A study of the gravitational wave form from pulsars II

We present analytical and numerical studies of the Fourier transform (FT) of the gravitational wave (GW) signal from a pulsar, taking into account the rotation and orbital motion of the Earth. We also briefly discuss the Zak-Gelfand Integral Transform. The Zak-Gelfand Integral Transform that arises in our analytic approach has also been useful for Schrodinger operators in periodic potentials in condensed matter physics (Bloch wave functions).Comment: 6 pages, Sparkler talk given at the Amaldi Conference on Gravitational waves, July 10th, 2001. Submitted to Classical and Quantum Gravit

Električna i preklopna svojstva tankih amorfnih slojeva ZnIn2Se4

In this work electrical and switching properties of amorphous ZnIn2Se4 thin films have been studied. The amorphous films were obtained by thermal evaporation in vacuum, of polycrystalline materials, on glass or pyrographite substrates. From electrical measurements, it was found that for all films the dark electrical resistivity decreases with an increase of film thickness and temperature. The ZnIn2Se4 films exhibit nonlinear I-V characteristics and switching phenomena. The threshold voltage decreases with increasing temperature and increases with increasing film thickness.Istraživala su se električna i preklopna svojstva tankih amorfnih slojeva ZnIn2Se4. Amorfni su slojevi pripremljeni naparavanjem polikristaliničnih materijala na staklene ili pirografitne podloge u vakuumu. Električna mjerenja pokazuju da se za sve slojeve električni otpor u tami smanjuje s povećanjem debljine sloja i temperature. Slojevi ZnIn2Se4 pokazuju nelinearnu ovisnost I − V i preklopna svojstva. Napon praga preklopa smanjuje se s povećanjem temperature i povećava za veće debljine slojeva

Učinak opuštanja na prekidačka svojstva tankih slojeva CuInSeTe

The switching properties of amorphous CuInSeTe thin films have been investigated. The amorphous quaternary semiconductor CuInSeTe thin films ∼ 220 nm and ∼ 330 nm thick have been prepared by thermal evaporation of the bulk compound under vacuum of about 10−4 Pa and with deposition rate about 8 nm/s. The structure of the bulk and thin films were investigated by the X-ray diffraction technique. The compositional studies of CuInSeTe in both powder and thin films were carried out by Perkin Elmer Model 1100 atomic absorption spectrometer. The annealing of the films at different annealing temperatures (300, 350, 400, 450 and 500 K) improves the switching characteristics and decrease the threshold voltage Vth. The threshold switching voltage and the threshold activation energy Es were found to decrease linearly with increasing annealing temperature. Moreover, the threshold switching voltage decreased exponentially with temperature.Istraživali smo prekidačka svojstva amorfnih tankih slojeva CuInSeTe. Tanke amorfne slojeve četiritvornog poluvodiča CuInSeTe debljine ∼ 220 nm i ∼ 330 nm pripremali smo naparavanjem spoja u vakuumu pri oko 10−4 Pa, brzinom naparavanja od oko 8 nm/s. Strukturu praha i tankih slojeva odredili smo rendgenskom difrakcijom. Sastav CuInSeTe u prahu i tankih slojeva ispitali smo pomoću Perkin Elmer-ovog (model 1100) apsorpcijskog spektrometra. Opuštanje tankih slojeva na nizu temperatura (300, 350, 400, 450 i 500 K) poboljšava njihova preklopna svojstva i smanjuje napon praga preklopnog napona Vth. Našli smo da se prag preklopnog napona i prag aktivacijske energije Es linearno smanjuju s povećanjem temperature opuštanja. K tome, prag preklopnog napona smanjuje se eksponencijalno s temperaturom opuštanja

Integrating transposable elements in the 3D genome

Chromosome organisation is increasingly recognised as an essential component of genome regulation, cell fate and cell health. Within the realm of transposable elements (TEs) however, the spatial information of how genomes are folded is still only rarely integrated in experimental studies or accounted for in modelling. Whilst polymer physics is recognised as an important tool to understand the mechanisms of genome folding, in this commentary we discuss its potential applicability to aspects of TE biology. Based on recent works on the relationship between genome organisation and TE integration, we argue that existing polymer models may be extended to create a predictive framework for the study of TE integration patterns. We suggest that these models may offer orthogonal and generic insights into the integration profiles (or "topography") of TEs across organisms. In addition, we provide simple polymer physics arguments and preliminary molecular dynamics simulations of TEs inserting into heterogeneously flexible polymers. By considering this simple model, we show how polymer folding and local flexibility may generically affect TE integration patterns. The preliminary discussion reported in this commentary is aimed to lay the foundations for a large-scale analysis of TE integration dynamics and topography as a function of the three-dimensional host genome

Izrada i značajke tankih polikristaliničnih hetero-spojeva n-Cd0.9Zn0.1S/p-CuGa0.3In0.7Se2

CuGa0.3In0.7Se2 polycrystalline thin films were prepared by thermal evaporation under vacuum of about 10-4Pa, with a deposition rate of about 200 nm/min. The selenization of these films at 723 K improves their properties. The activation energy as well as the optical energy gap of the investigated samples decreased with annealing and selenization. Polycrystalline thin film n-Cd0.9Zn0.1S/p-CuGa0.3In0.7Se2 heterojunctions were fabricated and the current density - voltage and capacitance - voltage characteristics of the junction were studied. The heterojunctions were exposed to light, and under illumination of 1000 mWcm-2, the open circuit voltage was 580 mV, the short circuit current density 4.8 mAcm-2, the fill factor 0.682 and the electrical conversion efficiency was 1.898% for cells of active area of 1 cm2.Tanke polikristalinične slojeve CuGa0.3In0.7Se2 pripremali smo naparavanjem u vakuumu oko 10−4 Pa, brzinom polaganja oko 200 nm/min. Seleniranje tih slojeva na 723 K poboljšava im svojstva. Aktivacijska energija i optički energijski procijep smanjuju se opuštanjem i seleniranjem. Pripremali smo i polikristalinične tankoslojne hetero-spojeve n-Cd0.9Zn0.1S/p-CuGa0.3In0.7Se2 i proučavali njihova značajke: gustoća struje – napon i kapacitet – napon. Ćelije ploštine 1 cm2 heterospojeva osvijetlili smo svjetlošću jakosti 1000 mW/cm2 i izmjerili napon otvorenog kruga od 580 mV, gustoću struje kratkog spoja 4.8 mAcm−2 , faktor punjenja 0.682 i učinkovitost pretvorbe 1.898%

Strukturna i električna svojstva tankih slojeva kalkogenida CuSbTe2, CuSbSe2 i CuSbS2

The ternary chalcogenides CuSbTe2, CuSbSe2 and CuSbS2 were synthesized by the direct fusion technique. The thin films of these compounds were prepared by thermal evaporation under vacuum of about 1.3 mPa (10−5 Torr) and the rate of deposition was 30 nm/min. The structural properties of CuSbTe2, CuSbSe2 and CuSbS2 in powder and thin film forms were investigated by X-ray diffraction (XRD) and transmission electronmicroscopy. Microprobe analysis technique was used to investigate the composition of the three alloys and of their films. The electrical conductivity σ and the thermoelectrical power Q have been measured for all asdeposited and annealed thin films, as a function of temperature in the range from 80 to 500 K. It was found that the electrical conductivity σ, the carrier concentration P, the mobility µ and the thermoelectric power Q increase when increasing the annealing temperature for CuSbTe2, CuSbSe2 and CuSbS2 thin films. The increase of σ, P, µ and Q, and also the decrease of the activation energy ∆E with increasing temperature for the as-deposited CuSbTe2, CuSbSe2 and CuSbS2 thin films, can be attributed to the change in the structure of these films from the amorphous to the crystalline state.Trokomponentne smo kalkogenide CuSbTe2, CuSbSe2 and CuSbS2 pripremili metodom talenja. Tanke smo slojeve tih spojeva pripremali isparavanjem u vakuumu od oko 1.3 mPa, brzinom nanošenja oko 30 nm/min. Strukturna svojstva tih kalkogenida, kako praškova, tako i tankih slojeva, istraživali smo difrakcijom rendgenskog zračenja i prolaznom elektronskom mikroskopijom. Pomoću mikroprobe odredili smo kemijski sastav spojeva i njihovih tankih slojeva. Izmjerili smo električnu vodljivost, σ, i termoelektričnu snagu, Q, svih svježe naparenih i opuštenih legura i njihovih tankih slojeva u ovisnosti o temperaturi u području 80 do 500 K. Električna vodljivost, gustoća nositelja, P, mobilnost, µ, i termoelektrična snaga, Q, povećavaju se ako se tanki slojevi opuštaju na višim temperaturama. Povećanje σ, P, µ and Q, a također smanjenje aktivacijske energije, ∆E, u tankim slojevima CuSbTe2, CuSbSe2 i CuSbS2 tumače se promjenama strukture tih slojeva od amorfnog u kristalinično stanje