Cosmic Microwave Background constraints of decaying dark matter particle properties

If a component of cosmological dark matter is made up of massive particles - such as sterile neutrinos - that decay with cosmological lifetime to emit photons, the reionization history of the universe would be affected, and cosmic microwave background anisotropies can be used to constrain such a decaying particle model of dark matter. The optical depth depends rather sensitively on the decaying dark matter particle mass m_{dm}, lifetime tau_{dm}, and the mass fraction of cold dark matter f that they account for in this model. Assuming that there are no other sources of reionization and using the WMAP 7-year data, we find that 250 eV < m_{dm} < 1 MeV, whereas 2.23*10^3 yr < tau_{dm} < 1.23*10^18 yr. The best fit values for m_{dm} and tau_{dm}/f are 17.3 keV and 2.03*10^16 yr respectively.Comment: 17 pages, 3 figure

Probing Sub-parsec Structure in the Lyman Alpha Forest with Gravitational Microlensing

We present the results of microlens ray-tracing simulations showing the effect of absorbing material between a source quasar and a lensing galaxy in a gravitational lens system. We find that, in addition to brightness fluctuations due to microlensing, the strength of the absorption line relative to the continuum varies with time, with the properties of the variations depending on the structure of the absorbing material. We conclude that such variations will be measurable via UV spectroscopy of image A of the gravitationally lensed quasar Q2237+0305 if the Lyman Alpha clouds between the quasar and the lensing galaxy possess structure on scales smaller than $\sim 0.1$ pc. The time scale for the variations is on the order of order years to decades, although very short term variability can occur. While the Lyman alpha lines may not be accessible at all wavelengths, this approach is applicable to any absorption system, including metal lines.Comment: 8 pages, 11 figures, to appear in MNRAS (note resolution of some figures reduced due to size limitations

Helium atom diffraction measurements of the surface structure and vibrational dynamics of CH_3-Si(111) and CD_3-Si(111) surfaces

The surface structure and vibrational dynamics of CH_3–Si(111) and CD_3–Si(111) surfaces were measured using helium atom scattering. The elastic diffraction patterns exhibited a lattice constant of 3.82 Å, in accordance with the spacing of the silicon underlayer. The excellent quality of the observed diffraction patterns, along with minimal diffuse background, indicated a high degree of long-range ordering and a low defect density for this interface. The vibrational dynamics were investigated by measurement of the Debye–Waller attenuation of the elastic diffraction peaks as the surface temperature was increased. The angular dependence of the specular (θ_i=θ_f) decay revealed perpendicular mean-square displacements of 1.0 x 10^(−5) Å^2 K^(−1) for the CH_3–Si(111) surface and 1.2 x 10^(−5) Å^2 K^(−1) for the CD_3–Si(111) surface, and a He-surface attractive well depth of ~7 meV. The effective surface Debye temperatures were calculated to be 983 K for the CH_3–Si(111) surface and 824 K for the CD_3–Si(111) surface. These relatively large Debye temperatures suggest that collisional energy accommodation at the surface occurs primarily through the Si–C local molecular modes. The parallel mean-square displacements were 7.1 x 10^(−4) and 7.2 x 10^(−4) Å^2 K^(−1) for the CH_3–Si(111) and CD_3–Si(111) surfaces, respectively. The observed increase in thermal motion is consistent with the interaction between the helium atoms and Si–CH_3 bending modes. These experiments have thus yielded detailed information on the dynamical properties of these robust and technologically interesting semiconductor interfaces

Inovatyvios lyderystės vaidmuo žinių valdymo ir inovacijų kūrimo procesuose šiuolaikinėje organizacijoje

The ability to create innovations is one of the most important sources of a competitive advantage forevery modern organization, region, and state. In today’s context as a particularly significant problem arises the issue of the role of leaders in organizing effective knowledge management and innovation processes. Although the topic of leadership was analyzed quite extensively in the second half of the 20th century, in the 21st century, it is recognized that organizations of this age need a new quality of leadership, as the organizations themselves and their environments are undergoing profound changes. This paper analyzes the changing approaches to leadership and its role in a modern organization, focusing on the concept of innovative leadership and its peculiarities in order to identify the components of this phenomenon and their links to knowledge management and innovation processes. After analyzing significant aspects of this topic, identified were the relationships between innovative leadership, knowledge management, and innovation performance, as well as an integral theoretical model of innovative leadership, knowledge management, and innovation performance for driving continuous innovation performance has been developed.Gebėjimas kurti inovacijas yra vienas svarbiausių kiekvienos šiuolaikinės organizacijos konkurencinio pranašumo šaltinis. Šiandienos aktualijų kontekste iškyla ypač reikšminga problema - lyderių vaidmuo, organizuojant efektyvius žinių vadybos bei inovacijų kūrimo procesus. Nors lyderystės tema buvo analizuojama gana plačiai XX a. antroje pusėje, tačiau XXI a. pripažįstama, kad šio laikmečio organizacijoms reikalinga naujos kokybės lyderystės, nes organizacijos ir jų aplinka keičiasi iš esmės. Šiame sraipsnyje yra analizuojami kintantys požiūriai į lyderystę ir jos vaidmenį šiuolaikinėje organizacijoje, susitelkiama į inovatyvios lyderystės sampratos ir jos raiškos ypatumų analizę, siekiant identifikuoti šio fenomeno dedamąsias ir jų sąsajas su žinių valdymo ir inovacijų kūrimo procesais. Išanalizavus reikšmingus šios temos aspektus, buvo nustatytos inovatyvios lyderystės, žinių valdymo ir inovacijų sąsajos ir suformuotas integralus teorinis inovatyvios lyderystės, žinių valdymo ir inovacijų kūrimo modelis organizacijoje