22,903 research outputs found
Spider (Arachnida: Araneae) distribution across the timberline in the Swiss Central Alps (Alp Flix, Grisons) and three morphologically remarkable species
We collected 6251 adult epigeic spiders from the dwarf-shrub heath to subalpine coniferous forest on Alp Flix (CH, canton Grisons, 1950 m) between May 2005 and May 2006 using pitfall traps. Total species richness and activity density of all species decreased from the open land to the forest, although this pattern varied according to family. The distribution of the 102 species found indicates that the small area around a single tree at the timberline provides habitats for both open land and forest spider species as well as some possible timberline specialists. Five species were new to the canton Grisons: Centromerita bicolor, Centromerita concinna, Hilaira excisa, Meioneta alpica and Tallusia experta. Three species showed remarkable morphological characteristics and were analysed in more detail. We found males of Pelecopsis radicicola without the characteristic longitudinal depression on the raised carapace. It is shown that the males of Meioneta alpica have a considerably variable lamella characteristica, which is nevertheless distinct from the sister species Meioneta ressli. Because we found intermediate forms of the head region described for Metopobactrus prominulus and M. schenkeli, respectively, M. schenkeli is considered a syn. nov. of M. prominulus. This study shows that the known distribution and taxonomic status of various spider taxa in the Central Alps are still incomplete and further work on arthropods in remote areas should be strongly encouraged
Streaking temporal double slit interference by an orthogonal two-color laser field
We investigate electron momentum distributions from single ionization of Ar
by two orthogonally polarized laser pulses of different color. The two-color
scheme is used to experimentally control the interference between electron wave
packets released at different times within one laser cycle. This intracycle
interference pattern is typically hard to resolve in an experiment. With the
two-color control scheme these features become the dominant contribution to the
electron momentum distribution. Furthermore the second color can be used for
streaking of the otherwise interfering wave packets establishing a which-way
marker. Our investigation shows that the visibility of the interference fringes
depends on the degree of the which-way information determined by the
controllable phase between the two pulses.Comment: submitted to PR
Wafer-Level Thermocompression Bonds
Thermocompression bonding of gold is a promising technique for achieving low temperature, wafer-level bonding without the application of an electric field or complicated pre-bond cleaning procedure. The presence of a ductile layer influences the fracture behavior of the bonds. The fabrication process was described. In addition, the effect of plasticity was explored by varying the gold bonding thickness between 0.23 to 1.4 µm. Wafers were bonded at 300°C and two different pressures: 1.25 and 7 MPa. The bond toughness of the specimens were characterized using a four-point bend delamination technique. Cohesive failure was found to be the dominant fracture mode in the thicker films. Bonds made with thin gold films failed adhesively and at lower strain energy release rates.Singapore-MIT Alliance (SMA
Gold Thermocompression Wafer Bonding
Thermocompression bonding of gold is a promising technique for the fabrication and packaging microelectronic and MEMS devices. The use of a gold interlayer and moderate temperatures and pressures results in a hermetic, electrically conductive bond. This paper documents work conducted to model the effect of patterning in causing pressure non-uniformities across the wafer and its effect on the subsequent fracture response. A finite element model was created that revealed pattern-dependent local pressure variations of more than a factor of three. This variation is consistent with experimental observations of bond quality across individual wafers A cohesive zone model was used to investigate the resulting effect of non-uniform bond quality on the fracture behavior. A good, qualitative agreement was obtained with experimental observations of the load-displacement response of bonds in fracture tests.Singapore-MIT Alliance (SMA
The Ca II infrared triplet's performance as an activity indicator compared to Ca II H and K
Aims. A large number of Calcium Infrared Triplet (IRT) spectra are expected
from the GAIA- and CARMENES missions. Conversion of these spectra into known
activity indicators will allow analysis of their temporal evolution to a better
degree. We set out to find such a conversion formula and to determine its
robustness.
Methods. We have compared 2274 Ca II IRT spectra of active main-sequence F to
K stars taken by the TIGRE telescope with those of inactive stars of the same
spectral type. After normalizing and applying rotational broadening, we
subtracted the comparison spectra to find the chromospheric excess flux caused
by activity. We obtained the total excess flux, and compared it to established
activity indices derived from the Ca II H & K lines, the spectra of which were
obtained simultaneously to the infrared spectra.
Results. The excess flux in the Ca II IRT is found to correlate well with
and , as well as , if the
-dependency is taken into account. We find an empirical conversion formula
to calculate the corresponding value of one activity indicator from the
measurement of another, by comparing groups of datapoints of stars with similar
B-V.Comment: 16 pages, 15 figures. Accepted for publication in Astronomy &
Astrophysic
Role of platelet activating factor (PAF) on leukocyte-independent plasma extravasation and mast cell activation during endotoxemia
Selective phosphodiesterase type 5 inhibition improves responsiveness to inhaled nitric oxide in endotoxin-challenged rats
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