1,232 research outputs found
Detection of the primary scintillation light from dense Ar, Kr and Xe with novel photosensitive gaseous detectors
The detection of primary scintillation light in combination with the charge
or secondary scintillation signals is an efficient technique to determine the
events t=0 as well as particle / photon separation in large mass TPC detectors
filled with noble gases and/or condensed noble gases. The aim of this work is
to demonstrate that costly photo-multipliers could be replaced by cheap novel
photosensitive gaseous detectors: wire counters, GEMs or glass capillary tubes
coupled with CsI photocathodes. We have performed systematic measurements with
Ar, Kr and Xe gas at pressures in the range of 1-50 atm as well as some
preliminary measurements with liquid Xe and liquid Ar. With the gaseous
detectors we succeeded in detecting scintillation light produced by 22 keV
X-rays with an efficiency of close to 100%. We also detected the scintillation
light produced by bs (5 keV deposit energy) with an efficiency close to 25%.
Successful detection of scintillation from 22 keV gammas open new experimental
possibilities not only for nTOF and ICARUS experiments, but also in others,
like WIMPs search through nuclear recoil emission
The Successful Operation of Hole-type Gaseous Detectors at Cryogenic Temperatures
We have demonstrated that hole-type gaseous detectors, GEMs and capillary
plates, can operate up to 77 K. For example, a single capillary plate can
operate at gains of above 10E3 in the entire temperature interval between 300
until 77 K. The same capillary plate combined with CsI photocathodes could
operate perfectly well at gains (depending on gas mixtures) of 100-1000.
Obtained results may open new fields of applications for capillary plates as
detectors of UV light and charge particles at cryogenic temperatures: noble
liquid TPCs, WIMP detectors or LXe scintillating calorimeters and cryogenic
PETs.Comment: Presented at the IEEE Nuclear Science Symposium, Roma, 200
Short-tailed whipscorpion genus Stenochrus.
91 pages : illustrations, maps ; 26 cm.The short-tailed whipscorpion genus, Stenochrus Chamberlin, 1922 (Schizomida: Hubbardiidae Cook, 1899), occurring in North and Central America, is redefined and revised based on simultaneous phylogenetic analysis of 61 morphological characters and 2968 aligned DNA nucleotides from two markers in the nuclear genome, the internal transcribed spacer (ITS) and 28S rDNA, and two markers in the mitochondrial genome, cytochome c oxidase subunit I (COI) and 12S rDNA, for a comprehensive taxon sample. Six new genera are described: Ambulantactus, gen. nov.; Baalrog, gen. nov.; Harveyus, gen. nov.; Nahual, gen. nov.; Schizophyxia, gen. nov.; Troglostenochrus, gen. nov. Heteroschizomus Rowland, 1973, stat. rev., is revalidated and its type species, Heteroschizomus goodnightorum Rowland, 1973, reinstated. Six new species are described: Ambulantactus aquismon, sp. nov.; Ambulantactus montielae, sp. nov.; Baalrog yacato, sp. nov.; Harveyus contrerasi, sp. nov.; Heteroschizomus kekchi, sp. nov.; Nahual bokmai, sp. nov. Eighteen new combinations are created by transferring species, previously accommodated in Stenochrus, to other genera: Ambulantactus davisi (Gertsch, 1940), comb. nov.; Baalrog magico (Monjaraz-Ruedas and Francke, 2018), comb. nov.; Baalrog sbordonii (Brignoli, 1973), comb. nov.; Harveyus mexicanus (Rowland, 1971a), comb. nov.; Harveyus mulaiki (Gertsch, 1940), comb. nov.; Harveyus reddelli (Rowland, 1971a), comb. nov.; Heteroschizomus meambar (Armas and Víquez, 2010), comb. nov.; Heteroschizomus orthoplax (Rowland, 1973a), comb. nov.; Heteroschizomus silvino (Rowland and Reddell, 1977), comb. nov.; Nahual caballero (Monjaraz-Ruedas and Francke, 2018), comb. nov.; Nahual lanceolatus (Rowland, 1975), comb. nov.; Nahual pallidus (Rowland, 1975), comb. nov.; Pacal moisii (Rowland, 1973), comb. nov.; Pacal tepezcuintle (Armas and Cruz-López, 2009), comb. nov.; Schizophyxia bartolo (Rowland, 1973), comb. nov.; Schizophyxia lukensi (Rowland, 1973), comb. nov.; Troglostenochrus palaciosi (Reddell and Cokendolpher, 1986), comb. nov.; Troglostenochrus valdezi (Monjaraz-Ruedas, 2012), comb. nov. The male of B. sbordonii is determined to be heterospecific with the holotype female and described as B. yacato. The females of H. goodnightorum and N. lanceolatus are described for the first time. Following these revisions, seven species remain within Stenochrus: Stenochrus alcalai Monjaraz-Ruedas and Francke, 2018; Stenochrus chimalapas Monjaraz-Ruedas and Francke, 2018; Stenochrus gruta Monjaraz-Ruedas and Francke, 2018; Stenochrus guatemalensis (Chamberlin, 1922); Stenochrus leon Armas, 1995; Stenochrus pecki (Rowland, 1973); Stenochrus portoricensis Chamberlin, 1922. Olmecazomus, nom. nov., is proposed as a replacement name for the junior homonym, Olmeca Monjaraz-Ruedas and Francke, 2017, creating three new combinations: Olmecazomus brujo (Monjaraz-Ruedas and Francke, 2017), comb. nov.; Olmecazomus cruzlopezi (Monjaraz-Ruedas and Francke, 2017), comb. nov.; Olmecazomus santibanezi (Monjaraz-Ruedas and Francke, 2017), comb. nov. A key to identification of the hubbardiid genera of North America is provided and the utility of various character systems for the diagnosis of schizomid genera discussed. The integration of morphological and molecular data not only increased knowledge of the schizomid diversity in the New World but disentangled what was once considered a homoplastic and variable morphology in a large "catch-all" genus into discrete units each diagnosable by unique character combinations
An important role for Myb-MuvB and its target gene KIF23 in a mouse model of lung adenocarcinoma
The conserved Myb-MuvB (MMB) multiprotein complex has an important role in transcriptional activation of mitotic genes. MMB target genes are overexpressed in several different cancer types and their elevated expression is associated with an advanced tumor state and a poor prognosis. This suggests that MMB could contribute to tumorigenesis by mediating overexpression of mitotic genes. However, although MMB has been extensively characterized biochemically, the requirement for MMB in tumorigenesis in vivo has not been investigated. Here we demonstrate that MMB is required for tumor formation in a mouse model of lung cancer driven by oncogenic K-RAS. We also identify a requirement for the mitotic kinesin KIF23, a key target gene of MMB, in tumorigenesis. RNA interference-mediated depletion of KIF23 inhibited lung tumor formation in vivo and induced apoptosis in lung cancer cell lines. Our results suggest that inhibition of KIF23 could be a strategy for treatment of lung cancer
Una nueva especie de alacrán del género Centruroides Marx (1890) (Scorpiones, Buthidae) de la depresión del Balsas, México
Se describe una nueva especie del género Centruroides Marx de la Depresión del Balsas en los Estados de Guerrero, Michoacán y México, en elevaciones que van de los 400 a los 1500 msnm. Esta especies se caracteriza por tener ocho hileras de dentículos en los dedos de la quela del pedipalpo y corresponde, dentro del género, a la sección de alacranes rayados, en la cual se le ha confundido con Centruroides limpidus limpidus Karsch y con Centruroides limpidus tecomanus Hoffmann. Las diferencias se observan en morfometría y patrón de coloración. Esta nueva especie es simpátrica con C. limpidus limpidus en la parte Este de su rango de distribución en el Estado de Michoacán y con C. infamatus infamatus Pocock en la Sierra de Coalcomán y regiones adyacentes en la parte Norte del Estado. Se registra también en una localidad en el Estado de Guerrero y en una localidad en el Estado de México.A new species of scorpion of the genus Centruroides Marx is described. It occurs in the Balsas River Depression in the states of Guerrero and Michoacan, Mexico, at elevations ranging from 400 m to 1500 m above sea level. It has eight rows of denticles on the pedipalp fingers, and belongs to the stripped section of the genus, where it had been previously confused with Centruroides limpidus limpidus Karsch and with Centruroides limpidus tecomanus Hoffmann. It differs in morphometrics and color pattern. The new species is sympatric with C. limpidus limpidus in the eastern part of its range in the state of Michoacan, and with Centruroides infamatus Pocock in the Sierra de Coalcoman and adjacent regions in the northern part of the state. One locality in Guerrero State and another one in Mexico State are recorded too
A High Position Resolution X-ray Detector: an Edge on Illuminated Capillary Plate Combined with a Gas Amplification Structure
We have developed and successfully tested a prototype of a new type of high
position resolution hybrid X-ray detector. It contains a thin wall lead glass
capillary plate converter of X-rays combined with a microgap parallel-plate
avalanche chamber filled with gas at 1 atm. The operation of these converters
was studied in a wide range of X-ray energies (from 6 to 60 keV) at incident
angles varying from 0-90 degree. The detection efficiency, depending on the
geometry, photon energy, incident angle and the mode of operation, was between
5-30 percent in a single step mode and up to 50 percent in a multi-layered
combination. Depending on the capillary geometry, the position resolution
achieved was between 0.050-0.250 mm in digital form and was practically
independent of the photon energy or gas mixture. The usual lead glass capillary
plates operated without noticeable charging up effects at counting rates of 50
Hz/mm2, and hydrogen treated capillaries up to 10E5 Hz/mm2. The developed
detector may open new possibilities for medical imaging, for example in
mammography, portal imaging, radiography (including security devices),
crystallography and many other applications.Comment: Presented at the IEEE Nuclear Science Symposium, Roma, Octber 200
The development of gaseous detectors with solid photocathodes for low temperature
There are several applications and fundamental research areas which require
the detection of VUV light at cryogenic temperatures. For these applications we
have developed and successfully tested special designs of gaseous detectors
with solid photocathodes able to operate at low temperatures: sealed gaseous
detectors with MgF2 windows and windowless detectors. We have experimentally
demonstrated, that both primary and secondary (due to the avalanche
multiplication inside liquids) scintillation lights could be recorded by
photosensitive gaseous detectors. The results of this work may allow one to
significantly improve the operation of some noble liquid gas TPCs.Comment: Presented at the X Vienna Conference on Instumentation, Vienna,
February 200
Iron deficiency after kidney transplantation
Iron deficiency (ID) is highly prevalent in kidney transplant recipients (KTRs) and has been independently associated with an excess mortality risk in this population. Several causes lead to ID in KTRs, including inflammation, medication and an increased iron need after transplantation. Although many studies in other populations indicate a pivotal role for iron as a regulator of the immune system, little is known about the impact of ID on the immune system in KTRs. Moreover, clinical trials in patients with chronic kidney disease or heart failure have shown that correction of ID, with or without anaemia, improves exercise capacity and quality of life, and may improve survival. ID could therefore be a modifiable risk factor to improve graft and patient outcomes in KTRs; prospective studies are warranted to substantiate this hypothesis.</p
Revision of the giant vinegaroons.
62 pages : illustrations (some color), map ; 26 cm.The North American vinegaroon, Mastigoproctus giganteus (Lucas, 1835), is demonstrated to comprise a complex of range-restricted species rather than a single widespread polymorphic species. Seven species are recognized based on morphological characters of the adult males, including the arrangement of spines on the prodorsal margin of the pedipalp trochanter, the position of the epistoma on the carapace, the presence of a stridulatory organ on opposing surfaces of the chelicerae and the pedipalp coxa, the presence of a patch of setae on sternite V, and the shape and macrosculpture of the retrolateral surface of the pedipalp femur. The two currently recognized subspecies are elevated to species: Mastigoproctus mexicanus (Butler, 1872), stat. nov., and Mastigoproctus scabrosus (Pocock, 1902), stat. nov. Mastigoproctus floridanus (Lönnberg, 1897) is revalidated from synonymy with M. giganteus. Redescriptions of M. giganteus and the other three species, based on both sexes, are provided, and three new species described: Mastigoproctus cinteotl, sp. nov., from Tamaulipas, Mexico; Mastigoproctus tohono, sp. nov., from Arizona and Sonora, Mexico; Mastigoproctus vandevenderi, sp. nov., from Sonora, Mexico. The present contribution raises the diversity of the Order Thelyphonida Latreille, 1804, in North America from one species to seven. Three species occur in the United States (one each in Arizona, Texas, and Florida), six species occur in Mexico, and two species occur in both countries
Kolotl.
28 pages : illustrations (some color), map ; 26 cm.The monophyly and phylogenetic position of Diplocentrus Peters, 1861, has remained ambiguous since the first published phylogenetic analysis of diplocentrid relationships, in which it was rendered paraphyletic by the placement of exemplar species from two other diplocentrid genera, Bioculus Stahnke, 1968, and Didymocentrus Kraepelin, 1905. The discovery of two diplocentrids with neobothriotaxic pedipalps, Diplocentrus magnus Beutelspacher and López-Forment, 1991, and Diplocentrus poncei Francke and Quijano-Ravell, 2009, from the central Mexican states of Guerrero and Michoacán, respectively, raised further questions about the limits of Diplocentrus. A recent phylogenetic analysis of 29 species of Diplocentrus and five exemplar species of the most closely related genera, based on 95 morphological characters and 4202 aligned nucleotides from DNA sequences of five markers in the nuclear and mitochondrial genomes, recovered the monophyly of Diplocentrus, excepting two neobothriotaxic species from central Mexico, justifying their removal from Diplocentrus. In the present contribution, Kolotl, n. gen. is created to accommodate the two species, Kolotl magnus (Beutelspacher and López-Forment, 1991), n. comb., and Kolotl poncei (Francke and Quijano-Ravell, 2009), n. comb., and both are redescribed
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