Optical transitions and nature of Stokes shift in spherical CdS quantum dots

We study the structure of the energy spectra along with the character of the states participating in optical transitions in colloidal CdS quantum dots (QDs) using the {\sl ab initio} accuracy charge patching method combined with the %pseudopotential based folded spectrum calculations of electronic structure of thousand-atom nanostructures. In particular, attention is paid to the nature of the large resonant Stokes shift observed in CdS quantum dots. We find that the top of the valence band state is bright, in contrast with the results of numerous {\bf k$\cdot$p} calculations, and determine the limits of applicability of the {\bf k$\cdot$p} approach. The calculated electron-hole exchange splitting suggests the spin-forbidden valence state may explain the nature of the ``dark exciton'' in CdS quantum dots.Comment: 5 pages, 4 figure

The Birth of a Galaxy - III. Propelling reionisation with the faintest galaxies

Starlight from galaxies plays a pivotal role throughout the process of cosmic reionisation. We present the statistics of dwarf galaxy properties at z > 7 in haloes with masses up to 10^9 solar masses, using a cosmological radiation hydrodynamics simulation that follows their buildup starting with their Population III progenitors. We find that metal-enriched star formation is not restricted to atomic cooling ($T_{\rm vir} \ge 10^4$ K) haloes, but can occur in haloes down to masses ~10^6 solar masses, especially in neutral regions. Even though these smallest galaxies only host up to 10^4 solar masses of stars, they provide nearly 30 per cent of the ionising photon budget. We find that the galaxy luminosity function flattens above M_UV ~ -12 with a number density that is unchanged at z < 10. The fraction of ionising radiation escaping into the intergalactic medium is inversely dependent on halo mass, decreasing from 50 to 5 per cent in the mass range $\log M/M_\odot = 7.0-8.5$. Using our galaxy statistics in a semi-analytic reionisation model, we find a Thomson scattering optical depth consistent with the latest Planck results, while still being consistent with the UV emissivity constraints provided by Ly$\alpha$ forest observations at z = 4-6.Comment: 21 pages, 15 figures, 4 tables. Accepted in MNRA

Lateral Root Initiation in the Parental Root Meristem of Cucurbits: Old Players in a New Position

While in most higher plants, including the model system Arabidopsis thaliana, the formation of lateral root primordia is induced in the elongation zone of the parental root, in seven plant families, including Cucurbitaceae, an alternative root branching mechanism is established such that lateral roots are initiated directly in the apical meristem of the parental root. In Arabidopsis, the transcription factor GATA23 and MEMBRANE-ASSOCIATED KINASE REGULATOR4 (MAKR4) are involved in the gene regulatory network of lateral root initiation. Among all marker genes examined, these are the earliest known marker genes up-regulated by auxin during lateral root initiation. In this study, putative functional orthologs of Arabidopsis GATA23 and MAKR4 were identified in cucumber (Cucumis sativus) and squash (Cucurbita pepo). Both cucurbits contained 26 genes encoding GATA family transcription factors and only one MAKR4 gene. Phylogenetic and transcriptional analysis of up-regulation by auxin led to the identification of GATA23 putative functional orthologs in Cucurbitaceae – CpGATA24 and CsGATA24. In squash, CpMAKR4 was up-regulated by naphthylacetic acid (NAA) and, similar to MAKR4 in Arabidopsis, indole-3-butyric acid (IBA). A detailed analysis of the expression pattern of CpGATA24 and CpMAKR4 in squash roots from founder cell specification until emergence of lateral root primordia was carried out using promoter-fluorescent reporter gene fusions and confocal microscopy. Their expression was induced in the protoxylem, and then expanded to founder cells in the pericycle. Thus, while the overall expression pattern of these genes was significantly different from that in Arabidopsis, in founder cells their expression was induced in the same order as in Arabidopsis. Altogether, these findings suggest that in Cucurbitaceae the putative functional orthologs of GATA23 and MAKR4 might play a role in founder cell specification and primordium positioning during lateral root initiation. The role of the protoxylem in auxin transport as a trigger of founder cells specification and lateral root initiation is discussed

Анальгезивна та протизапальна дії похідних 5,7-діацил- 3-H(алкіл)-6-арил-5Н-[1,2,4]тріазоло[3,4-b][1,3,4]тіадіазину

The search for new analgesic and anti-inflammatory drugs, exceeding by efficacy and/or safety the existinganalogues is very important and relevant. The nitrogenous heterocycles are promising in this respect, in particular,the compounds containing an imidazole triazol and tіadiazin moiety. The aim of the current study was to investigatethe antiexudative and antinociceptive activity of new derivatives of 5,7-diacyl-3-H(alkyl)-6-aryl-5H[1,2,4]triazol[3,4-b][1,3,4]thiadiazine.The antinociceptive and antiexudative activity studies were carried out on the white nonlinear mice. Theexperimental evaluation of specific activity was carried out on the models “Hot plate”, acetic acid induced writhing(antinociceptive action) and carrageenan edema (antiexudative action). The substance was used in a single oral routadministration in a dose of 25 mg/kg. Ketorolac was used as a reference product in the dose of 25 mg/kg (models“Hot plate”, acetic acid induced writhing). Diclofenac was used as a reference product in the dose of 25 mg/kg onthe model carrageenan edema. The experimental study showed the antinociceptive and antiexudative effects of thederivatives. The antinociceptive activity of 5,7-diacyl-3-H(alkіl)-6-aryl-5H[1,2,4]triazol[3,4-b][1,3,4]tіadiazin derivatiesrelated to the modification structure in the para position of benzene ring. The antiexudative activity is associated withacetyl groups thiadiazine ring. The most promising compound IFT_247 showed a significant antinociceptive effect,which is comparable to an active comparator ketorolac: “Hot plate” +232.46 % and +112.71 %; acetic acid inducedwrithing -66.67 % and -61.02 %, respectively.Поиск новых анальгезирующих и противовоспалительных препаратов, превосходящих по эффектив-ности и/или безопасности существующие аналоги, важен и актуален. В этом отношении перспективныазотистые гетероциклы, в частности соединения, содержащие в себе триазоловый и тиадиазиновыйфрагменты.Была поставлена цель исследовать антиноцицептивную и антиэксудативную активность новыхпроизводных 5,7-диацил-3-H(алкил)-6-арил-5Н-[1,2,4]триазоло[3,4-b][1,3,4]тиадиазина.Исследование проведено на белых нелинейных мышах обоего пола. Оценено антиноцицептивную иантиэксудативную активность пяти производных 5,7-диацил-3-H(алкил)-6-арил-5Н-[1,2,4]триазоло[3,4-b][1,3,4]тиадиазина на моделях “горячей пластины, уксуснокислых “корчей” (антиноцицептивный эффект)и каррагенинового отека (антиэкссудативное действие) при однократном внутрижелудочном введении вдозе 25 мг/кг. В качестве препаратов сравнения использовали кеторолак в дозе 25 мг/кг (“горячая пласти-на”, уксуснокислые “корчи”) и диклофенак натрия в дозе 25 мг/кг (каррагениновый отек). Исследованныесоединения показали наличие достоверного антиноцицептивного и антиэкссудативного эффектов.Антиноцицептивная активность ряда связана с модификацией структуры 5,7-диацил-3-H(алкил)-6-арил-5Н-[1,2,4]триазоло[3,4-b][1,3,4]тиадиазина в параположении бензольного кольца. Антиэкссудативнаяактивность – с ацетиловыми группами тиадиазинового кольца. Наиболее перспективным являетсясоединение IFT_247, проявляющее значительный анальгезирующий эффект в эксперименте и не усту-пающее по активности препарату сравнения – кеторолаку: “горячая пластина” – +232,46 и +112,71 %;уксуснокислые “корчи” – -66,67 и -61,02 % соответственно.Пошук нових анальгезивних і протизапальних препаратів, що переважають за ефективністю та/абобезпекою існуючі аналоги, є важливим і актуальним. У цьому відношенні перспективні азотисті гетеро-цикли, зокрема сполуки, що містять у собі тріазоловий і тіадіазиновий фрагменти.Було поставлено мету дослідити антиноцицептивну та антиексудативну активність нових похідних5,7-діацил-3-H(алкіл)-6-арил-5Н-[1,2,4]тріазоло[3,4-b][1,3,4]тіадіазину.Дослідження проведено на білих нелінійних мишах обох статей. Оцінено антиноцицептивну йантиексудативну активність п’яти похідних 5,7-діацил-3-H(алкіл)-6-арил-5Н-[1,2,4]тріазоло[3,4-b][1,3,4]тіадіазину на моделях “гарячої пластини”, оцтовокислих “корчів” (антиноцицептивний ефект) ікарагенінового набряку (антиексудативна дія) при одноразовому внутрішньошлунковому введенні в дозі25 мг/кг. Як препарати порівняння використовували кеторолак у дозі 25 мг/кг (“гаряча пластина”, оцтовокислі“корчі”) і диклофенак натрію в дозі 25 мг/кг (карагеніновий набряк). Досліджені сполуки показали наявністьдостовірного антиноцицептивного й антиексудативного ефектів. Антиноцицептивна активністьряду пов’язана з модифікацією структури 5,7-діацил-3-H(алкіл)-6-арил-5Н-[1,2,4]тріазоло[3,4-b][1,3,4]тіадіазину в параположенні бензольного кільця. Антиексудативна активність – з ацетиловими групамитіадіазинового кільця. Найбільш перспективною є сполука IFT_247, що проявляє значний анальгезивнийефект в експерименті й не поступається за активністю препарату порівняння – кеторолаку: “гарячапластина” – +232,46 і +112,71 %; оцтовокислі “корчі” – -66,67 і -61,02 % відповідно

Electronic Structure of Transition-Metal Dicyanamides Me[N(CN)2_2]2_2 (Me = Mn, Fe, Co, Ni, Cu)

The electronic structure of Me[N(CN)$_2$]$_2$ (Me=Mn, Fe, Co, Ni, Cu) molecular magnets has been investigated using x-ray emission spectroscopy (XES) and x-ray photoelectron spectroscopy (XPS) as well as theoretical density-functional-based methods. Both theory and experiments show that the top of the valence band is dominated by Me 3d bands, while a strong hybridization between C 2p and N 2p states determines the valence band electronic structure away from the top. The 2p contributions from non-equivalent nitrogen sites have been identified using resonant inelastic x-ray scattering spectroscopy with the excitation energy tuned near the N 1s threshold. The binding energy of the Me 3d bands and the hybridization between N 2p and Me 3d states both increase in going across the row from Me = Mn to Me = Cu. Localization of the Cu 3d states also leads to weak screening of Cu 2p and 3s states, which accounts for shifts in the core 2p and 3s spectra of the transition metal atoms. Calculations indicate that the ground-state magnetic ordering, which varies across the series is largely dependent on the occupation of the metal 3d shell and that structural differences in the superexchange pathways for different compounds play a secondary role.Comment: 20 pages, 11 figures, 2 table

Optimizing thermal transport in the Falicov-Kimball model: binary-alloy picture

We analyze the thermal transport properties of the Falicov-Kimball model concentrating on locating regions of parameter space where the thermoelectric figure-of-merit ZT is large. We focus on high temperature for power generation applications and low temperature for cooling applications. We constrain the static particles (ions) to have a fixed concentration, and vary the conduction electron concentration as in the binary-alloy picture of the Falicov-Kimball model. We find a large region of parameter space with ZT>1 at high temperature and we find a small region of parameter space with ZT>1 at low temperature for correlated systems, but we believe inclusion of the lattice thermal conductivity will greatly reduce the low-temperature figure-of-merit.Comment: 13 pages, 14 figures, typeset with ReVTe

The GEYSERS optical testbed: a platform for the integration, validation and demonstration of cloud-based infrastructure services

The recent evolution of cloud services is leading to a new service transformation paradigm to accommodate network infrastructures in a cost-scalable way. In this transformation, the network constitutes the key to efficiently connect users to services and applications. In this paper we describe the deployment, validation and demonstration of the optical integrated testbed for the “GEneralized architecture for dYnamic infrastructure SERviceS” (GEYSERS) project to accommodate such cloud based Infrastructure Services. The GEYSERS testbed is composed of a set of local physical testbeds allocated in the facilities of the GEYSERS partners. It is built up based on the requirements specification, architecture definition and per-layer development that constitutes the whole GEYSERS ecosystem, and validates the procedures on the GEYSERS prototypes. The testbed includes optical devices (layer 1), switches (layer 2), and IT resources deployed in different local testbeds provided by the project partners and interconnected among them to compose the whole testbed layout. The main goal of the GEYSERS testbed is twofold. On one hand, it aims at providing a validation ground for the architecture, concepts and business models proposed by GEYSERS, sustained by two main paradigms: Infrastructure as a Service (IaaS) and the coupled provisioning of optical network and IT resources. On the other hand, it is used as a demonstration platform for testing the software prototypes within the project and to demonstrate to the research and business community the project approach and solutions. In this work, we discuss our experience in the deployment of the testbed and share the results and insights learned from our trials in the process. Additionally, the paper highlights the most relevant experiments carried out in the testbed, aimed at the validation of the overall GEYSERS architecture