697 research outputs found

    Communication system features dual mode range acquisition plus time delay measurement

    Get PDF
    Communication system combines range acquisition system and time measurement system for tracking high velocity aircraft and spacecraft. The range acquisition system uses a pseudonoise code to determine range and the time measurement system reduces uncontrolled phase variations in the demodulated signal

    Flexible high-voltage supply for experimental electron microscope

    Get PDF
    Scanning microscope uses a field-emission tip for the electron source, an electron gun that simultaneously accelerates and focuses electrons from the source, and one auxiliary lens to produce a final probe size at the specimen on the order of angstroms

    ‘RE/TRS’ is a Girl’s Subject: Talking about Gender and the Discourse of ‘Religion’ in UK Educational Spaces

    Get PDF
    This article addresses what appears to be a retrenchment into narrower forms of identification and an increased suspicion of difference in the context of educational policy in the UK – especially in relation to ‘Religious Education’. The adoption of standardized management protocols – ‘managerialism’ – across most if not all policy contexts including public educational spaces reduces spaces for encountering or addressing genuine difference and for discovering something new and different. A theory of the ‘feminization of religion’ associated historically with Barbara Welter, provides some useful insights as to why this might be, suggesting that those in British society who would prefer to see greater separation from ‘religion’ in ‘secular’ schools may well also be caught up in forms of gender stereotyping

    Spin-state driven ferromagnetic and spin glass states in layered LaSrCoO4_4

    Full text link
    Famous for its spin-state puzzle, LaSrCoO4_4 (Co3+^{3+}) is an intermediate between antiferromagnetic (AFM) La2_2CoO4_4 (Co2+^{2+}) and ferromagnetic (FM) Sr2_2CoO4_4 (Co4+^{4+}). The appearance of the Co3+^{3+} valence state (not present in the end compounds) is intriguing because of the spin-state transitions associated with it. In this work, we report two magnetic transitions in LaSrCoO4_4: (i) a transition at T == Tc_c ≃\simeq 225 K, from the paramagnetic state to a state with an inhomogeneous long-range ferromagnetic (FM) order wherein finite FM clusters coexist with infinite FM matrix in the percolation sense, and (ii) the transition to the cluster spin glass (CSG) state at T == Tg_g ≃\simeq 8 K. Finite FM clusters (which at low temperatures give rise to the cluster spin glass state) and infinite FM matrix are formed due to the spin-spin interactions brought about by the inhomogeneously distributed Co3+^{3+} high spin (HS) and Co3+^{3+} low spin (LS) ions. A firm support to the presence of an unconventional (inhomogeneous) ferromagnetic order comes from the anomalous values of the critical exponents β\beta, γ\gamma and δ\delta for the spontaneous magnetization, `zero-field' magnetic susceptibility and the critical M - H isotherm, while the coexistence of HS Co3+^{3+} and LS Co3+^{3+} ions is confirmed by the results of the extended X-ray absorption fine structure spectroscopy.Comment: 18 pages, 6 figure

    Superconductivity in the YIr2Si2 and LaIr2Si2 Polymorphs

    Full text link
    We report on existence of superconductivity in YIr2Si2 and LaIr2Si2 compounds in relation to crystal structure. The two compounds crystallize in two structural polymorphs, both tetragonal. The high temperature polymorph (HTP) adopts the CaBe2Ge2-structure type (space group P4/nmm) while the low temperature polymorph (LTP) is of the ThCr2Si2 type (I4/mmm). By studying polycrystals prepared by arc melting we have observed that the rapidly cooled samples retain the HTP even at room temperature (RT) and below. Annealing such samples at 900C followed by slow cooling to RT provides the LTP. Both, the HTP and LTP were subsequently studied with respect to magnetism and superconductivity by electrical resistivity, magnetization, AC susceptibility and specific heat measurements. The HTP and LTP of both compounds respectively, behave as Pauli paramagnets. Superconductivity has been found exclusively in the HTP of both compounds below Tsc (= 2.52 K in YIr2Si2 and 1.24 K in LaIr2Si2). The relations of magnetism and superconductivity with the electronic and crystal structure are discussed with comparing experimental data with the results of first principles electronic structure calculations

    The effect of exposure to synthetic pheromone lures on male Zygaena filipendulae mating behaviour: implications for monitoring species of conservation interest

    Get PDF
    Pheromone based monitoring of insects of conservation value has the potential to revolutionise the way in which surveys are carried out. However, due to their effective use in pest management, concerns have been raised about potential negative effects of pheromone exposure on populations of rare insects. The effect of exposure to synthetic pheromone lures on male mating behaviour was examined in laboratory and field conditions using the six spot burnet moth Zygaena filipendulae (Linnaeus, 1758). For the laboratory experiment larvae were collected and cultured separately under controlled conditions. Virgin males were exposed to a synthetic pheromone lure for 24 h; then tested for responsiveness immediately after this exposure, 1 and 24 h later. Control males were tested three times: initially, 1 h later and 24 h later. The time taken for males to detect females, shown by exposure of their anal claspers, and the time taken for males to locate females were recorded. No significant difference was found between the time taken for control and exposed males to detect or locate females, and no significant difference between the proportions of males that successfully located females in exposed and control groups was found. In the field experiment the time males spent in the presence of contained females, both with and without a pheromone lure present, was recorded. Males spent more time in the presence of the females when the pheromone lure was present. Both experiments indicate male Z. filipendulae mating behaviour is not adversely affected by exposure to synthetic pheromone lures

    Inter-Cellular Variation in DNA Content of Entamoeba histolytica Originates from Temporal and Spatial Uncoupling of Cytokinesis from the Nuclear Cycle

    Get PDF
    Accumulation of multiple copies of the genome in a single nucleus and several nuclei in a single cell has previously been noted in Entamoeba histolytica, contributing to the genetic heterogeneity of this unicellular eukaryote. In this study, we demonstrate that this genetic heterogeneity is an inherent feature of the cell cycle of this organism. Chromosome segregation occurs on a variety of novel microtubular assemblies including multi-polar spindles. Cytokinesis in E. histolytica is completed by the mechanical severing of a thin cytoplasmic bridge, either independently or with the help of neighboring cells. Importantly, cytokinesis is uncoupled from the nuclear division cycle, both temporally and spatially, leading to the formation of unequal daughter cells. Sorting of euploid and polyploid cells showed that each of these sub-populations acquired heterogeneous DNA content upon further growth. Our study conclusively demonstrates that genetic heterogeneity originates from the unique mode of cell division events in this protist

    Ambivalent improvements: biography, biopolitics, and colonial Delhi

    Get PDF
    This paper explores the ambivalent feelings towards the Government of India produced in one of the government’s own employees. In establishing the Delhi Improvement Trust in the 1930s, Arthur Parke Hume had to battle against governmental cost cutting in an attempt to secure the rehousing of slum evictees. The refusal of the government to accept this welfarist commitment to investment led to the stalling of the improvement projects and great emotional disquiet for Hume. This is traced through his personal correspondence with his parents. In interweaving these insights with the imperial archive, three biographical approaches are adopted. A traditional chronology is used to order the events, an analytical approach is used to outline the discursive regularities of Hume’s observations, and a genealogical approach is used to suggest the influences on Hume’s writings and the broader governmental rationalities that he had to negotiate

    Chemical analysis of acoustically levitated drops by Raman spectroscopy

    Get PDF
    An experimental apparatus combining Raman spectroscopy with acoustic levitation, Raman acoustic levitation spectroscopy (RALS), is investigated in the field of physical and chemical analytics. Whereas acoustic levitation enables the contactless handling of microsized samples, Raman spectroscopy offers the advantage of a noninvasive method without complex sample preparation. After carrying out some systematic tests to probe the sensitivity of the technique to drop size, shape, and position, RALS has been successfully applied in monitoring sample dilution and preconcentration, evaporation, crystallization, an acid–base reaction, and analytes in a surface-enhanced Raman spectroscopy colloidal suspension
    • …
    corecore