Dark Before Light: Testing the Cosmic Expansion History through the Cosmic Microwave Background

The cosmic expansion history proceeds in broad terms from a radiation dominated epoch to matter domination to an accelerated, dark energy dominated epoch. We investigate whether intermittent periods of acceleration are possible in the early universe -- between Big Bang nucleosynthesis (BBN) and recombination and beyond. We establish that the standard picture is remarkably robust: observations of anisotropies in the cosmic microwave background exclude any extra period of accelerated expansion between 1 \leq z \lesssim 10^5 (corresponding to 5\times10^{-4}\ {\rm eV} \leq T \lesssim 25\ {\rm eV}).Comment: 7 pages, 5 figure

Cyclotron Production and PET/MR Imaging of 52Mn

Introduction The goal of this work is to advance the production and use of 52Mn (t½ = 5.6 d, β+: 242 keV, 29.6%) as a radioisotope for in vivo preclinical nuclear imaging. More specifically, the aims of this study were: (1) to measure the excitation function for the natCr(p,n)52Mn reaction at low energies to verify past results [1–4]; (2) to measure binding constants of Mn(II) to aid the design of a method for isolation of Mn from an irradiated Cr target via ion-exchange chromatography, building upon previously published methods [1,2,5–7]; and (3) to perform phantom imaging by positron emission tomography/magnetic resonance (PET/MR) imaging with 52Mn and non-radioactive Mn(II), since Mn has potential dual-modality benefits that are beginning to be investigated [8]. Material and Methods Thin foils of Cr metal are not available commercially, so we fabricated these in a manner similar to that reported by Tanaka and Furukawa [9]. natCr was electroplated onto Cu discs in an industrial-scale electroplating bath, and then the Cu backing was digested by nitric acid (HNO3). The remaining thin Cr discs (~1 cm diameter) were weighed to determine their thickness (~ 75–85 μm) and arranged into stacked foil targets, along with ~25 μm thick Cu monitor foils. These targets were bombarded with ~15 MeV protons for 1–2 min at ~1–2 μA from a CS-15 cyclotron (The Cyclotron Corporation, Berkeley, CA, USA). The beamline was perpendicular to the foils, which were held in a machined 6061-T6 aluminum alloy target holder. The target holder was mounted in a solid target station with front cooling by a jet of He gas and rear cooling by circulating chilled water (T ≈ 2–5 °C). Following bombardment, these targets were disassembled and the radioisotope products in each foil were counted using a high-purity Ge (HPGe) detector. Cross-sections were calculated for the natCr(p,n)52Mn reaction. Binding constants of Mn(II) were measured by incubating 54Mn(II) (t½ = 312 d) dichloride with anion- or cation-exchange resin (AG 1-X8 (Cl− form) or AG 50W-X8 (H+ form), respectively; both: 200–400 mesh; Bio-Rad, Hercules, CA) in hydrochloric acid (HCl) ranging from 10 mM-8 M (anion-exchange) and from 1 mM-1 M (cation-exchange) or in sulfuric acid (H2SO4) ranging from 10 mM-8 M on cation-exchange resin only. The amount of unbound 54Mn(II) was measured using a gamma counter, and binding constants (KD) were calculated for the various concentrations on both types of ion-exchange resin. We have used the unseparated product for preliminary PET and PET/MR imaging. natCr metal was bombarded and then digested in HCl, resulting in a solution of Cr(III)Cl3 and 52Mn(II)Cl2. This solution was diluted and imaged in a glass scintillation vial using a microPET (Siemens, Munich, Germany) small animal PET scanner. The signal was corrected for abundant cascade gamma-radiation from 52Mn that could cause random false coincidence events to be detected, and then the image was reconstructed by filtered back-projection. Additionally, we have used the digested target to spike non-radioactive Mn(II)Cl2 solutions for simultaneous PET/MR phantom imaging using a Biograph mMR (Siemens) clinical scanner. The phantom consisted of a 4×4 matrix of 15 mL conical tubes containing 10 mL each of 0, 0.5, 1.0, and 2.0 mM concentrations of non-radioactive Mn(II)Cl2 with 0, 7, 14, and 27 μCi (at start of PET acquisition) of 52Mn(II)Cl2 from the digested target added. The concentrations were based on previous MR studies that measured spin-lattice relaxation time (T1) versus concentration of Mn(II), and the activities were based on calculations for predicted count rate in the scanner. The PET/MR imaging consisted of a series of two-dimensional inversion-recovery turbo spin echo (2D-IR-TSE) MR sequences (TE = 12 ms; TR = 3,000 ms) with a wide range of inversion times (TI) from 23–2,930 ms with real-component acquisition, as well as a 30 min. list-mode PET acquisition that was reconstructed as one static frame by 3-D ordered subset expectation maximization (3D-OSEM). Attenuation correction was performed based on a two-point Dixon (2PD) MR sequence. The DICOM image files were loaded, co-registered, and windowed using the Inveon Research Workplace software (Siemens)

Measuring transverse velocities in gravitationally lensed extragalactic systems using an annual parallax effect

A parallax method to determine transverse velocity in a gravitationally lensed system is described. Using the annual motion of the Earth around the Sun allows us to probe the local structure of the magnification map that, under certain assumptions, can be used to infer the effective transverse velocity. The method is applied to OGLE data for QSO2237+0305 and the velocity value is estimated to be about (15 +/- 10) km/s if attributed to the lensing galaxy or about (420 +/- 300) km/s if attributed to the quasar. We find this estimate unreasonably small and conclude that we have not measured a parallax effect. We give a short list of properties that a system should possess to allow a successful implementation of this method.Comment: v2: journal reference update

Prospectus, February 9, 2005

https://spark.parkland.edu/prospectus_2005/1003/thumbnail.jp

A Spitzer Survey for Dust in Type IIn Supernovae

Recent observations suggest that Type IIn supernovae (SNe IIn) may exhibit late-time (>100 days) infrared (IR) emission from warm dust more than other types of core-collapse SNe. Mid-IR observations, which span the peak of the thermal spectral energy distribution, provide useful constraints on the properties of the dust and, ultimately, the circumstellar environment, explosion mechanism, and progenitor system. Due to the low SN IIn rate (<10% of all core-collapse SNe), few IR observations exist for this subclass. The handful of isolated studies, however, show late-time IR emission from warm dust that, in some cases, extends for five or six years post-discovery. While previous Spitzer/IRAC surveys have searched for dust in SNe, none have targeted the Type IIn subclass. This article presents results from a warm Spitzer/IRAC survey of the positions of all 68 known SNe IIn within a distance of 250 Mpc between 1999 and 2008 that have remained unobserved by Spitzer more than 100 days post-discovery. The detection of late-time emission from ten targets (~15%) nearly doubles the database of existing mid-IR observations of SNe IIn. Although optical spectra show evidence for new dust formation in some cases, the data show that in most cases the likely origin of the mid-IR emission is pre-existing dust, which is continuously heated by optical emission generated by ongoing circumstellar interaction between the forward shock and circumstellar medium. Furthermore, an emerging trend suggests that these SNe decline at ~1000--2000 days post-discovery once the forward shock overruns the dust shell. The mass-loss rates associated with these dust shells are consistent with luminous blue variable (LBV) progenitors.Comment: Accepted for publication to ApJ, 17 pages, 10 figures, 10 table

Analysis of myotube-motoneuron interaction within an in vitro 3D collagen-based model of skeletal muscle

In seeking to further our understanding of skeletal muscle physiology and function in both healthy and diseased tissues, there is a strong need to develop in vitro culture systems that better represent the in vivo condition. This project is aimed at developing an innervated 3D in vitro model of skeletal muscle. It is hoped that the incorporation of primary motoneurons into a 3D model of skeletal muscle established in our lab will promote myofibre development towards an adult phenotype and improve the biomimicity of the system. Furthermore, the formation of neuromuscular junctions (NMJ) within a 3D in vitro setting should allow for testing of the effects of neuromuscular agents in culture, thereby reducing the need for in vivo experimentation. Here we present data characterising the development and maturation of this 3D co-culture system in comparison to conventional 2D cultures and discuss the implications for the future of skeletal muscle tissue culture techniques

The massive eclipsing LMC Wolf-Rayet binary BAT99-129. 1 Orbital parameters, hydrogen content and spectroscopic characteristics

BAT99-129 in the LMC is one among a handful of extra-galactic eclipsing Wolf-Rayet binaries known. We present blue, medium-resolution, phase-dependent NTT-EMMI spectra of this system that allow us to separate the spectra of the two components of the binary and to obtain a reliable orbital solution for both stars. We assign an O5V spectral type to the companion, and WN3(h)a to the Wolf-Rayet component. We discuss the spectroscopic characteristics of the system: luminosity ratio, radii, rotation velocities. We find a possible oversynchronous rotation velocity for the O star. Surprisingly, the extracted Wolf-Rayet spectrum clearly shows the presence of blueshifted absorption lines, similar to what has been found in all single hot WN stars in the SMC and some in the LMC. We also discuss the presence of such intrinsic lines in the context of hydrogen in SMC and LMC Wolf-Rayet stars, WR+O binary evolution and GRB progenitors. Altogether, BAT99~129 is the extragalactic counterpart of the well-known Galactic WR binary V444 Cygni.Comment: 14 pages, 9 figures, accepted by A&A for publicatio

The Williams Scale of Attitude toward Paganism: development and application among British Pagans

This article builds on the tradition of attitudinal measures of religiosity established by Leslie Francis and colleagues with the Francis Scale of Attitude toward Christianity (and reflected in the Sahin-Francis Scale of Attitude toward Islam, the Katz-Francis Scale of Attitude toward Judaism, and the Santosh-Francis Scale of Attitude toward Hinduism) by introducing a new measure to assess the attitudinal disposition of Pagans. A battery of items was completed by 75 members of a Pagan Summer Camp. These items were reduced to produce a 21-item scale that measured aspects of Paganism concerned with: the God/Goddess, worshipping, prayer, and coven. The scale recorded an alpha coefficient of 0.93. Construct validity of the Williams Scale of Attitude toward Paganism was demonstrated by the clear association with measures of participation in private rituals

An evidence review of research on health interventions in humanitarian crises. Final Report

This review was conducted to provide a rigorous assessment of the current quality and depth of the evidence-base that informs humanitarian public health programming globally. It assesses the quantity and quality of intervention studies, rather than measuring the actual effectiveness of the intervention itself. The review addresses evidence on interventions in humanitarian crises (including early recovery and forced displacement) for health topics of: communicable disease control water, sanitation and hygiene (WASH) nutrition sexual and reproductive health (SRH), including gender-based violence (GBV) mental health and psychosocial support non-communicable disease (NCD) injury and physical rehabilitation health services health systems. In addition, contextual factors influencing the delivery of health-related interventions are included in the project, consisting of: * access to health services * health assessment methods * coordination * accountability * health worker security * urbanisation. The evidence review used the following two main methods: (i) A series of systematic literature reviews on evidence of humanitarian interventions related to the health topics and on the influence of contextual factors on the interventions. The systematic review on evidence of interventions for the different health topics included quantitative evidence from published and grey literature. The systematic review on the contextual factors included quantitative and qualitative evidence from the published literature. Standard systematic review methodologies were used. (ii) Qualitative individual interviews with expert practitioners, policy makers and academics to identify critical weaknesses and gaps in the evidence base for humanitarian public health actions (including related to the contextual factors) and to recommend priority areas for further research. A series of more general consultations with humanitarian health experts through meetings in London, Geneva, Paris, and New York