12,392 research outputs found
Late Holocene Pollen Stratigraphy in Four Northeastern United States Lakes
Four pollen diagrams from Maine, New York, and Pennsylvania provide fine resolution (40 or 80 years) records of vegetation change in northeastern United States during the past 2000 years. A long term increase in pollen accumulation rates (PAR) of Picea occurred at the three sites in Maine and New York. Around 1100 years ago, Tsuga and Fagus decreased and Quercus and Castanea increased at Ely Lake in northeastern Pennsylvania. Around 500 years ago, Tsuga and Fagus greatly decreased in Maine and northern New York, while in northeastern Pennsylvania there was an increase in Tsuga and Fagus and a decrease in Quercus and Castanea pollen. Non-arboreal PAR were negligible prior to the European settlement of the area, after which there was an abrupt increase in non-arboreal pollen types.Quatre diagrammes polliniques des états du Maine, de New York et de Pennsylvanie illustrent de manière détaillée (40 ou 80 ans) les changements survenus dans la végétation du nord-est des États-Unis sur une période de 2000 ans. Les trois diagrammes des états du Maine et de New York enregistrent un accroissement continu de l'influx pollinique (PAR) de Picea. Il y a environ 1100 ans, Tsuga et Fagus ont subi une diminution, tandis que Quercus et Castanea ont augmenté à Ely Lake, dans le nord-est de la Pennsylvanie. Il y a 500 ans, Tsuga et Fagus ont considérablement diminué dans les états du Maine et de New York, alors que leur représentation pollinique augmentait dans le nord-est de la Pennsylvanie et que Quercus et Castanea diminuaient. Les influx polliniques des herbacés étaient minimes avant l'arrivée des Européens dans la région, après quoi ces taxons ont connu une augmentation subite.Vier Pollen-Diagramme von Maine, New York und Pennsylvania geben detaillierte Auflôsungs-Nachweise der Vegetationswechsel im Nordosten der Vereinigten Staaten wàhrend der letzten 2000 Jahre. Ein langfristiges Anwachsen der Pollen-Akkumulationsraten (PAR) von Picea trat an den drei Fundstellen in Maine und im Staat New York auf. Vor ungefàhr 11000 Jahren, nahmen am Ely-See in Nordost-Pennsylvania Tsuga and Fagus ab und Quercus und Castanea zu. Vor ungefàhr 500 Jahren nahmen in Maine und im Norden des staats New York Tsuga und Fagus stark ab, wàhrend in Nordost-Pennsylvania Tsuga und Fagus zunahmen und Quercus und Casfanea-Pollen abnahmen. Die nicht von Bàumen stammenden PAR waren gering, bevor das Gebiet von Europàern besiedelt wurde, wàhrend danach die nicht von Bàumen stammenden Pollenarten plôtzlich anwuchsen
Influence of the Static Screen Inclination on the Effect-ive Separating Size and Concentration of Beach Sand Minerals
In this paper an attempt has been made to evaluate the effect of inclination of micro screen on the effective separating size of beach sand minerals. The results of these investigations indicate that the cut sizes of 130pm, 122pm, 63pm, 55pm and 40pm could be obtained from a feed
containing —1mm size range with a variable deck inclina-tion such as 35°, 40°, 67°, 70° and 75° respectively. The cut sizes are evaluated based on the partition curve according to Tromp. The typical size analysis data obtained at cut size of 63pm, indicate that the overflow and +300pm size fraction of the under flow contain rejec-table tailings amounting to 51% by weight with overall heavies loss contain 4.7%, Thus micro screen is effective for dual purpose such as classifications like hydrocyclone and preconcentration like a spiral concentrator. Hence, it can be concluded that the micro screen is not only an effective for classification at different cut points but also can work as a good preconcentrator for beach sands
Novel technique for the CO<sub>2</sub> laser fabrication of optical devices with sub-micrometer ablation depth precision
We present novel techniques for the processing of fibre end face and cladding surfaces using a 9.6 µm CO2 laser. We investigate the effects of pulse duration on process parameters
Long-term stability test of a triple GEM detector
The main aim of the study is to perform the long-term stability test of gain
of the single mask triple GEM detector. A simple method is used for this long-
term stability test using a radioactive X-ray source with high activity. The
test is continued till accumulation of charge per unit area > 12.0 mC/mm2. The
details of the chamber fabrication, the test set-up, the method of measurement
and the test results are presented in this paper.Comment: 8 pages, 5 figure
Coupled Fluctuations near Critical Wetting
Recent work on the complete wetting transition has emphasized the role played
by the coupling of fluctuations of the order parameter at the wall and at the
depinning fluid interface. Extending this approach to the wetting transition
itself we predict a novel crossover effect associated with the decoupling of
fluctuations as the temperature is lowered towards the transition temperature
T_W. Using this we are able to reanalyse recent Monte-Carlo simulation studies
and extract a value \omega(T_W)=0.8 at T_W=0.9T_C in very good agreement with
long standing theoretical predictions.Comment: 4 pages, LaTex, 1 postscript figur
Direct Measurement of the Radius and Density of the Transiting Exoplanet HD 189733B with the CHARA Array
We have measured the angular diameter of the transiting extrasolar planet
host star HD 189733 using the CHARA O/IR interferometric array. Combining our
new angular diameter of 0.377+/-0.024 mas with the Hipparcos parallax leads to
a linear radius for the host star of 0.779+/-0.052 Rsol and a radius for the
planet of 1.19+/-0.08 RJup. Adopting the mass of the planet as derived by its
discoverers, we derive a mean density of the planet of 0.91+/-0.18 g cm-3. This
is the first determination of the diameter of an extrasolar planet through
purely direct means.Comment: 14 pages, 5 figures, to be published in Astrophysical Journal Letter
Biometric analysis of brushtooth lizard fish Saurida undosquamis (Richardson, 1848) from Mumbai waters
The aim of the present study was to investigate the relationship between various morphometric measurements and meristic counts, and to establish the length-weight relationships (LWRs) and length-length relationships (LLRs) of Saurida undosquamis based on specimens collected from New Ferry Wharf landing centre of Mumbai coast during September 2013 to June 2015. The morphometric variables for the species under study exhibited high level of correlation with each other. Based on present study results, the fin formula of S. undosquamis in Mumbai water can be written as B 13-15, D 11-13, P 13-15, V 9, A 10-11, C 18-20, L47-53. Different values of regression coefficient (b) and correlation coefficient (r) in LLRs illustrates that different organ grows differently. The values of the regression coefficient b in the LWRs equations (W = aLb) were 2.90, 3.04 and 2.99 for male, female and pooled individuals respectively indicating an isometric growth with high correlation coefficient (r2). These parameters are useful for evaluating the relative condition of fish as well as for subsequent biological and population based studies
Possible thermochemical disequilibrium in the atmosphere of the exoplanet GJ 436b
The nearby extrasolar planet GJ 436b--which has been labelled as a 'hot
Neptune'--reveals itself by the dimming of light as it crosses in front of and
behind its parent star as seen from Earth. Respectively known as the primary
transit and secondary eclipse, the former constrains the planet's radius and
mass, and the latter constrains the planet's temperature and, with measurements
at multiple wavelengths, its atmospheric composition. Previous work using
transmission spectroscopy failed to detect the 1.4-\mu m water vapour band,
leaving the planet's atmospheric composition poorly constrained. Here we report
the detection of planetary thermal emission from the dayside of GJ 436b at
multiple infrared wavelengths during the secondary eclipse. The best-fit
compositional models contain a high CO abundance and a substantial methane
(CH4) deficiency relative to thermochemical equilibrium models for the
predicted hydrogen-dominated atmosphere. Moreover, we report the presence of
some H2O and traces of CO2. Because CH4 is expected to be the dominant
carbon-bearing species, disequilibrium processes such as vertical mixing and
polymerization of methane into substances such as ethylene may be required to
explain the hot Neptune's small CH4-to-CO ratio, which is at least 10^5 times
smaller than predicted
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