In celebration of the 60th birthday of Professor Alemdar Hasanoğlu (Hasanov)

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Efficiency of Finding Muon Track Trigger Primitives in CMS Cathode Strip Chambers

In the CMS Experiment, muon detection in the forward direction is accomplished by cathode strip chambers~(CSC). These detectors identify muons, provide a fast muon trigger, and give a precise measurement of the muon trajectory. There are 468 six-plane CSCs in the system. The efficiency of finding muon trigger primitives (muon track segments) was studied using~36 CMS CSCs and cosmic ray muons during the Magnet Test and Cosmic Challenge~(MTCC) exercise conducted by the~CMS experiment in~2006. In contrast to earlier studies that used muon beams to illuminate a very small chamber area ($< \! 0.01$~m$^2$), results presented in this paper were obtained by many installed CSCs operating {\em in situ} over an area of $\approx \! 23$~m$^2$ as a part of the~CMS experiment. The efficiency of finding 2-dimensional trigger primitives within 6-layer chambers was found to be~$99.93 \pm 0.03\%$. These segments, found by the CSC electronics within $800$~ns after the passing of a muon through the chambers, are the input information for the Level-1 muon trigger and, also, are a necessary condition for chambers to be read out by the Data Acquisition System

CMS physics technical design report : Addendum on high density QCD with heavy ions

Peer reviewe

Biome changes and their inferred climatic drivers in northern and eastern continental Asia at selected times since 40 cal ka bp

Recent global warming is pronounced in high-latitude regions (e.g. northern Asia), and will cause the vegetation to change. Future vegetation trends (e.g. the “arctic greening”) will feed back into atmospheric circulation and the global climate system. Understanding the nature and causes of past vegetation changes is important for predicting the composition and distribution of future vegetation communities. Fossil pollen records from 468 sites in northern and eastern Asia were biomised at selected times between 40 cal ka bp and today. Biomes were also simulated using a climate-driven biome model and results from the two approaches compared in order to help understand the mechanisms behind the observed vegetation changes. The consistent biome results inferred by both approaches reveal that long-term and broad-scale vegetation patterns reflect global to hemispheric-scale climate changes. Forest biomes increase around the beginning of the late deglaciation, become more widespread during the early and middle Holocene, and decrease in the late Holocene in fringe areas of the Asian Summer Monsoon. At the southern and southwestern margins of the taiga, forest increases in the early Holocene and shows notable species succession, which may have been caused by winter warming at ca. 7 cal ka bp. At the northeastern taiga margin (central Yakutia and northeastern Siberia), shrub expansion during the last deglaciation appears to prevent the permafrost from thawing and hinders the northward expansion of evergreen needle-leaved species until ca. 7 cal ka bp. The vegetation climate disequilibrium during the early Holocene in the taiga-tundra transition zone suggests that projected climate warming will not cause a northward expansion of evergreen needle-leaved species

Late Saalian and Eemian palaeoenvironmental history of the Bol'shoy Lyakhovsky Island (Laptev Sea region, Arctic Siberia)

Paleoenvironmental records from permafrost sequences complemented by IRSL and 230Th/U dates from Bol'shoy Lyakhovsky Island (73?20?N, 141?30?E) document the environmental history in the Laptev Sea region for at least the past 200 ka. Pollen spectra and insect fauna indicate that relatively wet grass-sedge tundra habitats predominated during an interstadial c. 200-170 ka ago. Summers were rather warm and wet, while stable isotopes reflect severe winter conditions. The pollen spectra reflect sparser grass-sedge vegetation cover during a late Saalian stadial, c. 170-130 ka ago, with environmental conditions much more sever compared with the previous interstadials. Open Poaceae and Artemisia plant associations dominated vegetation at the beginning of the Eemian Interglacial, c. 130 ka ago. Some shrubs (Alnus fruticosa, Salix, Betula nana) grew in more protected and wetter places as well. The climate was relatively warm during this time, resulting in the melting of the Saalian ice wedges. Later, during the interglacial optimum shrub tundra with Alnus fruticosa and Betula nana s.l. dominated vegetation. Climate was relatively wet and warm. Quantitative pollen-based climate reconstruction suggests that mean July temperatures were 4-5?C higher than the present during the optimum of the Eemian Interglacial, while late Eemian records indicate significant climate deterioration

Wound Dressings Made of Biodegradable Natural Polymers Polyhydroxyalkanoates (PHAs): Production and Properties

Рост количества производственных и бытовых травм и ожогов диктует необходимость поиска и разработки материалов и средств для восстановления повреждений кожных покровов. В статье представлены результаты исследования экспериментальных раневых покрытий, сконструированных из разрушаемых природных полиэфиров полигидроксиалканоатов (ПГА) методом электростатического формования. Исследования на лабораторных животных с модельными ожогами кожных покровов показали, что разработанные мембраны из ПГА обеспечивают регенерацию кожи через 7 суток, что сопоставимо с контролем, в котором применяли принятую в клинической практике коллагеновую повязку. Разработанные нетканые мембраны могут быть использованы в качестве эквивалента коллагеновой повязки при лечении ожоговых ран II степениIncreasing number of industrial and household injuries and burns lead to the necessity of research and development of new materials and resources for damaged skin regeneration. In this study results of experimental investigation of wound dressing made of natural degradable polyesters polyhydroxyalkanoates (PHAs) using electrospinning are presented. Studies on laboratory animals with model skin burns showed that the developed PHA membranes provide regeneration of the skin after 7 days and it is comparable with the control collagen dressings used in clinical practice. Developed nonwoven membranes may be used as the equivalent of collagen dressings in the treatment of II degree burn

High-order harmonic cut-off frequency in atomic silver irradiated by femtosecond laser pulses: theory and experiment

The results of theoretical and experimental study of high-order optical harmonic generation in the ensemble of silver atoms irradiated by intense femtosecond pulses of Ti:Sapphire laser are presented. It is shown that the photoemission spectra exhibit unusual behavior when the laser field strength approaches near-atomic values. In subatomic field strength the cut-off frequency increases linearly with laser pulse intensity. However, when the field strength approaches near-atomic region firstly cut-off frequency slows down and then saturates. To give new interpretation of such kind of photoemission spectrum behavior we have proposed the light-atom interaction theory based on the use of eigenfunctions of boundary value problem for “the atom in an external field” instead of the traditional basis of the “free atom” eigenfunctions. The results of computer simulations clearly demonstrate saturation of the cut-off frequency at near-atomic strength of a laser field. The problem of angular divergence of a harmonic emission is analyzed

High-order harmonic generation during different overlaps of two-colored pulses in laser-produced plasmas and gases

In high-order harmonic generation in low-dense media, the application of two-colored pump has been shown to enhance odd-order harmonics, as well as the generation of strong even harmonics. Here, we apply this approach to compare high-order harmonic generation from laser-produced plasmas and gases using different mechanisms of harmonic emission enhancement. We generate two-color pump (TCP, 806 nm + 403 nm and 1030 nm + 515 nm) using two nonlinear crystals of different thickness (0.2 and 0.4 mm in the case of experiments with plasmas using 806 nm pump; and 0.1 mm and 0.4 mm in the case of experiments with gases and plasmas using 1030 nm pump) to demonstrate the enhancement of odd and even harmonics in laser-produced plasmas and by applying weak second field (403 or 515 nm) at different overlaps of pump pulses. The high-order harmonic generation in two media using TCP pulses is optimized. We demonstrate the wavelength dependence and the prevailing role of the partial overlap between the two orthogonally polarized waves in laser-produced plasmas and gases over large ratios of the second-order and fundamental photons. Our results are supported by the non-perturbative single atom theory and the interference model simulations