a consistent endosymbiosis in the gut of a herbivorous marine fish.     

Antioxidant compounds and minerals in tomatoes by Trichodermaenriched biofertilizer and their relationship with the soil environments

The experiment was conducted to evaluate the efficacy of Trichoderma-enriched biofertilizer(BioF/compost)on antioxidants and minerals in ripe tomatoes and soil health improvements in terms of nutrient availability and microbial populations.The study was comprised of six treatments:control(zero input);recommended doses of NPK(135.5,45.6 and 22.9 kg ha~(–1),respectively);100%BioF/compost;75%BioF/compost+25%N;50%BioF/compost+50%N;and 25%BioF/compost+75%N.The recommended doses of P and K were used in the last three treatments.It was found that the application of 100%BioF/compost enhanced plant growth,leaf greenness,and produced 12.9%higher yield compared to the recommended doses of NPK and other treatments.Mineral contents(P,K,Ca,Mg,Cu,Fe,Mn and Zn)in tomato roots,shoots and fruits and antioxidant compounds,i.e.,ascorbic acid,β-carotine,and lycopene were increased significantly in fruits fertilized with100%BioF/compost.The high efficiency of Trichoderma compost might be the result of its potential of nutrient solubilization and harboring soil microorganisms.Collectively,BioF/compost increased soil fertility and favored growth of microbes in the rhizosphere which ultimately contributed to higher yield,antioxidant,and mineral concentrations in tomatoes.Thus,Trichoderma-enriched biofertilizer may reduce application of chemical fertilizers and therefore,can be considered as a noble practice in sustainable agriculture.     

砂梨变异的SRAP初步鉴定及亲缘关系分析

为了鉴定砂梨变异类型在DNA水平上是否发生遗传变异,以砂梨的两个变异单株及25个梨代表品种为试材,通过正交试验设计优化了SRAP扩增体系,并从88对SRAP引物中筛选出22对适宜的引物进行了PCR扩增,找出差异性片段,并应用系统聚类法,分析其与其它梨品种的亲缘关系。结果表明,砂梨适宜的SRAP体系为25μL反应体积中Mg2+2.4 mmol·L-1、dNTPs 0.1 mmol·L-1、Taq酶1.5 U、模板DNA 80 ng、引物0.18μmol·L-1;与对照品种‘清香’相比,‘02-1’有7条差异性片段,‘02-2’有13条差异性片段,说明其均在DNA水平上存在差异;聚类分析表明,‘02-1’首先与‘清香’聚为一类,‘02-2’先与‘新世纪’和‘黄花’聚类,再与‘清香’聚类,因此,推断‘02-1’可能为‘清香’的营养系变异,‘02-2’可能为‘清香’的姊妹系。     

Diatoms and the ecological conditions of their growth in sea ice in the arctic ocean

A summer field survey off Point Barrow, Alaska, revealed that Arctic sea ice develops a growth of phytoplanktonic diatoms. The diatoms are found in a brine solution in microfissures between ice crystals on the underside of the ice. The chlorophyll content of this layer is 100 times more than that of the surrounding sea waters; this has led to a hypothesis that a considerable fraction of the primary production of the Arctic Sea may be carried out in sea ice, especially during the spring and early summer months.     

舟山沿海潮间带底泥微生物分离和抗菌活性的初步研究

采用多种培养基对舟山沿海潮间带底泥微生物进行分离,并对分离的菌株采用纸片扩散法进行拮抗实验.结果表明,马铃薯蔗糖琼脂培养基分离真菌、蛋白胨琼脂培养基分离放线菌、MR2A培养基分离细菌的效果较好,从7个采样点分离到的484株菌株中,82株为放线菌,331株为真菌,71株为细菌;其中154株菌株(31.8%)具有抗菌活性,有部分菌株有较广的抗菌谱和强抗菌活性,拮抗菌株主要以抗革兰氏阳性菌为主(74.6%),抗革兰氏阴性菌(40.3%)和抗真菌(35.4%)的比例较低.     

舟山沿海潮间带底泥微生物分离和抗菌活性的初步研究

采用多种培养基对舟山沿海潮间带底泥微生物进行分离,并对分离的菌株采用纸片扩散法进行拮抗实验.结果表明,马铃薯蔗糖琼脂培养基分离真菌、蛋白胨琼脂培养基分离放线菌、MR2A培养基分离细菌的效果较好,从7个采样点分离到的484株菌株中,82株为放线菌,331株为真菌,71株为细菌;其中154株菌株(31.8%)具有抗菌活性,有部分菌株有较广的抗菌谱和强抗菌活性,拮抗菌株主要以抗革兰氏阳性菌为主(74.6%),抗革兰氏阴性菌(40.3%)和抗真菌(35.4%)的比例较低.     

Galapagos hydrothermal mounds: stratigraphy and chemistry revealed by deep-sea drilling

The Galápagos mounds sea-floor hydrothermal system is at least 300,000 years old and once produced manganese-poor sediments, which nearly blanketed the area of the present mounds field. Present-day mound deposits are limited manganese-rich exposures, suggesting that the system has changed from rock-to water-dominated and has diminished in intensity with time.     

Actinomycin D: uptake by sea urchin eggs and embryos

Actinomycin D is excluded from unfertilized eggs and developing embryos of the sea urchin Arbacia punctulata until the blastula hatches. The rate of uptake of actinomycin D by embryos doubles as development progresses after hatching to the gastrula stage.     

应用土柱模拟测定山地红壤镁素淋失量与有关因素的关系

据研究，福建丘陵山地红壤80％的土壤镁含量不足，缺镁成为我省山地果树生产中普通存在的问题。特别是由花岗岩、凝灰岩和第四纪红土发育的红壤供镁水平低或极低，这类土壤也是福建山地果园土壤的主要类型。而淋溶和排水是红壤镁素损失的主要途径，其损失量达3．0—39.0kg／hm^2，多雨地区和沙质