Qualitative and quantitative investigations on the macrobenthic fauna of Central Amazon lakes. 1. Lago Tupé, a black water lake on the lower Rio Negro

Lago Tupé is a black water "ria lake". It is connected with the Rio Negro throughout the year and shows similarly large fluctuations in water level, amounting to nearly 8 m in 1971. The exceptionally high minimum water level of the one-year sampling period implied that there was thermal stratification in the lake throughout the year; because of this the oxygen content of the bottom water layers did not exceed 0,6 mg/l, and H2S formed in the hypolimnion during the period of decreasing water level. These unfavourable external conditions led to the development of a qualitatively and, to a lesser extent, quantitatively poor benthic fauna in the lake centre. Dominant were Chaoboridae larvae (192 individuals/m² over the year) and Ostracoda (457 individuals/m² over the year); the Acari were sub-dominant (70 individuals/m² over the year), and Nematoda were also present 110 individuals/m² over the year). The mean annual biomass was 0.136 g/m². The corresponding patterns of abundance and biomass were also determined for the year. The benthic fauna of the littoral zone was investigated during the phases of low and rising water levels, also at a locally fixed sampling station. The characteristic littoral fauna appears only during the low water phase (November to January) when Chironomidae larvae are dominant with an abundance of 43-74 %. The rest of the fauna consists of many groups with low relative abundances. When the water level begins to rise the qualitative composition alters completely within a few weeks, Chaoboridae larvae and Ostracoda becoming dominant. Apart from the absence of Acari the resulting zoocoenose is qualitatively identical with the profundal zoocoenose. It is conceivable that some of the true littoral species migrate at rising water to the neighbouring inundated forest (igapó), and move back again when the water level falls. The rhythmic faunal movements between profundal, littoral and igapô zones, caused by the large water level fluctuations, are schematically represented. Biomass values were also determined in the littoral zone. The values for both this and abundance were much higher than in the lake centre at any given time. The feeding habits of the individual taxa of profundal and littoral zoocoenoses were examined. The Ostracoda are the detritophages of the profundal zoocoenose; they are fed on by the zoophagous Acari and to a certain extent by the chaoborid larvae. In the true littoral zone the phytophages feed on blue green algae and diatoms growing on firm substrates; these are absent from both igapó and profundal zone. The fungi, which are an important food source in the igapó, play a lesser role in the littoral. The larvae of the Tanypodinae are the zoophages of the true Littoral zone. Finally, comparable studies of the zoobenthos of other black water lakes are discussed; these lend support to the inferences from Lago Tupé i.e. the profundal zone of the black water lakes has qualitatively and quantitatively the poorest benthic fauna of all lacustrine biotopes in the Central Amazon

Do Entry Conditions Vary across Markets?

macroeconomics, entry conditions

Experimental investigations on sodium-filled heat pipes

The possibilities of producing heat pipes and, especially, the necessary capillary structures are discussed. Several types of heat pipes were made from stainless steel and tested at temperatures between 400 and 1055 deg C. The thermal power was determined by a calorimeter. Results indicate: bubble-free evaporation of sodium from rectangular open chennels is possible with a heat flux of more than 1,940 W/sq cm at 1055 C. The temperature drop along the tube could be measured only at low temperatures. A subdivided heat pipe worked against the gravitational field. A heat pipe with a capillary structure made of a rolled screen was supported by rings and bars operated at 250 W/sq cm heat flux in the evaporating region

Fermionic functional renormalization group for first-order phase transitions: a mean-field model

First-order phase transitions in many-fermion systems are not detected in the susceptibility analysis of common renormalization-group (RG) approaches. Here we introduce a counterterm technique within the functional renormalization-group (fRG) formalism which allows access to all stable and metastable configurations. It becomes possible to study symmetry-broken states which occur through first-order transitions as well as hysteresis phenomena. For continuous transitions, the standard results are reproduced. As an example, we study discrete-symmetry breaking in a mean-field model for a commensurate charge-density wave. An additional benefit of the approach is that away from the critical temperature for the breaking of discrete symmetries large interactions can be avoided at all RG scales.Comment: 17 pages, 8 figures. v2 corrects typos, adds references and a discussion of the literatur

Resonance magneto-resistance in double barrier structure with spin-valve

The conductance and tunnel magneto-resistance (TMR) of the double barrier magnetic tunnel junction with spin-valve sandwich (F/P/F) inserted between two insulating barrier, are theoretically investigated. It is shown, that resonant tunnelling, due to the quantum well states of the electron confined between two barriers, sharply depends on the mutual orientation of the magnetizations of ferromagnetic layers F. The calculated optimistic value of TMR exceeds 2000% .Comment: 3 pages, 4 figure

Weak Convergence of the Scaled Median of Independent Brownian Motions

We consider the median of n independent Brownian motions, and show that this process, when properly scaled, converges weakly to a centered Gaussian process. The chief difficulty is establishing tightness, which is proved through direct estimates on the increments of the median process. An explicit formula is given for the covariance function of the limit process. The limit process is also shown to be Holder continuous with exponent gamma for all gamma < 1/4.Comment: to appear in Probability Theory and Related Field

Behavioural Variation in Tullock contests

We conduct an experiment to uncover the reasons behind the typically large behavioral variation and low explanatory power of Nash equilibrium observed in Tullock contests. In our standard contest treatment, only 7% of choices are consistent with Nash equilibrium which is in line with the literature and roughly what random (uniform) choice would predict (6.25%). We consider a large class of social, risk and some other non-standard preferences and show that heterogeneity in preferences cannot explain these results. We then systematically vary the complexity of both components of Nash behaviour: (I) the difficulty to form correct beliefs and (II) the difficulty to formulate best responses. In treatments where both the difficulty of forming correct beliefs and of formulating best responses is reduced behavioural variation decreases substantially and the explanatory behaviour of Nash equilibrium increases dramatically (explaining 65% of choices with a further 20% being close to NE). Our results show that bounded rationality rather than heterogeneity in preferences is the reason behind the huge behavioral variation typically observed in Tullock contests

Low frequency noise due to magnetic inhomogeneities in submicron FeCoB/MgO/FeCoB magnetic tunnel junctions

We report on room temperature low frequency noise due to magnetic inhomogeneities/domain walls (MI/DWs) in elliptic submicron FeCoB/MgO/FeCoB magnetic tunnel junctions with an area between 0.0245 and 0.0675{\mu}m2. In the smaller area junctions we found an unexpected random telegraph noise (RTN1), deeply in the parallel state, possibly due to stray field induced MI/DWs in the hard layer. The second noise source (RTN2) is observed in the antiparallel state for the largest junctions. Strong asymmetry of RTN2 and of related resistance steps with current indicate spin torque acting on the MI/DWs in the soft layer at current densities below 5x10^5 A/cm2.Comment: 12 pages, 4 figure

Sociology and Human Sexuality

Greater toleration of premarital and extramarital coitus and the increased emphasis on sexual gratification in marriage are not novel trends in American society, but the pace of change today probably is unprecedented. There is intense public discussion of what were once exclusively personal matters. Practices that a generation ago were considered socially deviant, such as cohabitation or homosexuality, are tolerated, if not accepted

Clinical Laboratory Assessment of \u3cem\u3eMycoplasma genitalium\u3c/em\u3e Transcription-Mediated Amplification Using Primary Female Urogenital Specimens

Following analysis of primary cervix, vagina, and first-void female urine specimens for Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis via commercial transcription-mediated amplification (TMA), residual material was subjected to Mycoplasma genitalium research-use-only TMA. Representation within a 2,478-specimen retrospective study set was established by comparison to a 6-month audit of clinical C. trachomatis TMA (12,999 specimens) on the basis of the C. trachomatis detection rate, specimen source distribution, clinic location, and age. M. genitalium was detected in 282 (11.4%) patients. This rate was higher than those seen with T. vaginalis (9.0%; P _ 0.005), C. trachomatis (6.2%), and N. gonorrhoeae (1.4%). Positive M. genitalium results were confirmed by repeat testing or alternative-target TMA at a rate of 98.7%. The mean age of the M. genitalium-infected females (24.7 years) was lower than that of the T. vaginalis-infected females (mean, 30.1 years; P\u3c0.0001) and higher than that of the C. trachomatis-infected females (mean, 23.8 years; P_0.003). Of 566 patient encounters positive for at least one sexually transmitted infection (STI), 35.9% exhibited sole detection of M. genitalium (P \u3c 0.0004 versus sole detection of other STI agents) and 26.1% were solely positive for T. vaginalis (P \u3c 0.0002 versus C. trachomatis). The M. genitalium and T. vaginalis detection rates among 755 patients at urban emergency departments were 14.6% and 13.0%, respectively (P _ 0.37). A 10.0% M. genitalium detection rate from other facilities exceeded that of T. vaginalis (7.2%; P _ 0.004). Incorporation of M. genitalium TMA into comprehensive testing programs would detect M. genitalium in a significant proportion of females, particularly those in outpatient obstetrics and gynecology (OB/GYN) settings