41,097 research outputs found
West African pholcid spiders: an overview, with descriptions of five new species (Araneae, Pholcidae)
This paper summarizes current knowledge about West African pholcids. West Africa is here defined as the area south of 17°N and west of 5°E, including mainly the Upper Guinean subregion of the Guineo-Congolian center of endemism. This includes all of Senegal, The Gambia, Guinea Bissau, Guinea, Sierra Leone, Liberia, Ivory Coast, Ghana, Togo and Benin. An annotated list of the 14 genera and 38 species recorded from this area is given, together with distribution maps and an identification key to genera. Five species are newly described: Anansus atewa sp. nov., Artema bunkpurugu sp. nov., Leptopholcus kintampo sp. nov., Spermophora akwamu sp. nov., and S. ziama sp. nov. The female of Quamtana kitahurira is newly described. Additional new records are given for 16 previously described species, including 33 new country records. Distribution patterns of West African pholcids are discussed, as well as possible explanations for relatively low West African pholcid species diversity as compared to Central and East Africa
Polymer adsorption on heterogeneous surfaces
The adsorption of a single ideal polymer chain on energetically heterogeneous
and rough surfaces is investigated using a variational procedure introduced by
Garel and Orland (Phys. Rev. B 55 (1997), 226). The mean polymer size is
calculated perpendicular and parallel to the surface and is compared to the
Gaussian conformation and to the results for polymers at flat and energetically
homogeneous surfaces. The disorder-induced enhancement of adsorption is
confirmed and is shown to be much more significant for a heterogeneous
interaction strength than for spatial roughness. This difference also applies
to the localization transition, where the polymer size becomes independent of
the chain length. The localization criterion can be quantified, depending on an
effective interaction strength and the length of the polymer chain.Comment: accepted in EPJB (the Journal formerly known as Journal de Physique
Suppression of the Charge-Density-Wave State in SrCaCuO by External Pressure
The influence of external pressure on the charge-density-wave (CDW) ground
state of the quasi-one-dimensional two-leg ladder compound
SrCaCuO has been studied by optical reflectivity
measurements as a function of temperature (10 - 300~K) and pressure (0.3 -
4.3~GPa) over the spectral range 580 - 6000 cm. With increasing pressure
the CDW transition temperature decreases with the linear pressure
coefficient -70~K/GPa, and above 3~GPa the CDW phase is
suppressed at all temperatures. This behavior is similar to that in compounds
SrCaCuO with increasing Ca content at ambient
pressure, with the simple scaling . The size of the
CDW gap decreases with increasing pressure, whereas the dimensionality of the
high-temperature insulating phase in SrCaCuO within
the ladder plane is hardly affected by external pressure.Comment: accepted for publication in Phys. Rev.
East African pholcid spiders: an overview, with descriptions of eight new species (Araneae, Pholcidae)
This paper summarizes current knowledge about East African pholcids. East Africa is defined as the area from 12°S to 5°N and from 28° to 42°E, including all of Uganda, Kenya, Burundi, Rwanda, and Tanzania. An annotated list of the 15 genera and 87 species recorded from this area is given, together with distribution maps and an identification key to genera. Most East African species (90%) belong to one of only six genera: Buitinga Huber, 2003 (21 species); Smeringopus Simon, 1890 (18); Pholcus Walckenaer, 1805 (17); Spermophora Hentz, 1841 (12); Leptopholcus Simon, 1893 (5) and Quamtana Huber, 2003 (4). Eight species for which DNA sequence data have been published recently are newly described: Buitinga batwa sp. nov., B. wataita sp. nov., Spermophora mau sp. nov., S. maathaiae sp. nov., S. bukusu sp. nov., S. kirinyaga sp. nov., S. kyambura sp. nov. and Quamtana nyahururu sp. nov. Crossopriza johncloudsleyi Deeleman-Reinhold & van Harten, 2001, previously only known from Yemen, is redescribed based on specimens from Kenya. Additional new records are given for 21 previously described species
Distribution of Complex and Core Lipids within New Hyperthermophilic Members of the Archaea Domain
Core and complex lipids of several new hyperthermophilic archaeal isolates were analyzed. The organisms belong to the Sulfolobales,Archaeoglobus, Pyrobaculum, and Methanococcus. A detailed structural investigation of complex lipids of Pyrobaculum species is reported. The different lipid structures are of help for
a rapid and simple phylogenetic classification of the new isolates. They are in agreement with the classification based on other features
Compensating linkage for main rotor control
A compensating linkage for the rotor control system on rotary wing aircraft is described. The main rotor and transmission are isolated from the airframe structure by clastic suspension. The compensating linkage prevents unwanted signal inputs to the rotor control system caused by relative motion of the airframe structure and the main rotor and transmission
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