Frequency-dependent photothermal measurement of thermal diffusivity for opaque and non-opaque materials; Application to crystals of TIPS-pentacene

We propose the use of a frequency-dependent photothermal measurement as a complement to light-flash, i.e. time-dependent, measurements to determine the through-plane thermal diffusivity of small, thin samples, e.g. semiconducting polymers and small organic molecule crystals. The analysis is extended from its previous use with some opaque conducting polymers to materials with finite absorption coefficients, such as crystals of 6,13-bis(triisopropylsilylethynyl pentacene ("TIPS-pentacene"). Taking into account the finite absorption coefficients of the latter gives a value of diffusivity, D=0.10 mm2/s, much smaller than previously estimated and more consistent with its expected value. We also briefly discuss the effects of coating samples for the measurement to improve their optical properties.Comment: 11 pages, 6 figures, to be published in Journal of Applied Physic

Expression and function of transient receptor potential channels in the female bovine reproductive tract

© 2016 Elsevier Inc. The epithelium lining the oviduct is critical for early reproductive events, many of which are mediated via intracellular calcium ions. Despite this, little is known about the regulation of calcium homeostasis in the oviductal epithelium. Epithelial transient receptor potential channels (TRPCs) modulate calcium flux in other tissues, and their expression and functional regulation have therefore been examined using the bovine oviduct as a model for the human. The effects of FSH, LH, 17β-estradiol, and progesterone on TRPCs expression and intracellular calcium flux were determined. Transient receptor potential channels 1, 2, 3, 4, and 6 were expressed in the bovine reproductive tract, and their gene expression varied throughout the estrous cycle. In more detailed studies undertaken on TRPC1 and 6, we show that protein expression varied through the estrus cycle; specifically, 17β-estradiol, FSH, and LH individually and in combination upregulated TRPC1 and 6 expression in cultured bovine oviduct epithelial cells although progesterone antagonized these effects. Functional studies showed changes in calcium mobilization in bovine oviduct epithelial cells were dependent on TRPCs. In conclusion, TRPC1, 2, 3, 4, and 6 are present in the epithelium lining the bovine oviduct, and TRPC1 and 6 vary through the estrous cycle suggesting an important role in early reproductive function

Effect of Jitter on the Settling Time of Mesochronous Clock Retiming Circuits

It is well known that timing jitter can degrade the bit error rate (BER) of receivers that recover the clock from input data. However, timing jitter can also result in an indefinite increase in the settling time of clock recovery circuits, particularly in low swing mesochronous systems. Mesochronous clock retiming circuits are required in repeaterless low swing on-chip interconnects. We first discuss how timing jitter can result in a large increase in the settling time of the clock recovery circuit. Next, the circuit is modelled as a Markov chain with absorbing states. The mean time to absorption of the Markov chain, which represents the mean settling time of the circuit, is determined. The model is validated through behavioural simulations of the circuit, the results of which match well with the model predictions. We consider circuits with (i) data dependent jitter, (ii) random jitter, and (iii) combination of both of them. We show that a mismatch between the strengths of up and down corrections of the retiming can reduce the settling time. In particular, a 10% mismatch can reduce the mean settling time by up to 40%. We leverage this fact toward improving the settling time performance, and propose useful techniques based on biased training sequences and mismatched charge pumps. We also present a coarse+fine clock retiming circuit, which can operate in coarse first mode, to reduce the settling time substantially. These fast settling retiming circuits are verified with circuit simulations.Comment: 23 pages, 40 figure

First measurement of HI 21cm emission from a GRB host galaxy indicates a post-merger system

We report the detection and mapping of atomic hydrogen in HI 21cm emission from ESO 184-G82, the host galaxy of the gamma ray burst 980425. This is the first instance where HI in emission has been detected from a galaxy hosting a gamma ray burst. ESO 184-G82 is an isolated galaxy and contains a Wolf-Rayet region close to the location of the gamma ray burst and the associated supernova, SN 1998bw. This is one of the most luminous HII regions identified in the local Universe, with a very high inferred density of star formation. The HI 21cm observations reveal a high HI mass for the galaxy, twice as large as the stellar mass. The spatial and velocity distribution of the HI 21cm emission reveals a disturbed rotating gas disk, which suggests that the galaxy has undergone a recent minor merger that disrupted its rotation. We find that the Wolf-Rayet region and the gamma ray burst are both located in the highest HI column density region of the galaxy. We speculate that the merger event has resulted in shock compression of the gas, triggering extreme star formation activity, and resulting in the formation of both the Wolf-Rayet region and the gamma ray burst. The high HI column density environment of the GRB is consistent with the high HI column densities seen in absorption in the host galaxies of high redshift gamma ray bursts.Comment: Accepted for publication in MNRAS Letters. 5 pages, 5 figures, 2 tables. For the definitive version visit http://mnrasl.oxfordjournals.org

Cosmological Dynamics of a Dirac-Born-Infeld field

We analyze the dynamics of a Dirac-Born-Infeld (DBI) field in a cosmological set-up which includes a perfect fluid. Introducing convenient dynamical variables, we show the evolution equations form an autonomous system when the potential and the brane tension of the DBI field are arbitrary power-law or exponential functions of the DBI field. In particular we find scaling solutions can exist when powers of the field in the potential and warp-factor satisfy specific relations. A new class of fixed-point solutions are obtained corresponding to points which initially appear singular in the evolution equations, but on closer inspection are actually well defined. In all cases, we perform a phase-space analysis and obtain the late-time attractor structure of the system. Of particular note when considering cosmological perturbations in DBI inflation is a fixed-point solution where the Lorentz factor is a finite large constant and the equation of state parameter of the DBI field is $w=-1$. Since in this case the speed of sound $c_s$ becomes constant, the solution can be thought to serve as a good background to perturb about.Comment: 24 pages, 7 figures, minor corrections, references adde

Upaya Meningkatkan Kemampuan Membaca Permulaan Melalui Metode Global Pada Siswa Kelas I SDN 9 Ampana Kota

Penelitian ini adalah penelitian tindakan kelas. Terdiri beberapa aspek perlakuan dan pengamatan utama yaitu peningkatan kemampuan membaca permulaan dengan menggunakan metode global yang dilaksanakan di SDN 9 Ampana Kota, melibatkan 28 orang siswa terdiri atas 15 orang permpuan dan 13 orang laki-laki yang terdaftar pada tahun ajaran 2013/2014, menggunakan desain penelitian Kemmis dan Mc. Taggart yang terdiri atas dua siklus. Setiap siklus dilaksanakan dua kali pertemuan di kelas dan setiap siklus terdiri empat tahap yaitu perencanaan, pelaksanaan, observasi, dan refleksi. Hasil penelitian menunjukkan bahwa pada tindakan siklus I diperoleh rata-rata kemampuan siswa membaca permulaan mencapai 66% dan kemampuan siswa membaca secara klasikal 54%. Pada tindakan siklus II terjadi peningkatan daya serap kemampuan membaca permulaan mencapai 87% sedangkan kemampuan membaca secara klasikal 93%. Dengan demikian dapat dismipulkan bahwa pembelajaran dengan menggunakan metode global dapat meningkatkan kemampuan membaca permulaan siswa kelas I SDN 9 Ampana Kota

A Three-dimensional Deformable Brain Atlas for DBS Targeting. I. Methodology for Atlas Creation and Artifact Reduction.

BackgroundTargeting in deep brain stimulation (DBS) relies heavily on the ability to accurately localize particular anatomic brain structures. Direct targeting of subcortical structures has been limited by the ability to visualize relevant DBS targets.Methods and resultsIn this work, we describe the development and implementation, of a methodology utilized to create a three dimensional deformable atlas for DBS surgery. This atlas was designed to correspond to the print version of the Schaltenbrand-Bailey atlas structural contours. We employed a smoothing technique to reduce artifacts inherent in the print version.ConclusionsWe present the methodology used to create a three dimensional patient specific DBS atlas which may in the future be tested for clinical utility

Dynamics of a scalar field in Robertson-Walker spacetimes

We analyze the dynamics of a single scalar field in Friedmann-Robertson-Walker universes with spatial curvature. We obtain the fixed point solutions which are shown to be late time attractors. In particular, we determine the corresponding scalar field potentials which correspond to these stable solutions. The analysis is quite general and incorporates expanding and contracting universes with both positive and negative scalar potentials. We demonstrate that the known power law, exponential, and de-Sitter solutions are certain limits of our general set of solutions.Comment: 10 pages, v2:references added. Accepted for publication in PR

Exploring Islamic Geometries

Islamic design is a rich art form with spiritual and meditative meaning expressed through its infinite pattern. The iterative process of creating pattern, unified yet diverse, is an intri-cate geometric path conveying conceptual exploration. Process of form development in Is-lamic patterns defines its growing design, seeking explicit relationships between unity and multiplicity. As the grid expands and patterns unfold, new concepts are introduced for pat-tern exploration and formation. Reoccurring focal points of the Islamic geometries mark significant moments in which these patterns take form. By fusing traditional Islamic design fundamentals with contemporary concepts for interiors, I expand the realm of this rich art form from a two dimensional form to a three dimensional structure