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Sample records for reversed halo sign

  1. The Diagnostic Value of Halo and Reversed Halo Signs for Invasive Mold Infections in Compromised Hosts

    PubMed Central

    Georgiadou, Sarah P.; Sipsas, Nikolaos V.; Marom, Edith M.

    2011-01-01

    The halo sign is a CT finding of ground-glass opacity surrounding a pulmonary nodule or mass. The reversed halo sign is a focal rounded area of ground-glass opacity surrounded by a crescent or complete ring of consolidation. In severely immunocompromised patients, these signs are highly suggestive of early infection by an angioinvasive fungus. The halo sign and reversed halo sign are most commonly associated with invasive pulmonary aspergillosis and pulmonary mucormycosis, respectively. Many other infections and noninfectious conditions, such as neoplastic and inflammatory processes, may also manifest with pulmonary nodules associated with either sign. Although nonspecific, both signs can be useful for preemptive initiation of antifungal therapy in the appropriate clinical setting. This review aims to evaluate the diagnostic value of the halo sign and reversed halo sign in immunocompromised hosts and describes the wide spectrum of diseases associated with them. PMID:21467021

  2. The reversed halo sign: update and differential diagnosis.

    PubMed

    Godoy, M C B; Viswanathan, C; Marchiori, E; Truong, M T; Benveniste, M F; Rossi, S; Marom, E M

    2012-09-01

    The reversed halo sign is characterised by a central ground-glass opacity surrounded by denser air-space consolidation in the shape of a crescent or a ring. It was first described on high-resolution CT as being specific for cryptogenic organising pneumonia. Since then, the reversed halo sign has been reported in association with a wide range of pulmonary diseases, including invasive pulmonary fungal infections, paracoccidioidomycosis, pneumocystis pneumonia, tuberculosis, community-acquired pneumonia, lymphomatoid granulomatosis, Wegener granulomatosis, lipoid pneumonia and sarcoidosis. It is also seen in pulmonary neoplasms and infarction, and following radiation therapy and radiofrequency ablation of pulmonary malignancies. In this article, we present the spectrum of neoplastic and non-neoplastic diseases that may show the reversed halo sign and offer helpful clues for assisting in the differential diagnosis. By integrating the patient's clinical history with the presence of the reversed halo sign and other accompanying radiological findings, the radiologist should be able to narrow the differential diagnosis substantially, and may be able to provide a presumptive final diagnosis, which may obviate the need for biopsy in selected cases, especially in the immunosuppressed population. PMID:22553298

  3. Reversed Halo Sign on CT as a Presentation of Lymphocytic Interstitial Pneumonia

    PubMed Central

    Freeman, Marcus D; Grajo, Joseph R; Karamsadkar, Neel D; Steffensen, Thora S; Hazelton, Todd R

    2013-01-01

    A 52 year-old African American female with a past medical history of symptomatic uterine fibroids and increasing abdominal circumference underwent abdominal computed tomography (CT) as part of her workup. Because of an abnormality in the left lower lobe, CT of the chest was subsequently performed and showed a focal region of discontinuous crescentic consolidation with central ground glass opacification in the right lower lobe, suggestive of the reversed halo sign. The patient underwent percutaneous CT-guided core biopsy of the lesion, which demonstrated lymphocytic interstitial pneumonia, a benign lymphoproliferative disease characterized histologically by small lymphocytes and plasma cells. This case report describes the first histologically confirmed presentation of lymphocytic interstitial pneumonia with the reversed halo sign on CT. PMID:24421923

  4. Spontaneous pneumothorax followed by reversed halo sign in immunocompromised patient with pulmonary mucormycosis

    PubMed Central

    Moosavi Movahed, Majid; Hosamirudsari, Hadiseh; Mansouri, Fariba; Mohammadizia, Farzaneh

    2015-01-01

    Mucormycosis, an invasive fungus with a variety of clinical presentation, is a devastating infection in immunocompromised host. Here an unusual case of pulmonary mucormycosis is introduced in an immunodeficient patient in which pneumothorax was followed by reversed halo sign (RHS). The clinicians, who visit immunocompromised persons with pneumothorax, should be considerate to take immediate imaging and pathologic measures to confirm or reject mucormycosis. PMID:26288745

  5. [Reverse Chaddock sign].

    PubMed

    Tashiro, Kunio

    2011-08-01

    It is widely accepted that the Babinski reflex is the most well-known and important pathological reflex in clinical neurology. Among many other pathological reflexes that elicit an upgoing great toe, such as Chaddock, Oppenheim, Gordon, Schaefer, and Stransky, only the Chaddock reflex is said to be as sensitive as the Babinski reflex. The optimal receptive fields of the Babinski and Chaddock reflexes are the lateral plantar surface and the external inframalleolar area of the dorsum, respectively. It has been said that the Babinski reflex, obtained by stroking the sole, is by far the best and most reliable method of eliciting an upgoing great toe. However, the Chaddock reflex, the external malleolar sign, is also considered sensitive and reliable according to the literature and everyday neurological practice. The major problems in eliciting the Babinski reflex by stroking the lateral part of the sole are false positive or negative responses due to foot withdrawal, tonic foot response, or some equivocal movements. On the other hand, according to my clinical experience, the external inframalleolar area, which is the receptive field of the Chaddock reflex, is definitely suitable for eliciting the upgoing great toe. In fact, the newly proposed method to stimulate the dorsum of the foot from the medial to the lateral side, which I term the "reversed Chaddock method," is equally sensitive to demonstrate pyramidal tract involvement. With the "reversed Chaddock method", the receptive field of the Chaddock reflex may be postulated to be in the territory of the sural nerve, which could be supported by the better response obtained on stimulation of the postero-lateral calf than the anterior shin. With regard to the receptive fields of the Babinski and Chaddock reflexes, the first sacral dermatome (S1) is also considered a reflexogenous zone, but since the dermatome shows marked overlapping, the zones vary among individuals. As upgoing toe responses are consistently observed in

  6. Halo sign on indium-111 leukocyte scan in gangrenous cholecystitis

    SciTech Connect

    Bauman, J.M.; Boykin, M.; Hartshorne, M.F.; Cawthon, M.A.; Landry, A.J.

    1986-02-01

    A 56-year-old man with a long history of Crohn's disease was evaluated by In-111 labeled leukocyte scanning. A halo of leukocyte activity was seen around the gallbladder fossa. A gangrenous gallbladder was removed at surgery.

  7. Palm reversal errors in native-signing children with autism.

    PubMed

    Shield, Aaron; Meier, Richard P

    2012-01-01

    Children with autism spectrum disorder (ASD) who have native exposure to a sign language such as American Sign Language (ASL) have received almost no scientific attention. This paper reports the first studies on a sample of five native-signing children (four deaf children of deaf parents and one hearing child of deaf parents; ages 4;6 to 7;5) diagnosed with ASD. A domain-general deficit in the ability of children with ASD to replicate the gestures of others is hypothesized to be a source of palm orientation reversal errors in sign. In Study 1, naturalistic language samples were collected from three native-signing children with ASD and were analyzed for errors in handshape, location, movement and palm orientation. In Study 2, four native-signing children with ASD were compared to 12 typically developing deaf children (ages 3;7 to 6;9, all born to deaf parents) on a fingerspelling task. In both studies children with ASD showed a tendency to reverse palm orientation on signs specified for inward/outward orientation. Typically developing deaf children did not produce any such errors in palm orientation. We conclude that this kind of palm reversal has a perceptual rather than a motoric source, and is further evidence of a "self-other mapping" deficit in ASD. PMID:22981637

  8. Palm Reversal Errors in Native-Signing Children with Autism

    PubMed Central

    Shield, Aaron; Meier, Richard P.

    2012-01-01

    Children with autism spectrum disorder (ASD) who have native exposure to a sign language such as American Sign Language (ASL) have received almost no scientific attention. This paper reports the first studies on a sample of five native-signing children (four deaf children of deaf parents and one hearing child of deaf parents; ages 4;6 to 7;5) diagnosed with ASD. A domain-general deficit in the ability of children with ASD to replicate the gestures of others is hypothesized to be a source of palm orientation reversal errors in sign. In Study 1, naturalistic language samples were collected from three native-signing children with ASD and were analyzed for errors in handshape, location, movement and palm orientation. In Study 2, four native-signing children with ASD were compared to 12 typically-developing deaf children (ages 3;7 to 6;9, all born to deaf parents) on a fingerspelling task. In both studies children with ASD showed a tendency to reverse palm orientation on signs specified for inward/outward orientation. Typically-developing deaf children did not produce any such errors in palm orientation. We conclude that this kind of palm reversal has a perceptual rather than a motoric source, and is further evidence of a “self-other mapping” deficit in ASD. PMID:22981637

  9. Reverse Conversion Schemes for Signed-Digit Number Systems: A Survey

    NASA Astrophysics Data System (ADS)

    Chakraborty, Madhu Sudan

    2016-06-01

    Although signed-digit number systems have received a considerable attention, the transformation of signed-digit numbers back into the conventional forms, known as reverse conversion, is still a performance bottleneck of signed-digit arithmetic. In this paper, a literature survey of reverse conversion schemes for signed-digit number systems is performed on the basis of the articles published from recognized platforms for the past few decades. The survey reveals some specific problems of this field, which need further investigations.

  10. Palm Reversal Errors in Native-Signing Children with Autism

    ERIC Educational Resources Information Center

    Shield, Aaron; Meier, Richard P.

    2012-01-01

    Children with autism spectrum disorder (ASD) who have native exposure to a sign language such as American Sign Language (ASL) have received almost no scientific attention. This paper reports the first studies on a sample of five native-signing children (four deaf children of deaf parents and one hearing child of deaf parents; ages 4;6 to 7;5)…

  11. Impurity scattering in highly anisotropic superconductors and interband sign reversal of the order parameter

    SciTech Connect

    Mazin, I.I.; Golubov, A.

    1996-12-31

    The authors discuss various mechanisms that can lead to interband sign reversal of the order parameter in a multiband superconductor. In particular, they generalize Abrikosov-Gor`kov solution of the problem of weakly coupled superconductor with magnetic and nonmagnetic impurities on the case of arbitrary order parameter anisotropy, including extreme cases as d-pairing or interband sign reversal of the order parameter, and show that interband scattering by magnetic impurities can stabilize an interband sign-reversal state. They discuss a possibility of such state in YBa{sub 2}Cu{sub 3}O{sub 7} in the context of various experiments: Josephson tunneling, neutron scattering, isotope effect measurements.

  12. Transition from Sign-Reversed to Sign-Preserved Cooper-Pairing Symmetry in Sulfur-Doped Iron Selenide Superconductors

    NASA Astrophysics Data System (ADS)

    Wang, Qisi; Park, J. T.; Feng, Yu; Shen, Yao; Hao, Yiqing; Pan, Bingying; Lynn, J. W.; Ivanov, A.; Chi, Songxue; Matsuda, M.; Cao, Huibo; Birgeneau, R. J.; Efremov, D. V.; Zhao, Jun

    2016-05-01

    An essential step toward elucidating the mechanism of superconductivity is to determine the sign or phase of the superconducting order parameter, as it is closely related to the pairing interaction. In conventional superconductors, the electron-phonon interaction induces attraction between electrons near the Fermi energy and results in a sign-preserved s -wave pairing. For high-temperature superconductors, including cuprates and iron-based superconductors, prevalent weak coupling theories suggest that the electron pairing is mediated by spin fluctuations which lead to repulsive interactions, and therefore that a sign-reversed pairing with an s± or d -wave symmetry is favored. Here, by using magnetic neutron scattering, a phase sensitive probe of the superconducting gap, we report the observation of a transition from the sign-reversed to sign-preserved Cooper-pairing symmetry with insignificant changes in Tc in the S-doped iron selenide superconductors KxFe2 -y(Se1-zSz) 2 . We show that a rather sharp magnetic resonant mode well below the superconducting gap (2 Δ ) in the undoped sample (z =0 ) is replaced by a broad hump structure above 2 Δ under 50% S doping. These results cannot be readily explained by simple spin fluctuation-exchange pairing theories and, therefore, multiple pairing channels are required to describe superconductivity in this system. Our findings may also yield a simple explanation for the sometimes contradictory data on the sign of the superconducting order parameter in iron-based materials.

  13. Hall voltage sign reversal in thin superconducting films

    NASA Technical Reports Server (NTRS)

    Ferrell, Richard A.

    1992-01-01

    A novel approach to the superconducting Hall effect is developed, based on the opposing drift of the thermally excited quasi-particles. These collide quasi-elastically with the hydrodynamics superfluid velocity field circulating for outside the core of a vortex, thereby transferring momentum to the latter. The predicted Hall angle, by BCS theory, is of the order of kBTc divided by the Fermi energy, has sign opposite to that in the normal state because of the backflow, and disappears at low temperature.

  14. Transition from Sign-Reversed to Sign-Preserved Cooper-Pairing Symmetry in Sulfur-Doped Iron Selenide Superconductors.

    PubMed

    Wang, Qisi; Park, J T; Feng, Yu; Shen, Yao; Hao, Yiqing; Pan, Bingying; Lynn, J W; Ivanov, A; Chi, Songxue; Matsuda, M; Cao, Huibo; Birgeneau, R J; Efremov, D V; Zhao, Jun

    2016-05-13

    An essential step toward elucidating the mechanism of superconductivity is to determine the sign or phase of the superconducting order parameter, as it is closely related to the pairing interaction. In conventional superconductors, the electron-phonon interaction induces attraction between electrons near the Fermi energy and results in a sign-preserved s-wave pairing. For high-temperature superconductors, including cuprates and iron-based superconductors, prevalent weak coupling theories suggest that the electron pairing is mediated by spin fluctuations which lead to repulsive interactions, and therefore that a sign-reversed pairing with an s_{±} or d-wave symmetry is favored. Here, by using magnetic neutron scattering, a phase sensitive probe of the superconducting gap, we report the observation of a transition from the sign-reversed to sign-preserved Cooper-pairing symmetry with insignificant changes in T_{c} in the S-doped iron selenide superconductors K_{x}Fe_{2-y}(Se_{1-z}S_{z})_{2}. We show that a rather sharp magnetic resonant mode well below the superconducting gap (2Δ) in the undoped sample (z=0) is replaced by a broad hump structure above 2Δ under 50% S doping. These results cannot be readily explained by simple spin fluctuation-exchange pairing theories and, therefore, multiple pairing channels are required to describe superconductivity in this system. Our findings may also yield a simple explanation for the sometimes contradictory data on the sign of the superconducting order parameter in iron-based materials. PMID:27232038

  15. Spinal NTS2 receptor activation reverses signs of neuropathic pain.

    PubMed

    Tétreault, Pascal; Beaudet, Nicolas; Perron, Amélie; Belleville, Karine; René, Adeline; Cavelier, Florine; Martinez, Jean; Stroh, Thomas; Jacobi, Ashley M; Rose, Scott D; Behlke, Mark A; Sarret, Philippe

    2013-09-01

    Management of painful peripheral neuropathies remains challenging, since patients with chronic pain respond poorly to the available pharmacopeia. In recent years, the G-protein-coupled receptor neurotensin (NT) type 2 (NTS2) emerged as an attractive target for treating transitory pain states. To date, however, there is no evidence for its role in the regulation of chronic peripheral neuropathies. Here, we found that NTS2 receptors were largely localized to primary afferent fibers and superficial dorsal horns. Changes in the time course of the gene expression profile of NT, NTS1, and NTS2 were observed over a 28-d period following the sciatic nerve constriction [chronic constriction injury (CCI) model]. We next determined the effects of central delivery of selective-NTS2 agonists to CCI-treated rats on both mechanical allodynia (evoked withdrawal responses) and weight-bearing deficits (discomfort and quality-of-life proxies). The NTS2 analogs JMV431, levocabastine, and β-lactotensin were all effective in reducing ongoing tactile allodynia in CCI-treated rats. Likewise, amitriptyline, pregabalin, and morphine significantly attenuated CCI-induced mechanical hypersensitivity. NTS2 agonists were also efficient in reversing weight-bearing and postural deficits caused by nerve damage, unlike reference analgesics currently used in the clinic. Thus, NTS2 agonists may offer new treatment avenues for limiting pain associated with peripheral neuropathies and improve functional rehabilitation and well-being. PMID:23756650

  16. Reversible change of birefringence sign by optical and thermal processes in an azobenzene polymethacrylate

    SciTech Connect

    Rodriguez, F.J.; Sanchez, C.; Villacampa, B.; Alcala, R.; Cases, R.; Millaruelo, M.; Oriol, L.

    2005-01-10

    Birefringence ({delta}n) induced in an azobenzene polymethacrylate by combination of biphotonic and thermotropic processes has subsequently been changed in sign by room temperature illumination with linearly polarized blue light. The sign of {delta}n can be reversed again, by simply heating up the film to 100 deg. C. This change of {delta}n between positive and negative values can be repeated several times. Besides, by appropriate choice of film thickness and blue light irradiation conditions the same absolute value for positive and negative {delta}n values can be obtained.

  17. Alignment, reverse alignment, and wrong sign Yukawa couplings in two Higgs doublet models

    NASA Astrophysics Data System (ADS)

    Biswas, Ambalika; Lahiri, Amitabha

    2016-06-01

    We consider two Higgs doublet models with a softly broken U(1) symmetry, for various limiting values of the scalar mixing angles α and β . These correspond to the Standard Model Higgs particle being the lighter C P -even scalar (alignment) or the heavier C P -even scalar (reverse alignment), and also the limit in which some of the Yukawa couplings of this particle are the opposite sign of the vector boson couplings (wrong sign). In these limits we impose a criterion for naturalness by demanding that quadratic divergences cancel at one loop. We plot the allowed masses of the remaining physical scalars based on naturalness, stability, perturbative unitarity, and constraints coming from the ρ parameter. We also calculate the h →γ γ decay width in the wrong sign limit.

  18. Sign reversals of the output autocorrelation function for the stochastic Bernoulli-Verhulst equation

    SciTech Connect

    Lumi, N. Mankin, R.

    2015-10-28

    We consider a stochastic Bernoulli-Verhulst equation as a model for population growth processes. The effect of fluctuating environment on the carrying capacity of a population is modeled as colored dichotomous noise. Relying on the composite master equation an explicit expression for the stationary autocorrelation function (ACF) of population sizes is found. On the basis of this expression a nonmonotonic decay of the ACF by increasing lag-time is shown. Moreover, in a certain regime of the noise parameters the ACF demonstrates anticorrelation as well as related sign reversals at some values of the lag-time. The conditions for the appearance of this highly unexpected effect are also discussed.

  19. Sign reversal of dielectric anisotropy of ferroelectric liquid crystals doped with cadmium telluride quantum dots

    NASA Astrophysics Data System (ADS)

    Kumar, A.; Silotia, P.; Biradar, A. M.

    2011-08-01

    A small amount of cadmium telluride quantum dots (CdTe QDs) has been doped into various ferroelectric liquid crystals (FLCs) to observe the modifications in the alignment and dielectric anisotropy (Δɛ) of the composites. The CdTe QDs have induced a uniform homeotropic (HMT) alignment in most of the FLC mixtures. We observed an unexpected switching (from HMT to homogeneous configuration) of CdTe QDs doped FLC CS1026 (having positive Δɛ) by the application of high dc bias. This reverse switching has been attributed to the interaction between FLC molecules and CdTe QDs which caused the sign reversal of Δɛ of FLC CS1026.

  20. Selective Surface Charge Sign Reversal on Metallic Carbon Nanotubes for Facile Ultrahigh Purity Nanotube Sorting.

    PubMed

    Wang, Jing; Nguyen, Tuan Dat; Cao, Qing; Wang, Yilei; Tan, Marcus Y C; Chan-Park, Mary B

    2016-03-22

    Semiconducting (semi-) single-walled carbon nanotubes (SWNTs) must be purified of their metallic (met-) counterparts for most applications including nanoelectronics, solar cells, chemical sensors, and artificial skins. Previous bulk sorting techniques are based on subtle contrasts between properties of different nanotube/dispersing agent complexes. We report here a method which directly exploits the nanotube band structure differences. For the heterogeneous redox reaction of SWNTs with oxygen/water couple, the aqueous pH can be tuned so that the redox kinetics is determined by the availability of nanotube electrons only at/near the Fermi level, as predicted quantitatively by the Marcus-Gerischer (MG) theory. Consequently, met-SWNTs oxidize much faster than semi-SWNTs and only met-SWNTs selectively reverse the sign of their measured surface zeta potential from negative to positive at the optimized acidic pH when suspended with nonionic surfactants. By passing the redox-reacted nanotubes through anionic hydrogel beads, we isolate semi-SWNTs to record high electrically verified purity above 99.94% ± 0.04%. This facile charge sign reversal (CSR)-based sorting technique is robust and can sort SWNTs with a broad diameter range. PMID:26901408

  1. What determines the sign reversal of magnetoresistance in a molecular tunnel junction?

    PubMed

    Mandal, Subhasish; Pati, Ranjit

    2012-04-24

    The observations of both positive and negative signs in tunneling magnetoresistance (TMR) for the same organic spin-valve structure have baffled researchers working in organic spintronics. In this article, we provide an answer to this puzzle by exploring the role of metal-molecule interface on TMR in a single molecular spin-valve junction. A planar organic molecule sandwiched between two nickel electrodes is used to build a prototypical spin-valve junction. A parameter-free, single-particle Green's function approach in conjunction with a posteriori, spin-unrestricted density functional theory involving a hybrid orbital-dependent functional is used to calculate the spin-polarized current. The effect of external bias is explicitly included to investigate the spin-valve behavior. Our calculations show that only a small change in the interfacial distance at the metal-molecule junction can alter the sign of the TMR from a positive to a negative value. By changing the interfacial distance by 3%, the number of participating eigenchannels as well as their orbital characteristics changes for the antiparallel configuration, leading to the sign reversal in TMR. PMID:22409503

  2. The origin of the helicity hemispheric sign rule reversals in the mean-field solar-type dynamo

    NASA Astrophysics Data System (ADS)

    Pipin, V. V.; Zhang, H.; Sokoloff, D. D.; Kuzanyan, K. M.; Gao, Y.

    2013-11-01

    Observations of proxies of the magnetic helicity in the Sun over the past two solar cycles revealed reversals of the helicity hemispheric sign rule (negative in the North and positive in the South hemispheres). We apply the mean-field solar dynamo model to study the reversals of the magnetic helicity sign for the dynamo operating in the bulk of the solar convection zone. The evolution of the magnetic helicity is governed by the conservation law. We found that the reversal of the sign of the small-scale magnetic helicity follows the dynamo wave propagating inside the convection zone. Therefore, the spatial patterns of the magnetic helicity reversals reflect the processes which contribute to generation and evolution of the large-scale magnetic fields. At the surface, the patterns of the helicity sign reversals are determined by the magnetic helicity boundary conditions at the top of the convection zone. We demonstrate the impact of fluctuations in the dynamo parameters and variability in dynamo cycle amplitude on the reversals of the magnetic helicity sign rule. The obtained results suggest that the magnetic helicity of the large-scale axisymmetric field can be treated as an additional observational tracer for the solar dynamo and it probably can be used for the solar activity forecast as well.

  3. First Signs of Flow Reversal Within a Separated Turbulent Boundary Layer

    NASA Astrophysics Data System (ADS)

    Hammerton, Jared; Lang, Amy

    2015-11-01

    A shark's skin is covered in millions of microscopic scales that have been shown to be able to bristle in a reversing flow. The motive of this project is to further explore a potential bio-inspired passive separation control mechanism which can reduce drag. To better understand this mechanism, a more complete understanding of flow reversal within the turbulent boundary layer is required. In order to capture this phenomenon, water tunnel testing at The University of Alabama was conducted. Using a long flat plate and a rotating cylinder, a large turbulent boundary layer and adverse pressure gradient were generated. Under our testing conditions the boundary layer had a Reynolds number of 200,000 and a boundary layer height in the testing window of 5.6 cm. The adverse pressure gradient causes the viscous length scale to increase and thus increase the size of the individual components of the turbulent boundary layer. This will make the low speed streaks approximately 1 cm in width and thus large enough to measure. Results will be presented that test our hypothesis that the first signs of flow reversal will occur within the section of lowest momentum located furthest from the wall, or within the low speed streaks. This Project was funded by NSF REU Site Award 1358991.

  4. Sign reversal of transformation entropy change in Co2Cr(Ga,Si) shape memory alloys

    NASA Astrophysics Data System (ADS)

    Xu, Xiao; Omori, Toshihiro; Nagasako, Makoto; Kanomata, Takeshi; Kainuma, Ryosuke

    2015-11-01

    In situ X-ray diffraction (XRD) measurements and compression tests were performed on Co2Cr(Ga,Si) shape memory alloys. The reentrant martensitic transformation behavior was directly observed during the in situ XRD measurements. The high-temperature parent phase and low-temperature reentrant parent phase were found to have a continuous temperature dependence of lattice parameter, therefore suggesting that they are the same phase in nature. Moreover, compression tests were performed on a parent-phase single crystal sample; an evolution from normal to inverse temperature dependence of critical stress for martensitic transformation was directly observed. Based on the Clausius-Clapeyron analysis, a sign reversal of entropy change can be expected on the same alloy.

  5. Repeated nitrous oxide exposure in rats causes a thermoregulatory sign-reversal with concurrent activation of opposing thermoregulatory effectors

    PubMed Central

    Ramsay, Douglas S.; Woods, Stephen C.; Kaiyala, Karl J.

    2015-01-01

    Initial administration of 60% nitrous oxide (N2O) to rats at an ambient temperature of 21°C decreases core temperature (Tc), primarily via increased heat loss (HL). Over repeated N2O administrations, rats first develop tolerance to this hypothermia and subsequently exhibit hyperthermia (a sign-reversal) due primarily to progressive increases in heat production (HP). When rats initially receive 60% N2O in a thermal gradient, they become hypothermic while selecting cooler ambient temperatures that facilitate HL. This study investigated whether rats repeatedly administered 60% N2O in a thermal gradient would use the gradient to behaviorally facilitate, or oppose, the development of chronic tolerance and a hyperthermic sign-reversal. Male Long-Evans rats (N=16) received twelve 3-h administrations of 60% N2O in a gas-tight, live-in thermal gradient. Hypothermia (Sessions 1-3), complete chronic tolerance (Sessions 4-6), and a subsequent transient hyperthermic sign-reversal (Sessions 7-12) sequentially developed. Despite the progressive recovery and eventual hyperthermic sign-reversal of Tc, rats consistently selected cooler ambient temperatures during all N2O administrations. A final 60% N2O administration in a total calorimeter indicated that the hyperthermic sign-reversal resulted primarily from increased HP. Thus, rats did not facilitate chronic tolerance development by moving to warmer locations in the gradient, and instead selected cooler ambient temperatures while simultaneously increasing autonomic HP. The inefficient concurrent activation of opposing effectors and the development of a sign-reversal are incompatible with homeostatic models of drug-adaptation and may be better interpreted using a model of drug-induced allostasis. PMID:25938127

  6. Reverse and pseudoreverse cortical sign in thoracolumbar burst fracture: radiologic description and distinction—a propos of three cases

    PubMed Central

    Orndorff, Douglas G.; Jagannathan, Jay; Dumont, Aaron

    2008-01-01

    In thoracolumbar burst fracture the “reverse cortical sign” is a known entity that corresponds to a fragment of the posterior wall that has been flipped 180° with the cancellous surface of the fragment facing posteriorly in the canal and the cortical surface (posterior wall) facing anteriorly. The identification of such reverse cortical fragment is crucial as ligamentotaxis is classically contraindicated as the posterior longitudinal ligament is ruptured. Recognition of such a flipped cortical fragment has relied so far on the axial CT. The advent of CT scans with sagittal reconstruction has allowed us to better describe such entities that have received little attention in the literature. The goal of this report was therefore to describe the appearance of the reverse cortical sign and its likes as they can appear on axial CT scans, sagittal reconstructions and MRI. During 1-year practice at our institution we had to treat three patients with thoracolumbar burst fracture associated with what looked like a reverse cortical sign on the axial CT scans. Further analysis of the sagittal reconstruction CT could differentiate the true reverse cortical sign from a new entity that we coined “the pseudoreverse cortical sign” as observed in two out of the three cases. In the pseudo reverse cortical sign what appears to be a flipped piece of posterior vertebral body is actually part of the superior or inferior endplate that is depressed into the comminuted vertebral body. In such cases the posterior longitudinal ligament appears to be in continuity and therefore such fracture can theoretically be treated with posterior ligamentotaxis as evidenced in one of our case. Careful analysis of the CT scan and specifically the sagittal reconstruction and MRI can differentiate two separate entities that may correspond to a different severity injury. PMID:19082845

  7. Characterization of Disruption Halo Currents in the National Spherical Torus Experiment

    SciTech Connect

    S.P. Gerhardt, J. Menard, S. Sabbagh and F. Scotti

    2012-04-25

    This paper describes the general characteristics of disruptions halo currents in the National Spherical Torus Experiment [M. Ono, et al. Nuclear Fusion 40, 557 (2000)]. The commonly observed types of vertical motion and resulting halo current patterns are described, and it is shown that plasma discharges developing between components can facilitate halo current flow. The halo current fractions and toroidal peaking factors at various locations in the device are presented. The maximum product of these two metrics for localized halo current measurements is always significantly less than the worst-case expectations from conventional aspect ratio tokamaks (which are typically written in terms of the total halo current). The halo current fraction and impulse is often largest in cases with the fastest plasma current quenches and highest quench rates. The effective duration of the halo current pulse is comparable to or shorter than the plasma current quench time. The largest halo currents have tended to occur in lower β and lower elongation plasmas. The sign of the poloidal halo current is reversed when the toroidal field direction is reversed.

  8. Sign reversal of magnetization in Mn substituted SmCrO3

    NASA Astrophysics Data System (ADS)

    Dash, Bibhuti B.; Ravi, S.

    2016-05-01

    Single phase samples of orthorhombic SmCr1-xMnxO3 compounds were prepared for x=0 to 0.50. Analysis of X-ray diffraction patterns shows a systematic increase in lattice parameters with increase in Mn concentration. The phenomenon of magnetization reversal is observed for x=0.10-0.30 samples with a maximum magnetic compensation temperature of 126 K. The mechanism of magnetization reversal is explained by considering the competition between the paramagnetic moments of Mn3+ and Sm3+ ions under the influence of negative internal field due to antiferromagnetically ordered Cr3+ ions and the canted ferromagnetic component of Cr3+ ions. For x≥0.40, the samples exhibit ferromagnetic like behavior.

  9. Sign reversal of ac Josephson current in a ferromagnetic Josephson junction

    NASA Astrophysics Data System (ADS)

    Hikino, Shin-Ichi; Mori, Michiyasu; Takahashi, Saburo; Maekawa, Sadamichi

    2009-03-01

    It is known that in a superconductor/insulator/superconductor (SIS) junction, when a finite voltage is applied, the Josephson current shows a logarithmic divergence, i.e., the so-called Riedel peak(RP) at the gap voltage, V=2δ/e, (δ is a superconducting gap). In a double barrier Josephson junction such as SXS junction, on the other hand, the voltage dependence of Ic has not been investigated so far, where X is a normal metal (N) or a ferromagnet (F). We study the voltage dependence of Josephson critical current (Ic) in a variety of SXS junctions. In a SNS junction, Ic shows the RP at the gap voltage similar to a SIS junction. On the other hand, in a SFS junction, Ic shows a damped oscillation with the alternation of sign as a function of thickness (d) of F due to 0-π transition. The RP exhibits a strong dependence on d, and changes its sign. It is predicted that the RP disappears at the 0-π transition in the SFS junction.

  10. An O([Formula: see text]) algorithm for sorting signed genomes by reversals, transpositions, transreversals and block-interchanges.

    PubMed

    Yu, Shuzhi; Hao, Fanchang; Leong, Hon Wai

    2016-02-01

    We consider the problem of sorting signed permutations by reversals, transpositions, transreversals, and block-interchanges. The problem arises in the study of species evolution via large-scale genome rearrangement operations. Recently, Hao et al. gave a 2-approximation scheme called genome sorting by bridges (GSB) for solving this problem. Their result extended and unified the results of (i) He and Chen - a 2-approximation algorithm allowing reversals, transpositions, and block-interchanges (by also allowing transversals) and (ii) Hartman and Sharan - a 1.5-approximation algorithm allowing reversals, transpositions, and transversals (by also allowing block-interchanges). The GSB result is based on introduction of three bridge structures in the breakpoint graph, the L-bridge, T-bridge, and X-bridge that models goodreversal, transposition/transreversal, and block-interchange, respectively. However, the paper by Hao et al. focused on proving the 2-approximation GSB scheme and only mention a straightforward [Formula: see text] algorithm. In this paper, we give an [Formula: see text] algorithm for implementing the GSB scheme. The key idea behind our faster GSB algorithm is to represent cycles in the breakpoint graph by their canonical sequences, which greatly simplifies the search for these bridge structures. We also give some comparison results (running time and computed distances) against the original GSB implementation. PMID:26707923

  11. Sign reversal of transformation entropy change in Co{sub 2}Cr(Ga,Si) shape memory alloys

    SciTech Connect

    Xu, Xiao Omori, Toshihiro; Kainuma, Ryosuke; Nagasako, Makoto; Kanomata, Takeshi

    2015-11-02

    In situ X-ray diffraction (XRD) measurements and compression tests were performed on Co{sub 2}Cr(Ga,Si) shape memory alloys. The reentrant martensitic transformation behavior was directly observed during the in situ XRD measurements. The high-temperature parent phase and low-temperature reentrant parent phase were found to have a continuous temperature dependence of lattice parameter, therefore suggesting that they are the same phase in nature. Moreover, compression tests were performed on a parent-phase single crystal sample; an evolution from normal to inverse temperature dependence of critical stress for martensitic transformation was directly observed. Based on the Clausius-Clapeyron analysis, a sign reversal of entropy change can be expected on the same alloy.

  12. Recombinant TCR ligand reverses clinical signs and CNS damage of EAE induced by recombinant human MOG.

    PubMed

    Sinha, Sushmita; Subramanian, Sandhya; Emerson-Webber, Ashley; Lindner, Maren; Burrows, Gregory G; Grafe, Marjorie; Linington, Christopher; Vandenbark, Arthur A; Bernard, Claude C A; Offner, Halina

    2010-06-01

    Increasing evidence suggests that in addition to T cell-dependent effector mechanisms, autoantibodies are also involved in the pathogenesis of MS, including demyelinating antibodies specific for myelin oligodendrocyte glycoprotein (MOG). Our previous studies have demonstrated that recombinant T cell receptor ligands (RTLs) are very effective for treating T cell-mediated experimental autoimmune encephalomyelitis (EAE). In order to expand the scope of RTL therapy in MS patients, it was of interest to study RTL treatment of EAE involving a demyelinating antibody component. Therefore, we evaluated the therapeutic effects of RTL551, specific for T cells reactive to mouse (m)MOG-35-55 peptide, on EAE induced with recombinant human (rh)MOG in C57BL/6 mice. We report that RTL551 therapy can reverse disease progression and reduce demyelination and axonal damage induced by rhMOG without suppressing the anti-MOG antibody response. This result suggests that T cell-mediated inflammation and associated blood-brain barrier dysfunction are the central contributors to EAE pathogenesis and that successful regulation of these key players restricts potential damage by demyelinating antibodies. The results of our study lend support for the use of RTL therapy for treatment of MS subjects whose disease includes inflammatory T cells as well as those with an additional antibody component. PMID:19789980

  13. ``A red cross appeared in the sky'' and other celestial signs: Presumable European aurorae in the mid AD 770s were halo displays

    NASA Astrophysics Data System (ADS)

    Neuhäuser, D. L.; Neuhäuser, R.

    2015-12-01

    The interpretation of the strong 14C variation around AD 775 as one (or several) solar super-flare(s) by, e.g., Usoskin et al. (2013) is based on alleged aurora sightings in the mid AD 770s in Europe: A red cross/crucifix in AD 773/4/6 from the Anglo-Saxon Chronicle, inflamed shields in AD 776 (both listed in the aurora catalogue of Link 1962), and riders on white horses in AD 773 (newly proposed as aurora in Usoskin et al. 2013), the two latter from the Royal Frankish Annals. We discuss the reports about these three sightings in detail here. We can show that all three can be interpreted convincingly as halo displays: The red cross or crucifix is formed by the horizontal arc and a vertical pillar of light (either with the Sun during sunset or with the moon after sunset); the inflamed shields and the riders on white horses were both two mock suns, especially the latter narrated in form of a Christian adaptation of the antique dioscuri motive. While the latter event took place early in AD 774 (dated AD 773 in Usoskin et al. 2013), the two other sightings have to be dated AD 776, i.e. anyway too late for being in connection with a 14C rise that started before AD 775. We also sketch the ideological background of those sightings and there were many similar reports throughout that time. In addition, we present a small drawing of a lunar halo display with horizontal arc and vertical pillar forming a cross for shortly later, namely AD 806 June 4, the night of full moon, also from the Anglo-Saxon Chronicle; we also show historic observations of halo phenomena (mock suns and crosses) from G. Kirch and Hevelius - and a modern photograph.

  14. Artificial halos

    NASA Astrophysics Data System (ADS)

    Selmke, Markus

    2015-09-01

    Judged by their frequency and beauty, ice halos easily rival rainbows as a prominent atmospheric optics phenomenon. This article presents experimental halo demonstrations of varying complexity. Using a single commercially available hexagonal glass prism, a variety of artificial halos can be simulated. The experiments include laser beam path analysis, a modified classic spinning prism experiment, and a novel Monte-Carlo machine for three-dimensional rotations. Each of these experiments emulates different conditions of certain halo displays, and in combination, they allow a thorough understanding of these striking phenomena.

  15. Sign-a-Palooza

    ERIC Educational Resources Information Center

    McMorran, Charles; Reynolds, Veronica

    2010-01-01

    A halo of signs, some stuffed into thick plastic sheaths while others curled under yellow tape, cluttered the service desks of the New City Library. They bleated out messages of closings, procedures, and warnings. Their number undermined their cause. All too often a customer would ask a question that was answered by the very sign they had pushed…

  16. An Unusual Lunar Halo

    ERIC Educational Resources Information Center

    Cardon, Bartley L.

    1977-01-01

    Discusses a photograph of an unusual combination of lunar halos: the 22-degree refraction halo, the circumscribed halo, and a reflection halo. Deduces the form and orientations of the ice crystals responsible for the observed halo features. (MLH)

  17. Sign-Reversing Orbital Polarization in the Nematic Phase of FeSe due to the C2 Symmetry Breaking in the Self-Energy

    NASA Astrophysics Data System (ADS)

    Onari, Seiichiro; Yamakawa, Youichi; Kontani, Hiroshi

    2016-06-01

    To understand the nematicity in Fe-based superconductors, nontrivial k dependence of the orbital polarization [Δ Ex z(k ) , Δ Ey z(k )] in the nematic phase, such as the sign reversal of the orbital splitting between Γ and X , Y points in FeSe, provides significant information. To solve this problem, we study the spontaneous symmetry breaking with respect to the orbital polarization and spin susceptibility self-consistently. In FeSe, due to the sign-reversing orbital order, the hole and electron pockets are elongated along the ky and kx axes, respectively, consistently with experiments. In addition, an electron pocket splits into two Dirac cone Fermi pockets while increasing the orbital polarization. The orbital order in Fe-based superconductors originates from the strong positive feedback between the nematic orbital order and spin susceptibility.

  18. Sign-Reversing Orbital Polarization in the Nematic Phase of FeSe due to the C_{2} Symmetry Breaking in the Self-Energy.

    PubMed

    Onari, Seiichiro; Yamakawa, Youichi; Kontani, Hiroshi

    2016-06-01

    To understand the nematicity in Fe-based superconductors, nontrivial k dependence of the orbital polarization [ΔE_{xz}(k), ΔE_{yz}(k)] in the nematic phase, such as the sign reversal of the orbital splitting between Γ and X, Y points in FeSe, provides significant information. To solve this problem, we study the spontaneous symmetry breaking with respect to the orbital polarization and spin susceptibility self-consistently. In FeSe, due to the sign-reversing orbital order, the hole and electron pockets are elongated along the k_{y} and k_{x} axes, respectively, consistently with experiments. In addition, an electron pocket splits into two Dirac cone Fermi pockets while increasing the orbital polarization. The orbital order in Fe-based superconductors originates from the strong positive feedback between the nematic orbital order and spin susceptibility. PMID:27314734

  19. Persistence of a hyperthermic sign-reversal during nitrous oxide inhalation despite cue-exposure treatment with and without a drug-onset cue

    PubMed Central

    Kaiyala, Karl J.; Woods, Stephen C.; Ramsay, Douglas S.

    2015-01-01

    We asked whether chronic tolerance and the hyperthermic sign-reversal induced by repeated 60% N2O exposures could be extinguished using a cue-exposure paradigm. Rats received 18 N2O administrations in a total calorimetry system that simultaneously measures core temperature (Tc), metabolic heat production (HP), and body heat loss (HL). Each exposure entailed a 2-h baseline period followed by a 1.5-h N2O exposure. The 18 drug exposures induced a robust intra-administration hyperthermia in which the initial hypothermic effect of N2O inverted to a significant hyperthermic sign-reversal during N2O inhalation due primarily to an acquired robust increase in HP. The rats were then randomized to one of three extinction procedures (n=8/procedure) over a 20-d interval: 1) a N2O-abstinent home-cage group (HC) that received only the usual animal care; 2) a cue-exposure group (CEXP) in which the animals were placed in the calorimeter 8 times but received no N2O; and 3) a drug-onset-cue group (DOC) in which animals received a brief N2O exposure in the calorimeter that mimicked the first 3 min of an actual 60% N2O trial. Following the extinction sessions, all rats received a 60% N2O test trial and Tc, HP and HL were assessed. The hyperthermic sign-reversal remained fully intact during the test trial, with no significant differences observed among groups in any post-baseline change in any thermal outcome. These data suggest that cue exposure may not be an efficacious strategy to reduce sign-reversals that develop with chronic drug use. PMID:25938128

  20. Observation of double sign reversal of the hall resistance in Y 0.55Pr 0.45Ba 2Cu 3O 7- δ polycrystalline samples

    NASA Astrophysics Data System (ADS)

    dos Santos, Carlos A. M.; da Luz, M. S.; Machado, A. J. S.

    2004-08-01

    In order to study Hall effect in Y 0.55Pr 0.45Ba 2Cu 3O 7- δ polycrystalline samples we have measured longitudinal and transverse voltages at low magnetic field using Van der Pauw technique. The results of the Hall resistance RXY as a function of temperature presented double sign reversal which crosses to the positive sign at same temperature in which branching point ( TCj) of the electrical resistance RXX occurs. Magneto-resistance hysteresis loops demonstrated that the dissipation is dominated by weak coupling between superconducting clusters. The results suggest that the positive Hall voltage at superconducting state is due to quasiparticle current which is in good agreement with the recent discussion about the applying of the resistively shunted junction model to polycrystalline samples.

  1. Multiple sign reversal of the Hall effect in electron-doped superconductor Pr0.9LaCe0.1CuO4+/-δ thin films

    NASA Astrophysics Data System (ADS)

    Zhu, Beiyi

    We have investigated the temperature and field dependence of the Hall resistivity of the electron-doped Pr0.9LaCe0.1CuO4+/-δ(PLCCO) superconducting thin films(Tc 0 =22 K). In the low magnetic field region (0.03 ~ 0.1 T), a concrete triple sign reversal of the Hall resistivity ρxy has been observed in the ρxy (T) curve. With the increase of the magnetic field, the Hall resistivity ρxy (T) suffers triple, double, single sign reversal transitions and it will be completely disappear around 4.5 T. We contribute the triple sign reversal to the competition between the hole and the electron carriers in our electron-doped samples and a fourth sign reversal may be expected in the regime of the two-band system.

  2. NEW CONSTRAINTS ON THE GALACTIC HALO MAGNETIC FIELD USING ROTATION MEASURES OF EXTRAGALACTIC SOURCES TOWARD THE OUTER GALAXY

    SciTech Connect

    Mao, S. A.; McClure-Griffiths, N. M.; Gaensler, B. M.; Brown, J. C.; Van Eck, C. L.; Stil, J. M.; Taylor, A. R.; Haverkorn, M.; Kronberg, P. P.; Shukurov, A.

    2012-08-10

    We present a study of the Milky Way disk and halo magnetic field, determined from observations of Faraday rotation measure (RM) toward 641 polarized extragalactic radio sources in the Galactic longitude range 100 Degree-Sign -117 Degree-Sign , within 30 Degree-Sign of the Galactic plane. For |b| < 15 Degree-Sign , we observe a symmetric RM distribution about the Galactic plane. This is consistent with a disk field in the Perseus arm of even parity across the Galactic mid-plane. In the range 15 Degree-Sign < |b| < 30 Degree-Sign , we find median RMs of -15 {+-} 4 rad m{sup -2} and -62 {+-} 5 rad m{sup -2} in the northern and southern Galactic hemispheres, respectively. If the RM distribution is a signature of the large-scale field parallel to the Galactic plane, then this suggests that the halo magnetic field toward the outer Galaxy does not reverse direction across the mid-plane. The variation of RM as a function of Galactic latitude in this longitude range is such that RMs become more negative at larger |b|. This is consistent with an azimuthal magnetic field of strength 2 {mu}G (7 {mu}G) at a height 0.8-2 kpc above (below) the Galactic plane between the local and the Perseus spiral arm. We propose that the Milky Way could possess spiral-like halo magnetic fields similar to those observed in M51.

  3. Sign-reversed and magnitude-enhanced nonlinear absorption of Au-CdS core-shell hetero-nanorods

    NASA Astrophysics Data System (ADS)

    Nan, Fan; Liang, Shan; Liu, Xiao-Li; Peng, Xiao-Niu; Li, Min; Yang, Zhong-Jian; Zhou, Li; Hao, Zhong-Hua; Wang, Qu-Quan

    2013-04-01

    We synthesis uniform Au-CdS core-shell hetero-nanorods and demonstrate the effective plasmon-exciton interaction induced optical nonlinear enhancement in metal-semiconductor hetero-nanostructures. After growing CdS semiconductor shell onto the Au nanorods, the longitudinal plasmon resonance exhibits considerable red-shift with enlarged absorption intensity. Nonlinear absorption responses transform from saturable absorption to reverse saturable absorption, and effective nonlinear absorption coefficient β is increased from -7.7 to +22.2 cm/GW. The observed behaviors indicate strong plasmon-exciton interaction and great local field enhancement.

  4. Brown adipose tissue thermogenesis does not explain the intra-administration hyperthermic sign-reversal induced by serial administrations of 60% nitrous oxide to rats.

    PubMed

    Al-Noori, Salwa; Ramsay, Douglas S; Cimpan, Andreas; Maltzer, Zoe; Zou, Jessie; Kaiyala, Karl J

    2016-08-01

    Initial administration of ≥60% nitrous oxide (N2O) to rats promotes hypothermia primarily by increasing whole-body heat loss. We hypothesized that the drug promotes heat loss via the tail and might initially inhibit thermogenesis via brown adipose tissue (BAT), major organs of thermoregulation in rodents. Following repeated administrations, N2O inhalation evokes hyperthermia underlain by increased whole-body heat production. We hypothesized that elevated BAT thermogenesis plays a role in this thermoregulatory sign reversal. Using dual probe telemetric temperature implants and infrared (IR) thermography, we assessed the effects of nine repeated 60% N2O administrations compared to control (con) administrations on core temperature, BAT temperature, lumbar back temperature and tail temperature. Telemetric core temperature, telemetric BAT temperature, and IR BAT temperature were reduced significantly during initial 60% N2O inhalation (p≤0.001 compared to con). IR thermography revealed that acute N2O administration unexpectedly reduced tail temperature (p=0.0001) and also inhibited IR lumbar temperature (p<0.0001). In the 9th session, N2O inhalation significantly increased telemetric core temperature (p=0.007) indicative of a hyperthermic sign reversal, yet compared to control administrations, telemetric BAT temperature (p=0.86), IR BAT temperature (p=0.85) and tail temperature (p=0.47) did not differ significantly. Thus, an initial administration of 60% N2O at 21°C may promote hypothermia via reduced BAT thermogenesis accompanied by tail vasoconstriction as a compensatory mechanism to limit body heat loss. Following repeated N2O administrations rats exhibit a hyperthermic core temperature but a normalized BAT temperature, suggesting induction of a hyperthermia-promoting thermogenic adaptation of unknown origin. PMID:27503733

  5. Recombinant TCR ligand reverses clinical signs and CNS damage of EAE induced by recombinant human MOG1

    PubMed Central

    Sinha, Sushmita; Subramanian, Sandhya; Emerson-Webber, Ashley; Lindner, Maren; Burrows, Gregory G.; Grafe, Marjorie; Linington, Christopher; Vandenbark, Arthur A.; Bernard, Claude C. A.; Offner, Halina

    2009-01-01

    Increasing evidence suggests that in addition to T cell dependent effector mechanisms, autoantibodies are also involved in the pathogenesis of MS, including demyelinating antibodies specific for myelin oligodendrocyte glycoprotein (MOG). Our previous studies have demonstrated that recombinant T cell receptor ligands (RTLs) are very effective for treating T cell mediated experimental autoimmune encephalomyelitis (EAE). In order to expand the scope of RTL therapy in MS patients, it was of interest to study RTL treatment of EAE involving a demyelinating antibody component. Therefore, we evaluated the therapeutic effects of RTL551, specific for T cells reactive to mouse (m)MOG-35-55 peptide, on EAE induced with recombinant human (rh)MOG in C57BL/6 mice. We report that RTL551 therapy can reverse disease progression and reduce demyelination and axonal damage induced by rhMOG without suppressing the anti-MOG antibody response. This result suggests that T cell mediated inflammation and associated blood-brain barrier dysfunction are the central contributors to EAE pathogenesis, and that successful regulation of these key players restricts potential damage by demyelinating antibodies. The results of our study lend support for the use of RTL therapy for treatment of MS subjects whose disease includes inflammatory T cells as well as those with an additional antibody component. PMID:19789980

  6. The scale-dependence of halo assembly bias

    NASA Astrophysics Data System (ADS)

    Sunayama, Tomomi; Hearin, Andrew P.; Padmanabhan, Nikhil; Leauthaud, Alexie

    2016-05-01

    The two-point clustering of dark matter haloes is influenced by halo properties besides mass, a phenomenon referred to as halo assembly bias. Using the depth of the gravitational potential well, Vmax, as our secondary halo property, in this paper, we present the first study of the scale-dependence of assembly bias. In the large-scale linear regime, r ≥ 10 h-1 Mpc, our findings are in keeping with previous results. In particular, at the low-mass end (haloes with high Vmax show stronger large-scale clustering relative to haloes with low Vmax of the same mass; this trend weakens and reverses for Mvir ≳ Mcoll. In the non-linear regime, assembly bias in low-mass haloes exhibits a pronounced scale-dependent `bump' at 500 kpc h-1-5 Mpc h-1. This feature weakens and eventually vanishes for haloes of higher mass. We show that this scale-dependent signature can primarily be attributed to a special subpopulation of ejected haloes, defined as present-day host haloes that were previously members of a higher mass halo at some point in their past history. A corollary of our results is that galaxy clustering on scales of r ˜ 1-2 Mpc h-1 can be impacted by up to ˜15 per cent by the choice of the halo property used in the halo model, even for stellar mass-limited samples.

  7. A ''LIGHT'', CENTRALLY CONCENTRATED MILKY WAY HALO?

    SciTech Connect

    Rashkov, Valery; Pillepich, Annalisa; Deason, Alis J.; Madau, Piero; Rockosi, Constance M.; Mayer, Lucio

    2013-08-20

    We discuss a novel approach to ''weighing'' the Milky Way (MW) dark matter halo, one that combines the latest samples of halo stars selected from the Sloan Digital Sky Survey (SDSS) with state of the art numerical simulations of MW analogs. The fully cosmological runs employed in the present study include ''Eris'', one of the highest resolution hydrodynamical simulations of the formation of a M{sub vir} = 8 Multiplication-Sign 10{sup 11} M{sub Sun} late-type spiral, and the dark-matter-only M{sub vir} = 1.7 Multiplication-Sign 10{sup 12} M{sub Sun} ''Via Lactea II'' (VLII) simulation. Eris provides an excellent laboratory for creating mock SDSS samples of tracer halo stars, and we successfully compare their density, velocity anisotropy, and radial velocity dispersion profiles with the observational data. Most mock SDSS realizations show the same ''cold veil'' recently observed in the distant stellar halo of the MW, with tracers as cold as {sigma}{sub los} Almost-Equal-To 50 km s{sup -1} between 100 and 150 kpc. Controlled experiments based on the integration of the spherical Jeans equation as well as a particle tagging technique applied to VLII show that a ''heavy'' M{sub vir} Almost-Equal-To 2 Multiplication-Sign 10{sup 12} M{sub Sun} realistic host produces a poor fit to the kinematic SDSS data. We argue that these results offer added evidence for a ''light'', centrally concentrated MW halo.

  8. The halo Boltzmann equation

    NASA Astrophysics Data System (ADS)

    Biagetti, Matteo; Desjacques, Vincent; Kehagias, Alex; Racco, Davide; Riotto, Antonio

    2016-04-01

    Dark matter halos are the building blocks of the universe as they host galaxies and clusters. The knowledge of the clustering properties of halos is therefore essential for the understanding of the galaxy statistical properties. We derive an effective halo Boltzmann equation which can be used to describe the halo clustering statistics. In particular, we show how the halo Boltzmann equation encodes a statistically biased gravitational force which generates a bias in the peculiar velocities of virialized halos with respect to the underlying dark matter, as recently observed in N-body simulations.

  9. MHF: MLAPM Halo Finder

    NASA Astrophysics Data System (ADS)

    Gill, Stuart P. D.; Knebe, Alexander

    2015-11-01

    MHF is a Dark Matter halo finder that is based on the refinement grids of MLAPM. The grid structure of MLAPM adaptively refines around high-density regions with an automated refinement algorithm, thus naturally "surrounding" the Dark Matter halos, as they are simply manifestations of over-densities within (and exterior) to the underlying host halo. Using this grid structure, MHF restructures the hierarchy of nested isolated MLAPM grids into a "grid tree". The densest cell in the end of a tree branch marks center of a prospective Dark Matter halo. All gravitationally bound particles about this center are collected to obtain the final halo catalog. MHF automatically finds halos within halos within halos.

  10. "Invisible" Galactic Halos.

    ERIC Educational Resources Information Center

    Lugt, Karel Vander

    1993-01-01

    Develops a simple core-halo model of a galaxy that exhibits the main features of observed rotation curves and quantitatively illustrates the need to postulate halos of dark matter. Uses only elementary mechanics. (Author/MVL)

  11. Resolved Stellar Halos of M87 and NGC 5128

    NASA Astrophysics Data System (ADS)

    Bird, Sarah A.; Harris, William; Flynn, Chris; Blakeslee, John P.; Valtonen, Mauri

    2015-08-01

    We search halo fields of two giant elliptical galaxies: M87, using HST images at 10 kpc from the center, and NGC 5128 (Cen A), using VIMOS VLT images at 65 kpc from the center and archival HST data from 8 to 38 kpc from the center. We resolve thousands of red-giant-branch stars in these stellar halo fields using V and I filters, and, in addition, measure the metallicity using stellar isochrones. In Cen A, we find that the density of metal-rich and metal-poor halo stars falls off with the same slope in the de Vaucouleurs' law profile, from the inner halo of 8 kpc out to 70 kpc, with no sign of a transition to dominance by metal-poor stars. We also find that the metallicity distribution of the inner stellar halo of M87 is most similar to that of NGC 5128's inner stellar halo.

  12. ASSEMBLY BIAS AND THE DYNAMICAL STRUCTURE OF DARK MATTER HALOS

    SciTech Connect

    Faltenbacher, Andreas; White, Simon D. M.

    2010-01-01

    Based on the Millennium Simulation we examine assembly bias for the halo properties: shape, triaxiality, concentration, spin, shape of the velocity ellipsoid, and velocity anisotropy. For consistency, we determine all these properties using the same set of particles, namely all gravitationally self-bound particles belonging to the most massive substructure of a given friends-of-friends halo. We confirm that near-spherical and high-spin halos show enhanced clustering. The opposite is true for strongly aspherical and low-spin halos. Further, below the typical collapse mass, M{sub *}, more concentrated halos show stronger clustering, whereas less concentrated halos are less clustered which is reversed for masses above M{sub *}. Going beyond earlier work we show that: (1) oblate halos are more strongly clustered than prolate ones; (2) the dependence of clustering on the shape of the velocity ellipsoid coincides with that of the real-space shape, although the signal is stronger; (3) halos with weak velocity anisotropy are more clustered, whereas radially anisotropic halos are more weakly clustered; (4) for all highly clustered subsets we find systematically less radially biased velocity anisotropy profiles. These findings indicate that the velocity structure of halos is tightly correlated with environment.

  13. THE HALO OCCUPATION DISTRIBUTION OF SDSS QUASARS

    SciTech Connect

    Richardson, Jonathan; Chatterjee, Suchetana; Nagai, Daisuke; Zheng Zheng; Shen Yue

    2012-08-10

    We present an estimate of the projected two-point correlation function (2PCF) of quasars in the Sloan Digital Sky Survey (SDSS) over the full range of one- and two-halo scales, 0.02 h{sup -1} Mpc < r{sub p} < 120 h{sup -1} Mpc. This was achieved by combining data from SDSS DR7 on large scales and Hennawi et al. (with appropriate statistical corrections) on small scales. Our combined clustering sample is the largest spectroscopic quasar clustering sample to date, containing {approx}48, 000 quasars in the redshift range 0.4 {approx}< z {approx}< 2.5 with median redshift 1.4. We interpret these precise 2PCF measurements within the halo occupation distribution (HOD) framework and constrain the occupation functions of central and satellite quasars in dark matter halos. In order to explain the small-scale clustering, the HOD modeling requires that a small fraction of z {approx} 1.4 quasars, f{sub sat} = (7.4 {+-} 1.4) Multiplication-Sign 10{sup -4}, be satellites in dark matter halos. At z {approx} 1.4, the median masses of the host halos of central and satellite quasars are constrained to be M{sub cen} = 4.1{sup +0.3}{sub -0.4} Multiplication-Sign 10{sup 12} h{sup -1} M{sub Sun} and M{sub sat} = 3.6{sup +0.8}{sub -1.0} Multiplication-Sign 10{sup 14} h{sup -1} M{sub Sun }, respectively. To investigate the redshift evolution of the quasar-halo relationship, we also perform HOD modeling of the projected 2PCF measured by Shen et al. for SDSS quasars with median redshift 3.2. We find tentative evidence for an increase in the mass scale of quasar host halos-the inferred median mass of halos hosting central quasars at z {approx} 3.2 is M{sub cen} = 14.1{sup +5.8}{sub -6.9} Multiplication-Sign 10{sup 12} h{sup -1} M{sub Sun }. The cutoff profiles of the mean occupation functions of central quasars reveal that quasar luminosity is more tightly correlated with halo mass at higher redshifts. The average quasar duty cycle around the median host halo mass is inferred to be f{sub q

  14. Cold dark matter halos

    NASA Astrophysics Data System (ADS)

    Dubinski, John Joseph

    The dark halos arising in the Cold Dark Matter (CDM) cosmology are simulated to investigate the relationship between the structure and kinematics of dark halos and galaxies. Realistic cosmological initial conditions and tidal field boundary conditions are used in N-body simulations of the collapse of density peaks to form dark halos. The core radii of dark halos are no greater than the softening radius, rs = 1.4 kpc. The density profiles can be fit with an analytical Hernquist (1990) profile with an effective power law which varies between -1 in the center to -4 at large radii. The rotation curves of dark halos resemble the flat rotation curves of spiral galaxies in the observed range, 1.5 approximately less than r approximately less than 30 kpc. The halos are strongly triaxial and very flat with (c/a) = 0.50 and (b/a) = 0.71. The distribution of ellipticities for dark halos reaches a maximum at epsilon = 0.5 in contrast to the distribution for elliptical galaxies which peaks at epsilon = 0.2 suggesting that ellipticals are much rounder than dark halos. Dark halos are generally flatter than their progenitor density peaks. The final shape and orientation of a dark halo are largely determined by tidal torquing and are sensitive to changes in the strength and orientation of a tidal field. Dark halos are pressure supported objects with negligible rotational support as indicated by the mean dimensionless spin, lamda = 0.042 +/- 0.024. The angular momentum vector tends to align with the true minor axis of dark halos. Elliptical galaxies have a similar behavior implied by the observation of the tendency for alignment of the rotation vector and the apparent minor axis. The origin of this behavior may be traced to the tendency for tidal torques to misalign with the major axis of a density peak. Tidal torques are found to isotropize the velocity ellipsoids of dark halos at large radii, contrary to the expectation of radially anisotropic velocity ellipsoids in cold collapse

  15. Vital Signs

    MedlinePlus

    Your vital signs show how well your body is functioning. They are usually measured at doctor's offices, often as part ... be a sign of a serious breathing problem. Temperature, which measures how hot your body is. A ...

  16. Warning Signs.

    ERIC Educational Resources Information Center

    Our Children, 1999

    1999-01-01

    Presents various signs that may indicate emotional problems in children or teens, noting that if children exhibit any of the warning signs, it is important to talk to a doctor, counselor, or mental-health professional. The warning signs are categorized as things that trouble the child, things that limit the child, behavior problems, and sudden…

  17. Tokamak halo currents

    SciTech Connect

    Boozer, Allen H.

    2013-08-15

    A halo current flows for part of its path through the plasma edge and for part through the chamber walls and can be as large as tenths of the plasma current. The primary interest in halo currents is the large force that they can exert on machine components. Two discordant constraints are central to the theory: (1) Halo currents must produce the magnetic field distribution required to maintain plasma force balance—a distribution that depends on the two angular coordinates of a torus. (2) Halo currents must flow along the magnetic field lines in the plasma, which implies a dependence on a linear combination of the two angular coordinates—only one angular coordinate is free. The physics basis of these two constraints is explained as is their application to the calculation of the properties of halo currents, such as their broad toroidal spectrum. Existing codes could be used to (1) provide detailed comparisons with experiments to validate that the critical elements of physics are adequately included, (2) allow more complete predictions for future machines such as ITER, and (3) design shunts and resistive elements to ensure halo currents follow paths that are the least damaging to the machine. The physics of halo currents implies that it may be possible to feedback stabilize resistive wall modes beyond the ideal-wall limit.

  18. Detection of foot-and-mouth disease by reverse transcription polymerase chain reaction and virus isolation in contact sheep without clinical signs of foot-and-mouth disease.

    PubMed

    Callens, M; De Clercq, K; Gruia, M; Danes, M

    1998-05-01

    Summary Two non-vaccinated sheep were experimentally, infected with FMDV and one day later 4 other sheep were brought in contact. Although the contact sheep showed no clinical signs, serology indicated that all sheep became infected. Various secretion samples, taken over a period of at least one month, and various tissue samples were examined for the presence of FMDV by RT-PCR and by virus isolation. FMDV was most often found in saliva (mouth swabs), followed by nasal secretion and sera. Faecal material, wool and milk were less suitable. The period of detection with the highest frequency of positive isolations was between 2 to 4 days pi for the infected sheep and between 5 to 10 days pc for the contact animals. It was established that in subclinically infected sheep, with a very low amount of virus present, FMD viral RNA could be detected by a sensitive RT-PCR-ELISA although virus isolation and standard RT-PCR remained negative. Moreover there was some evidence of active spreading of FMDV from the contact sheep to two sentinel pigs. This indicates that serologically positive contact sheep without clinical signs may be considered as a danger for the transmission of FMDV. PMID:22077296

  19. Detection of foot-and-mouth disease by reverse transcription polymerase chain reaction and virus isolation in contact sheep without clinical signs of foot-and-mouth disease.

    PubMed

    Callens, M; De Clercq, K; Gruia, M; Danes, M

    1998-01-01

    Two non-vaccinated sheep were experimentally infected with FMDV and one day later 4 other sheep were brought in contact. Although the contact sheep showed no clinical signs, serology indicated that all sheep became infected. Various secretion samples, taken over a period of at least one month, and various tissue samples were examined for the presence of FMDV by RT-PCR and by virus isolation. FMDV was most often found in saliva (mouth swabs), followed by nasal secretion and sera. Faecal material, wool and milk were less suitable. The period of detection with the highest frequency of positive isolations was between 2 to 4 days pi for the infected sheep and between 5 to 10 days pc for the contact animals. It was established that in subclinically infected sheep, with a very low amount of virus present, FMD viral RNA could be detected by a sensitive RT-PCR-ELISA although virus isolation and standard RT-PCR remained negative. Moreover there was some evidence of active spreading of FMDV from the contact sheep to two sentinel pigs. This indicates that serologically positive contact sheep without clinical signs may be considered as a danger for the transmission of FMDV. PMID:9652065

  20. Halo vest instrumentation

    NASA Astrophysics Data System (ADS)

    Huston, Dryver R.; Krag, Martin

    1996-05-01

    The halo vest is a head and neck immobilization system that is often used on patients that are recovering from cervical trauma or surgery. The halo vest system consists of a rigid halo that is firmly attached to the skull, an upright support structure for stabilization and immobilization, and a torso-enveloping vest. The main purpose of this study was to measure the forces that are carried by the halo-vest structure as the subject undergoes various activities of daily living and external loading for different vest designs. A tethered strain gage load cell based instrumentation system was used to take these load measurements on ten different subjects. Three different halo-vest systems were evaluated. The primary difference between the vests was the amount of torso coverage and the use of shoulder straps. The loads were measured, analyzed and used to compare the vests and to create a model of halo-vest-neck mechanics. Future applications of this technology to standalone data logging, pin-load measuring and biofeedback applications are discussed.

  1. PARAMETERS FOR QUANTIFYING BEAM HALO

    SciTech Connect

    C.K. ALLEN; T.P. WANGLER

    2001-06-01

    Two different parameters for the quantitative description of beam halo are introduced, both based on moments of the particle distribution. One parameter is a measure of spatial halo formation and has been defined previously by Wangler and Crandall [3], termed the profile parameter. The second parameter relies on kinematic invariants to quantify halo formation in phase space; we call it the halo parameter. The profile parameter can be computed from experimental beam profile data. The halo parameter provides a theoretically more complete description of halo in phase space, but is difficult to obtain experimentally.

  2. Microscopic interpretation of sign reversal in the electrocaloric effect in a ferroelectric PbMg1/3Nb2/3O3-30PbTiO3 single crystal

    NASA Astrophysics Data System (ADS)

    Axelsson, A.-K.; Le Goupil, F.; Dunne, L. J.; Manos, G.; Valant, M.; Alford, N. McN.

    2013-03-01

    With increasing temperature, PbMg1/3Nb2/3O3-30PbTiO3 (PMN-30PT) crystals change from pseudo-rhombohedral to tetragonal to cubic phases. In addition to the usual positive electrocaloric effect (ECE), a negative ECE, whose origin is uncertain, is observed. Here, these two types of the ECE contributions in PbMg1/3Nb2/3O3-30PbTiO3 crystals are modelled theoretically using a one dimensional statistical mechanical lattice model, which is solved by an exact matrix method. The quasi one-dimensional model reproduces the trends in the experimental behaviour and attributes the electrocaloric sign reversal to free energy changes induced by the electric field.

  3. Historic halo displays as weather indicator: Criteria and examples

    NASA Astrophysics Data System (ADS)

    Neuhäuser, Dagmar L.; Neuhäuser, Ralph

    2016-04-01

    There are numerous celestial signs reported in historic records, many of them refer to atmospheric ("sub-lunar") phenomena, such as ice halos and aurorae. In an interdisciplinary collaboration between astrophysics and cultural astronomy, we noticed that celestial observations including meteorological phenomena are often misinterpreted, mostly due to missing genuine criteria: especially ice crystal halos were recorded frequently in past centuries for religious reasons, but are mistaken nowadays often for other phenomena like aurorae. Ice halo displays yield clear information on humidity and temperature in certain atmospheric layers, and thereby indicate certain weather patterns. Ancient so-called rain makers used halo observations for weather forecast; e.g., a connection between certain halo displays and rain a few day later is statistically significant. Ice halos exist around sun and moon and are reported for both (they can stay for several days): many near, middle, and far eastern records from day- and night-time include such observations with high frequency. (Partly based on publications on halos by D.L. Neuhäuser & R. Neuhäuser, available at http://www.astro.uni-jena.de/index.php/terra-astronomy.html)

  4. Vital Signs

    MedlinePlus

    Your vital signs show how well your body is functioning. They are usually measured at doctor's offices, often as part ... standing, which medicines you take, and your weight. Respiratory rate, which measures your breathing. Mild breathing changes can ...

  5. HALOE Science Investigation

    NASA Technical Reports Server (NTRS)

    Benner, D. Chris

    1998-01-01

    This cooperative agreement has investigated a number of spectroscopic problems of interest to the Halogen Occultation Experiment (HALOE). The types of studies performed are in two parts, namely, those that involve the testing and characterization of correlation spectrometers and those that provide basic molecular spectroscopic information. In addition, some solar studies were performed with the calibration data returned by HALOE from orbit. In order to accomplish this a software package was written as part of this cooperative agreement. The HALOE spectroscopic instrument package was used in various tests of the HALOE flight instrument. These included the spectral response test, the early stages of the gas response test and various spectral response tests of the detectors and optical elements of the instruments. Considerable effort was also expended upon the proper laboratory setup for many of the prelaunch tests of the HALOE flight instrument, including the spectral response test and the gas response test. These tests provided the calibration and the assurance that the calibration was performed correctly.

  6. Gaseous Halos and the Interstellar Disk-Halo Connection

    NASA Astrophysics Data System (ADS)

    Dettmar, Ralf Jurgen

    The presence of diffuse ionized gas (DIG) in the halos of spiral galaxies is discussed in the framework of the disk-halo interaction. The halo DIG is typically correlated with the presence of other components of the ISM in the halo including X-ray hot gas, cosmic rays, and magnetic fields. All these tracers of an extraplanar ISM correlate well with star formation in the disk thus corroborating the paradigm of an ISM driven by multiple and clustered supernovae.

  7. Renormalized halo bias

    SciTech Connect

    Assassi, Valentin; Baumann, Daniel; Green, Daniel; Zaldarriaga, Matias E-mail: dbaumann@damtp.cam.ac.uk E-mail: matiasz@ias.edu

    2014-08-01

    This paper provides a systematic study of renormalization in models of halo biasing. Building on work of McDonald, we show that Eulerian biasing is only consistent with renormalization if non-local terms and higher-derivative contributions are included in the biasing model. We explicitly determine the complete list of required bias parameters for Gaussian initial conditions, up to quartic order in the dark matter density contrast and at leading order in derivatives. At quadratic order, this means including the gravitational tidal tensor, while at cubic order the velocity potential appears as an independent degree of freedom. Our study naturally leads to an effective theory of biasing in which the halo density is written as a double expansion in fluctuations and spatial derivatives. We show that the bias expansion can be organized in terms of Galileon operators which aren't renormalized at leading order in derivatives. Finally, we discuss how the renormalized bias parameters impact the statistics of halos.

  8. The Outer Halo -- Halo Origins and Mass of the Galaxy

    NASA Astrophysics Data System (ADS)

    Morrison, Heather; Arabadjis, John; Dohm-Palmer, Robbie; Freeman, Ken; Harding, Paul; Mateo, Mario; Norris, John; Olszewski, Ed; Sneden, Chris

    2000-02-01

    Through our detection of distant halo stars, we are now well placed to map the regions of the Galactic halo where previously only satellite galaxies and a few globular clusters were known. Mapping this region is crucial for answering questions like: How and over what timescales was the Milky Way's stellar halo assembled? What is the total mass and shape of its dark halo? The Sagittarius dwarf has demonstrated that at least some of the stellar halo was accreted. But, HOW MUCH of the halo was accreted? Our previous efforts have proven that the Washington photometric system, in conjuction with spectroscopy, is capable of efficiently and unambiguously identifying halo stars out to 100 kpc or more. We require followup spectroscopy to map velocity substructure, which is more likely visible in the outer halo because of the long dynamical timescales, and to identify the rare objects in the extreme outer halo which will constrain the shape and size of its dark halo. We are applying for 4m/RCSP time at both CTIO and KPNO to observe faint outer-halo giant and BHB candidates.

  9. Vital Signs.

    ERIC Educational Resources Information Center

    Brown, Lester R.

    1993-01-01

    Presents an excerpt from the first edition of Vital Signs, a Worldwide Institute publication that provides an annual update on global environmental trends. Includes discussion of the dismantling of nuclear arms, reduction in chlorofluorocarbon production, growth in bicycle production, the decline in cigarette smoking, and decline in military…

  10. Sign reversal of field-angle resolved heat capacity oscillations in a heavy Fermion superconductor CeCoIn5 and d{x{2}-y{2}} pairing symmetry.

    PubMed

    An, K; Sakakibara, T; Settai, R; Onuki, Y; Hiragi, M; Ichioka, M; Machida, K

    2010-01-22

    To identify the superconducting gap symmetry in CeCoIn5 (T{c}=2.3 K), we measured the angle-resolved specific heat (C{phi}) in a field rotated around the c axis down to a very low temperature, 0.05T{c}, and made detailed theoretical calculations. In a field of 1 T, a sign reversal of the fourfold angular oscillation in C{phi} was observed at T approximately 0.1T{c} upon entering a quasiclassical regime where the maximum of C{phi} corresponds to the antinodal direction, coinciding with the angle-resolved density of states (ADOS) calculation. The C{phi} behavior, which exhibits minima along the [110] directions, unambiguously allows us to conclude d{x{2}-y{2}} symmetry of this system. The ADOS-quasiclassical region is confined to a narrow T and H domain within T/T{c} approximately 0.1 and 1.5 T (0.13H{c2}). PMID:20366675

  11. Halo Star Lithium Depletion

    SciTech Connect

    Pinsonneault, M. H.; Walker, T. P.; Steigman, G.; Narayanan, Vijay K.

    1999-12-10

    The depletion of lithium during the pre-main-sequence and main-sequence phases of stellar evolution plays a crucial role in the comparison of the predictions of big bang nucleosynthesis with the abundances observed in halo stars. Previous work has indicated a wide range of possible depletion factors, ranging from minimal in standard (nonrotating) stellar models to as much as an order of magnitude in models that include rotational mixing. Recent progress in the study of the angular momentum evolution of low-mass stars permits the construction of theoretical models capable of reproducing the angular momentum evolution of low-mass open cluster stars. The distribution of initial angular momenta can be inferred from stellar rotation data in young open clusters. In this paper we report on the application of these models to the study of lithium depletion in main-sequence halo stars. A range of initial angular momenta produces a range of lithium depletion factors on the main sequence. Using the distribution of initial conditions inferred from young open clusters leads to a well-defined halo lithium plateau with modest scatter and a small population of outliers. The mass-dependent angular momentum loss law inferred from open cluster studies produces a nearly flat plateau, unlike previous models that exhibited a downward curvature for hotter temperatures in the 7Li-Teff plane. The overall depletion factor for the plateau stars is sensitive primarily to the solar initial angular momentum used in the calibration for the mixing diffusion coefficients. Uncertainties remain in the treatment of the internal angular momentum transport in the models, and the potential impact of these uncertainties on our results is discussed. The 6Li/7Li depletion ratio is also examined. We find that the dispersion in the plateau and the 6Li/7Li depletion ratio scale with the absolute 7Li depletion in the plateau, and we use observational data to set bounds on the 7Li depletion in main-sequence halo

  12. Methods for Identifying Pair Halos

    NASA Astrophysics Data System (ADS)

    Wells, Brendan; Caputo, Regina; Atwood, William; Ritz, Steven M.

    2016-01-01

    The flux of very high energy gamma rays from active galactic nuclei (AGN) is attenuated via interactions with extragalactic background photons and is converted into e+e- pairs. With non-zero intergalactic magnetic fields, the electrons and positrons will deflect as they propagate and simultaneously lose energy by upscattering cosmic microwave background photons. "Pair halos," the visible consequences of these electromagnetic cascades, are faint and difficult to observe against their AGN counterparts. We investigate three methods for indirectly identifying pair halos, using a two-component approach to model the AGN core/halo image. We estimate each method's sensitivity by utilizing a new, detailed Monte Carlo pair-halo simulation.

  13. Jupiter's Ring Halo

    NASA Technical Reports Server (NTRS)

    1997-01-01

    A mosaic of four images taken through the clear filter (610 nanometers) of the solid state imaging (CCD) system aboard NASA's Galileo spacecraft on November 8, 1996, at a resolution of approximately 46 kilometers (km) per picture element (pixel) along the rings; however, because the spacecraft was only about 0.5 degrees above the ring plane, the image is highly foreshortened in the vertical direction. The images were obtained when Galileo was in Jupiter's shadow peering back toward the Sun; the ring was approximately 2,300,000 kilometers (km) away. The arc on the far right of the image is produced by sunlight scattered by small particles comprising Jupiter's upper atmospheric haze. The ring also efficiently scatters light, indicating that much of its brightness is due to particles that are microns or less in diameter. Such small particles are believed to have human-scale lifetimes, i.e., very brief compared to the solar system's age.

    Jupiter's ring system is composed of three parts -- a flat main ring, a lenticular halo interior to the main ring, and the gossamer ring, which lies exterior to the main ring. The near and far arms of Jupiter's main ring extend horizontally across the mosaic, joining together at the ring's ansa, on the far left side of the figure. The near arm of the ring appears to be abruptly truncated close to the planet, at the point where it passes into Jupiter's shadow.

    A faint mist of particles can be seen above and below the main rings; this vertically extended, toroidal 'halo' is unusual in planetary rings, and is probably caused by electromagnetic forces which can push small grains out of the ring plane. Halo material is present across this entire image, implying that it reaches more than 27,000 km above the ring plane. Because of shadowing, the halo is not visible close to Jupiter in the lower right part of the mosaic. In order to accentuate faint features in the image, different brightnesses are shown through color, with the brightest

  14. Adiabatic Halo Formation

    SciTech Connect

    Bazzani, A.; Turchetti, G.; Benedetti, C.; Rambaldi, S.; Servizi, G.

    2005-06-08

    In a high intensity circular accelerator the synchrotron dynamics introduces a slow modulation in the betatronic tune due to the space-charge tune depression. When the transverse motion is non-linear due to the presence of multipolar effects, resonance islands move in the phase space and change their amplitude. This effect introduces the trapping and detrapping phenomenon and a slow diffusion in the phase space. We apply the neo-adiabatic theory to describe this diffusion mechanism that can contribute to halo formation.

  15. Recombinant TCR ligand induces tolerance to myelin oligodendrocyte glycoprotein 35-55 peptide and reverses clinical and histological signs of chronic experimental autoimmune encephalomyelitis in HLA-DR2 transgenic mice.

    PubMed

    Vandenbark, Arthur A; Rich, Cathleen; Mooney, Jeff; Zamora, Alex; Wang, Chunhe; Huan, Jianya; Fugger, Lars; Offner, Halina; Jones, Richard; Burrows, Gregory G

    2003-07-01

    In a previous study, we demonstrated that myelin oligodendrocyte glycoprotein (MOG)-35-55 peptide could induce severe chronic experimental autoimmune encephalomyelitis (EAE) in HLA-DR2(+) transgenic mice lacking all mouse MHC class II genes. We used this model to evaluate clinical efficacy and mechanism of action of a novel recombinant TCR ligand (RTL) comprised of the alpha(1) and beta(1) domains of DR2 (DRB1*1501) covalently linked to the encephalitogenic MOG-35-55 peptide (VG312). We found that the MOG/DR2 VG312 RTL could induce long-term tolerance to MOG-35-55 peptide and reverse clinical and histological signs of EAE in a dose- and peptide-dependent manner. Some mice treated with lower doses of VG312 relapsed after cessation of daily treatment, but the mice could be successfully re-treated with a higher dose of VG312. Treatment with VG312 strongly reduced secretion of Th1 cytokines (TNF-alpha and IFN-gamma) produced in response to MOG-35-55 peptide, and to a lesser degree purified protein derivative and Con A, but had no inhibitory effect on serum Ab levels to MOG-35-55 peptide. Abs specific for both the peptide and MHC moieties of the RTLs were also present after treatment with EAE, but these Abs had only a minor enhancing effect on T cell activation in vitro. These data demonstrate the powerful tolerance-inducing therapeutic effects of VG312 on MOG peptide-induced EAE in transgenic DR2 mice and support the potential of this approach to inhibit myelin Ag-specific responses in multiple sclerosis patients. PMID:12816990

  16. HALOE test and evaluation software

    NASA Technical Reports Server (NTRS)

    Edmonds, W.; Natarajan, S.

    1987-01-01

    Computer programming, system development and analysis efforts during this contract were carried out in support of the Halogen Occultation Experiment (HALOE) at NASA/Langley. Support in the major areas of data acquisition and monitoring, data reduction and system development are described along with a brief explanation of the HALOE project. Documented listings of major software are located in the appendix.

  17. Strong bimodality in the host halo mass of central galaxies from galaxy-galaxy lensing

    NASA Astrophysics Data System (ADS)

    Mandelbaum, Rachel; Wang, Wenting; Zu, Ying; White, Simon; Henriques, Bruno; More, Surhud

    2016-04-01

    We use galaxy-galaxy lensing to study the dark matter haloes surrounding a sample of locally brightest galaxies (LBGs) selected from the Sloan Digital Sky Survey. We measure mean halo mass as a function of the stellar mass and colour of the central galaxy. Mock catalogues constructed from semi-analytic galaxy formation simulations demonstrate that most LBGs are the central objects of their haloes, greatly reducing interpretation uncertainties due to satellite contributions to the lensing signal. Over the full stellar mass range, 10.3 < log [M*/M⊙] < 11.6, we find that passive central galaxies have haloes that are at least twice as massive as those of star-forming objects of the same stellar mass. The significance of this effect exceeds 3σ for log [M*/M⊙] > 10.7. Tests using the mock catalogues and on the data themselves clarify the effects of LBG selection and show that it cannot artificially induce a systematic dependence of halo mass on LBG colour. The bimodality in halo mass at fixed stellar mass is reproduced by the astrophysical model underlying our mock catalogue, but the sign of the effect is inconsistent with recent, nearly parameter-free age-matching models. The sign and magnitude of the effect can, however, be reproduced by halo occupation distribution models with a simple (few-parameter) prescription for type dependence.

  18. Near Ballistic Halo-to-Halo Transfers between Planetary Moons

    NASA Astrophysics Data System (ADS)

    Lantoine, Gregory; Russell, Ryan P.

    2011-07-01

    Intermoon transfers are important components of planetary tour missions. However, these transfers are challenging to design due in part to the chaotic environment created by the multi-body dynamics. The specific objective of this work is to develop a systematic methodology to find fuel optimal, near ballistic Halo-to-Halo trajectories between planetary moons, and we achieve this goal by combining dynamical systems theory with a variety of nonlinear programming techniques. The spacecraft is constrained to start at a Halo orbit of a moon and end at another Halo orbit of a second moon. Our approach overcomes the obstacles of the chaotic dynamics by combining multiple "resonant-hopping" gravity assists with manifolds that control the low-energy transport near the Halo orbits of the moons. To help construct good initial guesses, contours of semimajor axes that can be reached by falling off a Halo orbit are presented. An empirical relationship is then derived to find quickly the boundary conditions on the Halo orbits that lead to ballistic capture and escape trajectories, and connect to desired resonances. The overall optimization procedure is broken into four parts of increasing fidelity: creation of the initial guess from unstable resonant orbits and manifolds, decomposition and optimization of the trajectory into two independent ideal three-body portions, end-to-end refinement in a patched three-body model, and transition to an ephemeris model using a continuation method. Each step is based on a robust multiple shooting approach to reduce the sensitivities associated with the close approach trajectories. Numerical results of an intermoon transfer in the Jovian system are presented. In an ephemeris model, using only 55 m/s and 205 days, a spacecraft can transfer between a Halo orbit of Ganymede and a Halo orbit of Europa.

  19. Infant Sign Training and Functional Analysis

    ERIC Educational Resources Information Center

    Normand, Matthew P.; Machado, Mychal A.; Hustyi, Kristin M.; Morley, Allison J.

    2011-01-01

    We taught manual signs to typically developing infants using a reversal design and caregiver-nominated stimuli. We delivered the stimuli on a time-based schedule during baseline. During the intervention, we used progressive prompting and reinforcement, described by Thompson et al. (2004, 2007), to establish mands. Following sign training, we…

  20. Headaches - danger signs

    MedlinePlus

    Migraine headache - danger signs; Tension headache - danger signs; Cluster headache - danger signs; Vascular headache - danger signs ... and bleeding in the brain can cause a headache. These problems include: Abnormal connection between the arteries ...

  1. Stroke Warning Signs

    MedlinePlus

    ... News Advocate Stroke Warning Signs Quiz Stroke Warning Signs and Symptoms THINK YOU ARE HAVING A STROKE? ... Learn more stroke signs and symptoms >>>> Stroke Warning Signs Hip-Hop F.A.S.T. Video Updated Guidelines ...

  2. Signing off

    NASA Astrophysics Data System (ADS)

    2001-05-01

    sharp that they cause paper cuts. Stains. If you accidentally spill some food or drink on your clothes, make sure you attempt to remove it as soon as possible and preferably within the same lunar cycle. Some teachers seem to think they should be worn with pride like the stains on a chemistry teacher's white coat. This is a myth. Materials. For scientists continually teaching about the wonder of smart materials, physics teachers are remarkably conservative in their choice of materials for their clothes. Try to break out from the traditional corduroy and tweed and practise what you teach. It is not acceptable to wear the actual tie you wore at school, as this will be at least 20 years old, be rather frayed and will have your name sewn in the back by your mum. Steven Chapman Science Year Manager, British Association for the Advancement of Science Signing Off takes a humorous and irreverent look at physics education. The views expressed here are those of the author and are not endorsed by the Editorial Board for Physics Education. Can you contribute a zany attitude or humorous anecdote? Please send your offering to ped@iop.org marked Signing Off.

  3. Kinematically Detected Halo Streams

    NASA Astrophysics Data System (ADS)

    Smith, Martin C.

    Clues to the origins and evolution of our Galaxy can be found in the kinematics of stars around us. Remnants of accreted satellite galaxies produce over-densities in velocity-space, which can remain coherent for much longer than spatial over-densities. This chapter reviews a number of studies that have hunted for these accretion relics, both in the nearby solar-neighborhood and the more-distant stellar halo. Many observational surveys have driven this field forwards, from early work with the Hipparcos mission, to contemporary surveys like RAVE and SDSS. This active field continues to flourish, providing many new discoveries, and will be revolutionized as the Gaia mission delivers precise proper motions for a billion stars in our Galaxy.

  4. Cullen Sign and Grey Turner Sign Revisited.

    PubMed

    Wright, William F

    2016-06-01

    Cullen sign and Grey Turner sign, named after Thomas Stephen Cullen, MB, and George Grey Turner, MBBS, respectively, are signs of abdominal wall hemorrhage and are generally associated with acute pancreatitis. However, the research from which these signs arose was documented long before Cullen and Grey Turner made their contributions. The present article examines the history, pathologic mechanisms, and clinical application of these signs in relation to acute pancreatitis and ectopic pregnancy. PMID:27214777

  5. Evidence for core-halo decoupling in halo systems

    SciTech Connect

    Aguilera, E. F.; Kolata, J. J.; Acosta, L.

    2010-01-15

    Evidence is presented showing that for the {sup 6}He+{sup 209}Bi system, the reaction cross sections can be entirely accounted for by interactions of the halo state of {sup 6}He plus reactions that occur with the {sup 4}He core. These and similar conclusions about core-halo decoupling reported earlier for {sup 8}B+{sup 58}Ni are further supported by proving that no such decoupling occurs for reactions with {sup 17}O, whose valence neutron is rather weakly bound but does not form a halo. The preceding conclusions are based on comparisons with purely experimental data, using a quite reasonable scaling. Thus such a decoupling seems to stand out as a characteristic feature of true halo systems.

  6. Halo model and halo properties in Galileon gravity cosmologies

    SciTech Connect

    Barreira, Alexandre; Li, Baojiu; Hellwing, Wojciech A.; Baugh, Carlton M.; Lombriser, Lucas; Pascoli, Silvia E-mail: baojiu.li@durham.ac.uk E-mail: llo@roe.ac.uk E-mail: silvia.pascoli@durham.ac.uk

    2014-04-01

    We investigate the performance of semi-analytical modelling of large-scale structure in Galileon gravity cosmologies using results from N-body simulations. We focus on the Cubic and Quartic Galileon models that provide a reasonable fit to CMB, SNIa and BAO data. We demonstrate that the Sheth-Tormen mass function and linear halo bias can be calibrated to provide a very good fit to our simulation results. We also find that the halo concentration-mass relation is well fitted by a power law. The nonlinear matter power spectrum computed in the halo model approach is found to be inaccurate in the mildly nonlinear regime, but captures reasonably well the effects of the Vainshtein screening mechanism on small scales. In the Cubic model, the screening mechanism hides essentially all of the effects of the fifth force inside haloes. In the case of the Quartic model, the screening mechanism leaves behind residual modifications to gravity, which make the effective gravitational strength time-varying and smaller than the standard value. Compared to normal gravity, this causes a deficiency of massive haloes and leads to a weaker matter clustering on small scales. For both models, we show that there are realistic halo occupation distributions of Luminous Red Galaxies that can match both the observed large-scale clustering amplitude and the number density of these galaxies.

  7. Signing off

    NASA Astrophysics Data System (ADS)

    2001-09-01

    Physics Related Aptitude Test As the teacher shortage bites anyone with a degree in science expects to walk into a school and be received, with open arms, as a physics teacher. Are they really suitable? To help you decide Signing Off provides the following invaluable psychometric test. Extensively researched and, for single users only, it comes completely free to Physics Education subscribers! (Copies of this Physics Related Aptitude Test are available to credit-card customers from prat@realripoff.com priced #35 per client, 125 dollars to US customers.) This invaluable psychometric test has been extensively researched. Your first lesson of the new school year introduces the study of electricity. Do you: A Use the notes prepared by your predecessor. B Find a video on electricity and play it to the class. C Arrange a series of exciting practical demonstrations to stimulate the young inquiring mind. D Let the children design and make their own circuits to light flashlight bulbs. Your 14-year-olds have completed a written test on heat and energy. Do you: A Mark correct only the work of students who have written their names neatly at the top LEFT HAND corner, as required. B Only set multiple choice tests, so that the computer can mark them for you. C Mark carefully by hand, explaining in detail to each student exactly how and why they have made errors and adding encouraging comments with lots of praise. D Give out correct sets of answers and allow students to mark their own work. There is a staff social. Do you: A Ask for a definition of the term 'social'. B Ask for a web-based version. C Determine to go, so that you can discuss setting up cross-curricular links with colleagues. D Join the organizing committee. Who do you admire most? A Sir Isaac Newton. B Bill Gates. C Leonardo da Vinci. D Leonardo di Caprio. You are required to teach biology class. Your response is: A Denial. B To ask for an appropriate computer simulation. C To attend a specialized course for biology

  8. The Outer Halo Metallicity Distribution

    NASA Astrophysics Data System (ADS)

    MA, ZHIBO; Morrison, H.; Harding, P.; Xue, X.; Rix, H.; Rockosi, C.; Johnson, J.; Lee, Y.; Cudworth, K.

    2012-01-01

    We present a new determination of the metallicity distribution function in the Milky Way halo, based on an in situ sample of more than 5000 K giants from SDSS/SEGUE. We have also measured the metallicity gradient in the halo, using our sample which stretches from 5 kpc to more than 100 kpc from the galactic center. The halo metallicity gradient has been a controversial topic in recent studies, but our in-situ study overcomes the problems caused in these studies by their extrapolations from local samples to the distant halo. We also describe our extensive checks of the log g and [Fe/H] measurements from the SEGUE Stellar Parameters pipeline, using globular and open cluster stars and SEGUE stars with follow-up high-resolution analysis. In addition, we present a new Bayesian estimate of distances to the K giants, which avoids the distance bias introduced by the red giant branch luminosity function.

  9. Supernumerary ice-crystal halos?

    PubMed

    Berry, M V

    1994-07-20

    Geometric-optics singularities in the intensity profiles of refraction halos formed by randomly oriented ice crystals are softened by diffraction and decorated with fine supernumerary fringes. If the crystals have a fixed symmetry axis (as in parhelia), the geometric singularity is a square-root divergence, as in the rainbow. However, the universal curve that describes diffraction is different from the rainbow's Airy function, with weak maxima (supernumerary fringes) on the geometrically dark region inside the halo (and even fainter fringes outside); these are much smaller than their counterparts on the light side of rainbows. If the crystals have no preferred orientation (as in the 22° halo), the geometric singularity is a step. In this case the universal diffraction function has no maxima, and its supernumeraries are shoulders rather than maxima. The low contrast of the fringes is probably the main reason why supernumerary halos are rarely if ever seen. PMID:20935824

  10. The inner structure of ΛCDM haloes - II. Halo mass profiles and low surface brightness galaxy rotation curves

    NASA Astrophysics Data System (ADS)

    Hayashi, E.; Navarro, J. F.; Power, C.; Jenkins, A.; Frenk, C. S.; White, S. D. M.; Springel, V.; Stadel, J.; Quinn, T. R.

    2004-12-01

    We use a set of high-resolution cosmological N-body simulations to investigate the inner mass profile of galaxy-sized cold dark matter (CDM) haloes. These simulations extend the numerical convergence study presented in Paper I of this series, and demonstrate that the mass profile of CDM galaxy haloes can be robustly estimated beyond a minimum converged radius of order rconv~ 1h-1 kpc in our highest-resolution runs. The density profiles of simulated haloes become progressively shallower from the virial radius inwards, and show no sign of approaching a well-defined power law near the centre. At rconv, the density profile is steeper than expected from the formula proposed by Navarro, Frenk & White, which has a ρ~r-1 cusp, but significantly shallower than the steeply divergent ρ~r-1.5 cusp proposed by Moore et al. We perform a direct comparison of the spherically averaged dark matter circular velocity profiles with Hα rotation curves of a sample of low surface brightness (LSB) galaxies. We find that most galaxies in the sample (about 70 per cent) have rotation curves that are consistent with the structure of CDM haloes. Of the remainder, 20 per cent have rotation curves which cannot be fit by any smooth fitting function with few free parameters, and 10 per cent are inconsistent with CDM haloes. However, the latter consist mostly of rotation curves that do not extend to large enough radii to accurately determine their shapes and maximum velocities. We conclude that the inner structure of CDM haloes is not manifestly inconsistent with the rotation curves of LSB galaxies.

  11. Warning Signs After Birth

    MedlinePlus

    ... Pregnancy > Postpartum care > Warning signs after birth Warning signs after birth E-mail to a friend Please ... infection Postpartum bleeding Postpartum depression (PPD) What warning signs should you look for? Call your provider if ...

  12. Rotation of tokamak halo currents

    SciTech Connect

    Boozer, Allen H.

    2012-05-15

    During tokamak disruptions, halo currents, which can be tenths of the total plasma current, can flow at the plasma edge along the magnetic field lines that intercept the chamber walls. Non-axisymmetric halo currents are required to maintain force balance as the plasma kinks when the edge safety factor drops to about two in a vertical displacement event. The plasma quickly assumes a definite toroidal velocity v{sub a}(r) with respect to that of the magnetic kink, v{sub k}, where v{sub a}(r) is set by the radial electric field required for ambipolarity. The plasma velocity, v{sub pl}=v{sub a}+v{sub k}, near the edge is influenced by the interaction with neutrals and with the potential in the halo required for quasi-neutrality on open magnetic field lines, and the plasma velocity in the core is influenced by external error fields. When plasma effects dominate magnetic locking, the magnetic kink should rotate at a diamagnetic speed of either the edge or the core. If the magnetic field lines of the halo plasma intercept the wall at locations of very different electrical conductivity, the toroidal rotation of the halo currents can intermittently stall at wall locations of high conductivity. Such stalling is seen in experiments. The toroidal phase difference between the stalled halo currents and the kink, which is expected to rotate smoothly, must satisfy {delta}{phi}<{+-}{pi}/2. A concern cited by ITER engineers is that the time varying force of the rotating halo could substantially increase the disruption loads on in-vessel components.

  13. Halo modelling in chameleon theories

    SciTech Connect

    Lombriser, Lucas; Koyama, Kazuya; Li, Baojiu E-mail: kazuya.koyama@port.ac.uk

    2014-03-01

    We analyse modelling techniques for the large-scale structure formed in scalar-tensor theories of constant Brans-Dicke parameter which match the concordance model background expansion history and produce a chameleon suppression of the gravitational modification in high-density regions. Thereby, we use a mass and environment dependent chameleon spherical collapse model, the Sheth-Tormen halo mass function and linear halo bias, the Navarro-Frenk-White halo density profile, and the halo model. Furthermore, using the spherical collapse model, we extrapolate a chameleon mass-concentration scaling relation from a ΛCDM prescription calibrated to N-body simulations. We also provide constraints on the model parameters to ensure viability on local scales. We test our description of the halo mass function and nonlinear matter power spectrum against the respective observables extracted from large-volume and high-resolution N-body simulations in the limiting case of f(R) gravity, corresponding to a vanishing Brans-Dicke parameter. We find good agreement between the two; the halo model provides a good qualitative description of the shape of the relative enhancement of the f(R) matter power spectrum with respect to ΛCDM caused by the extra attractive gravitational force but fails to recover the correct amplitude. Introducing an effective linear power spectrum in the computation of the two-halo term to account for an underestimation of the chameleon suppression at intermediate scales in our approach, we accurately reproduce the measurements from the N-body simulations.

  14. Rotation of tokamak halo currents

    NASA Astrophysics Data System (ADS)

    Boozer, Allen H.

    2012-05-01

    During tokamak disruptions, halo currents, which can be tenths of the total plasma current, can flow at the plasma edge along the magnetic field lines that intercept the chamber walls. Non-axisymmetric halo currents are required to maintain force balance as the plasma kinks when the edge safety factor drops to about two in a vertical displacement event. The plasma quickly assumes a definite toroidal velocity va(r) with respect to that of the magnetic kink, vk, where va(r) is set by the radial electric field required for ambipolarity. The plasma velocity, vpl=va+vk, near the edge is influenced by the interaction with neutrals and with the potential in the halo required for quasi-neutrality on open magnetic field lines, and the plasma velocity in the core is influenced by external error fields. When plasma effects dominate magnetic locking, the magnetic kink should rotate at a diamagnetic speed of either the edge or the core. If the magnetic field lines of the halo plasma intercept the wall at locations of very different electrical conductivity, the toroidal rotation of the halo currents can intermittently stall at wall locations of high conductivity. Such stalling is seen in experiments. The toroidal phase difference between the stalled halo currents and the kink, which is expected to rotate smoothly, must satisfy δϕ <±π/2. A concern cited by ITER engineers is that the time varying force of the rotating halo could substantially increase the disruption loads on in-vessel components.

  15. Statistics of substructures in dark matter haloes

    NASA Astrophysics Data System (ADS)

    Contini, E.; De Lucia, G.; Borgani, S.

    2012-03-01

    We study the amount and distribution of dark matter substructures within dark matter haloes, using a large set of high-resolution simulations ranging from group-size to cluster-size haloes, and carried out within a cosmological model consistent with Wilkinson Microwave Anisotropy Probe (WMAP) 7-year data. In particular, we study how the measured properties of subhaloes vary as a function of the parent halo mass, the physical properties of the parent halo and redshift. The fraction of halo mass in substructures increases with increasing mass: it is of the order of 5 per cent for haloes with M200˜ 1013 M⊙ and of the order of 10 per cent for the most massive haloes in our sample, with M200˜ 1015 M⊙. There is, however, a very large halo-to-halo scatter that can be explained only in part by a range of halo physical properties, e.g. concentration. At a given halo mass, less concentrated haloes contain significantly larger fractions of mass in substructures because of the reduced strength of tidal disruption. Most of the substructure mass is located at the outskirts of the parent haloes, in relatively few massive subhaloes. This mass segregation appears to become stronger at increasing redshift, and should reflect into a more significant mass segregation of the galaxy population at different cosmic epochs. When haloes are accreted on to larger structures, their mass is significantly reduced by tidal stripping. Haloes that are more massive at the time of accretion (these should host more luminous galaxies) are brought closer to the centre on shorter time-scales by dynamical friction, and therefore suffer a more significant stripping. The halo merger rate depends strongly on the environment with substructure in more massive haloes suffering more important mergers than their counterparts residing in less massive systems. This should translate into a different morphological mix for haloes of different mass.

  16. The Use of Sign Language Pronouns by Native-Signing Children with Autism

    ERIC Educational Resources Information Center

    Shield, Aaron; Meier, Richard P.; Tager-Flusberg, Helen

    2015-01-01

    We report the first study on pronoun use by an under-studied research population, children with autism spectrum disorder (ASD) exposed to American Sign Language from birth by their deaf parents. Personal pronouns cause difficulties for hearing children with ASD, who sometimes reverse or avoid them. Unlike speech pronouns, sign pronouns are…

  17. Building Halos by Digesting Satellites

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-05-01

    We think galactic halos are built through the addition of material from the smaller subhalos of satellites digested by their hosts. Though most of the stars in Milky-Way-mass halos were probably formed in situ, many were instead accumulated over time, as orbiting dwarf galaxies were torn apart and their stars flung throughout the host galaxy. A recent set of simulations has examined this brutal formation process.In the authors simulations, a subhalo first falls into the host halo. At this point, it can either survive to present day as a satellite galaxy, or it can be destroyed, its stars scattering throughout the host halo. [Deason et al. 2016]Subhalo FateThere are many open questions about the growth of Milky-Way-mass halos from the accretion of subhalos. Which subhalos are torn apart and accreted, and which ones survive intact? Are more small or large subhalos accreted? Does subhalo accretion affect the host galaxys metallicity? And what can we learn from all of this about the Milky Ways formation history?In a recently published study, a team of scientists from Stanford University and SLAC National Accelerator Laboratory set out to answer these questions using a suite of 45 zoom-in simulations of Milky-Way-mass halos. Led by Alis Deason, the team tracked the accretion history of these 45 test galaxies to determine how their halos were built.Piecing Together HistoryDeason and collaborators reach several new and interesting conclusions based on the outcomes of their simulations.Average accreted stellar mass from destroyed dwarfs for each host halo, as a function of the time of the last major accretion event. More stellar mass is accreted in more recent accretion events. [Deason et al. 2016]Most of the stellar mass accreted by the Milky-Way-mass halos typically comes from only one or two destroyed dwarfs. The accreted dwarfs are usually low-mass if they were accreted early on in the simulation (i.e., in the early universe), and high-mass if they were accreted

  18. POPULATION III STAR FORMATION IN LARGE COSMOLOGICAL VOLUMES. I. HALO TEMPORAL AND PHYSICAL ENVIRONMENT

    SciTech Connect

    Crosby, Brian D.; O'Shea, Brian W.; Smith, Britton D.; Turk, Matthew J.; Hahn, Oliver

    2013-08-20

    We present a semi-analytic, computationally inexpensive model to identify halos capable of forming a Population III star in cosmological simulations across a wide range of times and environments. This allows for a much more complete and representative set of Population III star forming halos to be constructed, which will lead to Population III star formation simulations that more accurately reflect the diversity of Population III stars, both in time and halo mass. This model shows that Population III and chemically enriched stars coexist beyond the formation of the first generation of stars in a cosmological simulation until at least z {approx} 10, and likely beyond, though Population III stars form at rates that are 4-6 orders of magnitude lower than chemically enriched stars by z = 10. A catalog of more than 40,000 candidate Population III forming halos were identified, with formation times temporally ranging from z = 30 to z = 10, and ranging in mass from 2.3 Multiplication-Sign 10{sup 5} M{sub Sun} to 1.2 Multiplication-Sign 10{sup 10} M{sub Sun }. At early times, the environment that Population III stars form in is very similar to that of halos hosting chemically enriched star formation. At later times Population III stars are found to form in low-density regions that are not yet chemically polluted due to a lack of previous star formation in the area. Population III star forming halos become increasingly spatially isolated from one another at later times, and are generally closer to halos hosting chemically enriched star formation than to another halo hosting Population III star formation by z {approx} 10.

  19. Universality in molecular halo clusters.

    PubMed

    Stipanović, P; Markić, L Vranješ; Bešlić, I; Boronat, J

    2014-12-19

    The ground state of weakly bound dimers and trimers with a radius extending well into the classically forbidden region is explored, with the goal to test the predicted universality of quantum halo states. The focus of the study is molecules consisting of T↓, D↓, ^{3}He, ^{4}He, and alkali atoms, where the interaction between particles is much better known than in the case of nuclei, which are traditional examples of quantum halos. The study of realistic systems is supplemented by model calculations in order to analyze how low-energy properties depend on the interaction potential. The use of variational and diffusion Monte Carlo methods enabled a very precise calculation of both the size and binding energy of the trimers. In the quantum halo regime, and for large values of scaled binding energies, all clusters follow almost the same universal line. As the scaled binding energy decreases, Borromean states separate from tango trimers. PMID:25554880

  20. Simulation of halo particles with Simpsons

    NASA Astrophysics Data System (ADS)

    Machida, Shinji

    2003-12-01

    Recent code improvements and some simulation results of halo particles with Simpsons will be presented. We tried to identify resonance behavior of halo particles by looking at tune evolution of individual macro particle.

  1. BEAM HALO IN PROTON LINAC BEAMS

    SciTech Connect

    T. WANGLER; K. CRANDALL

    2000-08-01

    In this paper we review the present picture of km halo in proton linacs. Space-charge forces acting in mismatched beams have been identified as a major cause of beam-halo. We present a definition of halo based on a ratio of moments of the distribution of the beam coordinates. We find from our initial studies that for halo detined in this way, a beam can have rms emittance growth without halo growth, but halo growth is always accompanied by rms emittance growth. We describe the beam-halo experiment that is in preparation at Los Alamos, which will address questions about the beam profiles, maximum particle amplitudes, and rms emittance growth associated with the halo.

  2. Accretion in the galactic halo

    NASA Astrophysics Data System (ADS)

    Stephens, Alex Courtney

    2000-10-01

    The Milky Way disk is enveloped in a diffuse, dynamically-hot collection of stars and star clusters collectively known as the ``stellar halo''. Photometric and chemical analyses suggest that these stars are ancient fossils of the galaxy formation epoch. Yet, little is known about the origin of this trace population. Is this system merely a vestige of the initial burst of star formation within the decoupled proto-Galaxy, or is it the detritus of cannibalized satellite galaxies? In an attempt to unravel the history of the Milky Way's stellar halo, I performed a detailed spectroscopic analysis of 55 metal-poor stars possessing ``extreme'' kinematic properties. It is thought that stars on orbits that either penetrate the remote halo or exhibit large retrograde velocities could have been associated with assimilated (or ``accreted'') dwarf galaxies. The hallmark of an accreted halo star is presumed to be a deficiency (compared with normal stars) of the α-elements (O, Mg, Si, Ca, Ti) with respect to iron, a consequence of sporadic bursts of star formation within the diminutive galaxies. Abundances for a select group of light metals (Li, Na, Mg, Si, Ca, Ti), iron-peak nuclides (Cr, Fe, Ni), and neutron-capture elements (Y, Ba) were calculated using line-strengths measured from high-resolution, high signal-to-noise spectral observations collected with the Keck I 10-m and KPNO 4-m telescopes. The abundances extracted from the spectra reveal: (1)The vast majority of outer halo stars possess supersolar [α/Fe] > 0.0) ratios. (2)The [α/Fe] ratio appears to decrease with increasing metallicity. (3)The outer halo stars have lower ratios of [α/Fe] than inner halo stars at a given metallicity. (4)At the largest metallicities, there is a large spread in the observed [α/Fe] ratios. (5)[α/Fe] anti-correlates with RAPO. (6)Only one star (BD+80° 245) exhibits the peculiar abundances expected of an assimilated star. The general conclusion extracted from these data is that the

  3. THE STELLAR HALOS OF MASSIVE ELLIPTICAL GALAXIES

    SciTech Connect

    Greene, Jenny E.; Murphy, Jeremy D.; Comerford, Julia M.; Gebhardt, Karl; Adams, Joshua J.

    2012-05-01

    We use the Mitchell Spectrograph (formerly VIRUS-P) on the McDonald Observatory 2.7 m Harlan J. Smith Telescope to search for the chemical signatures of massive elliptical galaxy assembly. The Mitchell Spectrograph is an integral-field spectrograph with a uniquely wide field of view (107'' Multiplication-Sign 107''), allowing us to achieve remarkably high signal-to-noise ratios of {approx}20-70 pixel{sup -1} in radial bins of 2-2.5 times the effective radii of the eight galaxies in our sample. Focusing on a sample of massive elliptical galaxies with stellar velocity dispersions {sigma}{sub *} > 150 km s{sup -1}, we study the radial dependence in the equivalent widths (EW) of key metal absorption lines. By twice the effective radius, the Mgb EWs have dropped by {approx}50%, and only a weak correlation between {sigma}{sub *} and Mgb EW remains. The Mgb EWs at large radii are comparable to those seen in the centers of elliptical galaxies that are {approx} an order of magnitude less massive. We find that the well-known metallicity gradients often observed within an effective radius continue smoothly to 2.5 R{sub e} , while the abundance ratio gradients remain flat. Much like the halo of the Milky Way, the stellar halos of our galaxies have low metallicities and high {alpha}-abundance ratios, as expected for very old stars formed in small stellar systems. Our observations support a picture in which the outer parts of massive elliptical galaxies are built by the accretion of much smaller systems whose star formation history was truncated at early times.

  4. The response of dark matter haloes to elliptical galaxy formation: a new test for quenching scenarios

    NASA Astrophysics Data System (ADS)

    Dutton, Aaron A.; Macciò, Andrea V.; Stinson, Gregory S.; Gutcke, Thales A.; Penzo, Camilla; Buck, Tobias

    2015-11-01

    We use cosmological hydrodynamical zoom-in simulations with the smoothed particle hydrodynamics code GASOLINE of four haloes of mass M200 ˜ 1013 M⊙ to study the response of the dark matter to elliptical galaxy formation. Our simulations include metallicity-dependent gas cooling, star formation and feedback from massive stars and supernovae, but not active galactic nuclei (AGN). At z = 2 the progenitor galaxies have stellar-to-halo mass ratios consistent with halo abundance matching, assuming a Salpeter initial mass function. However, by z = 0 the standard runs suffer from the well-known overcooling problem, overpredicting the stellar masses by a factor of ≳ 4. To mimic a suppressive halo quenching scenario, in our forced quenching (FQ) simulations, cooling and star formation are switched off at z = 2. The resulting z = 0 galaxies have stellar masses, sizes and circular velocities close to what is observed. Relative to the control simulations, the dark matter haloes in the FQ simulations have contracted, with central dark matter density slopes d log ρ/d log r ˜ -1.5, showing that dry merging alone is unable to fully reverse the contraction that occurs at z > 2. Simulations in the literature with AGN feedback, however, have found expansion or no net change in the dark matter halo. Thus, the response of the dark matter halo to galaxy formation may provide a new test to distinguish between ejective and suppressive quenching mechanisms.

  5. The HaloTag: Improving Soluble Expression and Applications in Protein Functional Analysis.

    PubMed

    N Peterson, Scott; Kwon, Keehwan

    2012-01-01

    Technological and methodological advances have been critical for the rapidly evolving field of proteomics. The development of fusion tag systems is essential for purification and analysis of recombinant proteins. The HaloTag is a 34 KDa monomeric protein derived from a bacterial haloalkane dehalogenase. The majority of fusion tags in use today utilize a reversible binding interaction with a specific ligand. The HaloTag system is unique in that it forms a covalent linkage to its chloroalkane ligand. This linkage permits attachment of the HaloTag to a variety of functional reporters, which can be used to label and immobilize recombinant proteins. The success rate for HaloTag expression of soluble proteins is very high and comparable to maltose binding protein (MBP) tag. Furthermore, cleavage of the HaloTag does not result in protein insolubility that often is observed with the MBP tag. In the present report, we describe applications of the HaloTag system in our ongoing investigation of protein-protein interactions of the Y. pestis Type 3 secretion system on a custom protein microarray. We also describe the utilization of affinity purification/mass spectroscopy (AP/MS) to evaluate the utility of the Halo Tag system to characterize DNA binding activity and protein specificity. PMID:23115610

  6. The HaloTag: Improving Soluble Expression and Applications in Protein Functional Analysis

    PubMed Central

    N Peterson, Scott; Kwon, Keehwan

    2012-01-01

    Technological and methodological advances have been critical for the rapidly evolving field of proteomics. The development of fusion tag systems is essential for purification and analysis of recombinant proteins. The HaloTag is a 34 KDa monomeric protein derived from a bacterial haloalkane dehalogenase. The majority of fusion tags in use today utilize a reversible binding interaction with a specific ligand. The HaloTag system is unique in that it forms a covalent linkage to its chloroalkane ligand. This linkage permits attachment of the HaloTag to a variety of functional reporters, which can be used to label and immobilize recombinant proteins. The success rate for HaloTag expression of soluble proteins is very high and comparable to maltose binding protein (MBP) tag. Furthermore, cleavage of the HaloTag does not result in protein insolubility that often is observed with the MBP tag. In the present report, we describe applications of the HaloTag system in our ongoing investigation of protein-protein interactions of the Y. pestis Type 3 secretion system on a custom protein microarray. We also describe the utilization of affinity purification/mass spectroscopy (AP/MS) to evaluate the utility of the Halo Tag system to characterize DNA binding activity and protein specificity. PMID:23115610

  7. Visibility of halos and rainbows.

    PubMed

    Gedzelman, S D

    1980-09-15

    A theory for the visibility of halos and rainbows is presented. The light reaching the observer's eye from the direction of the halo or rainbow is assumed to consist of two parts: (1) a beam of singly scattered sunlight (or moonlight) from a cloud of ice crystals or a rainswath, which, in turn, has suffered depletion by scattering or absorption in its passage to the observer, and (2) the general background brightness. The model is able to account for several long-known qualitative observations concerning halos, namely, that the brightest halos are produced by optically thin cirrostratus clouds (i.e., for which the cloud optical depth tau(c), halo is visible much more frequently than the bottom. (This is shown to result in good part from extinction by the turbid atmosphere.) With the rainbow the brightness of the beam increases monotonically with the optical depth tau(R) of the sunlit part of the rainswath, but the increase is quite small for tau(R) >/=1. On the other hand, the brightness of the background increases more rapidly with tau(R) for tau(R)> 1 so that the rainbow appears most easily visible for tau(R) less, similar1. This implies that the most easily visible rainbows are produced by light or moderate showers rather than heavy downpours. Finally, suggestions are made for applying the theory to other atmospheric optical phenomena, such as coronas and glories. PMID:20234562

  8. Halo Coronal Mass Ejections and Geomagnetic Storms

    NASA Technical Reports Server (NTRS)

    Gopalswamy, Nat

    2009-01-01

    In this letter, I show that the discrepancies in the geoeffectiveness of halo coronal mass ejections (CMEs) reported in the literature arise due to the varied definitions of halo CMEs used by different authors. In particular, I show that the low geoeffectiveness rate is a direct consequence of including partial halo CMEs. The geoeffectiveness of partial halo CMEs is lower because they are of low speed and likely to make a glancing impact on Earth. Key words: Coronal mass ejections, geomagnetic storms, geoeffectiveness, halo CMEs.

  9. Wart with Depigmented Halo and Generalized Vitiligo

    PubMed Central

    Ito, Takamichi; Yoshida, Yuichi; Adachi, Koji; Furue, Masutaka; Yamamoto, Osamu

    2012-01-01

    Depigmented haloes sometimes appear around melanocytic tumors or non-melanocytic tumors, but coexistence of warts and depigmented haloes is extremely rare. We report here an unusual case of warts accompanied by depigmented haloes and subsequently-triggered generalized vitiligo. A 55-year-old Japanese man presented with a 3-year history of brown nodules on the back, upper eyelid and dorsum of the left hand. Depigmented haloes appeared around the noldules and then gradually spread over a wide area, resulting in the development of generalized vitiligo. He had no history of antecedent treatment for these lesions before consultation. Histopathologically, the lesion showed papillomatosis and hyperkeratosis with lymphocytic exocytosis into the epidermis, which compatible to warts. Based on these clinical and histopathologic findings, a diagnosis of warts with depigmented halo and subsequently-triggered generalized vitiligo was made. None of the warts had resolved spontaneously after the appearance of haloes, and the depigmented haloes and generalized vitiligo remain unchanged. PMID:24031144

  10. Clouds Dominate the Galactic Halo

    NASA Astrophysics Data System (ADS)

    2003-01-01

    Using the exquisite sensitivity of the National Science Foundation's Robert C. Byrd Green Bank Telescope (GBT), astronomer Jay Lockman of the National Radio Astronomy Observatory (NRAO) in Green Bank, W. Va., has produced the best cross-section ever of the Milky Way Galaxy's diffuse halo of hydrogen gas. This image confirms the presence of discrete hydrogen clouds in the halo, and could help astronomers understand the origin and evolution of the rarefied atmosphere that surrounds our Galaxy. Lockman presented his findings at the American Astronomical Society meeting in Seattle, WA. Hydrogen Clouds Graphic Artist's Rendering of the Milky Way (background) with insert showing GBT image of cross-section of neutral atomic Hydrogen Credit: Kirk Woellert/National Science Foundation Patricia Smiley, NRAO. "The first observations with the Green Bank Telescope suggested that the hydrogen in the lower halo, the transition zone between the Milky Way and intergalactic space, is very clumpy," said Lockman. "The latest data confirm these results and show that instead of trailing away smoothly from the Galactic plane, a significant fraction of the hydrogen gas in the halo is concentrated in discrete clouds. There are even some filaments." Beyond the star-filled disk of the Milky Way, there exists an extensive yet diffuse halo of hydrogen gas. For years, astronomers have speculated about the origin and structure of this gas. "Even the existence of neutral hydrogen in the halo has been somewhat of a puzzle," Lockman remarked. "Unlike the Earth's atmosphere, which is hot enough to hold itself up against the force of gravity, the hydrogen in the halo is too cool to support itself against the gravitational pull of the Milky Way." Lockman points out that some additional factor has to be involved to get neutral hydrogen to such large distances from the Galactic plane. "This force could be cosmic rays, a supersonic wind, the blast waves from supernovae, or something we have not thought of

  11. Reionization histories of Milky Way mass halos

    SciTech Connect

    Li, Tony Y.; Wechsler, Risa H.; Abel, Tom; Alvarez, Marcelo A. E-mail: rwechsler@stanford.edu E-mail: malvarez@cita.utoronto.ca

    2014-04-20

    We investigate the connection between the reionization era and the present-day universe by examining the mass reionization histories of z = 0 dark matter halos. In a 600{sup 3} Mpc{sup 3} volume, we combine a dark matter N-body simulation with a three-dimensional seminumerical reionization model. This tags each particle with a reionization redshift, so that individual present-day halos can be connected to their reionization histories and environments. We find that the vast majority of present-day halos with masses larger than ∼ few × 10{sup 11} M {sub ☉} reionize earlier than the rest of the universe. We also find significant halo-to-halo diversity in mass reionization histories, and find that in realistic inhomogeneous models, the material within a given halo is not expected to reionize at the same time. In particular, the scatter in reionization times within individual halos is typically larger than the scatter among halos. From our fiducial reionization model, we find that the typical 68% scatter in reionization times within halos is ∼115 Myr for 10{sup 12±0.25} M {sub ☉} halos, decreasing slightly to ∼95 Myr for 10{sup 15±0.25} M {sub ☉} halos. We find a mild correlation between reionization history and environment: halos with shorter reionization histories are typically in more clustered environments, with the strongest trend on a scale of ∼20 Mpc. Material in Milky Way mass halos with short reionization histories is preferentially reionized in relatively large H II regions, implying reionization mostly by sources external to the progenitors of the present-day halo. We investigate the impact on our results of varying the reionization model parameters, which span a range of reionization scenarios with varying timing and morphology.

  12. Signs and Symptoms

    MedlinePlus

    ... print email share facebook twitter google plus linkedin Signs and Symptoms Partly because there are different types ... This section presents a general picture of CMT signs and symptoms. Contractures and bone deformities Many people ...

  13. Dermatomyositis: Signs and Symptoms

    MedlinePlus

    ... print email share facebook twitter google plus linkedin Signs and Symptoms What happens to someone with dermatomyositis? ... be damaged as a result. About Dermatomyositis (DM) Signs and Symptoms Diagnosis Causes/Inheritance Medical Management Research ...

  14. Anomalous transport properties in Eu1-xLaxB6 ( x=0.0 , 0.05, 0.1, 0.2, and 0.3): Hall sign reversal in Eu1-xLaxB6 (x=0.2)

    NASA Astrophysics Data System (ADS)

    Rhyee, Jong-Soo; Kim, J. Y.; Cho, B. K.; Lee, H. J.; Kim, H. C.; Park, Hyun Min

    2006-12-01

    We have investigated the electric and magnetic properties of series compounds of Eu1-xLaxB6 ( x=0.0 , 0.05, 0.1, 0.2, and 0.3). It is found that the magnetic ground state changes gradually with increasing La concentration from ferromagnetic to antiferromagnetic, which results in ferromagnetic transition at Tc=15K for Eu1-xLaxB6 (x=0.0) and antiferromagnetic transition at TN=9K for Eu1-xLaxB6 (x=0.3) . For Eu1-xLaxB6 ( x=0.05 , 0.1, and 0.2), the temperature-dependent resistivity ρ(T) shows anomalous gaplike increase at low temperatures below ≈15K whereas it is metallic at high temperatures. In addition, the temperature-dependent magnetization M(T) shows spin-glass-type thermal hysteresis, indicating magnetic instability at low temperatures below Tc and TN . Hall resistivity ρxy measurement shows a nonlinear behavior of ρxy(B) in the field and temperature ranges, 0T≤H≤2T and 2K≤T≤40K , for Eu1-xLaxB6 ( x=0.05 , 0.1, and 0.3), which is likely due to asymmetric magnetic scattering and spin-orbit coupling. Remarkably, a sign reversal of temperature-dependent Hall coefficient RH(T) was observed for Eu1-xLaxB6 (x=0.2):RH(T) is negative at high temperatures and positive at low temperatures below T≈25K . The temperature-dependent thermoelectric power TEP S(T) also shows the similar sign reversal at T≈26K for Eu1-xLaxB6 (x=0.2) , whereas it is negative for the whole temperature range 2K≤T≤300K for Eu1-xLaxB6 ( x=0.05 , 0.1, and 0.3). None of the known models, as we know, was found to describe fully the Hall and TEP sign change. Based on the investigated electric and magnetic properties, we conjectured that the sign reversal of RH(T) and S(T) would be closely correlated with the magnetic instability.

  15. The Use of Sign Language Pronouns by Native-Signing Children with Autism.

    PubMed

    Shield, Aaron; Meier, Richard P; Tager-Flusberg, Helen

    2015-07-01

    We report the first study on pronoun use by an under-studied research population, children with autism spectrum disorder (ASD) exposed to American Sign Language from birth by their deaf parents. Personal pronouns cause difficulties for hearing children with ASD, who sometimes reverse or avoid them. Unlike speech pronouns, sign pronouns are indexical points to self and other. Despite this transparency, we find evidence from an elicitation task and parental report that signing children with ASD avoid sign pronouns in favor of names. An analysis of spontaneous usage showed that all children demonstrated the ability to point, but only children with better-developed sign language produced pronouns. Differences in language abilities and self-representation may explain these phenomena in sign and speech. PMID:25643865

  16. The Use of Sign Language Pronouns by Native-Signing Children with Autism

    PubMed Central

    Shield, Aaron; Meier, Richard P.; Tager-Flusberg, Helen

    2015-01-01

    We report the first study on pronoun use by an under-studied research population, children with autism spectrum disorder (ASD) exposed to American Sign Language (ASL) from birth by their deaf parents. Personal pronouns cause difficulties for hearing children with ASD, who sometimes reverse or avoid them. Unlike speech pronouns, sign pronouns are indexical points to self and other. Despite this transparency, we find evidence from an elicitation task and parental report that signing children with ASD avoid sign pronouns in favor of names. An analysis of spontaneous usage showed that all children demonstrated the ability to point, but only children with better-developed sign language produced pronouns. Differences in language abilities and self-representation may explain these phenomena in sign and speech. PMID:25643865

  17. British Sign Name Customs

    ERIC Educational Resources Information Center

    Day, Linda; Sutton-Spence, Rachel

    2010-01-01

    Research presented here describes the sign names and the customs of name allocation within the British Deaf community. While some aspects of British Sign Language sign names and British Deaf naming customs differ from those in most Western societies, there are many similarities. There are also similarities with other societies outside the more…

  18. Sign, Symbol and Form.

    ERIC Educational Resources Information Center

    Ballinger, Louise Bowen; Ballinger, Raymond A.

    Signs are such a commonplace sight in our everyday lives, that we can easily miss the artistic beauty and graphic harmony of the symbols used. Thoughtfully well designed and planned signs communicate with a simplicity and directness that signmakers and designers have adhered to for ages. Even contemporary signs still reflect their timelessness…

  19. On the System of Person-Denoting Signs in Estonian Sign Language: Estonian Name Signs

    ERIC Educational Resources Information Center

    Paales, Liina

    2010-01-01

    This article discusses Estonian personal name signs. According to study there are four personal name sign categories in Estonian Sign Language: (1) arbitrary name signs; (2) descriptive name signs; (3) initialized-descriptive name signs; (4) loan/borrowed name signs. Mostly there are represented descriptive and borrowed personal name signs among…

  20. Bar Instability in Disk-Halo Systems

    NASA Astrophysics Data System (ADS)

    Sellwood, J. A.

    2016-03-01

    We show that the exponential growth rate of a bar in a stellar disk is substantially greater when the disk is embedded in a live halo than in a rigid one having the same mass distribution. We also find that the vigor of the instability in disk-halo systems varies with the shape of the halo velocity ellipsoid. Disks in rigid halos that are massive enough to be stable by the usual criteria, quickly form bars in isotropic halos and much greater halo mass is needed to avoid a strong bar; thus stability criteria derived for disks in rigid halos do not apply when the halo is responsive. The study presented here is of an idealized family of models with near uniform central rotation and that lack an extended halo; we present more realistic models with extended halos in a companion paper. The puzzle presented by the absence of strong bars in some galaxies having gently rising inner rotation curves is compounded by the results presented here.

  1. The Anemic Stellar Halo of M101

    NASA Astrophysics Data System (ADS)

    Holwerda, Benne

    2014-10-01

    Models of galaxy formation in a cosmological context predict that massive disk galaxies should have richly-structured extended stellar halos, containing ~10% of a galaxy's stars, originating in large part from the tidal disruption of dwarf galaxies. Observations of a number of nearby disk galaxies have generally agreed with these expectations. Recent new observations in integrated light with a novel array of low scattered-light telephoto lenses have failed to convincingly detect a stellar halo in the nearby massive face-on disk galaxy M101 (van Dokkum et al. 2014). They argue that any halo has to have <0.3% of the mass of the galaxy. This halo would be the least massive of any massive disk galaxy in the local Universe (by factors of several) -- such a halo is not predicted or naturally interpreted by the models, and would present a critical challenge to the picture of ubiquitous stellar halos formed from the debris of disrupting dwarf galaxies.We propose to resolve the stellar populations of this uniquely anemic stellar halo for 6 orbits with HST (ACS and WFC3), allowing us to reach surface brightness limits sufficient to clearly detect and characterize M101's stellar halo if it carries more than 0.1% of M101's mass. With resolved stellar populations, we can use the gradient of stellar populations as a function of radius to separate stellar halo from disk, which is impossible using integrated light observations. The resolved stellar populations will reveal the halo mass to much greater accuracy, measure the halo radial profile, constrain any halo lopsidedness, estimate the halo's stellar metallicity, and permit an analysis of outer disk stellar populations.

  2. Halo ion trap mass spectrometer.

    PubMed

    Austin, Daniel E; Wang, Miao; Tolley, Samuel E; Maas, Jeffrey D; Hawkins, Aaron R; Rockwood, Alan L; Tolley, H Dennis; Lee, Edgar D; Lee, Milton L

    2007-04-01

    We describe a novel radio frequency ion trap mass analyzer based on toroidal trapping geometry and microfabrication technology. The device, called the halo ion trap, consists of two parallel ceramic plates, the facing surfaces of which are imprinted with sets of concentric ring electrodes. Radii of the imprinted rings range from 5 to 12 mm, and the spacing between the plates is 4 mm. Unlike conventional ion traps, in which hyperbolic metal electrodes establish equipotential boundary conditions, electric fields in the halo ion trap are established by applying different radio frequency potentials to each ring. The potential on each ring can be independently optimized to provide the best trapping field. The halo ion trap features an open structure, allowing easy access for in situ ionization. The toroidal geometry provides a large trapping and analyzing volume, increasing the number of ions that can be stored and reducing the effects of space-charge on mass analysis. Preliminary mass spectra show resolution (m/Deltam) of 60-75 when the trap is operated at 1.9 MHz and 500 Vp-p. PMID:17335180

  3. Halo Microlensing and Dark Baryons

    NASA Astrophysics Data System (ADS)

    Crotts, A. P. S.

    1993-12-01

    (While Pierce lectures review past accomplishments, customarily, this talk concerns efforts which we have pursued for some years and which are now reaching fruition. We present elsewhere at this meeting results from research cited for the Prize.) Dark matter exists in the halos of spiral galaxies, and the least radical alternative for its identity is normal matter produced by primordial nucleosynthesis. This matter could easily be hidden in large, condensed objects. Paczynski pointed out in 1986 that if condensations of Galactic halo matter are sufficiently massive, they will produce detectable amplification of background starlight by gravitational lensing. Several groups recently reported possible detections of this effect after surveying large numbers of stars in the Galactic Bulge and LMC. The connection between these events and massive, dark halos is unclear and likely to remain so for some time, given the rate at which they are detected. Following Paczynski's realization, we stressed that a much higher event rate, a statistical control sample, sensitivity to a much broader mass range, and modulation of the predicted lensing rate with galactocentric distance can all be realized by a different experiment: observing the halo of M31 (and the Galaxy) using stars in M31. In some ways, M31 is a more difficult target than the LMC or the Bulge, given the faintness of its stars, but our observations in 1991 and 1993 indicate that these problems have been surmounted. We can detect stellar variability even under extremely crowded conditions like those in M31's inner disk, and can monitor a sufficient number of stars to study halo lensing. We present results from our initial survey which indicates that the required sensitivity can be reached to confirm or reject the hypothesis that sub-solar masses like those detected in our Galaxy make up the missing spiral galaxy mass. It is possible that we may use the data already obtained (and still being analyzed) to place

  4. Magnetized galactic haloes and velocity lags

    NASA Astrophysics Data System (ADS)

    Henriksen, R. N.; Irwin, J. A.

    2016-06-01

    We present an analytic model of a magnetized galactic halo surrounding a Mestel gravitating disc. The magnetic field is taken to be in energy equipartition with the pressure dominant rotating halo gas (not with the cosmic rays), and the whole system is in a steady state. A more flexible `anisotropic equipartition' model is also explored. A definite pressure law is required to maintain the equilibrium, but the halo density is constant. The velocity/magnetic system is scale-free. The objective is to find the rotational velocity lag in such a halo. The magnetic field is not force-free so that angular momentum may be transported from the halo to the intergalactic medium. We find that the `X'-shaped structure observed for halo magnetic fields can be obtained together with a simple analytic formula for the rate of decline of the velocity with height z. The formula also predicts the change in lag with radius, r.

  5. Procedure for simulating divergent-light halos

    NASA Astrophysics Data System (ADS)

    Gislén, Lars

    2003-11-01

    Divergent-light halos are halos produced by light from nearby light sources, like street lamps being scattered by small crystals of ice floating in the air. The use of ``brute-force'' Monte Carlo methods to simulate such halos is extremely inefficient, as most scattered rays will not hit the eye of the observer. I present a new procedure for Monte Carlo simulations of divergent-light halos. This procedure uses rotational symmetries to make a selected sampling of events that greatly improves the computational efficiency of the algorithm. We can typically generate a simulated halo display in minutes using a personal computer, several orders of magnitude more rapid than a simple brute-force method. The algorithm can also optionally generate three-dimensional pictures of divergent-light halo displays.

  6. Halotools: Galaxy-Halo connection models

    NASA Astrophysics Data System (ADS)

    Hearin, Andrew; Tollerud, Erik; Robitaille, Thomas; Droettboom, Michael; Zentner, Andrew; Bray, Erik; Craig, Matt; Bradley, Larry; Barbary, Kyle; Deil, Christoph; Tan, Kevin; Becker, Matthew R.; More, Surhud; Günther, Hans Moritz; Sipocz, Brigitta

    2016-04-01

    Halotools builds and tests models of the galaxy-halo connection and analyzes catalogs of dark matter halos. The core functions of the package include fast generation of synthetic galaxy populations using HODs, abundance matching, and related methods; efficient algorithms for calculating galaxy clustering, lensing, z-space distortions, and other astronomical statistics; a modular, object-oriented framework for designing galaxy evolution models; and end-to-end support for reducing halo catalogs and caching them as hdf5 files.

  7. Halo Effective Field Theory of 6He

    NASA Astrophysics Data System (ADS)

    Thapaliya, Arbin; Ji, Chen; Phillips, Daniel

    2016-03-01

    6He has a cluster structure with a tight 4He (α) core surrounded by two loosely bound neutrons (n) making it a halo nucleus. The leading-order (LO) Halo Effective Field Theory (EFT) [1, 2] calculations using momentum-space Faddeev equations pertinent to a bound 6He were carried out in [3]. In this work, we investigate 6He up to next-to-leading order (NLO) within Halo EFT.

  8. The evolution of galaxy star formation activity in massive haloes

    NASA Astrophysics Data System (ADS)

    Popesso, P.; Biviano, A.; Finoguenov, A.; Wilman, D.; Salvato, M.; Magnelli, B.; Gruppioni, C.; Pozzi, F.; Rodighiero, G.; Ziparo, F.; Berta, S.; Elbaz, D.; Dickinson, M.; Lutz, D.; Altieri, B.; Aussel, H.; Cimatti, A.; Fadda, D.; Ilbert, O.; Le Floch, E.; Nordon, R.; Poglitsch, A.; Xu, C. K.

    2015-02-01

    Context. There is now a large consensus that the current epoch of the cosmic star formation history (CSFH) is dominated by low mass galaxies while the most active phase, between redshifts 1 and 2, is dominated by more massive galaxies, which evolve more quickly. Aims: Massive galaxies tend to inhabit very massive haloes, such as galaxy groups and clusters. We aim to understand whether the observed "galaxy downsizing" could be interpreted as a "halo downsizing", whereas the most massive haloes, and their galaxy populations, evolve more rapidly than the haloes with lower mass. Methods: We studied the contribution to the CSFH of galaxies inhabiting group-sized haloes. This is done through the study of the evolution of the infra-red (IR) luminosity function of group galaxies from redshift 0 to redshift ~1.6. We used a sample of 39 X-ray-selected groups in the Extended Chandra Deep Field South (ECDFS), the Chandra Deep Field North (CDFN), and the COSMOS field, where the deepest available mid- and far-IR surveys have been conducted with Spitzer MIPS and with the Photodetector Array Camera and Spectrometer (PACS) on board the Herschel satellite. Results: Groups at low redshift lack the brightest, rarest, and most star forming IR-emitting galaxies observed in the field. Their IR-emitting galaxies contribute ≤10% of the comoving volume density of the whole IR galaxy population in the local Universe. At redshift ≳1, the most IR-luminous galaxies (LIRGs and ULIRGs) are mainly located in groups, and this is consistent with a reversal of the star formation rate (SFR) vs. density anti-correlation observed in the nearby Universe. At these redshifts, group galaxies contribute 60-80% of the CSFH, i.e. much more than at lower redshifts. Below z ~ 1, the comoving number and SFR densities of IR-emitting galaxies in groups decline significantly faster than those of all IR-emitting galaxies. Conclusions: Our results are consistent with a "halo downsizing" scenario and highlight the

  9. The local density of halo giants

    NASA Technical Reports Server (NTRS)

    Morrison, Heather L.

    1993-01-01

    A new estimate of the local density of halo giants - 36 +/- 7 with M(V) less than 0.5 per cu kpc - is presented. This number is derived from an objective-prism survey for nearby metal-weak stars, and so is free from many of the assumptions needed to derive the local halo density in the traditional way, from high proper motion surveys. This number agrees well with estimates of the local density of halo horizontal-branch stars, but is approximately a factor of 2 smaller than the density derived by Bahcall and Casertano (1986). This may be due to the inclusion of some thick disk stars in their proper-motion selected sample. The halo density derived from giants can be expressed as a disk-to-halo ratio of 850:1 (+/- 35 percent). Using these results, a simple model is built to predict numbers of halo giants in specified directions in the Galaxy. It is shown that it performs much better than the Bahcall-Soniera model, in the specific case of halo giants. The surface brightness due to the halo at the solar radius is calculated to be 27.7 V magnitudes per sq arcsec, if the Galaxy was viewed from the outside, edge-on, thus raising the possibility of detecting light from halo field stars in other galaxies similar to our own.

  10. PAHs in the halo of NGC 5529

    NASA Astrophysics Data System (ADS)

    Irwin, J. A.; Kennedy, H.; Parkin, T.; Madden, S.

    2007-11-01

    We present sensitive ISO λ 6.7~μm observations of the edge-on galaxy, NGC 5529, finding an extensive MIR halo around NGC 5529. The emission is dominated by PAHs in this band. The PAH halo has an exponential scale height of 3.7 kpc but can still be detected as far as ≈10 kpc from the plane to the limits of the high dynamic range (1770/1) data. This is the most extensive PAH halo yet detected in a normal galaxy. This halo shows substructure and the PAHs likely originate from some type of disk outflow. PAHs are long-lived in a halo environment and therefore continuous replenishment from the disk is not required (unless halo PAHs are also being destroyed or removed), consistent with the current low SFR of the galaxy. The PAHs correlate spatially with halo Hα emission, previously observed by Miller & Veilleux (2003, ApJS, 148, 383); both components are likely excited/ionized by in-disk photons that are leaking into the halo. The presence of halo gas may be related to the environment of NGC 5529 which contains at least 17 galaxies in a small group of which NGC 5529 is the dominant member. Of these, we have identified two new companions from the SDSS.

  11. Studying Stellar Halos with Future Facilities

    NASA Astrophysics Data System (ADS)

    Greggio, Laura; Falomo, Renato; Uslenghi, Michela

    2015-08-01

    Stellar halos around galaxies retain fundamental evidence of the processes which lead to their build up. Sophisticated models of galaxy formation in a cosmological context yield quantitative predictions about various observable characteristics, including the amount of substructure, the slope of radial mass profiles and three dimensional shapes, and the properties of the stellar populations in the galaxies halos. The comparison of such models with the observations leads to constraints on the general picture of galaxy formation in the hierarchical Universe, as well as on the physical processes taking place in the halos formation. With the current observing facilities, stellar halos can be effectively probed only for a limited number of nearby galaxies. In this contribution we illustrate the progress which we expect in this field with the future large aperture ground based telescopes (E-ELT and TNT), and with JWST. In particular we adress the following issues: (I) the characterization of the stellar populations in the halos innermost regions and substructures, (ii) the measurement of the halos profiles and shapes , and the halos mass content, (iii) the study of Globular Clusters inhabiting the halos of distant galaxies. In order to assess the expected capabilities of future facilities we present the results of a set of simulated images to evaluate to which level of accuracy it will be possible to probe the halos of distant galaxies.

  12. THE GALAXY-HALO/SUBHALO CONNECTION: MASS RELATIONS AND IMPLICATIONS FOR SOME SATELLITE OCCUPATIONAL DISTRIBUTIONS

    SciTech Connect

    Rodriguez-Puebla, A.; Avila-Reese, V.; Drory, N.

    2013-04-10

    We infer the local stellar-to-halo/subhalo mass relations (MRs) for central and satellite galaxies separately. Our statistical method is an extension of the abundance matching, halo occupation distribution, and conditional stellar mass function formalisms. We constrain the model using several combinations of observational data, consisting of the total galaxy stellar mass function (GSMF), its decomposition into centrals and satellites, and the projected two-point correlation functions (2PCFs) measured in different stellar mass (M{sub *}) bins. In addition, we use the {Lambda}CDM halo and subhalo mass functions. The differences among the resulting MRs are within the model-fit uncertainties (which are very small, smaller than the intrinsic scatter between galaxy and halo mass), no matter what combination of data are used. This shows that matching abundances or occupational numbers is equivalent, and that the GSMFs and 2PCFs are tightly connected. We also constrain the values of the intrinsic scatter around the central-halo (CH) and satellite-subhalo (SS) MRs assuming them to be constant: {sigma}{sub c} = 0.168 {+-} 0.051 dex and {sigma}{sub s} = 0.172 {+-} 0.057 dex, respectively. The CH and SS MRs are actually different, in particular when we take the subhalo mass at the present-day epoch instead of at their accretion time. When using the MRs for studying the satellite population (e.g., in the Milky Way, MW), the SS MR should be chosen instead of the average one. Our model allows one to calculate several population statistics. We find that the central galaxy M{sub *} is not on average within the mass distribution of the most massive satellite, even for cluster-sized halos, i.e., centrals are not a mere realization of the high end of the satellite mass function; however for >3 Multiplication-Sign 10{sup 13} M{sub Sun} halos, {approx}15% of centrals could be. We also find that the probabilities of MW-sized halos of having N Magellanic Cloud (MC) sized satellites agree

  13. Haloes seen in UVIS reflectance

    NASA Astrophysics Data System (ADS)

    Esposito, L. W.; Bradley, E. T.; Colwell, J. E.; Sremcevic, M.

    2012-12-01

    UVIS SOI reflectance spectra show bright 'haloes' around the locations of some of the strongest resonances in Saturn's A ring (Esposito etal 2005). UV spectra constrain the size and composition of the icy ring particles (Bradley etal 2010, 2012). We investigate the Janus 4:3, 5:3, 6:5 and Mimas 5:3 inner Lindblad resonances as well as at the Mimas 5:3 vertical resonance (bending wave location). Models of ring particle regolith evolution (Elliott and Esposito 2010) indicate the deeper regolith is made of older and purer ice. The strong resonances can cause streamline crowding (Lewis and Stewart 2005) which damps the interparticle velocity, allowing temporary clumps to grow, which in turn increase the velocity, eroding the clumps and releasing smaller particles and regolith (see the predator-prey model of Esposito etal 2012). This cyclic behavior, driven by the resonant perturbation from the moon, can yield collision velocities at particular azimuths greater than 1m/sec, sufficient to erode the aggregates (Blum 2006), exposing older, purer materials. Thus, the radial location of the strongest resonances can be where we find both large aggregates and disrupted fragments, in a balance maintained by the periodic moon forcing. If this stirring exposes older, and purer ice, the velocity threshold for eroding the aggregates can explain why only the strongest Lindblad resonances show haloes. Diffusion can explain the morphology of these haloes, although they are not well-resolved spatially by UVIS. Spectra determine the relative contributions of particle size and purity at these locations, for comparison to estimates from the regolith evolution models.

  14. THE PSEUDO-EVOLUTION OF HALO MASS

    SciTech Connect

    Diemer, Benedikt; Kravtsov, Andrey V.; More, Surhud

    2013-03-20

    A dark matter halo is commonly defined as a spherical overdensity of matter with respect to a reference density, such as the critical density or the mean matter density of the universe. Such definitions can lead to a spurious pseudo-evolution of halo mass simply due to redshift evolution of the reference density, even if its physical density profile remains constant over time. We estimate the amount of such pseudo-evolution of mass between z = 1 and 0 for halos identified in a large N-body simulation, and show that it accounts for almost the entire mass evolution of the majority of halos with M{sub 200{rho}-bar} Less-Than-Or-Equivalent-To 10{sup 12} h{sup -1} M{sub Sun} and can be a significant fraction of the apparent mass growth even for cluster-sized halos. We estimate the magnitude of the pseudo-evolution assuming that halo density profiles remain static in physical coordinates, and show that this simple model predicts the pseudo-evolution of halos identified in numerical simulations to good accuracy, albeit with significant scatter. We discuss the impact of pseudo-evolution on the evolution of the halo mass function and show that the non-evolution of the low-mass end of the halo mass function is the result of a fortuitous cancellation between pseudo-evolution and the absorption of small halos into larger hosts. We also show that the evolution of the low-mass end of the concentration-mass relation observed in simulations is almost entirely due to the pseudo-evolution of mass. Finally, we discuss the implications of our results for the interpretation of the evolution of various scaling relations between the observable properties of galaxies and galaxy clusters and their halo masses.

  15. Alignments between galaxies, satellite systems and haloes

    NASA Astrophysics Data System (ADS)

    Shao, Shi; Cautun, Marius; Frenk, Carlos S.; Gao, Liang; Crain, Robert A.; Schaller, Matthieu; Schaye, Joop; Theuns, Tom

    2016-08-01

    The spatial distribution of the satellite populations of the Milky Way and Andromeda are puzzling in that they are nearly perpendicular to the disks of their central galaxies. To understand the origin of such configurations we study the alignment of the central galaxy, satellite system and dark matter halo in the largest of the "Evolution and Assembly of GaLaxies and their Environments" (EAGLE) simulation. We find that centrals and their satellite systems tend to be well aligned with their haloes, with a median misalignment angle of $33^{\\circ}$ in both cases. While the centrals are better aligned with the inner $10$ kpc halo, the satellite systems are better aligned with the entire halo indicating that satellites preferentially trace the outer halo. The central - satellite alignment is weak (median misalignment angle of $52^{\\circ}$) and we find that around $20\\%$ of systems have a misalignment angle larger than $78^{\\circ}$, which is the value for the Milky Way. The central - satellite alignment is a consequence of the tendency of both components to align with the dark matter halo. As a consequence, when the central is parallel to the satellite system, it also tends to be parallel to the halo. In contrast, if the central is perpendicular to the satellite system, as in the case of the Milky Way and Andromeda, then the central - halo alignment is much weaker. Dispersion-dominated (spheroidal) centrals have a stronger alignment with both their halo and their satellites than rotation-dominated (disk) centrals. We also found that the halo, the central galaxy and the satellite system tend to be aligned with the surrounding large-scale distribution of matter, with the halo being the better aligned of the three.

  16. Alignments between galaxies, satellite systems and haloes

    NASA Astrophysics Data System (ADS)

    Shao, Shi; Cautun, Marius; Frenk, Carlos S.; Gao, Liang; Crain, Robert A.; Schaller, Matthieu; Schaye, Joop; Theuns, Tom

    2016-08-01

    The spatial distribution of the satellite populations of the Milky Way and Andromeda are puzzling in that they are nearly perpendicular to the discs of their central galaxies. To understand the origin of such configurations we study the alignment of the central galaxy, satellite system and dark matter halo in the largest of the `Evolution and Assembly of GaLaxies and their Environments' (EAGLE) simulation. We find that centrals and their satellite systems tend to be well aligned with their haloes, with a median misalignment angle of 33° in both cases. While the centrals are better aligned with the inner 10 kpc halo, the satellite systems are better aligned with the entire halo indicating that satellites preferentially trace the outer halo. The central-satellite alignment is weak (median misalignment angle of 52°) and we find that around 20 per cent of systems have a misalignment angle larger than 78°, which is the value for the Milky Way. The central-satellite alignment is a consequence of the tendency of both components to align with the dark matter halo. As a consequence, when the central is parallel to the satellite system, it also tends to be parallel to the halo. In contrast, if the central is perpendicular to the satellite system, as in the case of the Milky Way and Andromeda, then the central-halo alignment is much weaker. Dispersion-dominated (spheroidal) centrals have a stronger alignment with both their halo and their satellites than rotation-dominated (disc) centrals. We also found that the halo, the central galaxy and the satellite system tend to be aligned with the surrounding large-scale distribution of matter, with the halo being the better aligned of the three.

  17. Standardization of Sign Languages

    ERIC Educational Resources Information Center

    Adam, Robert

    2015-01-01

    Over the years attempts have been made to standardize sign languages. This form of language planning has been tackled by a variety of agents, most notably teachers of Deaf students, social workers, government agencies, and occasionally groups of Deaf people themselves. Their efforts have most often involved the development of sign language books…

  18. Correlating galaxy colour and halo concentration: a tunable halo model of galactic conformity

    NASA Astrophysics Data System (ADS)

    Paranjape, Aseem; Kovač, Katarina; Hartley, William G.; Pahwa, Isha

    2015-12-01

    We extend the halo occupation distribution (HOD) framework to generate mock galaxy catalogues exhibiting varying levels of `galactic conformity', which has emerged as a potentially powerful probe of environmental effects in galaxy evolution. Our model correlates galaxy colours in a group with the concentration of the common parent dark halo through a `group quenching efficiency' ρ which makes older, more concentrated haloes at fixed mass preferentially host redder galaxies. We find that, for a specific value of ρ, this 1-halo conformity matches corresponding measurements in a group catalogue based on the Sloan Digital Sky Survey. Our mocks also display conformity at large separations from isolated objects, potentially an imprint of halo assembly bias. A detailed study - using mocks with assembly bias erased while keeping 1-halo conformity intact - reveals a rather nuanced situation, however. At separations ≲4 Mpc, conformity is mainly a 1-halo effect dominated by the largest haloes and is not a robust indicator of assembly bias. Only at very large separations (≳8 Mpc) does genuine 2-halo conformity, driven by the assembly bias of small haloes, manifest distinctly. We explain all these trends in standard halo model terms. Our model opens the door to parametrized HOD analyses that self-consistently account for galactic conformity at all scales.

  19. XMM-NEWTON DETECTS A HOT GASEOUS HALO IN THE FASTEST ROTATING SPIRAL GALAXY UGC 12591

    SciTech Connect

    Dai Xinyu; Anderson, Michael E.; Bregman, Joel N.; Miller, Jon M.

    2012-08-20

    We present our XMM-Newton observation of the fastest rotating spiral galaxy UGC 12591. We detect hot gas halo emission out to 80 kpc from the galaxy center, and constrain the halo gas mass to be smaller than 4.5 Multiplication-Sign 10{sup 11} M{sub Sun }. We also measure the temperature of the hot gas as T = 0.64 {+-} 0.03 keV. Combining our x-ray constraints and the near-infrared and radio measurements in the literature, we find a baryon mass fraction of 0.03-0.05 in UGC 12591, suggesting a missing baryon mass of 70% compared with the cosmological mean value. Combined with another recent measurement in NGC 1961, the result strongly argues that the majority of missing baryons in spiral galaxies do not reside in their hot halos. We also find that UGC 12591 lies significantly below the baryonic Tully-Fisher relationship. Finally, we find that the baryon fractions of massive spiral galaxies are similar to those of galaxy groups with similar masses, indicating that the baryon loss is ultimately controlled by the gravitational potential well. The cooling radius of this gas halo is small, similar to NGC 1961, which argues that the majority of the stellar mass of this galaxy is not assembled as a result of cooling of this gas halo.

  20. Swirling around filaments: are large-scale structure vortices spinning up dark haloes?

    NASA Astrophysics Data System (ADS)

    Laigle, C.; Pichon, C.; Codis, S.; Dubois, Y.; Le Borgne, D.; Pogosyan, D.; Devriendt, J.; Peirani, S.; Prunet, S.; Rouberol, S.; Slyz, A.; Sousbie, T.

    2015-01-01

    The kinematic analysis of dark matter and hydrodynamical simulations suggests that the vorticity in large-scale structure is mostly confined to, and predominantly aligned with, their filaments, with an excess of probability of 20 per cent to have the angle between vorticity and filaments direction lower than 60° relative to random orientations. The cross-sections of these filaments are typically partitioned into four quadrants with opposite vorticity sign, arising from multiple flows, originating from neighbouring walls. The spins of haloes embedded within these filaments are consistently aligned with this vorticity for any halo mass, with a stronger alignment for the most massive structures up to an excess of probability of 165 per cent. The global geometry of the flow within the cosmic web is therefore qualitatively consistent with a spin acquisition for smaller haloes induced by this large-scale coherence, as argued in Codis et al. In effect, secondary anisotropic infall (originating from the vortex-rich filament within which these lower-mass haloes form) dominates the angular momentum budget of these haloes. The transition mass from alignment to orthogonality is related to the size of a given multi-flow region with a given polarity. This transition may be reconciled with the standard tidal torque theory if the latter is augmented so as to account for the larger scale anisotropic environment of walls and filaments.

  1. Correlates of Halo Error in Teacher Evaluation.

    ERIC Educational Resources Information Center

    Moritsch, Brian G.; Suter, W. Newton

    1988-01-01

    An analysis of 300 undergraduate psychology student ratings of teachers was undertaken to assess the magnitude of halo error and a variety of rater, ratee, and course characteristics. The raters' halo errors were significantly related to student effort in the course, previous experience with the instructor, and class level. (TJH)

  2. Confounding among Measures of Leniency and Halo.

    ERIC Educational Resources Information Center

    Alliger, George M.; Williams, Kevin J.

    1989-01-01

    The interrelationships among halo and leniency rating errors were examined using simulated rating data. As leniency increased, halo decreased when measured by dimension intercorrelations but increased when measured by standard deviations across dimensions. Implications of these results for the use of the various measures are discussed. (SLD)

  3. Comments on the Measurement of Halo.

    ERIC Educational Resources Information Center

    Fisicaro, Sebastiano A.; Vance, Robert J.

    1994-01-01

    This article presents arguments that the correlation measure "r" of halo is not conceptually more appropriate than the standard deviation (SD) measure. It also describes conditions under which halo effects occur and when the SD and r measures can be used. Neither measure is uniformly superior to the other. (SLD)

  4. Milky Way halo gas kinematics

    NASA Technical Reports Server (NTRS)

    Danly, L.

    1986-01-01

    Measurements of high resolution, short wavelength absorption data taken by IUE toward high latitude O and B stars are presented in a discussion of the large scale kinematic properties of Milky Way Halo gas. An analysis of these data demonstrates that: (1) the obsrved absorption widths (FWHM) of Si II are very large, ranging up to 150 Km/s for the most distant halo star; this is much larger than is generally appreciated from optical data; (2) the absorption is observed to be systematically negative in radial velocity, indicating that cool material is, on the whole, flowing toward the disk of the galaxy; (3) there is some evidence for asymmetry between the northern and southern galactic hemispheres, in accordance with the HI 21 cm data toward the galactic poles; (4) low column density gas with highly negative radial LSR velocity (V less than -70 km/s) can be found toward stars beyond 1-3 kpc in the northern galactic hemisphere in all four quadrants of galactic longitude; and (5) only the profiles toward stars in the direction of known high velocity HI features show a clear two component structure.

  5. Radiative reactions in halo effective field theory

    NASA Astrophysics Data System (ADS)

    Rupak, Gautam

    2016-03-01

    In this article we review the recent progress in radiative reaction calculations in halo effective field theory. We look at radiative capture and breakup processes that involve a halo nucleus with a single valence neutron or proton. Looking at 7Li(n,γ) 8Li,14C(n,γ)15C and related reactions, the dominant source of theoretical uncertainty in s- and p-wave halo nuclei reaction calculations is quantified in a model-independent framework. The analysis for neutron halos is extended to proton halo systems. The effective field theory results quantify which observable parameters of the strong interaction at low energy need to be determined more precisely for accurate cross-section calculations.

  6. Smooth halos in the cosmic web

    NASA Astrophysics Data System (ADS)

    Gaite, José

    2015-04-01

    Dark matter halos can be defined as smooth distributions of dark matter placed in a non-smooth cosmic web structure. This definition of halos demands a precise definition of smoothness and a characterization of the manner in which the transition from smooth halos to the cosmic web takes place. We introduce entropic measures of smoothness, related to measures of inequality previously used in economy and with the advantage of being connected with standard methods of multifractal analysis already used for characterizing the cosmic web structure in cold dark matter N-body simulations. These entropic measures provide us with a quantitative description of the transition from the small scales portrayed as a distribution of halos to the larger scales portrayed as a cosmic web and, therefore, allow us to assign definite sizes to halos. However, these ``smoothness sizes'' have no direct relation to the virial radii. Finally, we discuss the influence of N-body discreteness parameters on smoothness.

  7. On the Reversal of Star formation Rate-Density Relation at z = 1: Insights from Simulations

    NASA Astrophysics Data System (ADS)

    Tonnesen, Stephanie; Cen, Renyue

    2014-06-01

    Recent surveys have found a reversal of the star formation rate (SFR)-density relation at z = 1 from that at z = 0, while the sign of the slope of the color-density relation remains unchanged. We use adaptive mesh refinement cosmological hydrodynamic simulations of a 21 × 24 × 20 h -3 Mpc3 region to examine the SFR-density and color-density relations of galaxies at z = 0 and z = 1. The local environmental density is defined by the dark matter mass in spheres of radius 1 h -1 Mpc, and we probe two decades of environmental densities. Our simulations produce a large increase of SFR with density at z = 1, as in the Elbaz et al. observations. We also find a significant evolution to z = 0, where the SFR-density relation is much flatter. The simulated color-density relation is consistent from z = 1 to z = 0, in agreement with observations. We find that the increase in SFR with local density at z = 1 is due to a growing population of star-forming galaxies in higher-density environments. At z = 0 and z = 1 both the SFR and cold gas mass are correlated with the galaxy halo mass, and therefore the correlation between median halo mass and local density is an important cause of the SFR-density relation at both redshifts. However, at z = 0 the local density on 1 h -1 Mpc scales affects galaxy SFRs as much as halo mass. Finally, we find indications that while at z = 0 high-density environments depress galaxy SFRs, at z = 1 high-density environments tend to increase SFRs.

  8. On the reversal of star formation rate-density relation at z = 1: Insights from simulations

    SciTech Connect

    Tonnesen, Stephanie; Cen, Renyue E-mail: cen@astro.princeton.edu

    2014-06-20

    Recent surveys have found a reversal of the star formation rate (SFR)-density relation at z = 1 from that at z = 0, while the sign of the slope of the color-density relation remains unchanged. We use adaptive mesh refinement cosmological hydrodynamic simulations of a 21 × 24 × 20 h {sup –3} Mpc{sup 3} region to examine the SFR-density and color-density relations of galaxies at z = 0 and z = 1. The local environmental density is defined by the dark matter mass in spheres of radius 1 h {sup –1} Mpc, and we probe two decades of environmental densities. Our simulations produce a large increase of SFR with density at z = 1, as in the Elbaz et al. observations. We also find a significant evolution to z = 0, where the SFR-density relation is much flatter. The simulated color-density relation is consistent from z = 1 to z = 0, in agreement with observations. We find that the increase in SFR with local density at z = 1 is due to a growing population of star-forming galaxies in higher-density environments. At z = 0 and z = 1 both the SFR and cold gas mass are correlated with the galaxy halo mass, and therefore the correlation between median halo mass and local density is an important cause of the SFR-density relation at both redshifts. However, at z = 0 the local density on 1 h {sup –1} Mpc scales affects galaxy SFRs as much as halo mass. Finally, we find indications that while at z = 0 high-density environments depress galaxy SFRs, at z = 1 high-density environments tend to increase SFRs.

  9. THE RESOLVED STELLAR HALO OF NGC 253

    SciTech Connect

    Bailin, Jeremy; Bell, Eric F.; Chappell, Samantha N.; Radburn-Smith, David J.; De Jong, Roelof S.

    2011-07-20

    We have obtained Magellan/IMACS and Hubble Space Telescope (HST)/Advanced Camera for Surveys imaging data that resolve red giant branch stars in the stellar halo of the starburst galaxy NGC 253. The HST data cover a small area, and allow us to accurately interpret the ground-based data, which cover 30% of the halo to a distance of 30 kpc, allowing us to make detailed quantitative measurements of the global properties and structure of a stellar halo outside of the Local Group. The geometry of the halo is significantly flattened in the same sense as the disk, with a projected axis ratio of b/a {approx} 0.35 {+-} 0.1. The total stellar mass of the halo is estimated to be M{sub halo} {approx} (2.5 {+-} 1.5) x 10{sup 9} M{sub sun}, or 6% of the total stellar mass of the galaxy, and has a projected radial dependence that follows a power law of index -2.8 {+-} 0.6, corresponding to a three-dimensional power-law index of {approx} - 4. The total luminosity and profile shape that we measure for NGC 253 are somewhat larger and steeper than the equivalent values for the Milky Way and M31, but are well within the scatter of model predictions for the properties of stellar halos built up in a cosmological context. Structure within the halo is seen at a variety of scales: there is small kpc-scale density variation and a large shelf-like feature near the middle of the field. The techniques that have been developed will be essential for quantitatively comparing our upcoming larger sample of observed stellar halos to models of halo formation.

  10. RHAPSODY. I. STRUCTURAL PROPERTIES AND FORMATION HISTORY FROM A STATISTICAL SAMPLE OF RE-SIMULATED CLUSTER-SIZE HALOS

    SciTech Connect

    Wu, Hao-Yi; Hahn, Oliver; Wechsler, Risa H.; Mao, Yao-Yuan; Behroozi, Peter S.

    2013-02-15

    We present the first results from the RHAPSODY cluster re-simulation project: a sample of 96 'zoom-in' simulations of dark matter halos of 10{sup 14.8{+-}0.05} h {sup -1} M {sub Sun }, selected from a 1 h {sup -3} Gpc{sup 3} volume. This simulation suite is the first to resolve this many halos with {approx}5 Multiplication-Sign 10{sup 6} particles per halo in the cluster mass regime, allowing us to statistically characterize the distribution of and correlation between halo properties at fixed mass. We focus on the properties of the main halos and how they are affected by formation history, which we track back to z = 12, over five decades in mass. We give particular attention to the impact of the formation history on the density profiles of the halos. We find that the deviations from the Navarro-Frenk-White (NFW) model and the Einasto model depend on formation time. Late-forming halos tend to have considerable deviations from both models, partly due to the presence of massive subhalos, while early-forming halos deviate less but still significantly from the NFW model and are better described by the Einasto model. We find that the halo shapes depend only moderately on formation time. Departure from spherical symmetry impacts the density profiles through the anisotropic distribution of massive subhalos. Further evidence of the impact of subhalos is provided by analyzing the phase-space structure. A detailed analysis of the properties of the subhalo population in RHAPSODY is presented in a companion paper.

  11. THE CORRELATED FORMATION HISTORIES OF MASSIVE GALAXIES AND THEIR DARK MATTER HALOS

    SciTech Connect

    Tinker, Jeremy L.; George, Matthew R.; Leauthaud, Alexie; Bundy, Kevin; Finoguenov, Alexis; Massey, Richard; Rhodes, Jason; Wechsler, Risa H.

    2012-08-10

    Using observations in the COSMOS field, we report an intriguing correlation between the star formation activity of massive ({approx}10{sup 11.4} M{sub Sun }) central galaxies, their stellar masses, and the large-scale ({approx}10 Mpc) environments of their group-mass ({approx}10{sup 13.6} M{sub Sun }) dark matter halos. Probing the redshift range z = [0.2, 1.0], our measurements come from two independent sources: an X-ray-detected group catalog and constraints on the stellar-to-halo mass relation derived from a combination of clustering and weak lensing statistics. At z = 1, we find that the stellar mass in star-forming (SF) centrals is a factor of two less than in passive centrals at the same halo mass. This implies that the presence or lack of star formation in group-scale centrals cannot be a stochastic process. By z = 0, the offset reverses, probably as a result of the different growth rates of these objects. A similar but weaker trend is observed when dividing the sample by morphology rather than star formation. Remarkably, we find that SF centrals at z {approx} 1 live in groups that are significantly more clustered on 10 Mpc scales than similar mass groups hosting passive centrals. We discuss this signal in the context of halo assembly and recent simulations, suggesting that SF centrals prefer halos with higher angular momentum and/or formation histories with more recent growth; such halos are known to evolve in denser large-scale environments. If confirmed, this would be evidence of an early established link between the assembly history of halos on large scales and the future properties of the galaxies that form inside them.

  12. Ophthalmic halo reduced lenses design

    NASA Astrophysics Data System (ADS)

    Limon, Ofer; Zalevsky, Zeev

    2015-05-01

    The halo effect is a very problematic visual artifact occurring in extended depth of focus or multi-focal ophthalmic lenses such as e.g. intra-ocular (after cataract surgery) or contact lenses when used in dark illumination conditions. This artifact is generated due to surface structures added on top of those lenses in order to increase their depth of focus or to realize multiple focal lengths. In this paper we present novel solution that can resolve this major problem of ophthalmic lenses. The proposed solution involves modification to the surface structure that realizes the extended depth of focus. Our solution is fabricated and numerically and experimentally validated also in preliminary in-vivo trials.

  13. Signs of Overload

    MedlinePlus

    ... Listen Text Size Email Print Share Signs of Overload Page Content Article Body Although stress is a ... 12 (Copyright © 2004 American Academy of Pediatrics) The information contained on this Web site should not be ...

  14. Warning Signs of Bullying

    MedlinePlus

    ... to talk to kids about bullying. Respond to Bullying Learn how to respond to bullying . From stopping ... away . Back to top Signs a Child is Bullying Others Kids may be bullying others if they: ...

  15. Symptoms and Warning Signs

    MedlinePlus

    ... Signs Past Issues / Spring 2008 Table of Contents Anorexia Nervosa emaciation (extremely thin from lack of nutrition) relentless ... from diuretic abuse severe dehydration from purging Binge Eating Disorder frequently eating large amounts of food (binge-eating) ...

  16. The du Bois sign.

    PubMed

    Voelpel, James H; Muehlberger, Thomas

    2011-03-01

    According to the current literature, the term "du Bois sign" characterizes the condition of a shortened fifth finger as a symptom of congenital syphilis, Down syndrome, dyscrania, and encephalic malformation. Modern medical dictionaries and text books attribute the eponym to the French gynecologist Paul Dubois (1795-1871). Yet, a literature analysis revealed incorrect references to the person and unclear definitions of the term. Our findings showed that the origin of the term is based on observations made by the Swiss dermatologist Charles du Bois (1874-1947) in connection with congenital syphilis. In addition, a further eponymical fifth finger sign is closely associated with the du Bois sign. In conclusion, the du Bois sign has only limited diagnostic value and is frequently occurring in the normal healthy population. PMID:21263293

  17. AN EXPERIMENTALLY ROBUST TECHNIQUE FOR HALO MEASUREMENT

    SciTech Connect

    Amundson, J.; Pellico, W.; Spentzouris, P.; Sullivan, T.; Spentzouris, Linda; /IIT, Chicago

    2006-03-01

    We propose a model-independent quantity, L/G, to characterize non-Gaussian tails in beam profiles observed with the Fermilab Booster Ion Profile Monitor. This quantity can be considered a measure of beam halo in the Booster. We use beam dynamics and detector simulations to demonstrate that L/G is superior to kurtosis as an experimental measurement of beam halo when realistic beam shapes, detector effects and uncertainties are taken into account. We include the rationale and method of calculation for L/G in addition to results of the experimental studies in the Booster where we show that L/G is a useful halo discriminator.

  18. Dwarf Galaxies in the Halo of NGC 891

    NASA Astrophysics Data System (ADS)

    Schulz, Earl

    2014-07-01

    We report the results of a survey of the region within 40 arcmin of NGC 891, a nearby nearly perfectly edge-on spiral galaxy. Candidate "non-stars" with diameters greater than 15 arcsec were selected from the GSC 2.3.2 catalog and cross-comparison of observations in several bands using archived GALEX, DSS2, WISE, and Two Micron All Sky Survey images identified contaminating stars, artifacts, and background galaxies, all of which were excluded. The resulting 71 galaxies, many of which were previously uncataloged, comprise a size-limited survey of the region. A majority of the galaxies are in the background of NGC 891 and are for the most part members of the A347 cluster at a distance of about 75 Mpc. The new finds approximately double the known membership of A347, previously thought to be relatively sparse. We identify a total of seven dwarf galaxies, most of which are new discoveries. The newly discovered dwarf galaxies are dim and gas-poor and may be associated with the previously observed arcs of red giant branch halo stars in the halo and the prominent H I filament and the lopsided features in the disk of NGC 891. Several of the dwarfs show signs of disruption, consistent with being remnants of an ancient collision.

  19. Dwarf galaxies in the halo of NGC 891

    SciTech Connect

    Schulz, Earl

    2014-07-20

    We report the results of a survey of the region within 40 arcmin of NGC 891, a nearby nearly perfectly edge-on spiral galaxy. Candidate 'non-stars' with diameters greater than 15 arcsec were selected from the GSC 2.3.2 catalog and cross-comparison of observations in several bands using archived GALEX, DSS2, WISE, and Two Micron All Sky Survey images identified contaminating stars, artifacts, and background galaxies, all of which were excluded. The resulting 71 galaxies, many of which were previously uncataloged, comprise a size-limited survey of the region. A majority of the galaxies are in the background of NGC 891 and are for the most part members of the A347 cluster at a distance of about 75 Mpc. The new finds approximately double the known membership of A347, previously thought to be relatively sparse. We identify a total of seven dwarf galaxies, most of which are new discoveries. The newly discovered dwarf galaxies are dim and gas-poor and may be associated with the previously observed arcs of red giant branch halo stars in the halo and the prominent H I filament and the lopsided features in the disk of NGC 891. Several of the dwarfs show signs of disruption, consistent with being remnants of an ancient collision.

  20. Symmetry in halo displays and symmetry in halo-making crystals.

    PubMed

    Können, Gunther P

    2003-01-20

    The relation between the symmetry in halo displays and crystal symmetry is investigated for halo displays that are generated by ensembles of crystals. It is found that, regardless of the symmetry of the constituent crystals, such displays are always left-right (L-R) symmetric if the crystals are formed from the surrounding vapor. L-R symmetry of a halo display implies here that the cross sections for formation of a halo arc on the left-hand side of the solar vertical and its right-hand side mirror image are equal. This property leaves room for two types of halo display only: a full symmetric one (mmm-symmetric), and a partial symmetric one (mm2-symmetric) in which halo constituents lack their counterparts on the other side of the parhelic circle. A partial symmetric display can occur only for point halos. Its occurrence implies that a number of symmetry elements are not present in the shape of the halo-making crystals. These elements are a center of inversion, any rotatory-inversion axis that is parallel to the crystal spin axis P, a mirror plane perpendicular to the P axis, and a twofold rotation axis perpendicular to the P axis. A simple conceptual method is presented to reconstruct possible shapes of the halo-generating crystals from the halos in the display. The method is illustrated in two examples. Halos that may occur on the Saturnian satellite Titan are discussed. The possibilities for the Huygens probe to detect these halos during its descent through the Titan clouds in 2005 are detailed. PMID:12570252

  1. HIDE AND SEEK BETWEEN ANDROMEDA'S HALO, DISK, AND GIANT STREAM

    SciTech Connect

    Clementini, Gisella; Contreras Ramos, Rodrigo; Federici, Luciana; Macario, Giulia; Tosi, Monica; Bellazzini, Michele; Fusi Pecci, Flavio; Diolaiti, Emiliano; Cacciari, Carla; Beccari, Giacomo; Testa, Vincenzo; Giallongo, Emanuele; Di Paola, Andrea; Gallozzi, Stefano; Cignoni, Michele; Marano, Bruno; Marconi, Marcella; Ripepi, Vincenzo; Ragazzoni, Roberto; Smareglia, Riccardo

    2011-12-10

    Photometry in B, V (down to V {approx} 26 mag) is presented for two 23' Multiplication-Sign 23' fields of the Andromeda galaxy (M31) that were observed with the blue channel camera of the Large Binocular Telescope during the Science Demonstration Time. Each field covers an area of about 5.1 Multiplication-Sign 5.1 kpc{sup 2} at the distance of M31 ({mu}{sub M31} {approx} 24.4 mag), sampling, respectively, a northeast region close to the M31 giant stream (field S2) and an eastern portion of the halo in the direction of the galaxy minor axis (field H1). The stream field spans a region that includes Andromeda's disk and giant stream, and this is reflected in the complexity of the color-magnitude diagram of the field. One corner of the halo field also includes a portion of the giant stream. Even though these demonstration time data were obtained under non-optimal observing conditions, the B photometry, which was acquired in time-series mode, allowed us to identify 274 variable stars (among which 96 are bona fide and 31 are candidate RR Lyrae stars, 71 are Cepheids, and 16 are binary systems) by applying the image subtraction technique to the selected portions of the observed fields. Differential flux light curves were obtained for the vast majority of these variables. Our sample mainly includes pulsating stars that populate the instability strip from the Classical Cepheids down to the RR Lyrae stars, thus tracing the different stellar generations in these regions of M31 down to the horizontal branch of the oldest (t {approx} 10 Gyr) component.

  2. Degradation of HaloTag-fused nuclear proteins using bestatin-HaloTag ligand hybrid molecules.

    PubMed

    Tomoshige, Shusuke; Naito, Mikihiko; Hashimoto, Yuichi; Ishikawa, Minoru

    2015-10-14

    We have developed a protein knockdown technology using hybrid small molecules designed as conjugates of a ligand for the target protein and a ligand for ubiquitin ligase cellular inhibitor of apoptosis protein 1 (cIAP1). However, this technology has several limitations. Here, we report the development of a novel protein knockdown system to address these limitations. In this system, target proteins are fused with HaloTag to provide a common binding site for a degradation inducer. We designed and synthesized small molecules consisting of alkyl chloride as the HaloTag-binding degradation inducer, which binds to HaloTag, linked to BE04 (2), which binds to cIAP1. Using this system, we successfully knocked down HaloTag-fused cAMP responsive element binding protein 1 (HaloTag-CREB1) and HaloTag-fused c-jun (HaloTag-c-jun), which are ligand-unknown nuclear proteins, in living cells. HaloTag-binding degradation inducers can be synthesized easily, and are expected to be useful as biological tools for pan-degradation of HaloTag-fused proteins. PMID:26338696

  3. Genesis Halo Orbit Station Keeping Design

    NASA Technical Reports Server (NTRS)

    Lo, M.; Williams, K.; Wilson, R.; Howell, K.; Barden, B.

    2000-01-01

    As the fifth mission of NASA's Directory Program, Genesis is designed to collect solar wind samples for approximately two years in a halo orbit near the Sun-Earth L(sub 1) Lagrange point for return to the Earth.

  4. Few-Body Universality in Halo Nuclei

    NASA Astrophysics Data System (ADS)

    Hammer, H.-W.

    2016-03-01

    Few-body systems with resonant S-wave interactions show universal properties which are independent of the interaction at short distances. These properties include a geometric spectrum of three- and higher-body bound states and universal correlations between few-body observables. They can be observed on a wide range of scales from hadrons and nuclei to ultracold atoms. In this contribution, we focus on few-body universality in halo nuclei which can be considered as effective few-body systems consisting of halo nucleons and a core. This concept provides a unifying framework for halo nuclei with calculable corrections. Recent progress in this field with an emphasis on the possibility of finding Efimov states in halo nuclei is discussed.

  5. Dark matter particles in the galactic halo

    SciTech Connect

    Bernabei, R. Belli, P.; Montecchia, F.; Nozzoli, F.; Cappella, F.; D'Angelo, A.; Incicchitti, A.; Prosperi, D.; Cerulli, R.; Dai, C. J.; He, H. L.; Kuang, H. H.; Ma, J. M.; Sheng, X. D.; Ye, Z. P.

    2009-12-15

    Arguments on the investigation of the DarkMatter particles in the galactic halo are addressed. Recent results obtained by exploiting the annual modulation signature are summarized and the perspectives are discussed.

  6. The Gaseous Halo of NGC 891

    NASA Astrophysics Data System (ADS)

    Hodges-Kluck, Edmund

    2014-08-01

    The halos of disk galaxies contain a substantial mass of diffuse gas whose properties (temperature, density, structure, and metallicity) are important to understanding how the intergalactic medium was enriched and the long-term star-formation potential of the galaxy. However, we still do not know whether most of the halo material was expelled from the galaxy in a 'galactic fountain' or is fresh infall from the circum/intergalactic medium. NGC 891 is a nearby (D=10 Mpc), edge-on Milky Way analog whose halo has been intensively studied. I will present our recent work in the X-ray and UV bands aimed at trying to determine the origin of the hot and cool components of the halo gas by measuring their metal content, and discuss whether results from NGC 891 can be generalized to other galaxies.

  7. Dark matter particles in the galactic halo

    NASA Astrophysics Data System (ADS)

    Bernabei, R.; Belli, P.; Montecchia, F.; Nozzoli, F.; Cappella, F.; D'Angelo, A.; Incicchitti, A.; Prosperi, D.; Cerulli, R.; Dai, C. J.; He, H. L.; Kuang, H. H.; Ma, J. M.; Sheng, X. D.; Ye, Z. P.

    2009-12-01

    Arguments on the investigation of the DarkMatter particles in the galactic halo are addressed. Recent results obtained by exploiting the annual modulation signature are summarized and the perspectives are discussed.

  8. The accretion halo in AM Herculis systems

    NASA Technical Reports Server (NTRS)

    Achilleos, N.; Wickramasinghe, D. T.; Wu, Kinwah

    1992-01-01

    Previous phase-resolved spectropolarimetric observations of the AM Herculis systems V834 Centauri (E1405-451) and EF Eridani have shown broad, Zeeman-shifted absorption features during the bright phases. These features are thought to be nonphotospheric in origin, and to arise from a cool 'halo' of unshocked gas surrounding the accretion shock on the surface of the white dwarf primary. Preliminary models for the accretion halo region are presented and these models are used to perform a more detailed analysis of the relevant data for these two systems than has previously been done. To explain the observed halo Zeeman features, geometries which are consistent with the presence of linearly extended cyclotron emission regions are required. Such regions have previously been deduced from different considerations by other investigators. The estimated masses for the accretion halo are comparable to the mass of the cyclotron emission region.

  9. Solar Back-sided Halo CME

    NASA Video Gallery

    The Sun erupted with several CMEs (coronal mass ejections) during a period just over a day (Nov. 8-9, 2012), the largest of which was a halo CME. This CME appears to have originated from an active ...

  10. Dynamics of beam halo in mismatched beams

    SciTech Connect

    Wangler, T.P.; Garnett, R.W.; Gray, E.R.; Ryne, R.D.; Wang, T.S.

    1996-09-01

    High-power proton linacs for nuclear materials transmutation and production, and new accelerator-driven neutron spallation sources must be designed to control beam-halo formation, which leads to beam loss. The study of particle-core models is leading to a better understanding of the causes and characteristics of beam halo produced by space-charge forces in rms mismatched beams. Detailed studies of the models have resulted in predictions of the dependence of the maximum amplitude of halo particles on a mismatch parameter and on the space-charge tune-depression ratio. Scaling formulas have been derived which will provide guidance for choosing the aperture radius to contain the halo without loss.

  11. Simulating rainbows and halos in color.

    PubMed

    Gedzelman, S D

    1994-07-20

    Geometric optics rainbows and ice-crystal halos that include some effects of a Rayleigh-scattering atmosphere and a cloud of finite optical thickness are simulated in color by the use of a Monte Carlo approach. PMID:20935829

  12. On physical scales of dark matter halos

    SciTech Connect

    Zemp, Marcel

    2014-09-10

    It is common practice to describe formal size and mass scales of dark matter halos as spherical overdensities with respect to an evolving density threshold. Here, we critically investigate the evolutionary effects of several such commonly used definitions and compare them to the halo evolution within fixed physical scales as well as to the evolution of other intrinsic physical properties of dark matter halos. It is shown that, in general, the traditional way of characterizing sizes and masses of halos dramatically overpredicts the degree of evolution in the last 10 Gyr, especially for low-mass halos. This pseudo-evolution leads to the illusion of growth even though there are no major changes within fixed physical scales. Such formal size definitions also serve as proxies for the virialized region of a halo in the literature. In general, those spherical overdensity scales do not coincide with the virialized region. A physically more precise nomenclature would be to simply characterize them by their very definition instead of calling such formal size and mass definitions 'virial'. In general, we find a discrepancy between the evolution of the underlying physical structure of dark matter halos seen in cosmological structure formation simulations and pseudo-evolving formal virial quantities. We question the importance of the role of formal virial quantities currently ubiquitously used in descriptions, models, and relations that involve properties of dark matter structures. Concepts and relations based on pseudo-evolving formal virial quantities do not properly reflect the actual evolution of dark matter halos and lead to an inaccurate picture of the physical evolution of our universe.

  13. Phase transition theory of sprite halo

    NASA Astrophysics Data System (ADS)

    Hiraki, Yasutaka

    2010-04-01

    We present the phase transition theory for sprite halo using measurable lightning parameters (charge moment and discharge time) on the basis of steady state thermodynamics. A halo is located at the upper part of the tree-like structure of a sprite and is produced through electron impact excitation of neutral species under the lightning-induced electric field. We proposed in our previous studies that the occurrence criteria for halos and sprites are characterized by the above lightning parameters, and additionally, the intensity of a halo weakens rapidly with an increase in the discharge time T. We assume that this phenomenon is quite similar to the phase transition between the vapor and the liquid states of water; here the analogy is between the accelerated electrons and the water molecules. We demonstrate analytically a phase transition for a simply modeled halo based on the quasistatic theory of lightning-induced electric field. Choosing the luminosity of a halo as an order parameter, we show that it has a dependence of T-0.25 - Tc-0.25 near the critical point Tc, which is characteristic of the phase transition. Furthermore, the critical time scale Tc ≈ 5.5 ms is provided naturally from our modeling and is somewhat larger than the typical time scale of the halo luminosity in observations. We consider that this kind of formalism is useful in understanding the detailed relationship between lightning activity and occurrence of halos. We discuss this point for future observations along with the possibilities of the transition model of column and carrot structures.

  14. Computational triadic algebras of signs

    SciTech Connect

    Zadrozny, W.

    1996-12-31

    We present a finite model of Peirce`s ten classes of signs. We briefly describe Peirce`s taxonomy of signs; we prove that any finite collection of signs can be extended to a finite algebra of signs in which all interpretants are themselves being interpreted; and we argue that Peirce`s ten classes of signs can be defined using constraints on algebras of signs. The paper opens the possibility of defining multimodal cognitive agents using Peirce`s classes of signs, and is a first step towards building a computational logic of signs based on Peirce`s taxonomies.

  15. Bis(haloBODIPYs) with Labile Helicity: Valuable Simple Organic Molecules That Enable Circularly Polarized Luminescence.

    PubMed

    Ray, César; Sánchez-Carnerero, Esther M; Moreno, Florencio; Maroto, Beatriz L; Agarrabeitia, Antonia R; Ortiz, María J; López-Arbeloa, Íñigo; Bañuelos, Jorge; Cohovi, Komlan D; Lunkley, Jamie L; Muller, Gilles; de la Moya, Santiago

    2016-06-20

    Simple organic molecules (SOM) based on bis(haloBODIPY) are shown to enable circularly polarized luminescence (CPL), giving rise to a new structural design for technologically valuable CPL-SOMs. The established design comprises together synthetic accessibility, labile helicity, possibility of reversing the handedness of the circularly polarized emission, and reactive functional groups, making it unique and attractive as advantageous platform for the development of smart CPL-SOMs. PMID:27123965

  16. The Meaning of Signs:

    PubMed Central

    Stein, Claudia

    2006-01-01

    This article reconstructs the diagnostic act of the French pox in the French-disease hospital of sixteenth-century Augsburg. It focuses on how the participants in the clinical encounter imagined the configuration of the pox and its localization in the human body. Of central importance for answering this question is the early modern conception of physical signs. It has been argued that it was due to a specific understanding of bodily signs and their relationship to a disease and its causes, that disease definition and classification in the early modern period showed a high degree of flexibility and fluidity. This paper looks at how the sixteenth-century theoretical conception of physical signs not only shaped the diagnosis and treatment of the pox but also reflected the overall organization of institutions. PMID:17242549

  17. Nanomechanics of HaloTag tethers.

    PubMed

    Popa, Ionel; Berkovich, Ronen; Alegre-Cebollada, Jorge; Badilla, Carmen L; Rivas-Pardo, Jaime Andrés; Taniguchi, Yukinori; Kawakami, Masaru; Fernandez, Julio M

    2013-08-28

    The active site of the Haloalkane Dehydrogenase (HaloTag) enzyme can be covalently attached to a chloroalkane ligand providing a mechanically strong tether, resistant to large pulling forces. Here we demonstrate the covalent tethering of protein L and I27 polyproteins between an atomic force microscopy (AFM) cantilever and a glass surface using HaloTag anchoring at one end and thiol chemistry at the other end. Covalent tethering is unambiguously confirmed by the observation of full length polyprotein unfolding, combined with high detachment forces that range up to ∼2000 pN. We use these covalently anchored polyproteins to study the remarkable mechanical properties of HaloTag proteins. We show that the force that triggers unfolding of the HaloTag protein exhibits a 4-fold increase, from 131 to 491 pN, when the direction of the applied force is changed from the C-terminus to the N-terminus. Force-clamp experiments reveal that unfolding of the HaloTag protein is twice as sensitive to pulling force compared to protein L and refolds at a slower rate. We show how these properties allow for the long-term observation of protein folding-unfolding cycles at high forces, without interference from the HaloTag tether. PMID:23909704

  18. Beam halo studies in LEHIPA DTL

    NASA Astrophysics Data System (ADS)

    Roy, S.; Pande, R.; Rao, S. V. L. S.; Krishnagopal, S.; Singh, P.

    2015-11-01

    The Low Energy High Intensity Proton Accelerator (LEHIPA) project at Bhabha Atomic Research Centre (BARC) consists of a 20 MeV, 30 mA proton linac. The accelerator comprises of a 3 MeV Radio Frequency Quadrupole (RFQ) and a 20 MeV Drift Tube Linac (DTL). In such high intensity accelerators, beam halos are of concern as they not only cause an increase in emittance, but also lead to beam loss and radio activation. We have studied the effect of beam mismatch at the DTL input on halo formation and propagation. The particle core model is used to excite the three envelope eigen modes; the quadrupole mode, the fast mode and the slow mode by giving input beam mismatch. These modes get damped as the beam progresses through the DTL. The damping mechanism is clearly Landau damping and leads to increase in rms emittance of the beam. The evolution of these modes and the corresponding increase in beam emittance and maximum beam extent, as the beam propagates through the DTL, has been studied for different space charge tunes. The halo parameter based on the definition of Allen and Wangler has been calculated. It is seen that beam halos are very important for LEHIPA DTL, even at 20 MeV and leads to emittance and beam size increase and also to beam loss in some cases. The longitudinal halo is present even without mismatch and transverse halos arise in the presence of beam mismatch.

  19. MODIFIED GRAVITY SPINS UP GALACTIC HALOS

    SciTech Connect

    Lee, Jounghun; Zhao, Gong-Bo; Li, Baojiu; Koyama, Kazuya

    2013-01-20

    We investigate the effect of modified gravity on the specific angular momentum of galactic halos by analyzing the halo catalogs at z = 0 from high-resolution N-body simulations for a f(R) gravity model that meets the solar-system constraint. It is shown that the galactic halos in the f(R) gravity model tend to acquire significantly higher specific angular momentum than those in the standard {Lambda}CDM model. The largest difference in the specific angular momentum distribution between these two models occurs for the case of isolated galactic halos with mass less than 10{sup 11} h {sup -1} M {sub Sun }, which are likely least shielded by the chameleon screening mechanism. As the specific angular momentum of galactic halos is rather insensitive to other cosmological parameters, it can in principle be an independent discriminator of modified gravity. We speculate a possibility of using the relative abundance of low surface brightness galaxies (LSBGs) as a test of general relativity given that the formation of the LSBGs occurs in fast spinning dark halos.

  20. Eponymous signs in dermatology

    PubMed Central

    Madke, Bhushan; Nayak, Chitra

    2012-01-01

    Clinical signs reflect the sheer and close observatory quality of an astute physician. Many new dermatological signs both in clinical and diagnostic aspects of various dermatoses are being reported and no single book on dermatology literature gives a comprehensive list of these “signs” and postgraduate students in dermatology finds it difficult to have access to the description, as most of these resident doctor do not have access to the said journal articles. “Signs” commonly found in dermatologic literature with a brief discussion and explanation is reviewed in this paper. PMID:23189246

  1. Signs in Speare's "The Sign of the Beaver."

    ERIC Educational Resources Information Center

    Moseley, Ann

    1995-01-01

    Describes the use of signs in Elizabeth George Speare's "The Sign of the Beaver," in which a settler youth and a young Indian learn to communicate by signs, and how the signs reveal much about each character's culture. Summarizes the plot elements of the book, including characters who are not as sympathetic to the Indian point of view. (PA)

  2. Derivative Sign Patterns

    ERIC Educational Resources Information Center

    Clark, Jeffrey

    2011-01-01

    Analysis of the patterns of signs of infinitely differentiable real functions shows that only four patterns are possible if the function is required to exhibit the pattern at all points in its domain and that domain is the set of all real numbers. On the other hand all patterns are possible if the domain is a bounded open interval.

  3. Sign-away Pressures

    ERIC Educational Resources Information Center

    Rosen, Catherine E.

    1976-01-01

    Why would mental health clients sign release-of-information forms unless they thought a refusal to do so would jeopardize their access to service? The author believes that the practice of not advising clients of their rights to privacy has ethical implications that can compromise the value of the treatment. (Author)

  4. Signs of Success.

    ERIC Educational Resources Information Center

    Styles-Lopez, Robin

    1998-01-01

    Explains how to make a well-designed signage package that is effective and enhances visitor first impressions of an institution. Examines questions to ask when planning traffic-pattern signage and the significance of the different hierarchy of signs; concludes with advice on signage design. (GR)

  5. Sign Language Web Pages

    ERIC Educational Resources Information Center

    Fels, Deborah I.; Richards, Jan; Hardman, Jim; Lee, Daniel G.

    2006-01-01

    The World Wide Web has changed the way people interact. It has also become an important equalizer of information access for many social sectors. However, for many people, including some sign language users, Web accessing can be difficult. For some, it not only presents another barrier to overcome but has left them without cultural equality. The…

  6. Signing in Science

    ERIC Educational Resources Information Center

    Ashby, Rachael

    2013-01-01

    This article describes British Sign Language (BSL) as a viable option for teaching science. BSL is used by a vast number of people in Britain but is seldom taught in schools or included informally alongside lessons. With its new addition of a large scientific glossary, invented to modernise the way science is taught to deaf children, BSL breaks…

  7. Suicide Warning Signs

    MedlinePlus

    ... health professional or by call- ing the National Suicide Prevention Lifeline at 1-800-273-TALK if you or someone you know exhibits any of the following signs: n Threatening to ... or writing about death, dying, or suicide when these actions are out of the ordinary ...

  8. Reversible Sterilization

    ERIC Educational Resources Information Center

    Largey, Gale

    1977-01-01

    Notes that difficult questions arise concerning the use of sterilization for alleged eugenic and euthenic purposes. Thus, how reversible sterilization will be used with relation to the poor, mentally ill, mentally retarded, criminals, and minors, is questioned. (Author/AM)

  9. Simulating Halos with the Caterpillar Project

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-04-01

    The Caterpillar Project is a beautiful series of high-resolution cosmological simulations. The goal of this project is to examine the evolution of dark-matter halos like the Milky Ways, to learn about how galaxies like ours formed. This immense computational project is still in progress, but the Caterpillar team is already providing a look at some of its first results.Lessons from Dark-Matter HalosWhy simulate the dark-matter halos of galaxies? Observationally, the formation history of our galaxy is encoded in galactic fossil record clues, like the tidal debris from disrupted satellite galaxies in the outer reaches of our galaxy, or chemical abundance patterns throughout our galactic disk and stellar halo.But to interpret this information in a way that lets us learn about our galaxys history, we need to first test galaxy formation and evolution scenarios via cosmological simulations. Then we can compare the end result of these simulations to what we observe today.This figure illustrates the difference that mass resolution makes. In the left panel, the mass resolution is 1.5*10^7 solar masses per particle. In the right panel, the mass resolution is 3*10^4 solar masses per particle [Griffen et al. 2016]A Computational ChallengeDue to how computationally expensive such simulations are, previous N-body simulations of the growth of Milky-Way-like halos have consisted of only one or a few halos each. But in order to establish a statistical understanding of how galaxy halos form and find out whether the Milky Ways halo is typical or unusual! it is necessary to simulate a larger number of halos.In addition, in order to accurately follow the formation and evolution of substructure within the dark-matter halos, these simulations must be able to resolve the smallest dwarf galaxies, which are around a million solar masses. This requires an extremely high mass resolution, which adds to the computational expense of the simulation.First OutcomesThese are the challenges faced by

  10. HaloSat- A CubeSat to Study the Hot Galactic Halo

    NASA Astrophysics Data System (ADS)

    Kaaret, Philip

    We propose to develop, build, and fly HaloSat, a CubeSat capable of measuring the oxygen line emission from the hot Galactic halo. A dedicated CubeSat enables an instrument design and observing strategy to maximize the halo signal while minimizing foregrounds from solar wind charge exchange interactions within the solar system. We will use HaloSat to map the distribution of hot gas in the Milky Way and determine whether it fills an extended, and thus massive halo, or whether the halo is compact, and thus does not contribute significantly to the total mass of the Milky Way. HaloSat can be accomplished at modest cost using a CubeSat, a novel platform for space astrophysics missions. We will use a commercially available CubeSat bus and commercially available X-ray detectors to reduce development risk and minimize overall mission cost. HaloSat builds on the initiatives of GSFC/Wallops Flight Facility (WFF) in the development of CubeSats for low cost access to space and relies on the technical expertise of WFF personnel for spacecraft and mission design and operations. The team, from University of Iowa (UI), GSFC, Johns Hopkins, and CNRS (France), contains experts in X-ray detector development and data analysis and the astrophysics of hot plasmas and Galactic structure. The UI team will include a number of junior researchers (undergraduates, graduate students, and a postdoc) and help train them for future leadership roles on NASA space flight missions.

  11. Reversible Cardiomyopathies

    PubMed Central

    Patel, Harsh; Madanieh, Raef; Kosmas, Constantine E; Vatti, Satya K; Vittorio, Timothy J

    2015-01-01

    Cardiomyopathies (CMs) have many etiological factors that can result in severe structural and functional dysregulation. Fortunately, there are several potentially reversible CMs that are known to improve when the root etiological factor is addressed. In this article, we discuss several of these reversible CMs, including tachycardia-induced, peripartum, inflammatory, hyperthyroidism, Takotsubo, and chronic illness–induced CMs. Our discussion also includes a review on their respective pathophysiology, as well as possible management solutions. PMID:26052233

  12. Calcified gallstone fissures: the reversed Mercedes Benz sign.

    PubMed

    Strijk, S P

    1987-01-01

    This article describes the occurrence of an unusual radiating pattern of calcification in the center of large radiolucent gallstones. The radiographic findings are attributed to calcium deposition within the fissures of biliary calculi. PMID:3556975

  13. GRAVITATIONALLY CONSISTENT HALO CATALOGS AND MERGER TREES FOR PRECISION COSMOLOGY

    SciTech Connect

    Behroozi, Peter S.; Wechsler, Risa H.; Wu, Hao-Yi; Busha, Michael T.; Klypin, Anatoly A.; Primack, Joel R. E-mail: rwechsler@stanford.edu

    2013-01-20

    We present a new algorithm for generating merger trees and halo catalogs which explicitly ensures consistency of halo properties (mass, position, and velocity) across time steps. Our algorithm has demonstrated the ability to improve both the completeness (through detecting and inserting otherwise missing halos) and purity (through detecting and removing spurious objects) of both merger trees and halo catalogs. In addition, our method is able to robustly measure the self-consistency of halo finders; it is the first to directly measure the uncertainties in halo positions, halo velocities, and the halo mass function for a given halo finder based on consistency between snapshots in cosmological simulations. We use this algorithm to generate merger trees for two large simulations (Bolshoi and Consuelo) and evaluate two halo finders (ROCKSTAR and BDM). We find that both the ROCKSTAR and BDM halo finders track halos extremely well; in both, the number of halos which do not have physically consistent progenitors is at the 1%-2% level across all halo masses. Our code is publicly available at http://code.google.com/p/consistent-trees. Our trees and catalogs are publicly available at http://hipacc.ucsc.edu/Bolshoi/.

  14. The Milky Way, the Galactic Halo, and the Halos of Galaxies

    NASA Astrophysics Data System (ADS)

    Gerhard, Ortwin

    2016-08-01

    The Milky Way, ``our'' Galaxy, is currently the subject of intense study with many ground-based surveys, in anticipation of upcoming results from the Gaia mission. From this work we have been learning about the full three-dimensional structure of the Galactic box/peanut bulge, the distribution of stars in the bar and disk, and the many streams and substructures in the Galactic halo. The data indicate that a large fraction of the Galactic halo has been accreted from outside. Similarly, in many external galaxy halos there is now evidence for tidal streams and accretion of satellites. To study these features requires exquisite, deep photometry and spectroscopy. These observations illustrate how galaxy halos are still growing, and sometimes can be used to ``time'' the accretion events. In comparison with cosmological simulations, the structure of galaxy halos gives us a vivid illustration of the hierarchical nature of our Universe.

  15. HaloSat - A CubeSat to Study the Hot Galactic Halo

    NASA Astrophysics Data System (ADS)

    Kaaret, Philip

    2016-04-01

    Observations of the nearby universe fail to locate about half of the normal matter (baryons) observed in the early universe. The missing baryons may be in hot galactic halos. HaloSat is a CubeSat designed to map oxygen line emission (O VII and O VIII) around the Milky Way in order to constrain the mass and spatial distribution of hot gas in the halo. HaloSat has a grasp competitive with current X-ray observatories. Its observing program will be optimized to minimize contributions from solar wind charge exchange (SWCX) emission that limit the accuracy of current measurements. We will describe the HaloSat mission concept, progress towards its implementation, and plans for archiving and distribution of the data.

  16. Magnetic fields in halos of spiral galaxies and the interstellar disk-halo connection

    NASA Astrophysics Data System (ADS)

    Dettmar, Ralf-Jürgen

    2005-09-01

    Observations of magnetic fields in halos of edge-on disk galaxies are discussed in relation to the different gaseous phases of the interstellar medium. For this comparison the presence of diffuse ionized gas (DIG) is introduced as a valuable tracer for gaseous halos which are originating from the star-formation driven disk-halo connection of the interstellar medium. The distribution of extraplanar DIG correlates on local and global scales with cosmic rays and magnetic fields as inferred from observations of the non-thermal radio continuum radiation and its polarization. From the polarization a large scale and well ordered magnetic field in these gaseous halos can be deduced. These observations indicate the presence of physical processes which generate and maintain magnetic fields on galactic scales. The importance of differential rotation of the gaseous halos for such processes is briefly discussed and the possible influence of magnetic fields on the dynamics of dust particles is addressed.

  17. Wrong Signs in Regression Coefficients

    NASA Technical Reports Server (NTRS)

    McGee, Holly

    1999-01-01

    When using parametric cost estimation, it is important to note the possibility of the regression coefficients having the wrong sign. A wrong sign is defined as a sign on the regression coefficient opposite to the researcher's intuition and experience. Some possible causes for the wrong sign discussed in this paper are a small range of x's, leverage points, missing variables, multicollinearity, and computational error. Additionally, techniques for determining the cause of the wrong sign are given.

  18. The Formation and Evolution of Stripped Dark Matter Halos

    NASA Astrophysics Data System (ADS)

    Zhu, Jessica; Tuan, Austin Zong; Lee, Christoph; Primack, Joel R.

    2016-01-01

    We implement a model to describe the density profiles of stripped dark matter halos. Our model generalizes the Navarro-Frenk-White (NFW) distribution to allow for more flexibility in the slope of the outer halo. We find that the density distributions of stripped halos tend to have outer slopes steeper than assumed by the NFW distribution. We also examine the relationship between severity of stripping and halo shape, spin parameter and concentration, and find that highly stripped halos are more spheroidal, have lower spin parameters, and have higher concentrations compared to less stripped halos.

  19. Sun-Earth L1 Region Halo-To-Halo Orbit and Halo-To-LisaJous Orbit Transfers

    NASA Technical Reports Server (NTRS)

    Roberts, Craig E.; DeFazio, Robert

    2004-01-01

    Practical techniques for designing transfer trajectories between Libration Point Orbits (LPOs) are presented. Motivation for development of these techniques was provided by a hardware contingency experienced by the Solar Heliospheric Observatory (SOHO), a joint mission of the European Space Agency (ESA) and the National Aeronautics and Space Administration (NASA) orbiting the L1 point of the Sun-Earth system. A potential solution to the problem involved a transfer from SOHO s periodic halo orbit to a new LPO of substantially different dimensions. Assuming the SOHO halo orbit as the departure orbit, several practical LPO transfer techniques were developed to obtain new Lissajous or periodic halo orbits that satisfy mission requirements and constraints. While not implemented for the SOHO mission, practical LPO transfer techniques were devised that are generally applicable to current and future LPO missions.

  20. Manual Signing in Adults with Intellectual Disability: Influence of Sign Characteristics on Functional Sign Vocabulary

    ERIC Educational Resources Information Center

    Meuris, Kristien; Maes, Bea; De Meyer, Anne-Marie; Zink, Inge

    2014-01-01

    Purpose: The purpose of this study was to investigate the influence of sign characteristics in a key word signing (KWS) system on the functional use of those signs by adults with intellectual disability (ID). Method: All 507 signs from a Flemish KWS system were characterized in terms of phonological, iconic, and referential characteristics.…

  1. A Universal Model for Halo Concentrations

    NASA Astrophysics Data System (ADS)

    Diemer, Benedikt; Kravtsov, Andrey V.

    2015-01-01

    We present a numerical study of dark matter halo concentrations in ΛCDM and self-similar cosmologies. We show that the relation between concentration, c, and peak height, ν, exhibits the smallest deviations from universality if halo masses are defined with respect to the critical density of the universe. These deviations can be explained by the residual dependence of concentration on the local slope of the matter power spectrum, n, which affects both the normalization and shape of the c-ν relation. In particular, there is no well-defined floor in the concentration values. Instead, the minimum concentration depends on redshift: at fixed ν, halos at higher z experience steeper slopes n, and thus have lower minimum concentrations. We show that the concentrations in our simulations can be accurately described by a universal seven-parameter function of only ν and n. This model matches our ΛCDM results to <~ 5% accuracy up to z = 6, and matches scale-free Ωm = 1 models to <~ 15%. The model also reproduces the low concentration values of Earth-mass halos at z ≈ 30, and thus correctly extrapolates over 16 orders of magnitude in halo mass. The predictions of our model differ significantly from all models previously proposed in the literature at high masses and redshifts. Our model is in excellent agreement with recent lensing measurements of cluster concentrations.

  2. A UNIVERSAL MODEL FOR HALO CONCENTRATIONS

    SciTech Connect

    Diemer, Benedikt; Kravtsov, Andrey V.

    2015-01-20

    We present a numerical study of dark matter halo concentrations in ΛCDM and self-similar cosmologies. We show that the relation between concentration, c, and peak height, ν, exhibits the smallest deviations from universality if halo masses are defined with respect to the critical density of the universe. These deviations can be explained by the residual dependence of concentration on the local slope of the matter power spectrum, n, which affects both the normalization and shape of the c-ν relation. In particular, there is no well-defined floor in the concentration values. Instead, the minimum concentration depends on redshift: at fixed ν, halos at higher z experience steeper slopes n, and thus have lower minimum concentrations. We show that the concentrations in our simulations can be accurately described by a universal seven-parameter function of only ν and n. This model matches our ΛCDM results to ≲ 5% accuracy up to z = 6, and matches scale-free Ω{sub m} = 1 models to ≲ 15%. The model also reproduces the low concentration values of Earth-mass halos at z ≈ 30, and thus correctly extrapolates over 16 orders of magnitude in halo mass. The predictions of our model differ significantly from all models previously proposed in the literature at high masses and redshifts. Our model is in excellent agreement with recent lensing measurements of cluster concentrations.

  3. Mapping the Galactic Halo. VIII. Quantifying Substructure

    NASA Astrophysics Data System (ADS)

    Starkenburg, Else; Helmi, Amina; Morrison, Heather L.; Harding, Paul; van Woerden, Hugo; Mateo, Mario; Olszewski, Edward W.; Sivarani, Thirupathi; Norris, John E.; Freeman, Kenneth C.; Shectman, Stephen A.; Dohm-Palmer, R. C.; Frey, Lucy; Oravetz, Dan

    2009-06-01

    We have measured the amount of kinematic substructure in the Galactic halo using the final data set from the Spaghetti project, a pencil-beam high-latitude sky survey. Our sample contains 101 photometrically selected and spectroscopically confirmed giants with accurate distance, radial velocity, and metallicity information. We have developed a new clustering estimator: the "4distance" measure, which when applied to our data set leads to the identification of one group and seven pairs of clumped stars. The group, with six members, can confidently be matched to tidal debris of the Sagittarius dwarf galaxy. Two pairs match the properties of known Virgo structures. Using models of the disruption of Sagittarius in Galactic potentials with different degrees of dark halo flattening, we show that this favors a spherical or prolate halo shape, as demonstrated by Newberg et al. using the Sloan Digital Sky Survey data. One additional pair can be linked to older Sagittarius debris. We find that 20% of the stars in the Spaghetti data set are in substructures. From comparison with random data sets, we derive a very conservative lower limit of 10% to the amount of substructure in the halo. However, comparison to numerical simulations shows that our results are also consistent with a halo entirely built up from disrupted satellites, provided that the dominating features are relatively broad due to early merging or relatively heavy progenitor satellites.

  4. Static galactic halo and galactic wind

    NASA Technical Reports Server (NTRS)

    Ko, Chung-Ming

    1993-01-01

    Although the exact state of the interstellar medium (ISM) in our Galaxy (other galaxies as well) is not clear at all, the 'common consensus' is that a rough pressure balance (or equipartition of energy) exists between different components and phases: cold, warm, hot phases of the ISM, magnetic field, cosmic rays, etc. If the halo of a galaxy is taken to be an extension of the ISM, then its structure is influenced by various ISM components. A 'complete' description of the halo is evidently very complicated. This paper gives a brief account on cosmic ray halo, which emphasizes the role played by cosmic rays. The interaction between cosmic rays and thermal plasma is facilitated by magnetic field. The cosmic rays are scattered by hydromagnetic waves (e.g., Alfven waves) which in turn can be generated by cosmic ray streaming instability. This constitutes a self-consistent picture. Since we are interested in the structure of the halo, we adopted a hydrodynamic model in which the cosmic rays and waves are described by their pressures. In general there are two classes of halos: static and dynamic.

  5. Vital signs monitoring system

    NASA Technical Reports Server (NTRS)

    Steffen, Dale A. (Inventor); Sturm, Ronald E. (Inventor); Rinard, George A. (Inventor)

    1981-01-01

    A system is disclosed for monitoring vital physiological signs. Each of the system components utilizes a single hybrid circuit with each component having high accuracy without the necessity of repeated calibration. The system also has low power requirements, provides a digital display, and is of sufficiently small size to be incorporated into a hand-carried case for portable use. Components of the system may also provide independent outputs making the component useful, of itself, for monitoring one or more vital signs. The overall system preferably includes an ECG amplifier and cardiotachometer signal conditioner unit, an impedance pneumograph and respiration rate signal conditioner unit, a heart/breath rate processor unit, a temperature monitoring unit, a selector switch, a clock unit, and an LCD driver unit and associated LCDs, with the system being capable of being expanded as needed or desired, such as, for example, by addition of a systolic/diastolic blood pressure unit.

  6. Planetary Vital Signs

    NASA Astrophysics Data System (ADS)

    Kennel, Charles; Briggs, Stephen; Victor, David

    2016-07-01

    The climate is beginning to behave in unusual ways. The global temperature reached unprecedented highs in 2015 and 2016, which led climatologists to predict an enormous El Nino that would cure California's record drought. It did not happen the way they expected. That tells us just how unreliable temperature has become as an indicator of important aspects of climate change. The world needs to go beyond global temperature to a set of planetary vital signs. Politicians should not over focus policy on one indicator. They need to look at the balance of evidence. A coalition of scientists and policy makers should start to develop vital signs at once, since they should be ready at the entry into force of the Paris Agreement in 2020. But vital signs are only the beginning. The world needs to learn how to use the vast knowledge we will be acquiring about climate change and its impacts. Is it not time to use all the tools at hand- observations from space and ground networks; demographic, economic and societal measures; big data statistical techniques; and numerical models-to inform politicians, managers, and the public of the evolving risks of climate change at global, regional, and local scales? Should we not think in advance of an always-on social and information network that provides decision-ready knowledge to those who hold the responsibility to act, wherever they are, at times of their choosing?

  7. Halo cold dark matter and microlensing

    SciTech Connect

    Gates, Evalyn; Turner, Michael S.

    1993-12-01

    There is good evidence that most of the baryons in the Universe are dark and some evidence that most of the matter in the Universe is nonbaryonic with cold dark matter (cdm) being a promising possibility. We discuss expectations for the abundance of baryons and cdm in the halo of our galaxy and locally. We show that in plausible cdm models the local density of cdm is at least $10^{-25}\\gcmm3$. We also discuss what one can learn about the the local cdm density from microlensing of stars in the LMC by dark stars in the halo and, based upon a suite of reasonable two-component halo models, conclude that microlensing is not a sensitive probe of the local cdm density.

  8. Range corrections in proton halo nuclei

    NASA Astrophysics Data System (ADS)

    Ryberg, Emil; Forssén, Christian; Hammer, H.-W.; Platter, Lucas

    2016-04-01

    We analyze the effects of finite-range corrections in halo effective field theory for S-wave proton halo nuclei. We calculate the charge radius to next-to-leading order and the astrophysical S-factor for low-energy proton capture to fifth order in the low-energy expansion. As an application, we confront our results with experimental data for the S-factor for proton capture on Oxygen-16 into the excited 1 /2+ state of Fluorine-17. Our low-energy theory is characterized by a systematic low-energy expansion, which can be used to quantify an energy-dependent model error to be utilized in data fitting. Finally, we show that the existence of proton halos is suppressed by the need for two fine tunings in the underlying theory.

  9. Beam halo in high-intensity beams

    SciTech Connect

    Wangler, T.P. )

    1993-12-25

    In space-charge dominated beams the nonlinear space-charge forces produce a filamentation pattern, which in projection to the 2-D phase spaces results in a 2-component beam consisting of an inner core and a diffuse outer halo. The beam-halo is of concern for a next generation of cw, high-power proton linacs that could be applied to intense neutron generators for nuclear materials processing. We describe what has been learned about beam halo and the evolution of space-charge dominated beams using numerical simulations of initial laminar beams in uniform linear focusing channels. We present initial results from a study of beam entropy for an intense space-charge dominated beam.

  10. Beam halo in high-intensity beams

    SciTech Connect

    Wangler, T.P.

    1993-06-01

    In space-charge dominated beams the nonlinear space-charge forces produce a filamentation pattern, which in projection to the 2-D phase spaces results in a 2-component beam consisting of an inner core and a diffuse outer halo. The beam-halo is of concern for a next generation of cw, high-power proton linacs that could be applied to intense neutron generators for nuclear materials processing. The author describes what has been learned about beam halo and the evolution of space-charge dominated beams using numerical simulations of initial laminar beams in uniform linear focusing channels. Initial results are presented from a study of beam entropy for an intense space-charge dominated beam.

  11. Beam halo in high-intensity beams

    SciTech Connect

    Wangler, T.P.

    1993-01-01

    In space-charge dominated beams the nonlinear space-charge forces produce a filamentation pattern, which in projection to the 2-D phase spaces results in a 2-component beam consisting of an inner core and a diffuse outer halo. The beam-halo is of concern for a next generation of cw, high-power proton linacs that could be applied to intense neutron generators for nuclear materials processing. The author describes what has been learned about beam halo and the evolution of space-charge dominated beams using numerical simulations of initial laminar beams in uniform linear focusing channels. Initial results are presented from a study of beam entropy for an intense space-charge dominated beam.

  12. Anomalously Weak Dynamical Friction in Halos

    NASA Astrophysics Data System (ADS)

    Sellwood, J. A.; Debattista, Victor P.

    A bar rotating in a pressure-supported halo generally loses angular momentum and slows down due to dynamical friction. Valenzuela & Klypin report a counter-example of a bar that rotates in a dense halo with little friction for several Gyr, and argue that their result invalidates the claim by Debattista & Sellwood that fast bars in real galaxies require a low halo density. We show that it is possible for friction to cease for a while should the pattern speed of the bar fluctuate upward. The reduced friction is due to an anomalous gradient in the phase-space density of particles at the principal resonance created by the earlier evolution. The result obtained by Valenzuela & Klypin is probably an artifact of their adaptive mesh refinement method, but anyway could not persist in a real galaxy. The conclusion by Debattista & Sellwood still stands.

  13. THE EFFECTS OF HALO-TO-HALO VARIATION ON SUBSTRUCTURE LENSING

    SciTech Connect

    Chen, Jacqueline; Koushiappas, Savvas M.; Zentner, Andrew R. E-mail: koushiappas@brown.edu

    2011-11-10

    We explore the halo-to-halo variation of dark matter (DM) substructure in galaxy-sized DM halos, focusing on its implications for strongly gravitational lensed systems. We find that the median value for projected substructure mass fractions within projected radii of 3% of the host halo virial radius is approximately f{sub sub} Almost-Equal-To 0.25%, but that the variance is large with a 95 percentile range of 0 {<=} f{sub sub} {<=} 1%. We quantify possible effects of substructure on quadruply imaged lens systems using the cusp relation and the simple statistic, R{sub cusp}. We estimate that the probability of obtaining the large values of the R{sub cusp} which have been observed from substructure effects is roughly {approx}10{sup -3} to {approx}10{sup -2}. We consider a variety of possible correlations between host halo properties and substructure properties in order to probe possible sample biases. In particular, low-concentration host DM halos have more large substructures and give rise to large values of R{sub cusp} more often. However, there is no known observational bias that would drive observed quadruply imaged quasars to be produced by low-concentration lens halos. Finally, we show that the substructure mass fraction is a relatively reliable predictor of the value of R{sub cusp}.

  14. THE PANCHROMATIC HUBBLE ANDROMEDA TREASURY. II. TRACING THE INNER M31 HALO WITH BLUE HORIZONTAL BRANCH STARS

    SciTech Connect

    Williams, Benjamin F.; Dalcanton, Julianne J.; Gilbert, Karoline M.; Rosenfield, Philip; Bell, Eric F.; Guhathakurta, Puragra; Seth, Anil C.; Kalirai, Jason S.; Girardi, Leo E-mail: jd@astro.washington.edu E-mail: philrose@astro.washington.edu E-mail: raja@uco.lick.org E-mail: aseth@astro.utah.edu E-mail: lgirardi@pd.astro.it

    2012-11-01

    We attempt to constrain the shape of M31's inner stellar halo by tracing the surface density of blue horizontal branch (BHB) stars at galactocentric distances ranging from 2 kpc to 35 kpc. Our measurements make use of resolved stellar photometry from a section of the Panchromatic Hubble Andromeda Treasury survey, supplemented by several archival Hubble Space Telescope observations. We find that the ratio of BHB to red giant stars is relatively constant outside of 10 kpc, suggesting that the BHB is as reliable a tracer of the halo population as the red giant branch. In the inner halo, we do not expect BHB stars to be produced by the high-metallicity bulge and disk, making BHB stars a good candidate to be a reliable tracer of the stellar halo to much smaller galactocentric distances. If we assume a power-law profile r {sup -{alpha}} for the two-dimensional (2D) projected surface density BHB distribution, we obtain a high-quality fit with a 2D power-law index of {alpha} = 2.6{sup +0.3} {sub -0.2} outside of 3 kpc, which flattens to {alpha} < 1.2 inside of 3 kpc. This slope is consistent with previous measurements but is anchored to a radial baseline that extends much farther inward. Finally, assuming azimuthal symmetry and a constant mass-to-light ratio, the best-fitting profile yields a total halo stellar mass of 2.1{sup +1.7} {sub -0.4} Multiplication-Sign 10{sup 9} M {sub Sun }. These properties are comparable with both simulations of stellar halo formation by satellite disruption alone and simulations that include some in situ formation of halo stars.

  15. DISCOVERY OF A GIANT RADIO HALO IN A NEW PLANCK GALAXY CLUSTER PLCKG171.9-40.7

    SciTech Connect

    Giacintucci, Simona; Kale, Ruta; Venturi, Tiziana; Wik, Daniel R.; Markevitch, Maxim

    2013-03-20

    We report the discovery of a giant radio halo in a new, hot, X-ray luminous galaxy cluster recently found by Planck, PLCKG171.9-40.7. The radio halo was found using Giant Metrewave Radio Telescope observations at 235 MHz and 610 MHz, and in the 1.4 GHz data from an NRAO Very Large Array Sky Survey pointing that we have reanalyzed. The diffuse radio emission is coincident with the cluster X-ray emission, and has an extent of {approx}1 Mpc and a radio power of {approx}5 Multiplication-Sign 10{sup 24} W Hz{sup -1} at 1.4 GHz. Its integrated radio spectrum has a slope of {alpha} Almost-Equal-To 1.8 between 235 MHz and 1.4 GHz, steeper than that of a typical giant halo. The analysis of the archival XMM-Newton X-ray data shows that the cluster is hot ({approx}10 keV) and disturbed, consistent with X-ray-selected clusters hosting radio halos. This is the first giant radio halo discovered in one of the new clusters found by Planck.

  16. THE STELLAR METALLICITY DISTRIBUTION FUNCTION OF THE GALACTIC HALO FROM SDSS PHOTOMETRY

    SciTech Connect

    An, Deokkeun; Beers, Timothy C.; Johnson, Jennifer A.; Pinsonneault, Marc H.; Lee, Young Sun; Bovy, Jo; Ivezic, Zeljko; Carollo, Daniela; Newby, Matthew

    2013-01-20

    We explore the stellar metallicity distribution function of the Galactic halo based on SDSS ugriz photometry. A set of stellar isochrones is calibrated using observations of several star clusters and validated by comparisons with medium-resolution spectroscopic values over a wide range of metal abundance. We estimate distances and metallicities for individual main-sequence stars in the multiply scanned SDSS Stripe 82, at heliocentric distances in the range 5-8 kpc and |b| > 35 Degree-Sign , and find that the in situ photometric metallicity distribution has a shape that matches that of the kinematically selected local halo stars from Ryan and Norris. We also examine independent kinematic information from proper-motion measurements for high Galactic latitude stars in our sample. We find that stars with retrograde rotation in the rest frame of the Galaxy are generally more metal poor than those exhibiting prograde rotation, which is consistent with earlier arguments by Carollo et al. that the halo system comprises at least two spatially overlapping components with differing metallicity, kinematics, and spatial distributions. The observed photometric metallicity distribution and that of Ryan and Norris can be described by a simple chemical evolution model by Hartwick (or by a single Gaussian distribution); however, the suggestive metallicity-kinematic correlation contradicts the basic assumption in this model that the Milky Way halo consists primarily of a single stellar population. When the observed metallicity distribution is deconvolved using two Gaussian components with peaks at [Fe/H] Almost-Equal-To -1.7 and -2.3, the metal-poor component accounts for {approx}20%-35% of the entire halo population in this distance range.

  17. Determination of the large scale volume weighted halo velocity bias in simulations

    NASA Astrophysics Data System (ADS)

    Zheng, Yi; Zhang, Pengjie; Jing, Yipeng

    2015-06-01

    A profound assumption in peculiar velocity cosmology is bv=1 at sufficiently large scales, where bv is the volume-weighted halo(galaxy) velocity bias with respect to the matter velocity field. However, this fundamental assumption has not been robustly verified in numerical simulations. Furthermore, it is challenged by structure formation theory (Bardeen, Bond, Kaiser and Szalay, Astrophys. J. 304, 15 (1986); Desjacques and Sheth, Phys. Rev D 81, 023526 (2010), which predicts the existence of velocity bias (at least for proto-halos) due to the fact that halos reside in special regions (local density peaks). The major obstacle to measuring the volume-weighted velocity from N-body simulations is an unphysical sampling artifact. It is entangled in the measured velocity statistics and becomes significant for sparse populations. With recently improved understanding of the sampling artifact (Zhang, Zheng and Jing, 2015, PRD; Zheng, Zhang and Jing, 2015, PRD), for the first time we are able to appropriately correct this sampling artifact and then robustly measure the volume-weighted halo velocity bias. (1) We verify bv=1 within 2% model uncertainty at k ≲0.1 h /Mpc and z =0 - 2 for halos of mass ˜1012- 1013h-1M⊙ and, therefore, consolidate a foundation for the peculiar velocity cosmology. (2) We also find statistically significant signs of bv≠1 at k ≳0.1 h /Mpc . Unfortunately, whether this is real or caused by a residual sampling artifact requires further investigation. Nevertheless, cosmology based on the k ≳0.1 h /Mpc velocity data should be careful with this potential velocity bias.

  18. Rockstar: Phase-space halo finder

    NASA Astrophysics Data System (ADS)

    Behroozi, Peter; Wechsler, Risa; Wu, Hao-Yi

    2012-10-01

    Rockstar (Robust Overdensity Calculation using K-Space Topologically Adaptive Refinement) identifies dark matter halos, substructure, and tidal features. The approach is based on adaptive hierarchical refinement of friends-of-friends groups in six phase-space dimensions and one time dimension, which allows for robust (grid-independent, shape-independent, and noise-resilient) tracking of substructure. Our method is massively parallel (up to 10^5 CPUs) and runs on the largest current simulations (>10^10 particles) with high efficiency (10 CPU hours and 60 gigabytes of memory required per billion particles analyzed). Rockstar offers significant improvement in substructure recovery as compared to several other halo finders.

  19. Complex artificial halos for the classroom

    NASA Astrophysics Data System (ADS)

    Selmke, Markus; Selmke, Sarah

    2016-07-01

    Halos represent a common and imposing atmospheric optics phenomenon whose displays are caused by tiny air-borne ice crystals. Their variety stems from a certain set of orientation classes to which these crystals belong. We present a robust and inexpensive device, made of modular components, that allows for the replication of most of these orientation classes in the laboratory. Under the illumination of light, the corresponding artificial halo counterparts emerge. The mechanical realization of this device allows a thorough understanding and demonstration of these beautiful atmospheric optics phenomena.

  20. The Shape of Dark Matter Halos

    NASA Astrophysics Data System (ADS)

    Olling, Robert Paul

    1995-01-01

    After reviewing our current knowledge of dark matter (DM) in spiral galaxies (Chapter 1), I present a new method of deriving the shape of these dark halos (Chapter 2). Such information, if obtained for a large number of systems, can provide important boundary conditions for theories of the formation of galaxies (Chapter 5). The halo-shape determination method relies on the comparison of model predictions of the thickness of the gas layer with observations of this flaring. Calculating the model gas layer widths from the observed gaseous velocity dispersion and the potential due to the total mass distribution of the galaxy we learn the following: (a) beyond the optical disk the thickness of the gas layer is sensitive to the shape of the DM halo, (b) the thickness of the gas layer is proportional to the ratio of the gaseous velocity dispersion and the rotation speed, (c) the self-gravity of the gas contributes significantly to the vertical force, (d) the derived shape of the DM halo is independent of the dark matter's radial density distribution, and is independent of the mass-to-light ratio of the stellar disk (f). In Chapter 3 I present a new method (usable for inclinations larger than 60^circ) to determine the thickness of the gas layer of spiral galaxies from high resolution H sc I observations. I use VLA H sc I observations of the almost edge-on Scd galaxy NGC 4244 to determine the gaseous velocity dispersion, and the flaring and rotation curves. From the Keplerian decline of the rotation curve beyond the stellar disks it follows that the dark-to-luminous mass ratio is at most two and a half. Combining the model predictions for the radial variation of the thickness of the gas layer with the measured flaring curve I find that the dark matter halo of NGC 4244 is highly flattened. The best fit occurs for a halo with an E8 shape (with a mass one-eight of an E0 halo), while the uncertainty (E5-E9) is dominated by the errors in the gaseous velocity dispersion: a round

  1. Dark energy and extended dark matter halos

    NASA Astrophysics Data System (ADS)

    Chernin, A. D.; Teerikorpi, P.; Valtonen, M. J.; Dolgachev, V. P.; Domozhilova, L. M.; Byrd, G. G.

    2012-03-01

    The cosmological mean matter (dark and baryonic) density measured in the units of the critical density is Ωm = 0.27. Independently, the local mean density is estimated to be Ωloc = 0.08-0.23 from recent data on galaxy groups at redshifts up to z = 0.01-0.03 (as published by Crook et al. 2007, ApJ, 655, 790 and Makarov & Karachentsev 2011, MNRAS, 412, 2498). If the lower values of Ωloc are reliable, as Makarov & Karachentsev and some other observers prefer, does this mean that the Local Universe of 100-300 Mpc across is an underdensity in the cosmic matter distribution? Or could it nevertheless be representative of the mean cosmic density or even be an overdensity due to the Local Supercluster therein. We focus on dark matter halos of groups of galaxies and check how much dark mass the invisible outer layers of the halos are able to host. The outer layers are usually devoid of bright galaxies and cannot be seen at large distances. The key factor which bounds the size of an isolated halo is the local antigravity produced by the omnipresent background of dark energy. A gravitationally bound halo does not extend beyond the zero-gravity surface where the gravity of matter and the antigravity of dark energy balance, thus defining a natural upper size of a system. We use our theory of local dynamical effects of dark energy to estimate the maximal sizes and masses of the extended dark halos. Using data from three recent catalogs of galaxy groups, we show that the calculated mass bounds conform with the assumption that a significant amount of dark matter is located in the invisible outer parts of the extended halos, sufficient to fill the gap between the observed and expected local matter density. Nearby groups of galaxies and the Virgo cluster have dark halos which seem to extend up to their zero-gravity surfaces. If the extended halo is a common feature of gravitationally bound systems on scales of galaxy groups and clusters, the Local Universe could be typical or even

  2. HALOGEN: Approximate synthetic halo catalog generator

    NASA Astrophysics Data System (ADS)

    Avila Perez, Santiago; Murray, Steven

    2015-05-01

    HALOGEN generates approximate synthetic halo catalogs. Written in C, it decomposes the problem of generating cosmological tracer distributions (eg. halos) into four steps: generating an approximate density field, generating the required number of tracers from a CDF over mass, placing the tracers on field particles according to a bias scheme dependent on local density, and assigning velocities to the tracers based on velocities of local particles. It also implements a default set of four models for these steps. HALOGEN uses 2LPTic (ascl:1201.005) and CUTE (ascl:1505.016); the software is flexible and can be adapted to varying cosmologies and simulation specifications.

  3. Enhanced subbarrier fusion for proton halo nuclei

    NASA Astrophysics Data System (ADS)

    Kumar, Raj; Lay, J. A.; Vitturi, A.

    2014-02-01

    In this Brief Report we use a simple model to describe the dynamical effects of break-up processes in the subbarrier fusion involving weakly bound nuclei. We model two similar cases involving either a neutron or a proton halo nucleus, both schematically coupled to the break-up channels. We find that the decrease of the Coulomb barrier in the proton break-up channel leads, ceteris paribus, to a larger enhancement of the subbarrier fusion probabilities with respect to the neutron halo case.

  4. HALO-TO-HALO SIMILARITY AND SCATTER IN THE VELOCITY DISTRIBUTION OF DARK MATTER

    SciTech Connect

    Mao, Yao-Yuan; Strigari, Louis E.; Wechsler, Risa H.; Hahn, Oliver; Wu, Hao-Yi

    2013-02-10

    We examine the velocity distribution function (VDF) in dark matter halos from Milky Way to cluster mass scales. We identify an empirical model for the VDF with a wider peak and a steeper tail than a Maxwell-Boltzmann distribution, and discuss physical explanations. We quantify sources of scatter in the VDF of cosmological halos and their implication for direct detection of dark matter. Given modern simulations and observations, we find that the most significant uncertainty in the VDF of the Milky Way arises from the unknown radial position of the solar system relative to the dark matter halo scale radius.

  5. Planning Sign Languages: Promoting Hearing Hegemony? Conceptualizing Sign Language Standardization

    ERIC Educational Resources Information Center

    Eichmann, Hanna

    2009-01-01

    In light of the absence of a codified standard variety in British Sign Language and German Sign Language ("Deutsche Gebardensprache") there have been repeated calls for the standardization of both languages primarily from outside the Deaf community. The paper is based on a recent grounded theory study which explored perspectives on sign language…

  6. Sign Language Comprehension: The Case of Spanish Sign Language

    ERIC Educational Resources Information Center

    Rodriguez Ortiz, I. R.

    2008-01-01

    This study aims to answer the question, how much of Spanish Sign Language interpreting deaf individuals really understand. Study sampling included 36 deaf people (deafness ranging from severe to profound; variety depending on the age at which they learned sign language) and 36 hearing people who had good knowledge of sign language (most were…

  7. Sign Lowering and Phonetic Reduction in American Sign Language

    PubMed Central

    Tyrone, Martha E.; Mauk, Claude E.

    2010-01-01

    This study examines sign lowering as a form of phonetic reduction in American Sign Language. Phonetic reduction occurs in the course of normal language production, when instead of producing a carefully articulated form of a word, the language user produces a less clearly articulated form. When signs are produced in context by native signers, they often differ from the citation forms of signs. In some cases, phonetic reduction is manifested as a sign being produced at a lower location than in the citation form. Sign lowering has been documented previously, but this is the first study to examine it in phonetic detail. The data presented here are tokens of the sign WONDER, as produced by six native signers, in two phonetic contexts and at three signing rates, which were captured by optoelectronic motion capture. The results indicate that sign lowering occurred for all signers, according to the factors we manipulated. Sign production was affected by several phonetic factors that also influence speech production, namely, production rate, phonetic context, and position within an utterance. In addition, we have discovered interesting variations in sign production, which could underlie distinctions in signing style, analogous to accent or voice quality in speech. PMID:20607146

  8. 40 CFR 721.10392 - Halo substituted sulfamidylbenzyluracil (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Halo substituted... Specific Chemical Substances § 721.10392 Halo substituted sulfamidylbenzyluracil (generic). (a) Chemical... as halo substituted sulfamidylbenzyluracil (PMN P-10-426) is subject to reporting under this...

  9. 40 CFR 721.10392 - Halo substituted sulfamidylbenzyluracil (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Halo substituted... Specific Chemical Substances § 721.10392 Halo substituted sulfamidylbenzyluracil (generic). (a) Chemical... as halo substituted sulfamidylbenzyluracil (PMN P-10-426) is subject to reporting under this...

  10. The Constant Error of the Halo in Educational Outcomes Research.

    ERIC Educational Resources Information Center

    Pike, Gary R.

    1999-01-01

    Research suggests correlations between student gains and college experiences may be an artifact of halo effect. A study examined whether halo error underlies students' self-reported gains, significance of the error, and its effect on the relationship between college experiences and educational outcomes. Results confirm halo error may be an…

  11. 40 CFR 721.10392 - Halo substituted sulfamidylbenzyluracil (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Halo substituted... Specific Chemical Substances § 721.10392 Halo substituted sulfamidylbenzyluracil (generic). (a) Chemical... as halo substituted sulfamidylbenzyluracil (PMN P-10-426) is subject to reporting under this...

  12. Search for and analysis of radioactive halos in lunar material

    NASA Technical Reports Server (NTRS)

    Gentry, R. V.

    1976-01-01

    The lunar halo search was conducted because halos in terrestrial minerals serve as pointers to localized radioactivity, and make possible analytical studies on the problems of isotopic dating and mode of crystallization of the host mineral. Ancillary studies were conducted on terrestrial halos and on certain samples of special origin such as tektites and meteorites.

  13. The Dependence of Subhalo Abundance on Halo Concentration

    NASA Astrophysics Data System (ADS)

    Mao, Yao-Yuan; Williamson, Marc; Wechsler, Risa H.

    2015-09-01

    Hierarchical structure formation implies that the number of subhalos within a dark matter halo depends not only on halo mass, but also on the formation history of the halo. This dependence on the formation history, which is highly correlated with halo concentration, can account for the super-Poissonian scatter in subhalo occupation at a fixed halo mass that has been previously measured in simulations. Here we propose a model to predict the subhalo abundance function for individual host halos that incorporates both halo mass and concentration. We combine results of cosmological simulations with a new suite of zoom-in simulations of Milky Way-mass halos to calibrate our model. We show that the model can successfully reproduce the mean and the scatter of subhalo occupation in these simulations. The implications of this correlation between subhalo abundance and halo concentration are further investigated. We also discuss cases in which inferences about halo properties can be affected if this correlation between subhalo abundance and halo concentration is ignored; in these cases, our model would give a more accurate inference. We propose that with future deep surveys, satellite occupation in the low-mass regime can be used to verify the existence of halo assembly bias.

  14. Comment on Halo Effects in Rating and Evaluation Research.

    ERIC Educational Resources Information Center

    Feeley, Thomas Hugh

    2002-01-01

    Considers the existence of halo effects in individuals' evaluations of target communicators across different dimensions. Notes that halo effects result from raters' inability to discriminate among conceptually distinct and theoretically independent aspects of a target's behavior. Discusses current conceptions of halo error and suggests several…

  15. CDC Vital Signs: Hispanic Health

    MedlinePlus

    ... Search The CDC Cancel Submit Search The CDC Vital Signs Note: Javascript is disabled or is not supported ... message, please visit this page: About CDC.gov . Vital Signs Current issue Infographic Topics Covered Alcohol Cancer Cardiovascular ...

  16. CDC Vital Signs: Legionnaires' Disease

    MedlinePlus

    ... Search The CDC Cancel Submit Search The CDC Vital Signs Note: Javascript is disabled or is not supported ... message, please visit this page: About CDC.gov . Vital Signs Current issue Infographic Topics Covered Alcohol Cancer Cardiovascular ...

  17. Aging changes in vital signs

    MedlinePlus

    ... Vital signs include body temperature, heart rate (pulse), breathing rate, and blood pressure. As you age, your vital ... symptoms and signs of infection. HEART RATE AND BREATHING RATE As you grow older, your pulse rate is ...

  18. CDC Vital Signs: Preventing Melanoma

    MedlinePlus

    ... Search The CDC Cancel Submit Search The CDC Vital Signs Note: Javascript is disabled or is not supported ... message, please visit this page: About CDC.gov . Vital Signs Current issue Infographic Topics Covered Alcohol Cancer Cardiovascular ...

  19. Signs of a Heart Attack

    MedlinePlus

    ... attack Heart Health and Stroke Signs of a heart attack Related information Make the Call. Don't Miss ... to top More information on Signs of a heart attack Read more from womenshealth.gov Make the Call, ...

  20. Measles (Rubeola): Signs and Symptoms

    MedlinePlus

    ... Initiative World Health Organization Pan American Health Organization Signs and Symptoms Language: English Español (Spanish) Recommend on ... of a patient with Koplik spots, an early sign of measles infection. Three to five days after ...

  1. AN XMM-NEWTON SURVEY OF THE SOFT X-RAY BACKGROUND. III. THE GALACTIC HALO X-RAY EMISSION

    SciTech Connect

    Henley, David B.; Shelton, Robin L.

    2013-08-20

    We present measurements of the Galactic halo's X-ray emission for 110 XMM-Newton sight lines selected to minimize contamination from solar wind charge exchange emission. We detect emission from few million degree gas on {approx}4/5 of our sight lines. The temperature is fairly uniform (median = 2.22 Multiplication-Sign 10{sup 6} K, interquartile range = 0.63 Multiplication-Sign 10{sup 6} K), while the emission measure and intrinsic 0.5-2.0 keV surface brightness vary by over an order of magnitude ({approx}(0.4-7) Multiplication-Sign 10{sup -3} cm{sup -6} pc and {approx}(0.5-7) Multiplication-Sign 10{sup -12} erg cm{sup -2} s{sup -1} deg{sup -2}, respectively, with median detections of 1.9 Multiplication-Sign 10{sup -3} cm{sup -6} pc and 1.5 Multiplication-Sign 10{sup -12} erg cm{sup -2} s{sup -1} deg{sup -2}, respectively). The high-latitude sky contains a patchy distribution of few million degree gas. This gas exhibits a general increase in emission measure toward the inner Galaxy in the southern Galactic hemisphere. However, there is no tendency for our observed emission measures to decrease with increasing Galactic latitude, contrary to what is expected for a disk-like halo morphology. The measured temperatures, brightnesses, and spatial distributions of the gas can be used to place constraints on models for the dominant heating sources of the halo. We provide some discussion of such heating sources, but defer comparisons between the observations and detailed models to a later paper.

  2. Quine and the Segregrational Sign.

    ERIC Educational Resources Information Center

    Wolf, George

    1999-01-01

    In the context of theory of integrational linguistics, the segregational sign is distinguished from the integrational sign, and the operation of the former is analyzed. Focus is on how logic guides the sign, and how the theory of W. V. Quine accounts for these issues. (MSE)

  3. Kinship in Mongolian Sign Language

    ERIC Educational Resources Information Center

    Geer, Leah

    2011-01-01

    Information and research on Mongolian Sign Language is scant. To date, only one dictionary is available in the United States (Badnaa and Boll 1995), and even that dictionary presents only a subset of the signs employed in Mongolia. The present study describes the kinship system used in Mongolian Sign Language (MSL) based on data elicited from…

  4. Sign language for telemanipulation

    NASA Astrophysics Data System (ADS)

    Pook, Polly K.; Ballard, Dana H.

    1995-12-01

    Literal teleoperation doesn't work very well. Limited bandwidth, long latencies, non- anthropomorphic mappings all make the effort of teleoperation tedious at best and ineffective at worst. Instead, users of teleoperated and semi-autonomous systems want their robots to `just do it for them,' without sacrificing the operator's intent. Our goal is to maximize human strategic control in teleoperator assisted robotics. In our teleassisted regime, the human operator provides high-level contexts for low-level autonomous robot behaviors. The operator wears an EXOS hand master to communicate via a natural sign language, such as pointing to objects and adopting a grasp preshape. Each sign indicates intention: e.g., reaching or grasping; and, where applicable, a spatial context: e.g., the pointing axis or preshape frame. The robot, a Utah/MIT hand on a Puma arm, acts under local servo control within the proscribed contexts. This paper extends earlier work [Pook & Ballard 1994a] by adding remote visual sensors to the teleassistance repertoire. To view the robot site, the operator wears a virtual research helmet that is coupled to binocular cameras mounted on a second Puma 760. The combined hand-head sensors allows teleassistance to be performed remotely. The example task is to open a door. We also demonstrate the flexibility of the teleassistance model by bootstrapping a `pick and place' task from the door opening task.

  5. INFINITY construction contract signed

    NASA Technical Reports Server (NTRS)

    2010-01-01

    Key state and community leaders celebrated April 6 with the signing of a construction contract for the state-of-the-art INFINITY Science Center planned near John C. Stennis Space Center in south Mississippi. Gulfport Mayor George Schloegel (l to r), chair of non-profit INFINITY Science Center Inc., was joined for the signing ceremony at the Hancock Bank in Gulfport by Virginia Wagner, sister of late Hancock Bank President Leo Seal Jr.; and Roy Anderson III, president and CEO of Roy Anderson Corp. Seal was the first chair of INFINITY Science Center Inc., which has led in development of the project. Roy Anderson Corp. plans to begin construction on the 72,000-square-foot, $28 million science and education center in May. The Mississippi Department of Transportation (MDOT) also is set to begin construction of a $2 million access road to the new center. The April 6 ceremony was attended by numerous officials, including former Stennis Space Center Directors Jerry Hlass and Roy Estess; Mississippi Senate President Pro Tempore Billy Hewes, R-Gulfport; Mississippi Rep. Diane Peranich, D-Pass Christian; and MDOT Southern District Commissioner Wayne Brown.

  6. Reputation, Halo, and Ratings of Counseling Programs

    ERIC Educational Resources Information Center

    Thoreson, Richard W.; And Others

    1975-01-01

    This study tests the hypothesis that previous ratings of programs in psychology reflect both an experimental psychology and general institutional halo bias. It was found that applied programs in counseling psychology do receive ratings that differ from overall ratings of psychology in general. Programs ranked as strong, good, and adequate are…

  7. Halo and mirage demonstrations in atmospheric optics

    NASA Astrophysics Data System (ADS)

    Vollmer, Michael; Greenler, Robert

    2003-01-01

    Some laboratory demonstrations on atmospheric optics are presented. The focus is on dispersion effects in mirages, lateral mirages, and inferior mirages produced with small hot plates. We also show a demonstration of the upper-tangent-arc halo, produced with a hexagonal prism, rotating about two axes.

  8. The Hot Gaseous Halos of Spiral Galaxies

    NASA Astrophysics Data System (ADS)

    Bregman, J.

    2016-06-01

    In the Milky Way, absorption and emission line measurements of O VII and O VIII show that the halo environment is dominated by a nearly spherical halo of temperature 2 × 10^6 K, metallicity of 0.3-0.5 solar, and with a density decreasing as r^{-3/2}. The mass of the hot gas, estimated through extrapolation to the virial radius, is comparable to the stellar mass, but does not account for the missing mass. The Milky Way hot halo appears to be rotating at about 180 km/s, which is consistent with model expectations, depending on the time of infall. Around massive spiral galaxies, hot halos are seen in emission out to about 70 kpc in the best cases. These show similar gas density laws and metallicities in the range 0.1-0.5 solar. The gas mass is comparable to the stellar mass, but does not account for the missing baryons within the virial radius. If the density law can be extrapolated to about three virial radii, the missing baryons would be accounted for.

  9. GAS CONDENSATION IN THE GALACTIC HALO

    SciTech Connect

    Joung, M. Ryan; Bryan, Greg L.; Putman, Mary E.

    2012-02-01

    Using adaptive mesh refinement (AMR) hydrodynamic simulations of vertically stratified hot halo gas, we examine the conditions under which clouds can form and condense out of the hot halo medium to potentially fuel star formation in the gaseous disk. We find that halo clouds do not develop from linear isobaric perturbations. This is a regime where the cooling time is longer than the Brunt-Vaeisaelae time, confirming previous linear analysis. We extend the analysis into the nonlinear regime by considering mildly or strongly nonlinear perturbations with overdensities up to 100, also varying the initial height, the cloud size, and the metallicity of the gas. Here, the result depends on the ratio of cooling time to the time required to accelerate the cloud to the sound speed (similar to the dynamical time). If the ratio exceeds a critical value near unity, the cloud is accelerated without further cooling and gets disrupted by Kelvin-Helmholtz and/or Rayleigh-Taylor instabilities. If it is less than the critical value, the cloud cools and condenses before disruption. Accreting gas with overdensities of 10-20 is expected to be marginally unstable; the cooling fraction will depend on the metallicity, the size of the incoming cloud, and the distance to the galaxy. Locally enhanced overdensities within cold streams have a higher likelihood of cooling out. Our results have implications on the evolution of clouds seeded by cold accretion that are barely resolved in current cosmological hydrodynamic simulations and absorption line systems detected in galaxy halos.

  10. Highly-Ionized Gas in the Galactic Halo: A FUSE Survey of O 6 Absorption toward 22 Halo Stars

    NASA Astrophysics Data System (ADS)

    Zsargo, J.; Sembach, K. R.; Howk, J. C.; Savage, B. D.

    2002-12-01

    Far Ultraviolet Spectroscopic Explorer (FUSE) spectra of 22 Galactic halo stars are studied to determine the amount of O 6 in the Galactic halo between ~0.3 and ~10 kpc from the Galactic mid-plane. Strong O 6 λ 1031.93 absorption was detected toward 21 stars, and a reliable 3 σ upper limit was obtained toward HD 97991. The weaker member of the O 6 doublet at 1037.62 Å could be studied toward only six stars. The observed columns are reasonably consistent with a patchy exponential O 6 distribution with a mid-plane density of 1.7x10-8 cm-3 and scale height between 2.3 and 4 kpc. We do not see clear signs of strong high-velocity components in O 6 absorption along the Galactic sight lines, which indicates the general absence of high velocity O 6 within 2-5 kpc of the Galactic mid-plane. The correlation between the H 1 and O 6 intermediate velocity absorption is also poor. The O 6 velocity dispersions are much larger than the value of ~18 km/s expected from thermal broadening for gas at T ~ 3x105 K, the temperature at which O 6 is expected to reach its peak abundance in collisional ionization equilibrium. Turbulence, inflow, and outflow must have an effect on the shape of the O 6 profiles. Kinematical comparisons of O 6 with Ar 1 reveal that 9 of 21 sight lines are closely aligned in LSR velocity (|Δ VLSR| <=5 km/s ), while 8 of 21 exhibit significant velocity differences (|Δ VLSR| >= 15 km/s ). This dual behavior may indicate the presence of two different types of O 6-bearing environments toward the Galactic sight lines. Comparison of O 6 with other highly-ionized species suggests that the high ions are produced primarily by cooling hot gas in the Galactic fountain flow, and that turbulent mixing also has a significant contribution. The role of turbulent mixing is most important toward sight lines that sample supernova remnants like Loop I and IV. We are also able to show that the O 6 enhancement toward the Galactic center region that was observed in the FUSE

  11. Non-Gaussian halo mass function and non-spherical halo collapse: theory vs. simulations

    SciTech Connect

    Achitouv, Ixandra E.; Corasaniti, Pier Stefano E-mail: Pier-Stefano.Corasaniti@obspm.fr

    2012-02-01

    The mass distribution of dark matter halos is a sensitive probe of primordial non-Gaussianity (NG). We derive an analytical formula of the halo mass function by perturbatively computing excursion set path-integrals for a non-Gaussian density field with non-vanishing skewness, f{sub NL}. We assume a stochastic barrier model which captures the main features of the ellipsoidal collapse of halos. Contrary to previous results based on extensions of the Press-Schechter formalism to NG initial conditions, we find that the non-spherical collapse of halos directly alter the signature of primordial NG. This points toward a potential degeneracy between the effect of primordial non-Gaussianity and that of non-linear halo collapse. The inferred mass function is found to be in remarkable agreement with N-body simulations of NG local type. Deviations are well within numerical uncertainties for all values of f{sub NL}{sup loc} in the range of validity of the perturbative calculation (|f{sub nl}{sup loc}|∼<200). Moreover, the comparison with simulation results suggests that for |f{sub NL}|∼>30 the non-linear collapse of halos, as described by our barrier model, strongly deviates from that of Gaussian initial conditions. This is not surprising since the effect of non-linear gravitational processes may be altered by initially large NG. Hence, in the lack of prior theoretical knowledge, halo collapse model parameters should be included in statistical halo mass function data analysis which aim to constrain the signature of primordial NG.

  12. Cryogenic ion implantation near amorphization threshold dose for halo/extension junction improvement in sub-30 nm device technologies

    SciTech Connect

    Park, Hugh; Todorov, Stan; Colombeau, Benjamin; Rodier, Dennis; Kouzminov, Dimitry; Zou Wei; Guo Baonian; Khasgiwale, Niranjan; Decker-Lucke, Kurt

    2012-11-06

    We report on junction advantages of cryogenic ion implantation with medium current implanters. We propose a methodical approach on maximizing cryogenic effects on junction characteristics near the amorphization threshold doses that are typically used for halo implants for sub-30 nm technologies. BF{sub 2}{sup +} implant at a dose of 8 Multiplication-Sign 10{sup 13}cm{sup -2} does not amorphize silicon at room temperature. When implanted at -100 Degree-Sign C, it forms a 30 - 35 nm thick amorphous layer. The cryogenic BF{sub 2}{sup +} implant significantly reduces the depth of the boron distribution, both as-implanted and after anneals, which improves short channel rolloff characteristics. It also creates a shallower n{sup +}-p junction by steepening profiles of arsenic that is subsequently implanted in the surface region. We demonstrate effects of implant sequences, germanium preamorphization, indium and carbon co-implants for extension/halo process integration. When applied to sequences such as Ge+As+C+In+BF{sub 2}{sup +}, the cryogenic implants at -100 Degree-Sign C enable removal of Ge preamorphization, and form more active n{sup +}-p junctions and steeper B and In halo profiles than sequences at room temperature.

  13. The Milky Way, the Galactic halo, and the Halos of Galaxies

    NASA Astrophysics Data System (ADS)

    Gerhard, Ortwin

    2015-08-01

    The Milky Way, "our" Galaxy, is currently the subject of intense study with many ground-based surveys, in anticipation of upcoming results from the GAIA mission. From this work we have been learning about the full three-dimensional structure of the Galactic box/peanut bulge, the distribution of stars in the bar and disk, and the many streams in the Galactic halo. The data tell us that most of the Galactic bulge formed from the disk, and that a large fraction of the Galactic halo has been accreted from outside. Similarly, in many external galaxy halos there is now evidence for tidal streams and accretion of satellites. To see these features requires exquisite data - mostly very deep photometry, but some halo substructures have also been found with kinematic data. These observations illustrate how galaxy halos are still growing, and sometimes can be used to "time" the accretion events. In comparison with cosmological simulations, the structure of galaxy halos gives us a vivid illustration of the hierarchical nature of our Universe.

  14. The age of the halo as determined from halo field stars

    NASA Astrophysics Data System (ADS)

    Guo, Jin-Cheng; Liu, Chao; Liu, Ji-Feng

    2016-03-01

    The age of the Galactic halo is a critical parameter that can constrain the origin of the stellar halo. In general, the Galactic stellar halo is believed to be very old. However, different independent measurements and techniques based on various types of stars are required so that the age estimates of the Galactic halo are accurate, robust, and reliable. In this work, we provide a novel approach to determine the age of the halo with turn-off stars. We first carefully select 63 field halo turn-off stars from the literature. Then, we compare them with the GARSTEC model, which takes the process of atomic diffusion into account in the B - V vs. metallicity plane. Finally, we run Monte Carlo simulations to consider the uncertainty of the color index and obtain the age of 10.5 ± 1.5 Gyr. This result is in agreement with previous studies. Future works are needed to collect more turn-off samples with more accurate photometry to reduce the uncertainty of the age.

  15. The Impact of Theoretical Uncertainties in the Halo Mass Function and Halo

    SciTech Connect

    Wu, Hao-Yi; Zentner, Andrew R.; Wechsler, Risa H.; /KIPAC, Menlo Park /SLAC /Pittsburgh U. /KIPAC, Menlo Park /SLAC

    2010-06-04

    We study the impact of theoretical uncertainty in the dark matter halo mass function and halo bias on dark energy constraints from imminent galaxy cluster surveys. We find that for an optical cluster survey like the Dark Energy Survey, the accuracy required on the predicted halo mass function to make it an insignificant source of error on dark energy parameters is {approx}1%. The analogous requirement on the predicted halo bias is less stringent ({approx}5%), particularly if the observable-mass distribution can be well constrained by other means. These requirements depend upon survey area but are relatively insensitive to survey depth. The most stringent requirements are likely to come from a survey over a significant fraction of the sky that aims to observe clusters down to relatively low mass, M{sub th}{approx} 10{sup 13.7} h{sup -1} M{sub sun}; for such a survey, the mass function and halo bias must be predicted to accuracies of {approx}0.5% and {approx}1%, respectively. These accuracies represent a limit on the practical need to calibrate ever more accurate halo mass and bias functions. We find that improving predictions for the mass function in the low-redshift and low-mass regimes is the most effective way to improve dark energy constraints.

  16. Vasectomy reversal.

    PubMed

    Belker, A M

    1987-02-01

    A vasovasostomy may be performed on an outpatient basis with local anesthesia, but also may be performed on an outpatient basis with epidural or general anesthesia. Local anesthesia is preferred by most of my patients, the majority of whom choose this technique. With proper preoperative and intraoperative sedation, patients sleep lightly through most of the procedure. Because of the length of time often required for bilateral microsurgical vasoepididymostomy, epidural or general anesthesia and overnight hospitalization are usually necessary. Factors influencing the preoperative choice for vasovasostomy or vasoepididymostomy in patients undergoing vasectomy reversal are considered. The preoperative planned choice of vasovasostomy or vasoepididymostomy for patients having vasectomy reversal described herein does not have the support of all urologists who regularly perform these procedures. My present approach has evolved as the data reported in Tables 1 and 2 have become available, but it may change as new information is evaluated. However, it offers a logical method for planning choices of anesthesia and inpatient or outpatient status for patients undergoing vasectomy reversal procedures. PMID:3811050

  17. Dark Halo and Disk Galaxy Scaling Laws

    NASA Astrophysics Data System (ADS)

    Navarro, J. F.

    I highlight recent progress in our understanding of the origin of disk galaxy scaling laws in a hierarchically clustering universe. Numerical simulations of galaxy formation in Cold Dark Matter (CDM) dominated universes indicate that the slope and scatter of the I-band Tully-Fisher (TF) relation are well reproduced in this model, although not, as proposed in recent work, because of the cosmological equivalence between halo mass and circular velocity, but rather as a result of the dynamical response of the halo to the assembly of the luminous component of the galaxy. The zero-point of the TF relation is determined mainly by the stellar mass-to-light ratio (ΥI) as well as by the concentration (c) of the dark halo. For c ~ 10, as is typical of halos formed in the `concordance' ΛCDM model, we find that this requires ΥI ~ 1.5, in reasonable agreement with the mass-to-light ratios expected of stellar populations with colors similar to those of TF galaxies. This conclusion supersedes that of Navarro & Steinmetz (2000a,b), who claimed the ΛCDM halos were too concentrated to be consistent with the observed TF relation. The disagreement can be traced to an incorrect normalization of the power spectrum used in that work. Our new results show that simulated disk galaxies in the ΛCDM scenario are not clearly inconsistent with the observed I-band Tully-Fisher relation. On the other hand, their angular momenta is much lower than observed. Accounting simultaneously for the spin, size and luminosity of disk galaxies remains a challenge for hierarchical models of galaxy formation.

  18. PEEK-Halo effect in interbody fusion.

    PubMed

    Phan, Kevin; Hogan, Jarred A; Assem, Yusuf; Mobbs, Ralph J

    2016-02-01

    Recent developments have seen poly[aryl-ether-ether-ketone] (PEEK) being increasingly used in vertebral body fusion. More novel approaches to improve PEEK have included the introduction of titanium-PEEK (Ti-PEEK) composites and coatings. This paper aims to describe a potential complication of PEEK based implants relating to poorer integration with the surrounding bone, producing a "PEEK-Halo" effect which is not seen in Ti-PEEK composite implants. We present images from two patients undergoing anterior lumbar interbody fusion (ALIF). The first patient underwent an L5/S1 ALIF using a PEEK implant whilst the second patient underwent L4/L5 ALIF using a Ti-PEEK composite implant. Evidence of osseointegration was sought using CT imaging and confirmed using histological preparations of a sheep tibia model. The PEEK-Halo effect is demonstrated by a halo effect between the PEEK implant and the bone graft on CT imaging. This phenomenon is secondary to poor osseointegration of PEEK implants. The PEEK-Halo effect was not demonstrated in the second patient who received a Ti-PEEK composite graft. Histological analysis of graft/bone interface surfaces in PEEK versus Ti-PEEK implants in a sheep model further confirmed poorer osseointegration of the PEEK implant. In conclusion, the PEEK-Halo effect is seen secondary to minimal osseointegration of PEEK at the adjacent vertebral endplate following a PEEK implant insertion. This effect is not seen with Ti-PEEK implants, and may support the role of titanium in improving the bone-implant interface of PEEK substrates. PMID:26474500

  19. Comparing halo bias from abundance and clustering

    NASA Astrophysics Data System (ADS)

    Hoffmann, K.; Bel, J.; Gaztañaga, E.

    2015-06-01

    We model the abundance of haloes in the ˜(3 Gpc h-1)3 volume of the MICE Grand Challenge simulation by fitting the universal mass function with an improved Jackknife error covariance estimator that matches theory predictions. We present unifying relations between different fitting models and new predictions for linear (b1) and non-linear (c2 and c3) halo clustering bias. Different mass function fits show strong variations in their performance when including the low mass range (Mh ≲ 3 × 1012 M⊙ h-1) in the analysis. Together with fits from the literature, we find an overall variation in the amplitudes of around 10 per cent in the low mass and up to 50 per cent in the high mass (galaxy cluster) range (Mh > 1014 M⊙ h-1). These variations propagate into a 10 per cent change in b1 predictions and a 50 per cent change in c2 or c3. Despite these strong variations, we find universal relations between b1 and c2 or c3 for which we provide simple fits. Excluding low-mass haloes, different models fitted with reasonable goodness in this analysis, show per cent level agreement in their b1 predictions, but are systematically 5-10 per cent lower than the bias directly measured with two-point halo-mass clustering. This result confirms previous findings derived from smaller volumes (and smaller masses). Inaccuracies in the bias predictions lead to 5-10 per cent errors in growth measurements. They also affect any halo occupation distribution fitting or (cluster) mass calibration from clustering measurements.

  20. Arabic sign language: a perspective.

    PubMed

    Abdel-Fattah, M A

    2005-01-01

    Sign language in the Arab World has been recently recognized and documented. Many efforts have been made to establish the sign language used in individual countries, including Jordan, Egypt, Libya, and the Gulf States, by trying to standardize the language and spread it among members of the Deaf community and those concerned. Such efforts produced many sign languages, almost as many as Arabic-speaking countries, yet with the same sign alphabets. This article gives a tentative account of some sign languages in Arabic through reference to their possible evolution, which is believed to be affected by the diglossic situation in Arabic, and by comparing some aspects of certain sign languages (Jordanian, Palestinian, Egyptian, Kuwaiti, and Libyan) for which issues such as primes, configuration, and movement in addition to other linguistic features are discussed. A contrastive account that depicts the principal differences among Arabic sign languages in general and the spoken language is given. PMID:15778217

  1. Snamprogetti signs MTBE contracts

    SciTech Connect

    Alperowicz, N.

    1992-04-15

    Snamprogetti (Milan) will use a Russian-developed dehydrogenation process in a world-scale methyl tert-butyl ether (MTBE) plant it is to build at Arzew, Algeria for a previously announced joint venture of Sonatrach (Algiers), Total (Paris), and Ecofuel (Milan). The 600,000-m.t./year plant will be the first in the West to use the improved Snamprogetti-Yarsintez fluidized-bed dehydrogenation (FBD) technology proven on a demonstration plant at Yaroslavl, Russia. The process has also been selected for use in Oxyfuel Corp.`s 500,000-m.t./year MTBE plant near Beaumont, TX. Although the environmental permit is already in place, final agreement for this project has not yet been signed.

  2. Characteristic time for halo current growth and rotation

    SciTech Connect

    Boozer, Allen H.

    2015-10-15

    A halo current flows for part of its path through the plasma edge and for part through the chamber walls and during tokamak disruptions can be as large as tenths of the plasma current. The primary interest in halo currents is the large force that they can exert on machine components particularly if the toriodal rotation of the halo current resonates with a natural oscillation frequency of the tokamak device. Halo currents arise when required to slow down the growth of a kink that is too unstable to be stabilized by the chamber walls. The width of the current channel in the halo plasma is comparable to the amplitude of the kink, and the halo current grows linearly, not exponentially, in time. The current density in the halo is comparable to that of the main plasma body. The rocket force due to plasma flowing out of the halo and recombining on the chamber walls can cause the non-axisymmetric magnetic structure produced by the kink to rotate toroidally at a speed comparable to the halo speed of sound. Gerhardt's observations of the halo current in NSTX shot 141 687 [Nucl. Fusion 53, 023005 (2013)] illustrate many features of the theory of halo currents and are discussed as a summary of the theory.

  3. Halo mass distribution reconstruction across the cosmic web

    NASA Astrophysics Data System (ADS)

    Zhao, Cheng; Kitaura, Francisco-Shu; Chuang, Chia-Hsun; Prada, Francisco; Yepes, Gustavo; Tao, Charling

    2015-08-01

    We study the relation between halo mass and its environment from a probabilistic perspective. We find that halo mass depends not only on local dark matter density, but also on non-local quantities such as the cosmic web environment and the halo-exclusion effect. Given these accurate relations, we have developed the HADRON-code (Halo mAss Distribution ReconstructiON), a technique which permits us to assign halo masses to a distribution of haloes in three-dimensional space. This can be applied to the fast production of mock galaxy catalogues, by assigning halo masses, and reproducing accurately the bias for different mass cuts. The resulting clustering of the halo populations agree well with that drawn from the BigMultiDark N-body simulation: the power spectra are within 1σ up to scales of k = 0.2 h Mpc-1, when using augmented Lagrangian perturbation theory based mock catalogues. Only the most massive haloes show a larger deviation. For these, we find evidence of the halo-exclusion effect. A clear improvement is achieved when assigning the highest masses to haloes with a minimum distance separation. We also compute the two- and three-point correlation functions, and find an excellent agreement with N-body results. Our work represents a quantitative application of the cosmic web classification. It can have further interesting applications in the multitracer analysis of the large-scale structure for future galaxy surveys.

  4. Can MACHOs probe the shape of the galaxy halo ?

    NASA Technical Reports Server (NTRS)

    Frieman, Joshua; Scoccimarro, Roman

    1994-01-01

    Microlensing searches in our galaxy have recently discovered several candidates in the direction of the Large Magellanic Cloud (LMC). We study the prospects for such searches to yield useful information about the flattening of the Galaxy dark matter halo, using a self-consistent oblate halo model and allowing for the possibility of misalignment between the disk and halo symmetry axes. The microlensing optical depth for the LMC, tau(LMC), depends sensitively on the disk-halo tilt angle in the Milky Way, as does the ratio tau(SMC)/tau(LMC). If the tilt angle is as large as 30 deg, a much larger spread in values for tau(LMC) is consistent with rotation curve constraints than previously thought. Disk-halo tilt and halo flattening do not significantly affect the massive compact halo object (MACHO) masses inferred from event durations.

  5. Dynamics of the Disruption Halo Current Toroidal Asymmetry in NSTX

    SciTech Connect

    S.P. Gerhardt

    2012-09-27

    This paper describes the dynamics of disruption halo current non-axisymmetries in the lower divertor of the National Spherical Torus Experiment [M. Ono, et al. Nuclear Fusion 40, 557 (2000)]. While. The halo currents typically have a strongly asymmetric structure where they enter the divertor floor, and this asymmetry has been observed to complete up to 7 toroidal revolutions over the duration of the halo current pulse. However, the rotation speed and toroidal extend of the asymmetry can vary significantly during the pulse. The rotation speed, halo current pulse duration, and total number of revolutions tend to be smaller in cases with large halo currents. The halo current pattern is observed to become toroidally symmetric at the end of the halo current pulse. It is proposed that this symmeterization is due to the loss of most or all of the closed field line geometry in the final phase of the vertical displacement event.

  6. The Structure of Dark Matter Halos in Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Burkert, A.

    1995-07-01

    Recent observations indicate that dark matter halos have flat central density profiles. Cosmological simulations with nonbaryonic dark matter, however, predict self-similar halos with central density cusps. This contradiction has lead to the conclusion that dark matter must be baryonic. Here it is shown that the dark matter halos of dwarf spiral galaxies represent a one-parameter family with self-similar density profiles. The observed global halo parameters are coupled with each other through simple scaling relations which can be explained by the standard cold dark matter model if one assumes that all the halos formed from density fluctuations with the same primordial amplitude. We find that the finite central halo densities correlate with the other global parameters. This result rules out scenarios where the flat halo cores formed subsequently through violent dynamical processes in the baryonic component. These cores instead provide important information on the origin and nature of dark matter in dwarf galaxies.

  7. Hot Stars in the Galactic Halo

    NASA Astrophysics Data System (ADS)

    Adelman, Saul J.; Upgren, Arthur R.; Adelman, Carol J.

    2011-03-01

    Participants; Preface; Foreword; Acknowledgements; Part I. Introductory Papers: 1. What is the galaxy's halo population?; 2. Theoretical properties of horizontal-branch stars; 3. A review of A-type horizontal-branch stars; Part II. Surveys: 4. A progress report on the Edinburgh-Cape object survey; 5. A 300 square degree survey of young stars at high galactic latitudes; 6. The isolation of a new sample of B stars in the halo; 7. A northern catalog of FHB/A stars; 8. Recent progress on a continuing survey of galactic globular clusters for blue stragglers; 9. UV observations with FAUST and the galactic model; 10. Hot stars at the South Galactic Pole; Part III. Clusters: 11. Population II horizontal branches: a photometric study of globular clusters; 12. The period-shift effect in Oosterhoff type II globular clusters; 13. UV photometry of hot stars in omega centauri; 14. Spectroscopic and UBV observations of blue stars at the NGP; 15. Population I horizontal branches: probing the halo-to-disk transition; Part IV. Stars: 16. Very hot subdwarf O stars; 17. Quantitative spectroscopy of the very hot subluminous O-stars: K646, PG1159-035, and KPD0005+5106; 18. Analyzing the helium-rich hot sdO stars in the Palomar Green Survey; 19. Late type companions of hot sd O stars; 20. Hot stars in globular clusters; 21. Faint blue stars from the Hamburg Schmidt Survey; 22. Stellar winds and the evolution of sdB's to sdO's; 23. Halo stars in the Vilnius photometric system; 24. Horizontal branch stars in the geneva photometric system; 25. Zeeman observations of FHB stars and hot subdwarf stars; 26. What does a FHB star's spectrum look like?; 27. A technique for distinguishing FHB stars from A-type stars; 28. eEemental abundances of halo A and interloper stars; 29. The mass of blue horizontal branch stars in the globular cluster NGC6397; 30. IUE observations of blue HB stars in the globular clusters M3 and NGC6752; 31. Metallicities and kinematics of the local RR lyraes: lukewarm stars

  8. Hot Stars in the Galactic Halo

    NASA Astrophysics Data System (ADS)

    Adelman, Saul J.; Upgren, Arthur R.; Adelman, Carol J.

    1994-08-01

    Participants; Preface; Foreword; Acknowledgements; Part I. Introductory Papers: 1. What is the galaxy's halo population?; 2. Theoretical properties of horizontal-branch stars; 3. A review of A-type horizontal-branch stars; Part II. Surveys: 4. A progress report on the Edinburgh-Cape object survey; 5. A 300 square degree survey of young stars at high galactic latitudes; 6. The isolation of a new sample of B stars in the halo; 7. A northern catalog of FHB/A stars; 8. Recent progress on a continuing survey of galactic globular clusters for blue stragglers; 9. UV observations with FAUST and the galactic model; 10. Hot stars at the South Galactic Pole; Part III. Clusters: 11. Population II horizontal branches: a photometric study of globular clusters; 12. The period-shift effect in Oosterhoff type II globular clusters; 13. UV photometry of hot stars in omega centauri; 14. Spectroscopic and UBV observations of blue stars at the NGP; 15. Population I horizontal branches: probing the halo-to-disk transition; Part IV. Stars: 16. Very hot subdwarf O stars; 17. Quantitative spectroscopy of the very hot subluminous O-stars: K646, PG1159-035, and KPD0005+5106; 18. Analyzing the helium-rich hot sdO stars in the Palomar Green Survey; 19. Late type companions of hot sd O stars; 20. Hot stars in globular clusters; 21. Faint blue stars from the Hamburg Schmidt Survey; 22. Stellar winds and the evolution of sdB's to sdO's; 23. Halo stars in the Vilnius photometric system; 24. Horizontal branch stars in the geneva photometric system; 25. Zeeman observations of FHB stars and hot subdwarf stars; 26. What does a FHB star's spectrum look like?; 27. A technique for distinguishing FHB stars from A-type stars; 28. eEemental abundances of halo A and interloper stars; 29. The mass of blue horizontal branch stars in the globular cluster NGC6397; 30. IUE observations of blue HB stars in the globular clusters M3 and NGC6752; 31. Metallicities and kinematics of the local RR lyraes: lukewarm stars

  9. A Speeding Binary in the Galactic Halo

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-04-01

    The recent discovery of a hyper-velocity binary star system in the halo of the Milky Way poses a mystery: how was this system accelerated to its high speed?Accelerating StarsUnlike the uniform motion in the Galactic disk, stars in the Milky Ways halo exhibit a huge diversity of orbits that are usually tilted relative to the disk and have a variety of speeds. One type of halo star, so-called hyper-velocity stars, travel with speeds that can approach the escape velocity of the Galaxy.How do these hyper-velocity stars come about? Assuming they form in the Galactic disk, there are multiple proposed scenarios through which they could be accelerated and injected into the halo, such as:Ejection after a close encounter with the supermassive black hole at the Galactic centerEjection due to a nearby supernova explosionEjection as the result of a dynamical interaction in a dense stellar population.Further observations of hyper-velocity stars are necessary to identify the mechanism responsible for their acceleration.J1211s SurpriseModels of J1211s orbit show it did not originate from the Galactic center (black dot). The solar symbol shows the position of the Sun and the star shows the current position of J1211. The bottom two panels show two depictions(x-y plane and r-z plane) of estimated orbits of J1211 over the past 10 Gyr. [Nmeth et al. 2016]To this end, a team of scientists led by Pter Nmeth (Friedrich Alexander University, Erlangen-Nrnberg) recently studied the candidate halo hyper-velocity star SDSS J121150.27+143716.2. The scientists obtained spectroscopy of J1211 using spectrographs at the Keck Telescope in Hawaii and ESOs Very Large Telescope in Chile. To their surprise, they discovered the signature of a companion in the spectra: J1211 is actually a binary!Nmeth and collaborators found that J1211, located roughly 18,000 light-years away, is moving at a rapid ~570 km/s relative to the galactic rest frame. The binary system consists of a hot (30,600 K) subdwarf and a

  10. THE HALO OCCUPATION DISTRIBUTION OF X-RAY-BRIGHT ACTIVE GALACTIC NUCLEI: A COMPARISON WITH LUMINOUS QUASARS

    SciTech Connect

    Richardson, Jonathan; Chatterjee, Suchetana; Myers, Adam D.; Zheng Zheng; Hickox, Ryan E-mail: schatte1@uwyo.edu

    2013-09-10

    We perform halo occupation distribution (HOD) modeling of the projected two-point correlation function (2PCF) of high-redshift (z {approx} 1.2) X-ray-bright active galactic nuclei (AGNs) in the XMM-COSMOS field measured by Allevato et al. The HOD parameterization is based on low-luminosity AGNs in cosmological simulations. At the median redshift of z {approx} 1.2, we derive a median mass of 1.02{sub -0.23}{sup +0.21} Multiplication-Sign 10{sup 13} h{sup -1} M{sub sun} for halos hosting central AGNs and an upper limit of {approx}10% on the AGN satellite fraction. Our modeling results indicate (at the 2.5{sigma} level) that X-ray AGNs reside in more massive halos compared to more bolometrically luminous, optically selected quasars at similar redshift. The modeling also yields constraints on the duty cycle of the X-ray AGN, and we find that at z {approx} 1.2 the average duration of the X-ray AGN phase is two orders of magnitude longer than that of the quasar phase. Our inferred mean occupation function of X-ray AGNs is similar to recent empirical measurements with a group catalog and suggests that AGN halo occupancy increases with increasing halo mass. We project the XMM-COSMOS 2PCF measurements to forecast the required survey parameters needed in future AGN clustering studies to enable higher precision HOD constraints and determinations of key physical parameters like the satellite fraction and duty cycle. We find that N {sup 2}/A {approx} 5 Multiplication-Sign 10{sup 6} deg{sup -2} (with N the number of AGNs in a survey area of A deg{sup 2}) is sufficient to constrain the HOD parameters at the 10% level, which is easily achievable by upcoming and proposed X-ray surveys.

  11. Radio haloes in Sunyaev-Zel'dovich-selected clusters of galaxies: the making of a halo?

    NASA Astrophysics Data System (ADS)

    Bonafede, A.; Intema, H.; Brüggen, M.; Vazza, F.; Basu, K.; Sommer, M.; Ebeling, H.; de Gasperin, F.; Röttgering, H. J. A.; van Weeren, R. J.; Cassano, R.

    2015-12-01

    Radio haloes are synchrotron radio sources detected in some massive galaxy clusters. Their size of Mpc indicates that (re)acceleration processes are taking place in the host cluster. X-ray catalogues of galaxy clusters have been used in the past to search for radio haloes and to understand their connection with cluster-cluster mergers and with the thermal component of the intracluster medium. More recently, the Sunyaev-Zel'dovich effect has been proven to be a better route to search for massive clusters in a wider redshift range. With the aim of discovering new radio haloes and understanding their connection with cluster-cluster mergers, we have selected the most massive clusters from the Planck early source catalogue and we have observed with the Giant Metrewave Radio Telescope at 323 MHz those objects for which deep observations were not available. We have discovered new peculiar radio emission in three of the observed clusters, finding (i) a radio halo in the cluster RXCJ0949.8+1708, (ii) extended emission in Abell 1443 that we classify as a radio halo plus a radio relic, with a bright filament embedded in the radio halo, and (iii) low-power radio emission in CIZA J1938.3+5409 that is ten times below the radio-X-ray correlation and represents the first direct detection of the radio emission in the `upper-limit' region of the radio-X-ray diagram. We discuss the properties of these new radio haloes in the framework of theoretical models for the radio emission.

  12. Precise halo orbit design and optimal transfer to halo orbits from earth using differential evolution

    NASA Astrophysics Data System (ADS)

    Nath, Pranav; Ramanan, R. V.

    2016-01-01

    The mission design to a halo orbit around the libration points from Earth involves two important steps. In the first step, we design a halo orbit for a specified size and in the second step, we obtain an optimal transfer trajectory design to the halo orbit from an Earth parking orbit. Conventionally, the preliminary design for these steps is obtained using higher order analytical solution and the dynamical systems theory respectively. Refinements of the design are carried out using gradient based methods such as differential correction and pseudo arc length continuation method under the of circular restricted three body model. In this paper, alternative single level schemes are developed for both of these steps based on differential evolution, an evolutionary optimization technique. The differential evolution based scheme for halo orbit design produces precise halo orbit design avoiding the refinement steps. Further, in this approach, prior knowledge of higher order analytical solutions for the halo orbit design is not needed. The differential evolution based scheme for the transfer trajectory, identifies the precise location on the halo orbit that needs minimum energy for insertion and avoids exploration of multiple points. The need of a close guess is removed because the present scheme operates on a set of bounds for the unknowns. The constraint on the closest approach altitude from Earth is handled through objective function. The use of these schemes as the design and analysis tools within the of circular restricted three body model is demonstrated through case studies for missions to the first libration point of Sun-Earth system.

  13. Intracranial halo pin penetration causing brain injury secondary to poor halo care technique: a case report and literature review.

    PubMed

    Male, Kishore Reddy; Guha, Abhijit; James, Stuart; Ahuja, Sashin

    2008-01-01

    : This is a case report of intra cranial penetration by halo pins resulting in cerebritis and fits secondary to incorrect halo care by the patient and his family. Halo pin penetration into the skull with brain injury is itself a rare incident. Previously documented case reports were in patients with a previous cranioplasties and they were highlight the fact that halo not to be used in cranioplasty patients. Cranial penetration of the halo pins has generally been secondary to a fall/medical condition as epilepsy. This incident how ever highlights the fact the halo care itself along with proper techniques used for tightening the halo pins by the carer plays a crucial role in preventing complications such as this. PMID:19068118

  14. A Ly{alpha} HALO AROUND A QUASAR AT REDSHIFT z = 6.4

    SciTech Connect

    Willott, Chris J.; Chet, Savironi; Hutchings, John B.; Bergeron, Jacqueline

    2011-12-15

    We present long-slit spectroscopic data that reveal extended Ly{alpha} emission around the z = 6.417 radio-quiet quasar CFHQS J2329-0301. The Ly{alpha} emission is extended over 15 kpc and has a luminosity of >8 Multiplication-Sign 10{sup 36} W, comparable to the most luminous Ly{alpha} halos known. The emission has complex kinematics, in part due to foreground absorption, which only partly covers the extended nebula. The velocity ranges from -500 km s{sup -1} to +500 km s{sup -1}, with a peak remarkably close to the systemic velocity identified by broad Mg II emission of the quasar. There is no evidence for infall or outflow of the halo gas. We speculate that the Ly{alpha} emission mechanism is recombination after quasar photoionization of gas sitting within a high-mass dark matter halo. The immense Ly{alpha} luminosity indicates a higher covering factor of cold gas compared with typical radio-quiet quasars at lower redshift.

  15. Dark-Matter Halos of Tenuous Galaxies

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-03-01

    A series of recent deep-imaging surveys has revealed dozens of lurking ultra-diffuse galaxies (UDGs) in nearby galaxy clusters. A new study provides key information to help us understand the origins of these faint giants.What are UDGs?There are three main possibilities for how UDGs galaxies with the sizes of giants, but luminosities no brighter than those of dwarfs formed:They are tidal dwarfs, created in galactic collisions when streams of matter were pulled away from the parent galaxies and halos to form dwarfs.They are descended from normal galaxies and were then altered by tidal interactions with the galaxy cluster.They are ancient remnant systems large galaxies whose gas was swept away, putting an early halt to star formation. The gas removal did not, however, affect their large dark matter halos, which permitted them to survive in the cluster environment.The key to differentiating between these options is to obtain mass measurements for the UDGs how large are their dark matter halos? In a recent study led by Michael Beasley (Institute of Astrophysics of the Canary Islands, University of La Laguna), a team of astronomers has determined a clever approach for measuring these galaxies masses: examine their globular clusters.Masses from Globular ClustersVCC 1287s mass measurements put it outside of the usual halo-mass vs. stellar-mass relationships for nearby galaxies: it has a significantly higher halo mass than is normal, given its stellar mass. [Adapted from Beasley et al. 2016]Beasley and collaborators selected one UDG, VCC 1287, from the Virgo galaxy cluster, and they obtained spectra of the globular clusters around it using the OSIRIS spectrograph on the Great Canary Telescope. They then determined VCC 1287s total halo mass in two ways: first by using the dynamics of the globular clusters, and then by relying on a relation between total globular cluster mass and halo mass.The two masses they found are in good agreement with each other; both are around 80

  16. Massive black holes in galactic halos?

    NASA Technical Reports Server (NTRS)

    Lacey, C. G.; Ostriker, J. P.

    1985-01-01

    In the present attempt to resolve the problems posed by the composition of dark halos and the heating of stellar disks, under the assumption that galaxy halos are composed of massive black holes, it is noted that the black holes must have masses of the order of one million solar masses. The heating mechanism proposed yields predictions for the dependence of the velocity dispersion on time, and for the shape of the velocity ellipsoid, which are in good agreement with observations. Attention is given to the constraints set by dynamical friction causing black holes to spiral to the Galactic center, by the possible presence of dark matter in dwarf spheroidal galaxies, and by the accretion of interstellar gas by the black holes that produce luminous objects in the Galaxy.

  17. Halo formation in high-power klystrons

    SciTech Connect

    Pakter, R.; Chen, C.

    1999-07-01

    Beam losses and radio-frequency (rf) pulse shortening are important issues in the development of high-power microwave (HPM) sources such as high-power klystrons and relativistic magnetrons. In this paper, the authors explore the formation and characteristics of halos around intense relativistic electron beams in a Periodic Permanent Magnet focusing klystron as well as in a uniform solenoidal focusing klystron. A self-consistent electrostatic model is used to investigate intense relativistic electron beam transport as an rf field induced mismatch between the electron beam and the focusing field develops. To model the effect of such mismatch in the PPM klystron experiment, they initialize the beam with an envelope mismatch. For zero canonical angular momentum and an initial mismatch of 100 percent, for example, the preliminary results show halo particles with a maximum radius extending up to several core radii at the rf output section. Transient effects and the influence of finite canonical angular momentum are being studied.

  18. Cool Carbon Stars in the Galactic Halo

    NASA Astrophysics Data System (ADS)

    Gigoyan, K. S.

    2016-06-01

    In this paper we report current status of search and study for Faint High Latitude Carbon Stars (FHLCs). Data for more than 1800 spectroscopically confirmed FHLCs are known, which are found thanks to objective prism surveys and photometric selections. More than half of the detected objects belongs to group of dwarf Carbon (dC) stars. Many-sided investigations based on modern astrophysical databases are necessary to study the space distribution of different groups of the FHLC stars and their possible origin in the Halo of our Galaxy. We report about the selection of FHLCs by the spectroscopic surveys: First Byurakan Survey (FBS), Hamburg/ESO Survey (HES), LAMOST Pilot Survey and SDSS, as well as by photometric selection: APM Survey for Cool Carbon Stars in the Galactic Halo, SDSS and 2MASS JHK colours.

  19. Linking the Halo to its Surroundings

    NASA Astrophysics Data System (ADS)

    Arimoto, N.

    The Galactic halo is unlikely built up from galaxy populations similar to the dwarf spheroidal galaxies (dSph's) in the Local Group, but it is possible that the halo was formed by accreted dwarf galaxies that had much larger mass and higher star formation rates such as the Saggitarius dSph. Cosmological simulations show that dSph galaxies formed via hierarchical clustering of numerous smaller building blocks. Stars formed at the galaxy centre tend to form from metal-rich infall gas, which builds up the metallicity gradients. Infalling gas has larger rotational velocity and smaller velocity dispersion due to the dissipative processes, resulting the two distinct old stellar populations of different chemical and kinematic properties, which are recently discovered in the Sculptor dSph galaxy.

  20. Beam halo in mismatched proton beams.

    SciTech Connect

    Wangler, Thomas P.,; Allen, C. K.; Chan, D.; Colestock, P. L. ,; Crandall, K. R.; Qiang, J.; Garnett, R. W.; Lysenko, W. P.; Gilpatrick, J. D.; Schneider, J. D.; Schulze, M. E.; Sheffield, R. L.; Smith, H. V.

    2002-01-01

    Progress was made during the past decade towards a better understanding of halo formation caused by beam mismatch in high-intensity beams. To test these ideas an experiment was carried out at Los Alamos with proton beams in a 52-quadrupole focusing channel. Rms emittances and beam widths were obtained from measured beam profiles for comparison with the maximum emittance growth predictions of a free-energy model and the maximum haloamplitude predictions of a particle-core model. The experimental results are also compared with multiparticle simulations. In this paper we will present the experimental results and discuss the implications with respect to the validity of both the models and the simulations. Keywords: beam halo, emittance growth, beam profiles, simulations, space charge, mismatch

  1. Stellar halos around Local Group galaxies

    NASA Astrophysics Data System (ADS)

    McConnachie, Alan W.

    2016-08-01

    The Local Group is now home to 102 known galaxies and candidates, with many new faint galaxies continuing to be discovered. The total stellar mass range spanned by this population covers a factor of close to a billion, from the faintest systems with stellar masses of order a few thousand to the Milky Way and Andromeda, with stellar masses of order 1011 M ⊙. Here, I discuss the evidence for stellar halos surrounding Local Group galaxies spanning from dwarf scales (with the case of the Andromeda II dwarf spheroidal), though to intermediate mass systems (M33) and finishing with M31. Evidence of extended stellar populations and merging is seen across the luminosity function, indicating that the processes that lead to halo formation are common at all mass scales.

  2. The Red Halos of Disk Galaxies

    NASA Astrophysics Data System (ADS)

    Zackrisson, E.; Bergvall, N.; Flynn, C.; Caldwell, B.; Östlin, G.; Micheva, G.

    2008-10-01

    Deep optical/near-IR surface photometry of galaxies outside the Local Group have revealed the existence of faint and very red halos around objects as diverse as spirals and blue compact galaxies. The colors of these structures are much too extreme to be reconciled with resolved stellar populations like those seen in the halos of the Milky Way or M 31, and alternative explanations like dust reddening, high metallicities or nebular emission are also disfavored. A stellar population obeying an extremely bottom-heavy initial mass function, similar to that recently reported for the LMC field population, is on the other hand consistent with all available data. Because of its high mass-to-light ratio, such a population would effectively behave as baryonic dark matter and could account for some of the baryons still missing from local inventories. Here, we report on a number of recent developments in this field.

  3. Stop Sign Crater

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    With its rim eroded off by catastrophic floods in Tiu Vallis and its strangely angular shape, this 12 km diameter crater looks vaguely like a stop sign.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

    Image information: VIS instrument. Latitude 8.6, Longitude 329.2 East (30.8 West). 19 meter/pixel resolution.

  4. THE SPHERICALIZATION OF DARK MATTER HALOS BY GALAXY DISKS

    SciTech Connect

    Kazantzidis, Stelios; Abadi, Mario G.; Navarro, Julio F. E-mail: mario@oac.uncor.ed

    2010-09-01

    Cosmological simulations indicate that cold dark matter (CDM) halos should be triaxial. Validating this theoretical prediction is, however, less than straightforward because the assembly of galaxies is expected to modify halo shapes and to render them more axisymmetric. We use a suite of N-body simulations to quantitatively investigate the effect of the growth of a central disk galaxy on the shape of triaxial dark matter halos. In most circumstances, the halo responds to the presence of the disk by becoming more spherical. The net effect depends weakly on the timescale of the disk assembly but noticeably on the orientation of the disk relative to the halo principal axes, and it is maximal when the disk symmetry axis is aligned with the major axis of the halo. The effect depends most sensitively on the overall gravitational importance of the disk. Our results indicate that exponential disks whose contribution peaks at less than {approx}50% of their circular velocity are unable to noticeably modify the shape of the gravitational potential of their surrounding halos. Many dwarf and low surface brightness galaxies are expected to be in this regime, and therefore their detailed kinematics could be used to probe halo triaxiality, one of the basic predictions of the CDM paradigm. We argue that the complex disk kinematics of the dwarf galaxy NGC 2976 might be the reflection of a triaxial halo. Such signatures of halo triaxiality should be common in galaxies where the luminous component is subdominant.

  5. Galaxy Formation in Triaxial Halos: Black Hole-Bulge-Dark Halo Correlation

    NASA Astrophysics Data System (ADS)

    El-Zant, Amr A.; Shlosman, Isaac; Begelman, Mitchell C.; Frank, Juhan

    2003-06-01

    The masses of supermassive black holes (SBHs) show correlations with bulge properties in disk and elliptical galaxies. We study the formation of galactic structure within flat-core, mildly triaxial halos and show that these correlations can be understood within the framework of a baryonic component modifying the orbital structure in the underlying potential. In particular, we find that terminal properties of bulges and their central SBHs are constrained by the destruction of box orbits in the harmonic cores of dark halos and the emergence of progressively less eccentric loop orbits there. SBH masses, M•, should exhibit a tighter correlation with bulge velocity dispersions, σB, than with bulge masses, MB, in accord with observations, if there is a significant scatter in the MH-σH relation for the halo. In the context of this model the observed M•-σB relation implies that halos should exhibit a Faber-Jackson type relationship between their masses and velocity dispersions. The most important prediction of our model is that halo properties determine the bulge and SBH parameters. The model also has important implications for galactic morphology and the process of disk formation.

  6. Capture Reactions with Halo Effective Field Theory

    NASA Astrophysics Data System (ADS)

    Higa, R.

    2015-12-01

    Loosely bound nuclei far from the stability region emerge as a quantum phenomenon with many universal properties. The connection between these properties and the underlying symmetries can be best explored with halo/cluster EFT, an effective field theory where the softness of the binding momentum and the hardness of the core(s) form the expansion parameter of a given perturbative approach. In the following I highlight a particular application where these ideas are being tested, namely capture reactions.

  7. The Halo B2B Studio

    NASA Astrophysics Data System (ADS)

    Gorzynski, Mark; Derocher, Mike; Mitchell, April Slayden

    Research underway at Hewlett-Packard on remote communication resulted in the identification of three important components typically missing in existing systems. These missing components are: group nonverbal communication capabilities, high-resolution interactive data capabilities, and global services. Here we discuss some of the design elements in these three areas as part of the Halo program at HP, a remote communication system shown to be effective to end-users.

  8. Halo abundances within the cosmic web

    NASA Astrophysics Data System (ADS)

    Alonso, D.; Eardley, E.; Peacock, J. A.

    2015-03-01

    We investigate the dependence of the mass function of dark-matter haloes on their environment within the cosmic web of large-scale structure. A dependence of the halo mass function on large-scale mean density is a standard element of cosmological theory, allowing mass-dependent biasing to be understood via the peak-background split. On the assumption of a Gaussian density field, this analysis can be extended to ask how the mass function depends on the geometrical environment: clusters, filaments, sheets and voids, as classified via the tidal tensor (the Hessian matrix of the gravitational potential). In linear theory, the problem can be solved exactly, and the result is attractively simple: the conditional mass function has no explicit dependence on the local tidal field, and is a function only of the local density on the filtering scale used to define the tidal tensor. There is nevertheless a strong implicit predicted dependence on geometrical environment, because the local density couples statistically to the derivatives of the potential. We compute the predictions of this model and study the limits of their validity by comparing them to results deduced empirically from N-body simulations. We have verified that, to a good approximation, the abundance of haloes in different environments depends only on their densities, and not on their tidal structure. In this sense we find relative differences between halo abundances in different environments with the same density which are smaller than ˜13 per cent. Furthermore, for sufficiently large filtering scales, the agreement with the theoretical prediction is good, although there are important deviations from the Gaussian prediction at small, non-linear scales. We discuss how to obtain improved predictions in this regime, using the `effective-universe' approach.

  9. Merger rates of dark matter haloes

    NASA Astrophysics Data System (ADS)

    Neistein, Eyal; Dekel, Avishai

    2008-08-01

    We derive analytic merger rates for dark matter haloes within the framework of the extended Press-Schechter (EPS) formalism. These rates become self-consistent within EPS once we realize that the typical merger in the limit of a small time-step involves more than two progenitors, contrary to the assumption of binary mergers adopted in earlier studies. We present a general method for computing merger rates that span the range of solutions permitted by the EPS conditional mass function, and focus on a specific solution that attempts to match the merger rates in N-body simulations. The corrected EPS merger rates are more accurate than the earlier estimates of Lacey & Cole by ~20 per cent for major mergers and by up to a factor of ~3 for minor mergers of mass ratio 1:104. Based on the revised merger rates, we provide a new algorithm for constructing Monte Carlo EPS merger trees, which could be useful in semi-analytic modelling. We provide analytic expressions and plot numerical results for several quantities that are very useful in studies of galaxy formation. This includes (i) the rate of mergers of a given mass ratio per given final halo, (ii) the fraction of mass added by mergers to a halo and (iii) the rate of mergers per given main progenitor. The creation and destruction rates of haloes serve for a self-consistency check. Our method for computing merger rates can be applied to conditional mass functions beyond EPS, such as those obtained by the ellipsoidal collapse model or extracted from N-body simulations.

  10. Is the Milky Way's Hot Halo Convectively Unstable?

    NASA Astrophysics Data System (ADS)

    Henley, David B.; Shelton, Robin L.

    2014-03-01

    We investigate the convective stability of two popular types of model of the gas distribution in the hot Galactic halo. We first consider models in which the halo density and temperature decrease exponentially with height above the disk. These halo models were created to account for the fact that, on some sight lines, the halo's X-ray emission lines and absorption lines yield different temperatures, implying that the halo is non-isothermal. We show that the hot gas in these exponential models is convectively unstable if γ < 3/2, where γ is the ratio of the temperature and density scale heights. Using published measurements of γ and its uncertainty, we use Bayes' theorem to infer posterior probability distributions for γ, and hence the probability that the halo is convectively unstable for different sight lines. We find that, if these exponential models are good descriptions of the hot halo gas, at least in the first few kiloparsecs from the plane, the hot halo is reasonably likely to be convectively unstable on two of the three sight lines for which scale height information is available. We also consider more extended models of the halo. While isothermal halo models are convectively stable if the density decreases with distance from the Galaxy, a model of an extended adiabatic halo in hydrostatic equilibrium with the Galaxy's dark matter is on the boundary between stability and instability. However, we find that radiative cooling may perturb this model in the direction of convective instability. If the Galactic halo is indeed convectively unstable, this would argue in favor of supernova activity in the Galactic disk contributing to the heating of the hot halo gas.

  11. Is the Milky Way's hot halo convectively unstable?

    SciTech Connect

    Henley, David B.; Shelton, Robin L.

    2014-03-20

    We investigate the convective stability of two popular types of model of the gas distribution in the hot Galactic halo. We first consider models in which the halo density and temperature decrease exponentially with height above the disk. These halo models were created to account for the fact that, on some sight lines, the halo's X-ray emission lines and absorption lines yield different temperatures, implying that the halo is non-isothermal. We show that the hot gas in these exponential models is convectively unstable if γ < 3/2, where γ is the ratio of the temperature and density scale heights. Using published measurements of γ and its uncertainty, we use Bayes' theorem to infer posterior probability distributions for γ, and hence the probability that the halo is convectively unstable for different sight lines. We find that, if these exponential models are good descriptions of the hot halo gas, at least in the first few kiloparsecs from the plane, the hot halo is reasonably likely to be convectively unstable on two of the three sight lines for which scale height information is available. We also consider more extended models of the halo. While isothermal halo models are convectively stable if the density decreases with distance from the Galaxy, a model of an extended adiabatic halo in hydrostatic equilibrium with the Galaxy's dark matter is on the boundary between stability and instability. However, we find that radiative cooling may perturb this model in the direction of convective instability. If the Galactic halo is indeed convectively unstable, this would argue in favor of supernova activity in the Galactic disk contributing to the heating of the hot halo gas.

  12. Constraining the halo mass function with observations

    NASA Astrophysics Data System (ADS)

    Castro, Tiago; Marra, Valerio; Quartin, Miguel

    2016-08-01

    The abundances of dark matter halos in the universe are described by the halo mass function (HMF). It enters most cosmological analyses and parametrizes how the linear growth of primordial perturbations is connected to these abundances. Interestingly, this connection can be made approximately cosmology independent. This made it possible to map in detail its near-universal behavior through large-scale simulations. However, such simulations may suffer from systematic effects, especially if baryonic physics is included. In this paper we ask how well observations can constrain directly the HMF. The observables we consider are galaxy cluster number counts, galaxy cluster power spectrum and lensing of type Ia supernovae. Our results show that DES is capable of putting the first meaningful constraints on the HMF, while both Euclid and J-PAS can give stronger constraints, comparable to the ones from state-of-the-art simulations. We also find that an independent measurement of cluster masses is even more important for measuring the HMF than for constraining the cosmological parameters, and can vastly improve the determination of the halo mass function. Measuring the HMF could thus be used to cross-check simulations and their implementation of baryon physics. It could even, if deviations cannot be accounted for, hint at new physics.

  13. Scaling Limit Analysis of Borromean Halos

    NASA Astrophysics Data System (ADS)

    Souza, L. A.; Bellotti, F. F.; Frederico, T.; Yamashita, M. T.; Tomio, Lauro

    2016-05-01

    The analysis of the core recoil momentum distribution of neutron-rich isotopes of light exotic nuclei is performed within a model of halo nuclei described by a core and two neutrons dominated by the s-wave channel. We adopt the renormalized three-body model with a zero-range force, which accounts for the Efimov physics. This model is applicable to nuclei with large two-neutron halos compared to the core size, and a neutron-core scattering length larger than the interaction range. The halo wave function in momentum space is obtained by using as inputs the two-neutron separation energy and the energies of the singlet neutron-neutron and neutron-core virtual states. Within our model, we obtain the momentum probability densities for the Borromean exotic nuclei Lithium-11 (^{11}Li), Berylium-14 (^{14}Be) and Carbon-22 (^{22}C). A fair reproduction of the experimental data was obtained in the case of the core recoil momentum distribution of ^{11}Li and ^{14}Be, without free parameters. By extending the model to ^{22}C, the combined analysis of the core momentum distribution and matter radius suggest (i) a ^{21}C virtual state well below 1 MeV; (ii) an overestimation of the extracted matter ^{22}C radius; and (iii) a two-neutron separation energy between 100 and 400 keV.

  14. Signs of Change: Contemporary Attitudes to Australian Sign Language

    ERIC Educational Resources Information Center

    Slegers, Claudia

    2010-01-01

    This study explores contemporary attitudes to Australian Sign Language (Auslan). Since at least the 1960s, sign languages have been accepted by linguists as natural languages with all of the key ingredients common to spoken languages. However, these visual-spatial languages have historically been subject to ignorance and myth in Australia and…

  15. The Halo of NGC 2438 scrutinized

    NASA Astrophysics Data System (ADS)

    Oettl, Silvia; Kimeswenger, Stefan

    2015-08-01

    Haloes and multiple shells around planetary nebulae trace the mass-loss history of the central star. The haloes provide us with information about abundances, ionization or kinematics. Detailed investigations of these haloes can be used to study the evolution of the old stellar population in our galaxy and beyond.Different observations show structures in the haloes like radial rays, blisters and rings (e.g., Ramos-Larios et al. 2012, MNRAS 423, 3753 or Matsuura et al. 2009, ApJ, 700, 1067). The origin of these features has been associated with ionization shadows (Balick 2004, AJ, 127, 2262). They can be observed in regions, where dense knots are opaque to stellar ionizing photons. In this regions we can see leaking UV photons.In this work, we present a detailed investigation of the multiple shell PN NGC 2438. We derive a complete data set of the main nebula. This allows us to analize the physical conditions from photoionization models, such as temperature, density and ionization, and clumping.Data from ESO (3.6m telescope - EFOSC1 - direct imaging and long slit spectroscopy) and from SAAO (spectroscopic observations using a small slit) were available. These data were supplemented by imaging data from the HST archive and by archival VLA observations. The low-excitation species are found to be dominated by clumps. The emission line ratios show no evidence for shocks. We find the shell in ionization equilibrium: a significant amount of UV radiation infiltrates the inner nebula. Thus the shell still seems to be ionized.The photoionization code CLOUDY was used to model the nebular properties and to derive a more accurate distance and ionized mass. The model supports the hypothesis that photoionization is the dominant process in this nebula, far out into the shell.If we want to use extragalactic planetary nebulae as probes of the old stellar population, we need to assess the potential impact of a halo on the evolution. Also the connection of observations and models must

  16. THE SPACE MOTION OF LEO I: THE MASS OF THE MILKY WAY'S DARK MATTER HALO

    SciTech Connect

    Boylan-Kolchin, Michael; Bullock, James S.; Sohn, Sangmo Tony; Van der Marel, Roeland P.; Besla, Gurtina

    2013-05-10

    We combine our Hubble Space Telescope measurement of the proper motion of the Leo I dwarf spheroidal galaxy (presented in a companion paper) with the highest resolution numerical simulations of Galaxy-size dark matter halos in existence to constrain the mass of the Milky Way's dark matter halo (M{sub vir,MW}). Despite Leo I's large Galactocentric space velocity (200 km s{sup -1}) and distance (261 kpc), we show that it is extremely unlikely to be unbound if Galactic satellites are associated with dark matter substructure, as 99.9% of subhalos in the simulations are bound to their host. The observed position and velocity of Leo I strongly disfavor a low-mass Milky Way: if we assume that Leo I is the least bound of the Milky Way's classical satellites, then we find that M{sub vir,MW} > 10{sup 12} M{sub Sun} at 95% confidence for a variety of Bayesian priors on M{sub vir,MW}. In lower mass halos, it is vanishingly rare to find subhalos at 261 kpc moving as fast as Leo I. Should an additional classical satellite be found to be less bound than Leo I, this lower limit on M{sub vir,MW} would increase by 30%. Imposing a mass-weighted {Lambda}CDM prior, we find a median Milky Way virial mass of M{sub vir,MW} = 1.6 Multiplication-Sign 10{sup 12} M{sub Sun }, with a 90% confidence interval of [1.0-2.4] Multiplication-Sign 10{sup 12} M{sub Sun }. We also confirm a strong correlation between subhalo infall time and orbital energy in the simulations and show that proper motions can aid significantly in interpreting the infall times and orbital histories of satellites.

  17. The Making of the Milky Way Halo

    NASA Astrophysics Data System (ADS)

    1999-02-01

    The VLT Watches a Dissolving Stellar Cluster A group of ESO astronomers [1] has used new observations, obtained with the first 8.2-m VLT Unit Telescope (UT1) during the "Science Verification" programme, to show that a globular cluster in the Milky Way galaxy is "evaporating" and has already lost its faintest stars. This is the first observational result of its kind and has important implications for future studies. It may be explained by a gradual loss of such stars from the cluster into the Milky Way halo, a roughly spherical region around the much flatter, spiral structure in which most of the stars and nebulae are located. The new result lends strong support to current theories about the evolution of the structure of this halo and also provides insights into the formation of the galaxy in which we live. Globular clusters and the halo of the Milky Way The stars that we observe in the halo of the Milky Way represent only a small fraction of the total mass in this region. Investigations of the motions of stars in our Galaxy have shown that this halo must harbour much more matter, which is hidden from our view. The same phenomenon has been observed in other galaxies, and astronomers refer to it as "dark matter". It is at this moment not known what this matter consists of. The brightest objects in the halo are the globular clusters . They are large groupings of stars that were formed together in the very early evolutionary phases of the Milky Way, some 12,000 - 14,000 million years ago. This happened soon after the moment when the first structures emerged in the large cloud of primordial hydrogen in which our Galaxy was born. A popular scenario describes the first build-up of galactic structure, i.e. of stars and gas, as when normal matter began to collect inside the dark-matter halo, due to its strong gravitational attraction. The globular clusters were most probably the first denizens of this protogalaxy . It is believed that the Milky Way Galaxy subsequently

  18. Light-element abundance variations in the Milky Way halo

    NASA Astrophysics Data System (ADS)

    Martell, S. L.; Grebel, E. K.

    2010-09-01

    We present evidence for the contribution of high-mass globular clusters to the stellar halo of the Galaxy. Using SDSS-II/SEGUE spectra of over 1900 G- and K-type halo giants, we identify for the first time a subset of stars with CN bandstrengths significantly larger, and CH bandstrengths lower, than the majority of halo field stars, at fixed temperature and metallicity. Since CN bandstrength inhomogeneity and the usual attendant abundance variations are presently understood as a result of star formation in globular clusters, we interpret this subset of halo giants as a result of globular cluster dissolution into the Galactic halo. We find that 2.5% of our sample is CN-strong, and can infer based on recent models of globular cluster evolution that the fraction of halo field stars initially formed within globular clusters may be as large as 50%.

  19. Distribution Function in the Center of the Dark Matter Halo

    NASA Astrophysics Data System (ADS)

    Ma, Ding; He, Ping

    N-body simulations of dark matter halos show that the density profiles of the halos behave as ρ(r) ∝ r-α(r), where the density logarithmic slope α ≃ 1-1.5 in the center and α ≃ 3-4 in the outer parts of the halos. However, some observations are not in agreement with simulations in the very central region of the halos. The simulations also show that the velocity dispersion anisotropy parameter β ≈ 0 in the inner part of the halo and the so-called pseudo-phase-space density ρ/σ3 behaves as a power law in radius r. With these results in mind, we study the distribution function and the pseudo-phase-space density ρ/σ3 of the center of dark matter halos and find that they are closely related.

  20. Listing all sorting reversals in quadratic time

    PubMed Central

    2011-01-01

    We describe an average-case O(n2) algorithm to list all reversals on a signed permutation π that, when applied to π, produce a permutation that is closer to the identity. This algorithm is optimal in the sense that, the time it takes to write the list is Ω(n2) in the worst case. PMID:21504604

  1. Arabic Sign Language: A Perspective

    ERIC Educational Resources Information Center

    Abdel-Fattah, M. A.

    2005-01-01

    Sign language in the Arab World has been recently recognized and documented. Many efforts have been made to establish the sign language used in individual countries, including Jordan, Egypt, Libya, and the Gulf States, by trying to standardize the language and spread it among members of the Deaf community and those concerned. Such efforts produced…

  2. NUHOMS{reg_sign} update

    SciTech Connect

    Rich, N.

    1995-12-31

    NUHOMS{reg_sign} is the dry spent fuel storage and transportation technology selected to date by the majority of commercial nuclear utilities. The author first gives a system overview of the NUHOMS{reg_sign}. Next she discusses the project status and licensing status. She closes with an update of the multi-purpose canister.

  3. Sign Program for a University.

    ERIC Educational Resources Information Center

    Architectural and Engineering News, 1968

    1968-01-01

    A co-ordinated sign program for a multi-campus university not only helps students and visitors find their way around, but is a design element that adds identification and unity. Graphic designer, Paul Arthur, has designed a modular sign system for the University of Tennessee with all elements having standard color, lettering, size and materials.…

  4. Signing Apes and Evolving Linguistics.

    ERIC Educational Resources Information Center

    Stokoe, William C.

    Linguistics retains from its antecedents, philology and the study of sacred writings, some of their apologetic and theological bias. Thus it has not been able to face squarely the question how linguistic function may have evolved from animal communication. Chimpanzees' use of signs from American Sign Language forces re-examination of language…

  5. Kinematic Parameters of Signed Verbs

    ERIC Educational Resources Information Center

    Malaia, Evie; Wilbur, Ronnie B.; Milkovic, Marina

    2013-01-01

    Purpose: Sign language users recruit physical properties of visual motion to convey linguistic information. Research on American Sign Language (ASL) indicates that signers systematically use kinematic features (e.g., velocity, deceleration) of dominant hand motion for distinguishing specific semantic properties of verb classes in production…

  6. Symmetry in Sign Language Poetry

    ERIC Educational Resources Information Center

    Sutton-Spence, Rachel; Kaneko, Michiko

    2007-01-01

    This paper considers the range of ways that sign languages use geometric symmetry temporally and spatially to create poetic effect. Poets use this symmetry in sign language art to highlight duality and thematic contrast, and to create symbolic representations of beauty, order and harmony. (Contains 8 tables, 14 figures and 6 notes.)

  7. Keresan Pueblo Indian Sign Language.

    ERIC Educational Resources Information Center

    Kelley, Walter P.; McGregor, Tony L.

    This paper describes the use of Keresan Pueblo Indian Sign Language (KPISL) in one small, Keresan-speaking pueblo in central New Mexico, where 15 out of 650 tribal members have severe to profound hearing loss (twice the national average). KPISL did not originate for the same purposes as the Plains Indian Sign Language, (PISL) which was developed…

  8. The shapes and alignments of dark matter halos

    SciTech Connect

    Schneider, Michael D.; Frenk, Carlos S.; Cole, Shaun E-mail: c.s.frenk@durham.ac.uk

    2012-05-01

    We present measurements of the triaxial dark matter halo shapes and alignment correlation functions in the Millennium and Millennium-2 dark matter N-body simulations. These two simulations allow us to measure the distributions of halo shapes down to 10% of the virial radius over a halo mass range of 6 × 10{sup 9}–2 × 10{sup 14} h{sup −1}M{sub s}un. We largely confirm previous results on the distributions of halo axis ratios as a function of halo mass, but we find that the median angle between halo major axes at different halo radii can vary by a factor of 2 between the Millennium-1 and 2 simulations because of the different mass resolution. Thus, error in the shape determinations from limited resolution is potentially degenerate with the misalignment of halo inner and outer shapes used to constrain Brightest Cluster Galaxy alignments in previous works. We also present simplifying parameterizations for the 3-D halo-mass alignment correlation functions that are necessary ingredients for triaxial halo models of large-scale structure and models of galaxy intrinsic alignments as contaminants for cosmic shear surveys. We measure strong alignments between halos of all masses and the surrounding dark matter overdensities out to several tens of h{sup −1} Mpc, in agreement with observed shear-galaxy and cluster shape correlations. We use these measurements to forecast the contribution to the weak lensing signal around galaxy clusters from correlated mass along the line-of-sight. For prolate clusters with major axes aligned with the line-of-sight the fraction of the weak lensing signal from mass external to the cluster can be twice that predicted if the excess halo alignment correlation is assumed to be zero.

  9. Data-Parallel Halo Finder Operator in PISTON

    SciTech Connect

    Widanagamaachchi, W. N.

    2012-08-01

    PISTON is a portable framework which supports the development of visualization and analysis operators using a platform-independent, data-parallel programming model. Operators such as isosurface, cut-surface and threshold have been implemented in this framework, with the exact same operator code achieving good parallel performance on different architectures. An important analysis operator in cosmology is the halo finder. A halo is a cluster of particles and is considered a common feature of interest found in cosmology data. As the number of cosmological simulations carried out in the recent past has increased, the resultant data of these simulations and the required analysis tasks have increased as well. As a consequence, there is a need to develop scalable and efficient tools to carry out the needed analysis. Therefore, we are currently implementing a halo finder operator using PISTON. Researchers have developed a wide variety of techniques to identify halos in raw particle data. The most basic algorithm is the friend-of-friends (FOF) halo finder, where the particles are clustered based on two parameters: linking length and halo size. In a FOF halo finder, all particles which lie within the linking length are considered as one halo and the halos are filtered based on the halo size parameter. A naive implementation of a FOF halo finder compares each and every particle pair, requiring O(n{sup 2}) operations. Our data-parallel halo finder operator uses a balanced k-d tree to reduce this number of operations in the average case, and implements the algorithm using only the data-parallel primitives in order to achieve portability and performance.

  10. Driveway identification signing and marking

    SciTech Connect

    Not Available

    1986-09-01

    A primary purpose of a public highway is to provide access to commercial establishments. Driveways to fast-food restaurants, banks, retail stores, and office buildings line many road sections. A bewildering array of reflectorized, unreflectorized, lighted, and unlighted high- and low-mounted signs with varying messages direct motorists in and out of many of the driveways, while other access points have no signs. In a very few cases, the Manual of Uniform Traffic Control Devices-type signing for one-way roads has been installed for the one-way-type circulation design at some of these establishments. Should MUTCD-type one-way signs be recommended practice to control and provide a more uniform identification of these driveways when necessary. Are there signs not presently in the MUTCD that should be added to cope with this situation.

  11. Levy-Student distributions for halos in accelerator beams

    SciTech Connect

    Cufaro Petroni, Nicola; De Martino, Salvatore; De Siena, Silvio; Illuminati, Fabrizio

    2005-12-15

    We describe the transverse beam distribution in particle accelerators within the controlled, stochastic dynamical scheme of stochastic mechanics (SM) which produces time reversal invariant diffusion processes. This leads to a linearized theory summarized in a Schroedinger-like (SL) equation. The space charge effects have been introduced in recent papers by coupling this S-L equation with the Maxwell equations. We analyze the space-charge effects to understand how the dynamics produces the actual beam distributions, and in particular we show how the stationary, self-consistent solutions are related to the (external and space-charge) potentials both when we suppose that the external field is harmonic (constant focusing), and when we a priori prescribe the shape of the stationary solution. We then proceed to discuss a few other ideas by introducing generalized Student distributions, namely, non-Gaussian, Levy infinitely divisible (but not stable) distributions. We will discuss this idea from two different standpoints: (a) first by supposing that the stationary distribution of our (Wiener powered) SM model is a Student distribution; (b) by supposing that our model is based on a (non-Gaussian) Levy process whose increments are Student distributed. We show that in the case (a) the longer tails of the power decay of the Student laws and in the case (b) the discontinuities of the Levy-Student process can well account for the rare escape of particles from the beam core, and hence for the formation of a halo in intense beams.

  12. Automatic Recognition of Road Signs

    NASA Astrophysics Data System (ADS)

    Inoue, Yasuo; Kohashi, Yuuichirou; Ishikawa, Naoto; Nakajima, Masato

    2002-11-01

    The increase in traffic accidents is becoming a serious social problem with the recent rapid traffic increase. In many cases, the driver"s carelessness is the primary factor of traffic accidents, and the driver assistance system is demanded for supporting driver"s safety. In this research, we propose the new method of automatic detection and recognition of road signs by image processing. The purpose of this research is to prevent accidents caused by driver"s carelessness, and call attention to a driver when the driver violates traffic a regulation. In this research, high accuracy and the efficient sign detecting method are realized by removing unnecessary information except for a road sign from an image, and detect a road sign using shape features. At first, the color information that is not used in road signs is removed from an image. Next, edges except for circular and triangle ones are removed to choose sign shape. In the recognition process, normalized cross correlation operation is carried out to the two-dimensional differentiation pattern of a sign, and the accurate and efficient method for detecting the road sign is realized. Moreover, the real-time operation in a software base was realized by holding down calculation cost, maintaining highly precise sign detection and recognition. Specifically, it becomes specifically possible to process by 0.1 sec(s)/frame using a general-purpose PC (CPU: Pentium4 1.7GHz). As a result of in-vehicle experimentation, our system could process on real time and has confirmed that detection and recognition of a sign could be performed correctly.

  13. N-body dark matter haloes with simple hierarchical histories

    NASA Astrophysics Data System (ADS)

    Jiang, Lilian; Helly, John C.; Cole, Shaun; Frenk, Carlos S.

    2014-05-01

    We present a new algorithm which groups the subhaloes found in cosmological N-body simulations by structure finders such as SUBFIND into dark matter haloes whose formation histories are strictly hierarchical. One advantage of these `Dhaloes' over the commonly used friends-of-friends (FoF) haloes is that they retain their individual identity in the cases when FoF haloes are artificially merged by tenuous bridges of particles or by an overlap of their outer diffuse haloes. Dhaloes are thus well suited for modelling galaxy formation and their merger trees form the basis of the Durham semi-analytic galaxy formation model, GALFORM. Applying the Dhalo construction to the Λ cold dark matter Millennium II Simulation, we find that approximately 90 per cent of Dhaloes have a one-to-one, bijective match with a corresponding FoF halo. The remaining 10 per cent are typically secondary components of large FoF haloes. Although the mass functions of both types of haloes are similar, the mass of Dhaloes correlates much more tightly with the virial mass, M200, than FoF haloes. Approximately 80 per cent of FoF and bijective and non-bijective Dhaloes are relaxed according to standard criteria. For these relaxed haloes, all three types have similar concentration-M200 relations and, at fixed mass, the concentration distributions are described accurately by log-normal distributions.

  14. On detecting halo assembly bias with galaxy populations

    NASA Astrophysics Data System (ADS)

    Lin, Yen-Ting; Mandelbaum, Rachel; Huang, Yun-Hsin; Huang, Hung-Jin; Dalal, Neal; Diemer, Benedikt; Kravtsov, Andrey

    2016-01-01

    The fact that the clustering and concentration of dark matter halos depend not only on their mass, but also the formation epoch, is a prominent, albeit subtle, feature of the cold dark matter structure formation theory, and is known as assembly bias. At low mass scales (~1012 Msun), early-forming halos are predicted to be more strongly clustered than the late-forming ones. In this study we aim to robustly detect the signature of assembly bias observationally, making use of formation time indicators of central galaxies in low mass halos as a proxy for the halo formation history. Weak gravitational lensing is employed to ensure our early- and late-forming halo samples have similar masses, and are free of contamination of satellites from more massive halos. For the two formation time indicators used (resolved star formation history and current specific star formation rate), we do not find convincing evidence of assembly bias. We attribute the lack of detection to the possibility that these indicators do not correlate well with the halo formation history, and suggest alternatives that should perform better for future studies. In addition, we have developed a method to constrain the probability distribution function of halo mass of a given galaxy sample, and also demonstrate that the abundance matching-based halo mass assignments to galaxy groups and clusters may be biased, likely due to interlopers from more massive galactic systems.

  15. Typical CT and MRI signs of hepatic epithelioid hemangioendothelioma

    PubMed Central

    GAN, LU; CHANG, RUIPING; JIN, HUALAN; YANG, LI

    2016-01-01

    To investigate the typical magnetic resonance imaging (MRI) and computed tomography (CT) features of hepatic epithelioid hemangioendothelioma (HEH), the CT and MRI findings of 14 histopathologically confirmed cases of HEH were retrospectively analyzed. Non-contrast and dynamic contrast-enhanced scans were conducted in all cases. A total of 229 lesions were detected in the 14 cases. All cases were classified as one of three types: (i) Solitary nodular type (1 case, 7%); (ii) multifocal nodular type (11 cases, 79%); or (iii) diffuse type (2 cases, 14%). The diameter of the lesions ranged from 5 to 105 mm. For the first two types (solitary and multifocal nodular types), the CT findings included low density lesions with clear margins on non-contrast scans, centripetal enhancement in arterial phase, and homogeneous enhancement in the portal venous and delay phases. The findings of non-contrast MRI scans for these two types included low signal intensity on T1-weighted images, heterogeneous high signal intensity on T2-weighted images, and heterogeneous high signal intensity on diffusion-weighted images. The lesions were predominantly located in submarginal areas. On contrast-enhanced MRI, the findings for the first two types included peripheral ring-like enhancement with a central low signal intensity (‘black target-like’ sign) and a central enhanced core surrounded by a low signal intensity halo (‘white target-like’ sign). The findings for the third HEH type (diffuse type) on CT and MRI scans included low density or heterogeneous signal intensity lesions involving regions of part or the whole liver, coalescent lesions (‘strip-like’ sign), and gradual enhancement along central vessels (‘lollipop’ sign). Collectively, these findings indicate that the ‘white target-like’ sign, ‘black target-like’ sign, ‘lollipop’ sign and ‘strip-like’ sign, in addition to capsular contraction and submarginal location, on CT and MRI imaging may have

  16. Mapping stellar content to dark matter haloes - II. Halo mass is the main driver of galaxy quenching

    NASA Astrophysics Data System (ADS)

    Zu, Ying; Mandelbaum, Rachel

    2016-04-01

    We develop a simple yet comprehensive method to distinguish the underlying drivers of galaxy quenching, using the clustering and galaxy-galaxy lensing of red and blue galaxies in Sloan Digital Sky Survey. Building on the iHOD framework developed by Zu & Mandelbaum, we consider two quenching scenarios: (1) a `halo' quenching model in which halo mass is the sole driver for turning off star formation in both centrals and satellites; and (2) a `hybrid' quenching model in which the quenched fraction of galaxies depends on their stellar mass, while the satellite quenching has an extra dependence on halo mass. The two best-fitting models describe the red galaxy clustering and lensing equally well, but halo quenching provides significantly better fits to the blue galaxies above 1011 h-2 M⊙. The halo quenching model also correctly predicts the average halo mass of the red and blue centrals, showing excellent agreement with the direct weak lensing measurements of locally brightest galaxies. Models in which quenching is not tied to halo mass, including an age-matching model in which galaxy colour depends on halo age at fixed M*, fail to reproduce the observed halo mass for massive blue centrals. We find similar critical halo masses responsible for the quenching of centrals and satellites (˜1.5 × 1012 h-1 M⊙), hinting at a uniform quenching mechanism for both, e.g. the virial shock heating of infalling gas. The success of the iHOD halo quenching model provides strong evidence that the physical mechanism that quenches star formation in galaxies is tied principally to the masses of their dark matter haloes rather than the properties of their stellar components.

  17. LSE-Sign: A lexical database for Spanish Sign Language.

    PubMed

    Gutierrez-Sigut, Eva; Costello, Brendan; Baus, Cristina; Carreiras, Manuel

    2016-03-01

    The LSE-Sign database is a free online tool for selecting Spanish Sign Language stimulus materials to be used in experiments. It contains 2,400 individual signs taken from a recent standardized LSE dictionary, and a further 2,700 related nonsigns. Each entry is coded for a wide range of grammatical, phonological, and articulatory information, including handshape, location, movement, and non-manual elements. The database is accessible via a graphically based search facility which is highly flexible both in terms of the search options available and the way the results are displayed. LSE-Sign is available at the following website: http://www.bcbl.eu/databases/lse/. PMID:25630312

  18. Characterizing stellar halo populations - I. An extended distribution function for halo K giants

    NASA Astrophysics Data System (ADS)

    Das, Payel; Binney, James

    2016-08-01

    We fit an extended distribution function (EDF) to K giants in the Sloan Extension for Galactic Understanding and Exploration survey. These stars are detected to radii ˜80 kpc and span a wide range in [Fe/H]. Our EDF, which depends on [Fe/H] in addition to actions, encodes the entanglement of metallicity with dynamics within the Galaxy's stellar halo. Our maximum-likelihood fit of the EDF to the data allows us to model the survey's selection function. The density profile of the K giants steepens with radius from a slope ˜-2 to ˜-4 at large radii. The halo's axis ratio increases with radius from 0.7 to almost unity. The metal-rich stars are more tightly confined in action space than the metal-poor stars and form a more flattened structure. A weak metallicity gradient ˜-0.001 dex kpc-1, a small gradient in the dispersion in [Fe/H] of ˜0.001 dex kpc-1, and a higher degree of radial anisotropy in metal-richer stars result. Lognormal components with peaks at ˜-1.5 and ˜-2.3 are required to capture the overall metallicity distribution, suggestive of the existence of two populations of K giants. The spherical anisotropy parameter varies between 0.3 in the inner halo to isotropic in the outer halo. If the Sagittarius stream is included, a very similar model is found but with a stronger degree of radial anisotropy throughout.

  19. Characterising stellar halo populations I: An extended distribution function for halo K giants

    NASA Astrophysics Data System (ADS)

    Das, Payel; Binney, James

    2016-05-01

    We fit an Extended Distribution Function (EDF) to K giants in the Sloan Extension for Galactic Understanding and Exploration (SEGUE) survey. These stars are detected to radii ˜80 kpc and span a wide range in [Fe/H]. Our EDF, which depends on [Fe/H] in addition to actions, encodes the entanglement of metallicity with dynamics within the Galaxy's stellar halo. Our maximum-likelihood fit of the EDF to the data allows us to model the survey's selection function. The density profile of the K giants steepens with radius from a slope ˜-2 to ˜-4 at large radii. The halo's axis ratio increases with radius from 0.7 to almost unity. The metal-rich stars are more tightly confined in action space than the metal-poor stars and form a more flattened structure. A weak metallicity gradient ˜-0.001 dex/kpc, a small gradient in the dispersion in [Fe/H] of ˜0.001 dex/kpc, and a higher degree of radial anistropy in metal-richer stars result. Lognormal components with peaks at ˜-1.5 and ˜-2.3 are required to capture the overall metallicity distribution, suggestive of the existence of two populations of K giants. The spherical anisotropy parameter varies between 0.3 in the inner halo to isotropic in the outer halo. If the Sagittarius stream is included, a very similar model is found but with a stronger degree of radial anisotropy throughout.

  20. COMPOSITION OF LOW-REDSHIFT HALO GAS

    SciTech Connect

    Cen Renyue

    2013-06-20

    Halo gas in low-z (z < 0.5) {>=}0.1 L{sub *} galaxies in high-resolution, large-scale cosmological hydrodynamic simulations is examined with respect to three components: cold, warm, and hot with temperatures of <10{sup 5}, 10{sup 5-6}, and >10{sup 6} K, respectively. Utilizing O VI {lambda}{lambda}1032, 1038 absorption lines, the warm component is compared to observations, and agreement is found with respect to the galaxy-O VI line correlation, the ratio of the O VI line incidence rate in blue to red galaxies, and the amount of O VI mass in star-forming galaxies. A detailed account of the sources of warm halo gas (stellar feedback heating, gravitational shock heating, and accretion from the intergalactic medium), inflowing and outflowing warm halo gas metallicity disparities, and their dependencies on galaxy types and environment is also presented. With the warm component securely anchored, our simulations make the following additional predictions. First, cold gas is the primary component in inner regions with its mass comprising 50% of all gas within galactocentric radius r = (30, 150) kpc in (red, blue) galaxies. Second, at r > (30, 200) kpc in (red, blue) galaxies the hot component becomes the majority. Third, the warm component is a perpetual minority, with its contribution peaking at {approx}30% at r = 100-300 kpc in blue galaxies and never exceeding 5% in red galaxies. The significant amount of cold gas in low-z early-type galaxies, which was found in simulations and in agreement with recent observations (Thom et al.), is intriguing, as is the dominance of hot gas at large radii in blue galaxies.

  1. Composition of Low-redshift Halo Gas

    NASA Astrophysics Data System (ADS)

    Cen, Renyue

    2013-06-01

    Halo gas in low-z (z < 0.5) >=0.1 L * galaxies in high-resolution, large-scale cosmological hydrodynamic simulations is examined with respect to three components: cold, warm, and hot with temperatures of <105, 105-6, and >106 K, respectively. Utilizing O VI λλ1032, 1038 absorption lines, the warm component is compared to observations, and agreement is found with respect to the galaxy-O VI line correlation, the ratio of the O VI line incidence rate in blue to red galaxies, and the amount of O VI mass in star-forming galaxies. A detailed account of the sources of warm halo gas (stellar feedback heating, gravitational shock heating, and accretion from the intergalactic medium), inflowing and outflowing warm halo gas metallicity disparities, and their dependencies on galaxy types and environment is also presented. With the warm component securely anchored, our simulations make the following additional predictions. First, cold gas is the primary component in inner regions with its mass comprising 50% of all gas within galactocentric radius r = (30, 150) kpc in (red, blue) galaxies. Second, at r > (30, 200) kpc in (red, blue) galaxies the hot component becomes the majority. Third, the warm component is a perpetual minority, with its contribution peaking at ~30% at r = 100-300 kpc in blue galaxies and never exceeding 5% in red galaxies. The significant amount of cold gas in low-z early-type galaxies, which was found in simulations and in agreement with recent observations (Thom et al.), is intriguing, as is the dominance of hot gas at large radii in blue galaxies.

  2. Carbon Stars in the Galactic Halo

    NASA Astrophysics Data System (ADS)

    Totten, E. J.; Irwin, M. J.

    1996-04-01

    A byproduct of the APM high redshift quasar survey (Irwin et al. 1991) was the discovery of ~ 20 distant (20-100kpc) cool AGB carbon stars (all N-type) at high Galactic latitude. In August we used the INT+IDS to survey the rest of the high latitude SGC sky visible from La Palma and found 10 more similar carbon stars. Before this work there were only a handful of published faint high latitude cool carbon stars known (eg. Margon et al., 1984, Mould et al., 1985) and there has been speculation as to their origin (eg. Sanduleak, 1980, van den Bergh & Lafontaine, 1984). Intermediate age carbon stars (3 -- 7 Gyrs) seem unlikely to have formed in the halo in isolation from other star forming regions so how did they get there ? One possiblity that we are investigating, is that they arise from either the disruption of tidally captured dSph galaxies or are a manifestion of the long sought after optical component of the Magellanic Stream. Lack of proper motion rules out the possibility of them being dwarf carbon stars (eg. Warren et al., 1992); indeed no N-type carbon stars have been found to be dwarf carbon stars. Our optical spectroscopy confirms their carbon star type (they are indistinguishable from cool AGB carbon stars in nearby dwarf galaxies) and hence probable large distances. We are extending our survey to the NGC region, obtaining radial velocities and good S:N fluxed spectra for all the carbon stars. This will enable us to investigate their kinematics, true spatial distribution and hence their origin. Even, in the event that these objects are somehow an integral part of the Galactic halo, then their velocities and large distances will enable direct studies of the velocity ellipsoid and rotation of the outer halo (eg. Green et al., 1994).

  3. 77 FR 16264 - Manufacturer of Controlled Substances, Notice of Registration; Halo Pharmaceutical Inc.

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-20

    ... FR 77850, Halo Pharmaceutical Inc., 30 North Jefferson Road, Whippany, New Jersey 07981, made... Enforcement Administration Manufacturer of Controlled Substances, Notice of Registration; Halo Pharmaceutical... determined that the registration of Halo Pharmaceutical Inc. to manufacture the listed basic classes...

  4. Resolving the stellar halos of six massive disk galaxies beyond the Local Group

    NASA Astrophysics Data System (ADS)

    Monachesi, Antonela; Bell, Eric F.; Radburn-Smith, David J.; de Jong, Roelof S.; Bailin, Jeremy; Holwerda, Benne; Streich, David

    2016-08-01

    Models of galaxy formation in a hierarchical universe predict substantial scatter in the halo-to-halo stellar properties, owing to stochasticity in galaxies' merger histories. Currently, only few detailed observations of stellar halos are available, mainly for the Milky Way and M31. We present the stellar halo color/metallicity and density profiles of red giant branch stars out to ~60 kpc along the minor axis of six massive nearby Milky Way-like galaxies beyond the Local Group from the Galaxy Halos, Outer disks, Substructure, Thick disks and Star clusters (GHOSTS) HST survey. This enlargement of the sample of galaxies with observations of stellar halo properties is needed to understand the range of possible halo properties, i.e. not only the mean properties but also the halo-to-halo scatter, what a `typical' halo looks like, and how similar the Milky Way halo is to other halos beyond the Local Group.

  5. An unusual cause of Grey Turner's sign.

    PubMed

    Gosling, Oliver Burton; Hunter, Alison Emma; Edwards, Gray Alexander Dyfan; Squires, Benjamin

    2013-01-01

    A woman in her late 70s presented to the acute general surgical take with a 3-day history of worsening right leg pain and swelling. She had undergone right revision total hip arthroplasty 20 months previously and reported chronic postoperative right thigh pain attributed to a femoral deep venous thrombosis for which she had been warfarinised. On examination, Grey Turner's sign (bruising of the flanks indicating retroperitoneal haemorrhage) was present, as well as a large tender mass in the right iliac fossa and pitting oedema throughout the right lower limb. Urgent CT scan with intravenous contrast revealed a right retroperitoneal haematoma secondary to a right acetabular screw protruding into the right external iliac vein. The patient was successfully managed with warfarin reversal and surgical removal of the relevant acetabular screw. At 2-month follow-up, the patient's symptoms continue to resolve. PMID:23682085

  6. [Imaging signs in chest diagnostics].

    PubMed

    Krombach, G A

    2016-08-01

    Signs in chest imaging are defined as typical findings which can be easily recognized on x‑ray photographs or computed tomography (CT) scans of the chest. They are caused by different typical pathophysiological processes. Due to the association of a certain pathophysiological cause with a given sign, knowledge and use of these signs can allow the possible differential diagnoses to be narrowed down. If other imaging findings and clinical data are additionally taken into account, the diagnosis can be made with a high degree of confidence in many cases. PMID:27369549

  7. Halos of unified dark matter scalar field

    SciTech Connect

    Bertacca, Daniele; Bartolo, Nicola; Matarrese, Sabino E-mail: nicola.bartolo@pd.infn.it

    2008-05-15

    We investigate the static and spherically symmetric solutions of Einstein's equations for a scalar field with a non-canonical kinetic term, assumed to provide both the dark matter and dark energy components of the Universe. In particular, we give a prescription to obtain solutions (dark halos) whose rotation curve v{sub c}(r) is in good agreement with observational data. We show that there exist suitable scalar field Lagrangians that allow us to describe the cosmological background evolution and the static solutions with a single dark fluid.

  8. Project ECHO: Electronic Communications from Halo Orbit

    NASA Astrophysics Data System (ADS)

    Borrelli, Jason; Cooley, Bryan; Debole, Marcy; Hrivnak, Lance; Nielsen, Kenneth; Sangmeister, Gary; Wolfe, Matthew

    The design of a communications relay to provide constant access between the Earth and the far side of the Moon is presented. Placement of the relay in a halo orbit about the L2 Earth-Moon Lagrange point allows the satellite to maintain constant simultaneous communication between Earth and scientific payloads on the far side of the Moon. The requirements of NASA's Discovery-class missions adopted and modified for this design are: total project cost should not exceed $150 million excluding launch costs, launch must be provided by Delta-class vehicle, and the satellite should maintain an operational lifetime of 10 to 15 years. The spacecraft will follow a transfer trajectory to the L2 point, after launch by a Delta II 7925 vehicle in 1999. Low-level thrust is used for injection into a stationkeeping-free halo orbit once the spacecraft reaches the L2 point. The shape of this halo orbit is highly elliptical with the maximum excursion from the L2 point being 35000 km. A spun section and despun section connected through a bearing and power transfer assembly (BAPTA) compose the structure of the spacecraft. Communications equipment is placed on the despun section to provide for a stationary dual parabolic offset-feed array antenna system. The dual system is necessary to provide communications coverage during portions of maximum excursion on the halo orbit. Transmissions to the NASA Deep Space Network 34 m antenna include six channels (color video, two voice, scientific data from lunar payloads, satellite housekeeping and telemetry and uplinked commands) using the S- and X-bands. Four radioisotope thermoelectric generators (RTG's) provide a total of 1360 W to power onboard systems and any two of the four Hughes 13 cm ion thrusters at once. Output of the ion thrusters is approximately 17.8 mN each with xenon as the propellant. Presence of torques generated by solar pressure on the antenna dish require the addition of a 'skirt' extending from the spun section of the satellite

  9. Project ECHO: Electronic Communications from Halo Orbit

    NASA Technical Reports Server (NTRS)

    Borrelli, Jason; Cooley, Bryan; Debole, Marcy; Hrivnak, Lance; Nielsen, Kenneth; Sangmeister, Gary; Wolfe, Matthew

    1994-01-01

    The design of a communications relay to provide constant access between the Earth and the far side of the Moon is presented. Placement of the relay in a halo orbit about the L2 Earth-Moon Lagrange point allows the satellite to maintain constant simultaneous communication between Earth and scientific payloads on the far side of the Moon. The requirements of NASA's Discovery-class missions adopted and modified for this design are: total project cost should not exceed $150 million excluding launch costs, launch must be provided by Delta-class vehicle, and the satellite should maintain an operational lifetime of 10 to 15 years. The spacecraft will follow a transfer trajectory to the L2 point, after launch by a Delta II 7925 vehicle in 1999. Low-level thrust is used for injection into a stationkeeping-free halo orbit once the spacecraft reaches the L2 point. The shape of this halo orbit is highly elliptical with the maximum excursion from the L2 point being 35000 km. A spun section and despun section connected through a bearing and power transfer assembly (BAPTA) compose the structure of the spacecraft. Communications equipment is placed on the despun section to provide for a stationary dual parabolic offset-feed array antenna system. The dual system is necessary to provide communications coverage during portions of maximum excursion on the halo orbit. Transmissions to the NASA Deep Space Network 34 m antenna include six channels (color video, two voice, scientific data from lunar payloads, satellite housekeeping and telemetry and uplinked commands) using the S- and X-bands. Four radioisotope thermoelectric generators (RTG's) provide a total of 1360 W to power onboard systems and any two of the four Hughes 13 cm ion thrusters at once. Output of the ion thrusters is approximately 17.8 mN each with xenon as the propellant. Presence of torques generated by solar pressure on the antenna dish require the addition of a 'skirt' extending from the spun section of the satellite

  10. Solitonic axion condensates modeling dark matter halos

    NASA Astrophysics Data System (ADS)

    Castañeda Valle, David; Mielke, Eckehard W.

    2013-09-01

    Instead of fluid type dark matter (DM), axion-like scalar fields with a periodic self-interaction or some truncations of it are analyzed as a model of galaxy halos. It is probed if such cold Bose-Einstein type condensates could provide a viable soliton type interpretation of the DM 'bullets' observed by means of gravitational lensing in merging galaxy clusters. We study solitary waves for two self-interacting potentials in the relativistic Klein-Gordon equation, mainly in lower dimensions, and visualize the approximately shape-invariant collisions of two 'lump' type solitons.

  11. Universal properties of dark matter halos.

    PubMed

    Boyarsky, A; Neronov, A; Ruchayskiy, O; Tkachev, I

    2010-05-14

    We discuss the universal relation between density and size of observed dark matter halos that was recently shown to hold on a wide range of scales, from dwarf galaxies to galaxy clusters. Predictions of cold dark matter (ΛCDM) N-body simulations are consistent with this relation. We demonstrate that this property of ΛCDM can be understood analytically in the secondary infall model. Qualitative understanding given by this model provides a new way to predict which deviations from ΛCDM or large-scale modifications of gravity can affect universal behavior and, therefore, to constrain them observationally. PMID:20866958

  12. Invariant mass spectroscopy of halo nuclei

    SciTech Connect

    Nakamura, Takashi

    2008-11-11

    We have applied the invariant mass spectroscopy to explore the low-lying exited states of halo nuclei at intermediate energies around 70 MeV/nucleon at RIKEN. As examples, we show here the results of Coulomb breakup study for {sup 11}Li using the Pb target, as well as breakup reactions of {sup 14}Be with p and C targets. The former study revealed a strong Coulomb breakup cross section reflecting the large enhancement of E1 strength at low excitation energies (soft E1 excitation). The latter revealed the observation of the first 2{sup +} state in {sup 14}Be.

  13. HOW WELL DO COSMOLOGICAL SIMULATIONS REPRODUCE INDIVIDUAL HALO PROPERTIES?

    SciTech Connect

    Trenti, Michele; Smith, Britton D.; Hallman, Eric J.; Skillman, Samuel W.; Shull, J. Michael

    2010-03-10

    Cosmological simulations of galaxy formation often rely on prescriptions for star formation and feedback that depend on halo properties such as halo mass, central overdensity, and virial temperature. In this paper, we address the convergence of individual halo properties, based on their number of particles N, focusing, in particular, on the mass of halos near the resolution limit of a simulation. While it has been established that the halo mass function is sampled on average down to N {approx} 20-30 particles, we show that individual halo properties exhibit significant scatter, and some systematic biases, as one approaches the resolution limit. We carry out a series of cosmological simulations using the Gadget2 and Enzo codes with N{sub p} = 64{sup 3} to N{sub p} = 1024{sup 3} total particles, keeping the same large-scale structure in the simulation box. We consider boxes of small (l{sub box} = 8 Mpc h {sup -1}), medium (l{sub box} = 64 Mpc h {sup -1}), and large (l{sub box} = 512 Mpc h {sup -1}) size to probe different halo masses and formation redshifts. We cross-identify dark matter halos in boxes at different resolutions and measure the scatter in their properties. The uncertainty in the mass of single halos depends on the number of particles (scaling approximately as N {sup -1/3}), but the rarer the density peak, the more robust its identification. The virial radius of halos is very stable and can be measured without bias for halos with N {approx}> 30. In contrast, the average density within a sphere containing 25% of the total halo mass is severely underestimated (by more than a factor 2) and the halo spin is moderately overestimated for N {approx}< 100. If sub-grid physics is implemented upon a cosmological simulation, we recommend that rare halos ({approx}3sigma peaks) be resolved with N {approx}> 100 particles and common halos ({approx}1sigma peaks) with N {approx}> 400 particles to avoid excessive numerical noise and possible systematic biases in the

  14. MASS-DEPENDENT BARYON ACOUSTIC OSCILLATION SIGNAL AND HALO BIAS

    SciTech Connect

    Wang Qiao; Zhan Hu

    2013-05-10

    We characterize the baryon acoustic oscillations (BAO) feature in halo two-point statistics using N-body simulations. We find that nonlinear damping of the BAO signal is less severe for halos in the mass range we investigate than for dark matter. The amount of damping depends weakly on the halo mass. The correlation functions show a mass-dependent drop of the halo clustering bias below roughly 90 h {sup -1} Mpc, which coincides with the scale of the BAO trough. The drop of bias is 4% for halos with mass M > 10{sup 14} h {sup -1} M{sub Sun} and reduces to roughly 2% for halos with mass M > 10{sup 13} h {sup -1} M{sub Sun }. In contrast, halo biases in simulations without BAO change more smoothly around 90 h {sup -1} Mpc. In Fourier space, the bias of M > 10{sup 14} h {sup -1} M{sub Sun} halos decreases smoothly by 11% from wavenumber k = 0.012 h Mpc{sup -1} to 0.2 h Mpc{sup -1}, whereas that of M > 10{sup 13} h {sup -1} M{sub Sun} halos decreases by less than 4% over the same range. By comparing the halo biases in pairs of otherwise identical simulations, one with and the other without BAO, we also observe a modulation of the halo bias. These results suggest that precise calibrations of the mass-dependent BAO signal and scale-dependent bias on large scales would be needed for interpreting precise measurements of the two-point statistics of clusters or massive galaxies in the future.

  15. The Prevalence of the 22 deg Halo in Cirrus Clouds

    NASA Technical Reports Server (NTRS)

    Diedenhoven, vanBastiaan

    2014-01-01

    Halos at 22 deg from the sun attributed to randomly-orientated, pristine hexagonal crystals are frequently observed through ice clouds. These frequent sightings of halos formed by pristine crystals pose an apparent inconsistency with the dominance of distorted, nonpristine ice crystals indicated by in situ and remote sensing data. Furthermore, the 46 deg halo, which is associated with pristine hexagonal crystals as well, is observed far less frequently than the 22 deg halo. Considering that plausible mechanisms that could cause crystal distortion such as aggregation, sublimation, riming and collisions are stochastic processes that likely lead to distributions of crystals with varying distortion levels, here the presence of the 22 deg and 46 deg halo features in phase functions of mixtures of pristine and distorted hexagonal ice crystals is examined. We conclude that the 22 deg halo feature is generally present if the contribution by pristine crystals to the total scattering cross section is greater than only about 10% in the case of compact particles or columns, and greater than about 40% for plates. The 46 deg halo feature is present only if the mean distortion level is low and the contribution of pristine crystals to the total scattering cross section is above about 20%, 50% and 70%, in the case of compact crystals, plates and columns, respectively. These results indicate that frequent sightings of 22 deg halos are not inconsistent with the observed dominance of distorted, non-pristine ice crystals. Furthermore, the low mean distortion levels and large contributions by pristine crystals needed to produce the 461 halo features provide a potential explanation of the common sighting of the 22 deg halo without any detectable 46 deg halo.

  16. Simultaneous Visualization of Parental and Progeny Viruses by a Capsid-Specific HaloTag Labeling Strategy.

    PubMed

    Liu, An-An; Zhang, Zhenfeng; Sun, En-Ze; Zheng, Zhenhua; Zhang, Zhi-Ling; Hu, Qinxue; Wang, Hanzhong; Pang, Dai-Wen

    2016-01-26

    Real-time, long-term, single-particle tracking (SPT) provides us an opportunity to explore the fate of individual viruses toward understanding the mechanisms underlying virus infection, which in turn could lead to the development of therapeutics against viral diseases. However, the research focusing on the virus assembly and egress by SPT remains a challenge because established labeling strategies could neither specifically label progeny viruses nor make them distinguishable from the parental viruses. Herein, we have established a temporally controllable capsid-specific HaloTag labeling strategy based on reverse genetic technology. VP26, the smallest pseudorabies virus (PrV) capsid protein, was fused with HaloTag protein and labeled with the HaloTag ligand during virus replication. The labeled replication-competent recombinant PrV harvested from medium can be applied directly in SPT experiments without further modification. Thus, virus infectivity, which is critical for the visualization and analysis of viral motion, is retained to the largest extent. Moreover, progeny viruses can be distinguished from parental viruses using diverse HaloTag ligands. Consequently, the entire course of virus infection and replication can be visualized continuously, including virus attachment and capsid entry, transportation of capsids to the nucleus along microtubules, docking of capsids on the nucleus, endonuclear assembly of progeny capsids, and the egress of progeny viruses. In combination with SPT, the established strategy represents a versatile means to reveal the mechanisms and dynamic global picture of the life cycle of a virus. PMID:26720596

  17. Flow reversals in turbulent convection via vortex reconnections.

    PubMed

    Chandra, Mani; Verma, Mahendra K

    2013-03-15

    We employ detailed numerical simulations to probe the mechanism of flow reversals in two-dimensional turbulent convection. We show that the reversals occur via a vortex reconnection of two attracting corner rolls having the same sign of vorticity, thus leading to major restructuring of the flow. Large fluctuations in heat transport are observed during the reversal due to the flow reconfiguration. The flow configurations during the reversals have been analyzed quantitatively using large-scale modes. Using these tools, we also show why flow reversals occur for a restricted range of Rayleigh and Prandtl numbers. PMID:25166544

  18. Warning Signs of Mental Illnesses

    MedlinePlus

    ... Change Direction initiative is working to change the culture of mental health in America. It encourages people ... signs of emotional suffering and to change the culture around mental health and mental illness. Learn more ...

  19. Ivy Sign in Moyamoya Disease.

    PubMed

    Sivrioglu, Ali Kemal; Saglam, Muzaffer; Yildiz, Bulent; Anagnostakou, Vania; Kizilkilic, Osman

    2016-02-01

    Moyamoya disease is an idiopathic disease characterized by the progressive stenosis and collateral development of the distal internal carotid arteries. In this disease, several collateral vascular structures develop following stenosis and occlusion. The ivy sign is a characteristic Magnetic rezonance imaging (MRI) finding frequently encountered in patients with moyamoya. It can be observed both in post contrast T1-weighted images and Fluid attenuated inversion recovery (FLAIR) images. While this sign manifests in the form of contrasting on the cortical surfaces due to the formation of leptomeningeal collateral development and increased numbers of pial vascular webs on post contrast images, in FLAIR images it originates from the slow arterial flow in the leptomeningeal collateral vascular structures. In this case, we presented the Digital subtraction angiography (DSA) signs of moyamoya disease and "ivy sign" in MRI and its development mechanism in a 16 years old female patient. PMID:27026766

  20. Deaf Phone: Sign Language Telephone

    NASA Astrophysics Data System (ADS)

    Hsing, R.; Sosnowski, Thomas P.

    1985-12-01

    Using the technologies of image processing, spatial/temporal resolution reduction and picture coding, a terminal has been designed and constructed which allows the transmission of deaf sign language over low bandwidth telephone lines in real time. Using the hardware, six deaf subjects have evaluated this system. A series of psycho-physical experiments were conducted to determine the minimum image quality required to convey meaning in hand-sign language as used by the deaf.

  1. Investigating Halo and Ceiling Effects in Student Evaluations of Instruction

    ERIC Educational Resources Information Center

    Keeley, Jared W.; English, Taylor; Irons, Jessica; Henslee, Amber M.

    2013-01-01

    Many measurement biases affect student evaluations of instruction (SEIs). However, two have been relatively understudied: halo effects and ceiling/floor effects. This study examined these effects in two ways. To examine the halo effect, using a videotaped lecture, we manipulated specific teacher behaviors to be "good" or "bad"…

  2. Detecting Halo Effects in Performance-Based Examinations

    ERIC Educational Resources Information Center

    Bechger, Timo M.; Maris, Gunter; Hsiao, Ya Ping

    2010-01-01

    The main purpose of this article is to demonstrate how halo effects may be detected and quantified using two independent ratings of the same person. A practical illustration is given to show how halo effects can be avoided. (Contains 2 tables, 7 figures, and 2 notes.)

  3. SECULAR DAMPING OF STELLAR BARS IN SPINNING DARK MATTER HALOS

    SciTech Connect

    Long, Stacy; Shlosman, Isaac; Heller, Clayton

    2014-03-01

    We demonstrate using numerical simulations of isolated galaxies that growth of stellar bars in spinning dark matter halos is heavily suppressed in the secular phase of evolution. In a representative set of models, we show that for values of the cosmological spin parameter λ ≳ 0.03, bar growth (in strength and size) becomes increasingly quenched. Furthermore, the slowdown of the bar pattern speed weakens considerably with increasing λ until it ceases completely. The terminal structure of the bars is affected as well, including extent and shape of their boxy/peanut bulges. The essence of this effect lies in the modified angular momentum exchange between the disk and the halo facilitated by the bar. For the first time we have demonstrated that a dark matter halo can emit and not purely absorb angular momentum. Although the halo as a whole is not found to emit, the net transfer of angular momentum from the disk to the halo is significantly reduced or completely eliminated. The paradigm shift implies that the accepted view that disks serve as sources of angular momentum and halos serve as sinks must be revised. Halos with λ ≳ 0.03 are expected to form a substantial fraction, based on the lognormal distribution of λ. The dependence of secular bar evolution on halo spin, therefore, implies profound corollaries for the cosmological evolution of galactic disks.

  4. Halo abundance matching: accuracy and conditions for numerical convergence

    NASA Astrophysics Data System (ADS)

    Klypin, Anatoly; Prada, Francisco; Yepes, Gustavo; Heß, Steffen; Gottlöber, Stefan

    2015-03-01

    Accurate predictions of the abundance and clustering of dark matter haloes play a key role in testing the standard cosmological model. Here, we investigate the accuracy of one of the leading methods of connecting the simulated dark matter haloes with observed galaxies- the halo abundance matching (HAM) technique. We show how to choose the optimal values of the mass and force resolution in large volume N-body simulations so that they provide accurate estimates for correlation functions and circular velocities for haloes and their subhaloes - crucial ingredients of the HAM method. At the 10 per cent accuracy, results converge for ˜50 particles for haloes and ˜150 particles for progenitors of subhaloes. In order to achieve this level of accuracy a number of conditions should be satisfied. The force resolution for the smallest resolved (sub)haloes should be in the range (0.1-0.3)rs, where rs is the scale radius of (sub)haloes. The number of particles for progenitors of subhaloes should be ˜150. We also demonstrate that the two-body scattering plays a minor role for the accuracy of N-body simulations thanks to the relatively small number of crossing-times of dark matter in haloes, and the limited force resolution of cosmological simulations.

  5. On Detecting Halo Assembly Bias with Galaxy Populations

    NASA Astrophysics Data System (ADS)

    Lin, Yen-Ting; Mandelbaum, Rachel; Huang, Yun-Hsin; Huang, Hung-Jin; Dalal, Neal; Diemer, Benedikt; Jian, Hung-Yu; Kravtsov, Andrey

    2016-03-01

    The fact that the clustering of dark matter halos depends not only on their mass, but also the formation epoch is a prominent, albeit subtle, feature of the cold dark matter structure formation theory and is known as assembly bias. At low-mass scales (˜ {10}12 {h}-1 {M}⊙ ), early-forming halos are predicted to be more strongly clustered than the late-forming ones. In this study, we aim to robustly detect the signature of assembly bias observationally, making use of formation time indicators of central galaxies in low-mass halos as a proxy for the halo formation history. Weak gravitational lensing is employed to ensure our early- and late-forming halo samples have similar masses, and are free of contamination of satellites from more massive halos. For the two formation time indicators used (resolved star formation history and current specific star formation rate), we do not find convincing evidence of assembly bias. For a pair of early- and late-forming galaxy samples with mean mass {M}200c≈ 9× {10}11 {h}-1 {M}⊙ , the relative bias is 1.00 ± 0.12. We attribute the lack of detection to the possibilities that either the current measurements of these indicators are too noisy, or they do not correlate well with the halo formation history. Alternative proxies for the halo formation history that should perform better are suggested for future studies.

  6. The Cosmogrid Simulation: Statistical Properties of Small Dark Matter Halos

    NASA Astrophysics Data System (ADS)

    Ishiyama, Tomoaki; Rieder, Steven; Makino, Junichiro; Portegies Zwart, Simon; Groen, Derek; Nitadori, Keigo; de Laat, Cees; McMillan, Stephen; Hiraki, Kei; Harfst, Stefan

    2013-04-01

    We present the results of the "Cosmogrid" cosmological N-body simulation suites based on the concordance LCDM model. The Cosmogrid simulation was performed in a 30 Mpc box with 20483 particles. The mass of each particle is 1.28 × 105 M ⊙, which is sufficient to resolve ultra-faint dwarfs. We found that the halo mass function shows good agreement with the Sheth & Tormen fitting function down to ~107 M ⊙. We have analyzed the spherically averaged density profiles of the three most massive halos which are of galaxy group size and contain at least 170 million particles. The slopes of these density profiles become shallower than -1 at the innermost radius. We also find a clear correlation of halo concentration with mass. The mass dependence of the concentration parameter cannot be expressed by a single power law, however a simple model based on the Press-Schechter theory proposed by Navarro et al. gives reasonable agreement with this dependence. The spin parameter does not show a correlation with the halo mass. The probability distribution functions for both concentration and spin are well fitted by the log-normal distribution for halos with the masses larger than ~108 M ⊙. The subhalo abundance depends on the halo mass. Galaxy-sized halos have 50% more subhalos than ~1011 M ⊙ halos have.

  7. Lyman-Werner UV escape fractions from primordial haloes

    NASA Astrophysics Data System (ADS)

    Schauer, Anna T. P.; Whalen, Daniel J.; Glover, Simon C. O.; Klessen, Ralf S.

    2015-12-01

    Population III (Pop III) stars can regulate star formation in the primordial Universe in several ways. They can ionize nearby haloes, and even if their ionizing photons are trapped by their own haloes, their Lyman-Werner (LW) photons can still escape and destroy H2 in other haloes, preventing them from cooling and forming stars. LW escape fractions are thus a key parameter in cosmological simulations of early reionization and star formation but have not yet been parametrized for realistic haloes by halo or stellar mass. To do so, we perform radiation hydrodynamical simulations of LW UV escape from 9-120 M⊙ Pop III stars in 105-107 M⊙ haloes with ZEUS-MP. We find that photons in the LW lines (i.e. those responsible for destroying H2 in nearby systems) have escape fractions ranging from 0 to 85 per cent. No LW photons escape the most massive halo in our sample, even from the most massive star. Escape fractions for photons elsewhere in the 11.18-13.6 eV energy range, which can be redshifted into the LW lines at cosmological distances, are generally much higher, being above 60 per cent for all but the least massive stars in the most massive haloes. We find that shielding of H2 by neutral hydrogen, which has been neglected in most studies to date, produces escape fractions that are up to a factor of 3 smaller than those predicted by H2 self-shielding alone.

  8. Halo-Independent Comparison of Direct Dark Matter Detection Data

    DOE PAGESBeta

    Del Nobile, Eugenio

    2014-01-01

    We review the halo-independent formalism that allows comparing data from different direct dark matter detection experiments without making assumptions on the properties of the dark matter halo. We apply this method to spin-independent WIMP-nuclei interactions, for both isospin-conserving and isospin-violating couplings, and to WIMPs interacting through an anomalous magnetic moment.

  9. The Prolate Dark Matter Halo of the Andromeda Galaxy

    NASA Astrophysics Data System (ADS)

    Hayashi, Kohei; Chiba, Masashi

    2014-07-01

    We present new limits on the global shape of the dark matter halo in the Andromeda galaxy using and generalizing non-spherical mass models developed by Hayashi & Chiba and compare our results with theoretical predictions of cold dark matter (CDM) models. This is motivated by the fact that CDM models predict non-spherical virialized dark halos, which reflect the process of mass assembly in the galactic scale. Applying our models to the latest kinematic data of globular clusters and dwarf spheroidal galaxies in the Andromeda halo, we find that the most plausible cases for Andromeda yield a prolate shape for its dark halo, irrespective of assumed density profiles. We also find that this prolate dark halo in Andromeda is consistent with theoretical predictions in which the satellites are distributed anisotropically and preferentially located along major axes of their host halos. It is a reflection of the intimate connection between galactic dark matter halos and the cosmic web. Therefore, our result is profound in understanding internal dynamics of halo tracers in Andromeda, such as orbital evolutions of tidal stellar streams, which play important roles in extracting the abundance of CDM subhalos through their dynamical effects on stream structures.

  10. Separate universe consistency relation and calibration of halo bias

    NASA Astrophysics Data System (ADS)

    Li, Yin; Hu, Wayne; Takada, Masahiro

    2016-03-01

    The linear halo bias is the response of the dark matter halo number density to a long-wavelength fluctuation in the dark matter density. Using abundance matching between separate universe simulations which absorb the latter into a change in the background, we test the consistency relation between the change in a one-point function, the halo mass function, and a two-point function, the halo-matter cross-correlation in the long-wavelength limit. We find excellent agreement between the two at the 1%-2% level for average halo biases between 1 ≲b¯ 1≲4 and no statistically significant deviations at the 4%-5% level out to b¯1≈8 . The halo bias inferred assuming instead a universal mass function is significantly different and inaccurate at the 10% level or more. The separate universe technique provides a way of calibrating the linear halo bias efficiently for even highly biased rare halos in the Λ cold dark matter model. Observational violation of the consistency relation would indicate new physics, e.g. in the dark matter, dark energy, or primordial non-Gaussianity sectors.

  11. Beam halo definitions based upon moments of the particle distribution

    NASA Astrophysics Data System (ADS)

    Allen, C. K.; Wangler, T. P.

    2002-12-01

    Two different parameters for the quantitative description of beam halo are discussed. Both are based on moments of the particle distribution and represent a convenient and model-independent method for quantifying the magnitude of beam halo observed in either spatial or phase-space projections. One parameter is a measure of spatial profile of the beam and has been defined by Wangler and Crandall previously. The current authors defined a new parameter using kinematic invariants to quantify halo formation in 2D phase space. Here we expand the development and present detailed numerical results. Although the spatial-profile parameter and the phase-space halo parameter both reduce to the same value when the distribution has the elliptical symmetry, in general these parameters are not equal. Halo in the 1D spatial profiles is relatively easily measured, but is variable as the beam distribution evolves and can hide as it rotates in phase space. The 2D phase-space halo is more difficult to measure, but it varies more smoothly as the halo evolves. It provides a more reliable characterization of the halo as an intrinsic property of the beam.

  12. The prolate dark matter halo of the Andromeda galaxy

    SciTech Connect

    Hayashi, Kohei; Chiba, Masashi E-mail: chiba@astr.tohoku.ac.jp

    2014-07-01

    We present new limits on the global shape of the dark matter halo in the Andromeda galaxy using and generalizing non-spherical mass models developed by Hayashi and Chiba and compare our results with theoretical predictions of cold dark matter (CDM) models. This is motivated by the fact that CDM models predict non-spherical virialized dark halos, which reflect the process of mass assembly in the galactic scale. Applying our models to the latest kinematic data of globular clusters and dwarf spheroidal galaxies in the Andromeda halo, we find that the most plausible cases for Andromeda yield a prolate shape for its dark halo, irrespective of assumed density profiles. We also find that this prolate dark halo in Andromeda is consistent with theoretical predictions in which the satellites are distributed anisotropically and preferentially located along major axes of their host halos. It is a reflection of the intimate connection between galactic dark matter halos and the cosmic web. Therefore, our result is profound in understanding internal dynamics of halo tracers in Andromeda, such as orbital evolutions of tidal stellar streams, which play important roles in extracting the abundance of CDM subhalos through their dynamical effects on stream structures.

  13. Secular Damping of Stellar Bars in Spinning Dark Matter Halos

    NASA Astrophysics Data System (ADS)

    Long, Stacy; Shlosman, Isaac; Heller, Clayton

    2014-03-01

    We demonstrate using numerical simulations of isolated galaxies that growth of stellar bars in spinning dark matter halos is heavily suppressed in the secular phase of evolution. In a representative set of models, we show that for values of the cosmological spin parameter λ >~ 0.03, bar growth (in strength and size) becomes increasingly quenched. Furthermore, the slowdown of the bar pattern speed weakens considerably with increasing λ until it ceases completely. The terminal structure of the bars is affected as well, including extent and shape of their boxy/peanut bulges. The essence of this effect lies in the modified angular momentum exchange between the disk and the halo facilitated by the bar. For the first time we have demonstrated that a dark matter halo can emit and not purely absorb angular momentum. Although the halo as a whole is not found to emit, the net transfer of angular momentum from the disk to the halo is significantly reduced or completely eliminated. The paradigm shift implies that the accepted view that disks serve as sources of angular momentum and halos serve as sinks must be revised. Halos with λ >~ 0.03 are expected to form a substantial fraction, based on the lognormal distribution of λ. The dependence of secular bar evolution on halo spin, therefore, implies profound corollaries for the cosmological evolution of galactic disks.

  14. HALOE Algorithm Improvements for Upper Tropospheric Sounding

    NASA Technical Reports Server (NTRS)

    Thompson, Robert E.

    2001-01-01

    This report details the ongoing efforts by GATS, Inc., in conjunction with Hampton University and University of Wyoming, in NASA's Mission to Planet Earth UARS Science Investigator Program entitled "HALOE Algorithm Improvements for Upper Tropospheric Sounding." The goal of this effort is to develop and implement major inversion and processing improvements that will extend HALOE measurements further into the troposphere. In particular, O3, H2O, and CH4 retrievals may be extended into the middle troposphere, and NO, HCl and possibly HF into the upper troposphere. Key areas of research being carried out to accomplish this include: pointing/tracking analysis; cloud identification and modeling; simultaneous multichannel retrieval capability; forward model improvements; high vertical-resolution gas filter channel retrievals; a refined temperature retrieval; robust error analyses; long-term trend reliability studies; and data validation. The current (first year) effort concentrates on the pointer/tracker correction algorithms, cloud filtering and validation, and multichannel retrieval development. However, these areas are all highly coupled, so progress in one area benefits from and sometimes depends on work in others.

  15. Halogen Occultation Experiment (HALOE) optical filter characterization

    NASA Technical Reports Server (NTRS)

    Harvey, Gale A.

    1989-01-01

    The Halogen Occultation Experiment (HALOE) is a solar occultation experiment that will fly on the Upper Atmosphere Research Satellite to measure mixing ratio profiles of O3, H2O, NO2, NO, CH4, HCl, and HF. The inversion of the HALOE data will be critically dependent on a detailed knowledge of eight optical filters. A filter characterization program was undertaken to measure in-band transmissions, out-of-band transmissions, in-band transmission shifts with temperature, reflectivities, and age stability. Fourier Transform Infrared Spectrometers were used to perform measurements over the spectral interval 400/cm to 6300/cm (25 micrometers to 1.6 micrometers). Very high precision (0.1 percent T) in-band measurements and very high resolution (0.0001 percent T) out-of-band measurements have been made. The measurements revealed several conventional leaks at 0.01 percent transmission and greatly enhanced (1,000) leaks to the 2-element filters when placed in a Fabry-Perot cavity. Filter throughput changes by 5 percent for a 25 C change in filter temperature.

  16. MACHO (MAssive Compact Halo Objects) Data

    DOE Data Explorer

    The primary aim of the MACHO Project is to test the hypothesis that a significant fraction of the dark matter in the halo of the Milky Way is made up of objects like brown dwarfs or planets: these objects have come to be known as MACHOs, for MAssive Compact Halo Objects. The signature of these objects is the occasional amplification of the light from extragalactic stars by the gravitational lens effect. The amplification can be large, but events are extremely rare: it is necessary to monitor photometrically several million stars for a period of years in order to obtain a useful detection rate. For this purpose MACHO has a two channel system that employs eight CCDs, mounted on the 50 inch telescope at Mt. Stromlo. The high data rate (several GBytes per night) is accommodated by custom electronics and on-line data reduction. The Project has taken more than 27,000 images with this system since June 1992. Analysis of a subset of these data has yielded databases containing light curves in two colors for 8 million stars in the LMC and 10 million in the bulge of the Milky Way. A search for microlensing has turned up four candidates toward the Large Magellanic Cloud and 45 toward the Galactic Bulge. The web page for data provides links to MACHO Project data portals and various specialized interfaces for viewing or searching the data. (Specialized Interface)

  17. HALOE Algorithm Improvements for Upper Tropospheric Sounding

    NASA Technical Reports Server (NTRS)

    McHugh, Martin J.; Gordley, Larry L.; Russell, James M., III; Hervig, Mark E.

    1999-01-01

    This report details the ongoing efforts by GATS, Inc., in conjunction with Hampton University and University of Wyoming, in NASA's Mission to Planet Earth UARS Science Investigator Program entitled "HALOE Algorithm Improvements for Upper Tropospheric Soundings." The goal of this effort is to develop and implement major inversion and processing improvements that will extend HALOE measurements further into the troposphere. In particular, O3, H2O, and CH4 retrievals may be extended into the middle troposphere, and NO, HCl and possibly HF into the upper troposphere. Key areas of research being carried out to accomplish this include: pointing/tracking analysis; cloud identification and modeling; simultaneous multichannel retrieval capability; forward model improvements; high vertical-resolution gas filter channel retrievals; a refined temperature retrieval; robust error analyses; long-term trend reliability studies; and data validation. The current (first-year) effort concentrates on the pointer/tracker correction algorithms, cloud filtering and validation, and multi-channel retrieval development. However, these areas are all highly coupled, so progress in one area benefits from and sometimes depends on work in others.

  18. HALOE Algorithm Improvements for Upper Tropospheric Sounding

    NASA Technical Reports Server (NTRS)

    Thompson, Robert Earl; McHugh, Martin J.; Gordley, Larry L.; Hervig, Mark E.; Russell, James M., III; Douglass, Anne (Technical Monitor)

    2001-01-01

    This report details the ongoing efforts by GATS, Inc., in conjunction with Hampton University and University of Wyoming, in NASA's Mission to Planet Earth Upper Atmospheric Research Satellite (UARS) Science Investigator Program entitled 'HALOE Algorithm Improvements for Upper Tropospheric Sounding.' The goal of this effort is to develop and implement major inversion and processing improvements that will extend Halogen Occultation Experiment (HALOE) measurements further into the troposphere. In particular, O3, H2O, and CH4 retrievals may be extended into the middle troposphere, and NO, HCl and possibly HF into the upper troposphere. Key areas of research being carried out to accomplish this include: pointing/tracking analysis; cloud identification and modeling; simultaneous multichannel retrieval capability; forward model improvements; high vertical-resolution gas filter channel retrievals; a refined temperature retrieval; robust error analyses; long-term trend reliability studies; and data validation. The current (first year) effort concentrates on the pointer/tracker correction algorithms, cloud filtering and validation, and multichannel retrieval development. However, these areas are all highly coupled, so progress in one area benefits from and sometimes depends on work in others.

  19. Frost halos from supercooled water droplets

    PubMed Central

    Jung, Stefan; Tiwari, Manish K.; Poulikakos, Dimos

    2012-01-01

    Water freezing on solid surfaces is ubiquitous in nature. Even though icing/frosting impairs the performance and safety in many processes, its mechanism remains inadequately understood. Changing atmospheric conditions, surface properties, the complexity of icing physics, and the unorthodox behavior of water are the primary factors that make icing and frost formation intriguing and difficult to predict. In addition to its unquestioned scientific and practical importance, unraveling the frosting mechanism under different conditions is a prerequisite to develop “icephobic” surfaces, which may avoid ice formation and contamination. In this work we demonstrate that evaporation from a freezing supercooled sessile droplet, which starts explosively due to the sudden latent heat released upon recalescent freezing, generates a condensation halo around the droplet, which crystallizes and drastically affects the surface behavior. The process involves simultaneous multiple phase transitions and may also spread icing by initiating sequential freezing of neighboring droplets in the form of a domino effect and frost propagation. Experiments under controlled humidity conditions using substrates differing up to three orders of magnitude in thermal conductivity establish that a delicate balance between heat diffusion and vapor transport determines the final expanse of the frozen condensate halo, which, in turn, controls frost formation and propagation. PMID:23012410

  20. Inhomogeneous chemical enrichment in the Galactic Halo

    NASA Astrophysics Data System (ADS)

    Kobayashi, Chiaki

    2016-08-01

    In a galaxy, chemical enrichment takes place in an inhomogeneous fashion, and the Galactic Halo is one of the places where the inhomogeneous effects are imprinted and can be constrained from observations. I show this using my chemodynamical simulations of Milky Way type galaxies. The scatter in the elemental abundances originate from radial migration, merging/accretion of satellite galaxies, local variation of star formation and chemical enrichment, and intrinsic variation of nucleosynthesis yields. In the simulated galaxies, there is no strong age-metallicity relation. This means that the most metal-poor stars are not always the oldest stars, and can be formed in chemically unevolved clouds at later times. The long-lifetime sources of chemical enrichment such as asymptotic giant branch stars or neutron star mergers can contribute at low metallicities. The intrinsic variation of yields are important in the early Universe or metal-poor systems such as in the Galactic halo. The carbon enhancement of extremely metal-poor (EMP) stars can be best explained by faint supernovae, the low [α/Fe] ratios in some EMP stars naturally arise from low-mass (~ 13 - 15M ⊙) supernovae, and finally, the [α/Fe] knee in dwarf spheroidal galaxies can be produced by subclasses of Type Ia supernovae such as SN 2002cx-like objects and sub-Chandrasekhar mass explosions.

  1. 23 CFR 750.710 - Landmark signs.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 23 Highways 1 2014-04-01 2014-04-01 false Landmark signs. 750.710 Section 750.710 Highways FEDERAL... Outdoor Advertising Control § 750.710 Landmark signs. (a) 23 U.S.C. 131(c) permits the existence of signs... Secretary, to be landmark signs, including signs on farm structures or natural surfaces, of historic...

  2. 23 CFR 750.710 - Landmark signs.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 23 Highways 1 2010-04-01 2010-04-01 false Landmark signs. 750.710 Section 750.710 Highways FEDERAL... Outdoor Advertising Control § 750.710 Landmark signs. (a) 23 U.S.C. 131(c) permits the existence of signs... Secretary, to be landmark signs, including signs on farm structures or natural surfaces, of historic...

  3. 23 CFR 750.710 - Landmark signs.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 23 Highways 1 2013-04-01 2013-04-01 false Landmark signs. 750.710 Section 750.710 Highways FEDERAL... Outdoor Advertising Control § 750.710 Landmark signs. (a) 23 U.S.C. 131(c) permits the existence of signs... Secretary, to be landmark signs, including signs on farm structures or natural surfaces, of historic...

  4. 23 CFR 750.710 - Landmark signs.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 23 Highways 1 2012-04-01 2012-04-01 false Landmark signs. 750.710 Section 750.710 Highways FEDERAL... Outdoor Advertising Control § 750.710 Landmark signs. (a) 23 U.S.C. 131(c) permits the existence of signs... Secretary, to be landmark signs, including signs on farm structures or natural surfaces, of historic...

  5. 23 CFR 750.710 - Landmark signs.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 23 Highways 1 2011-04-01 2011-04-01 false Landmark signs. 750.710 Section 750.710 Highways FEDERAL... Outdoor Advertising Control § 750.710 Landmark signs. (a) 23 U.S.C. 131(c) permits the existence of signs... Secretary, to be landmark signs, including signs on farm structures or natural surfaces, of historic...

  6. SUBSTRUCTURE IN THE STELLAR HALOS OF THE AQUARIUS SIMULATIONS

    SciTech Connect

    Helmi, Amina; Cooper, A. P.; Cole, S.; Frenk, C. S.; White, S. D. M.; Navarro, J. F.

    2011-05-20

    We characterize the substructure in the simulated stellar halos of Cooper et al. which were formed by the disruption of satellite galaxies within the cosmological N-body simulations of galactic halos of the Aquarius project. These stellar halos exhibit a wealth of tidal features: broad overdensities and very narrow faint streams akin to those observed around the Milky Way. The substructures are distributed anisotropically on the sky, a characteristic that should become apparent in the next generation of photometric surveys. The normalized RMS of the density of stars on the sky appears to be systematically larger for our halos compared with the value estimated for the Milky Way from main-sequence turnoff stars in the Sloan Digital Sky Survey. We show that this is likely to be due in part to contamination by faint QSOs and redder main-sequence stars, and might suggest that {approx}10% of the Milky Way halo stars have formed in situ.

  7. The Effects of Angular Momentum on Halo Profiles

    NASA Astrophysics Data System (ADS)

    Lentz, Erik W.; Quinn, Thomas R.; Rosenberg, Leslie J.

    2016-05-01

    The near universality of DM halo density profiles provided by N-body simulations proved to be robust against changes in total mass density, power spectrum, and some forms of initial velocity dispersion. Here we study the effects of coherently spinning up an isolated DM-only progenitor on halo structure. Halos with spins within several standard deviations of the simulated mean (λ ≲ 0.20) produce profiles with negligible deviations from the universal form. Only when the spin becomes quite large (λ ≳ 0.20) do departures become evident. The angular momentum distribution also exhibits a near universal form, which is also independent of halo spin up to λ ≲ 0.20. A correlation between these epidemic profiles and the presence of a strong bar in the virialized halo is also observed. These bar structures bear resemblance to the radial orbit instability in the rotationless limit.

  8. The X-ray halo of Cygnus X-1

    NASA Technical Reports Server (NTRS)

    Bode, M. F.; Norwell, G. A.; Priedhorsky, W. C.; Evans, A.

    1985-01-01

    Four Einstein HRI images of Cygnus X-1 were examined for the presence of a halo due to scattering of X-rays by interstellar grains. The analysis technique exploits the intrinsic aperiodic variability of the source to map the point response function of the optics. A residual, nonvariable component to the surface brightness distribution (comprising approximately more than 12 percent of the source flux) is interpreted as a scattered halo. The halo flux does not reflect the short term time variability of the central source as it is smoothed by differential time delays of order days. The Cygnus X-1 halo is consistent with those of other sources derived in previous studies using different techniques. Comparison is made with a scattering model, and the sensitivity of the halo flux to maximal grain size is demonstrated.

  9. The starformation driven interstellar disk-halo connection

    NASA Astrophysics Data System (ADS)

    Dettmar, Ralf-Jürgen

    2005-08-01

    The evidence for starformation in the disks of spiral galaxies driving the disk-halo interaction is briefly reviewed. It is argued that diffuse ionized gas (DIG) in the halos of edge-on disk galaxies traces the presence of extraplanar gas well since it correlates with the star formation rate in the underlying disk as well as with other gaseous phases and components of the ISM such as X-ray hot gas, cosmic rays, and magnetic fields. The dependence on the starformation rate is demonstrated using a survey of H+ halos with more than 70 objects. This survey allows us to establish a minimum energy release per unit area that is required to start the disk-halo mass exchange. Observations of extraplanar HII regions let us conclude that also molecular hydrogen must be present. In addition, well ordered magnetic field in the gaseous halos can be deduced from the polarization of synchrotron radiocontinuum maps.

  10. STATISTICS OF DARK MATTER HALOS FROM THE EXCURSION SET APPROACH

    SciTech Connect

    Lapi, A.; Salucci, P.; Danese, L.

    2013-08-01

    We exploit the excursion set approach in integral formulation to derive novel, accurate analytic approximations of the unconditional and conditional first crossing distributions for random walks with uncorrelated steps and general shapes of the moving barrier; we find the corresponding approximations of the unconditional and conditional halo mass functions for cold dark matter (DM) power spectra to represent very well the outcomes of state-of-the-art cosmological N-body simulations. In addition, we apply these results to derive, and confront with simulations, other quantities of interest in halo statistics, including the rates of halo formation and creation, the average halo growth history, and the halo bias. Finally, we discuss how our approach and main results change when considering random walks with correlated instead of uncorrelated steps, and warm instead of cold DM power spectra.

  11. Zooming in on accretion - I. The structure of halo gas

    NASA Astrophysics Data System (ADS)

    Nelson, Dylan; Genel, Shy; Pillepich, Annalisa; Vogelsberger, Mark; Springel, Volker; Hernquist, Lars

    2016-08-01

    We study the properties of gas in and around 1012 M⊙ haloes at z = 2 using a suite of high-resolution cosmological hydrodynamic `zoom' simulations. We quantify the thermal and dynamical structure of these gaseous reservoirs in terms of their mean radial distributions and angular variability along different sightlines. With each halo simulated at three levels of increasing resolution, the highest reaching a baryon mass resolution of ˜10 000 solar masses, we study the interface between filamentary inflow and the quasi-static hot halo atmosphere. We highlight the discrepancy between the spatial resolution available in the halo gas as opposed to within the galaxy itself, and find that stream morphologies become increasingly complex at higher resolution, with large coherent flows revealing density and temperature structure at progressively smaller scales. Moreover, multiple gas components co-exist at the same radius within the halo, making radially averaged analyses misleading. This is particularly true where the hot, quasi-static, high entropy halo atmosphere interacts with cold, rapidly inflowing, low entropy accretion. Haloes at this mass have a well-defined virial shock, associated with a sharp jump in temperature and entropy at ≳ 1.25 rvir. The presence, radius, and radial width of this boundary feature, however, vary not only from halo to halo, but also as a function of angular direction, covering roughly ˜75 per cent of the 4π sphere. We investigate the process of gas virialization as imprinted in the halo structure, and discuss different modes for the accretion of gas from the intergalactic medium.

  12. Zooming in on accretion - I. The structure of halo gas

    NASA Astrophysics Data System (ADS)

    Nelson, Dylan; Genel, Shy; Pillepich, Annalisa; Vogelsberger, Mark; Springel, Volker; Hernquist, Lars

    2016-05-01

    We study the properties of gas in and around 1012 M⊙ haloes at z = 2 using a suite of high-resolution cosmological hydrodynamic `zoom' simulations. We quantify the thermal and dynamical structure of these gaseous reservoirs in terms of their mean radial distributions and angular variability along different sightlines. With each halo simulated at three levels of increasing resolution, the highest reaching a baryon mass resolution of ˜10,000 solar masses, we study the interface between filamentary inflow and the quasi-static hot halo atmosphere. We highlight the discrepancy between the spatial resolution available in the halo gas as opposed to within the galaxy itself, and find that stream morphologies become increasingly complex at higher resolution, with large coherent flows revealing density and temperature structure at progressively smaller scales. Moreover, multiple gas components co-exist at the same radius within the halo, making radially averaged analyses misleading. This is particularly true where the hot, quasi-static, high entropy halo atmosphere interacts with cold, rapidly inflowing, low entropy accretion. Haloes at this mass have a well-defined virial shock, associated with a sharp jump in temperature and entropy at ≳ 1.25 rvir. The presence, radius, and radial width of this boundary feature, however, vary not only from halo to halo, but also as a function of angular direction, covering roughly ˜ 75% of the 4π sphere. We investigate the process of gas virialization as imprinted in the halo structure, and discuss different modes for the accretion of gas from the intergalactic medium.

  13. Zooming in on accretion - I. The structure of halo gas

    NASA Astrophysics Data System (ADS)

    Nelson, Dylan; Genel, Shy; Pillepich, Annalisa; Vogelsberger, Mark; Springel, Volker; Hernquist, Lars

    2016-08-01

    We study the properties of gas in and around 10^12 solar mass halos at z=2 using a suite of high-resolution cosmological hydrodynamic 'zoom' simulations. We quantify the thermal and dynamical structure of these gaseous reservoirs in terms of their mean radial distributions and angular variability along different sightlines. With each halo simulated at three levels of increasing resolution, the highest reaching a baryon mass resolution of ~10,000 solar masses, we study the interaction of filamentary inflow and the quasi-static hot halo atmosphere. We highlight the discrepancy between the spatial resolution available in the halo gas as opposed to within the galaxy itself, and find that stream morphologies become increasingly complex at higher resolution, with large coherent flows revealing density and temperature structure at progressively smaller scales. Moreover, multiple gas components co-exist at the same radius within the halo, making radially averaged analyses misleading. This is particularly true where the hot, quasi-static, high entropy halo atmosphere interacts with cold, rapidly inflowing, low entropy accretion. We investigate the process of gas virialization and identify different regimes for the heating of gas as it accretes from the intergalactic medium. Haloes at this mass have a well-defined virial shock, associated with a sharp jump in temperature and entropy at ~1.25 r_vir. The presence, radius, and radial width of this boundary feature, however, vary not only from halo to halo, but also as a function of angular direction, covering roughly ~85% of the 4pi sphere. Our findings are relevant for the proper interpretation of observations pertaining to the circumgalactic medium, including evidence for large amounts of cold gas surrounding massive haloes at intermediate redshifts.

  14. Kinematic imprint of clumpy disk formation on halo objects

    NASA Astrophysics Data System (ADS)

    Inoue, Shigeki

    2013-02-01

    Context. Clumpy disk galaxies in the distant universe, at redshift of z ≳ 1, have been observed to host several giant clumps in their disks. They are thought to correspond to early formative stages of disk galaxies. On the other hand, halo objects, such as old globular clusters and halo stars, are likely to consist of the oldest stars in a galaxy (age ≳ 10 Gyr), clumpy disk formation can thus be presumed to take place in a pre-existing halo system. Aims: Giant clumps orbit in the same direction in a premature disk and are so massive that they may be expected to interact gravitationally with halo objects and exercise influence on the kinematic state of the halo. Accordingly, I scrutinize the possibility that the clumps leave a kinematic imprint of the clumpy disk formation on a halo system. Methods: I perform a restricted N-body calculation with a toy model to study the kinematic influence on a halo by orbital motions of clumps and the dependence of the results on masses (mass loss), number, and orbital radii of the clumps. Results: I show that halo objects can catch clump motions and acquire disky rotation in a dynamical friction time scale of the clumps, ~0.5 Gyr. The influence of clumps is limited within a region around the disk, while the halo system shows vertical gradients of net rotation velocity and orbital eccentricity. The significance of the kinematic influence strongly depends on the clump masses; the lower limit of postulated clump mass would be ~5 × 108 M⊙. The result also depends on whether the clumps are subjected to rapid mass loss or not, which is an open question under debate in recent studies. The existence of such massive clumps is not unrealistic. I therefore suggest that the imprints of past clumpy disk formation could remain in current galactic halos.

  15. Halo plasma heating by neutral beam injection in TMX-U

    SciTech Connect

    Hsu, W.L.; Bauer, W.; Kerst, R.A.; Wilson, K.L.; Simonen, T.C.; Foote, J.H.; Pickles, W.L.

    1985-05-01

    The electron temperature and density of the halo in TMX-U have been measured by Langmuir probes to study the heating of the halo plasma by neutral beam injection. This study is motivated by the recent interest in using a pair of halo recyclers to enhance the halo density and thereby increase halo shielding. In present TMX-U operation, without halo recyclers, a halo density of 2 x 10/sup 12/ cm/sup -3/ with electron temperature of 20 eV has been measured during the heating phase with neutral beam injection only. A halo power balance model incorporating several heating mechanisms resulting from neutral beam injection is described. The model accurately predicts the measured temperatures. At the halo density range that one expects to achieve with halo recyclers, the model predicts the existing TMX-U neutral beam sources to heat the halo to at least 30 eV.

  16. Reversal Transition Records from Intrusions: Implications for the Reversal Process.

    NASA Astrophysics Data System (ADS)

    Fuller, M. D.; Williams, I. S.

    2014-12-01

    The nature of reversals of the geomagnetic field and the details of the transition fields remain controversial. However, reversal records from the Agno batholith and Tatoosh intrusion confirm the suggestion of Valet et al., (2012) from studies of lava records, that there is a threefold division in reversal transition directions. In the Agno, the first phase, or precursor, consists of a CCW loop of the VGP moving from high southerly latitude reverse poles to reach North America. The second phase takes the VGP along a half CCW loop from the tip of South America to northern latitudes at the intensity minimum. The third phase, or rebound is a smaller CCW loop and the main intensity recovery begins. The first and third phases appear to be paleosecular variation loops analogous to present London-Paris secular variation loops. The Tatoosh intrusion gives a similar, but less complete record with the VGPs again confined to the East Pacific and the Americas. Away from the reversal region, secular variation loops in the Tatoosh were shown to be comparable in duration to the precursor in the transition record, consistent with the first phase being a paleosecular variation loop in the Agno. Using westward drift estimates from the present field, this should last about1800 years. This gives ~3300 for phase 2, in an intensity low of >16,000 years. A feature of R to N reversal field models is a low latitude magnetic field flux concentration of the same sign as the polar vortex of the south geographic pole. This is followed by northward flux flow, e.g. Shao et al., (1999). The reversal is achieved by northward motion of this flux feature. The feature is locked in longitudinal mantle coordinates and similarly the VGPs in the Agno and Tatoosh records are confined to the longitudes of the eastern Pacific and the Americas. Whether we are approaching a reversal remains to be seen, although judging by these intrusion records the field intensity would need to decrease much further before

  17. Skin signs in anorexia nervosa

    PubMed Central

    2009-01-01

    Anorexia nervosa (AN) is a significant cause of morbidity and mortality among adolescent females and young women. AN is associated with severe medical and psychological consequences, including death, osteoporosis, growth delay, and developmental delay. Skin signs are almost always detectable in severe AN and awareness of them may help in the early diagnosis of hidden AN. Skin signs are the expression of the medical consequences of starvation, vomiting, abuse of drugs, such as laxatives and diuretics, and of the psychiatric morbidity. They include xerosis, lanugo-like body hair, telogen effluvium, carotenoderma, acne, hyperpigmentation, seborrhoeic dermatitis, acrocyanosis, perniosis, petechiae, livedo reticularis, interdigital intertrigo, paronychia, acquired striae distensae, acral coldness. The most characteristic cutaneous sign of vomiting is Russell’s sign (knuckle calluses). Symptoms due to laxative or diuretic abuse include adverse reactions by drugs. Symptoms due to psychiatric morbidity (artefacta) include the consequences of self-induced trauma. The role of the dermatologist in the management of eating disorders is to make an early diagnosis of the “hidden” signs of eating disorders in patients who tend to minimize or deny their disorder. PMID:20808514

  18. Skin signs in anorexia nervosa.

    PubMed

    Strumia, Renata

    2009-09-01

    Anorexia nervosa (AN) is a significant cause of morbidity and mortality among adolescent females and young women. AN is associated with severe medical and psychological consequences, including death, osteoporosis, growth delay, and developmental delay. Skin signs are almost always detectable in severe AN and awareness of them may help in the early diagnosis of hidden AN. Skin signs are the expression of the medical consequences of starvation, vomiting, abuse of drugs, such as laxatives and diuretics, and of the psychiatric morbidity. They include xerosis, lanugo-like body hair, telogen effluvium, carotenoderma, acne, hyperpigmentation, seborrhoeic dermatitis, acrocyanosis, perniosis, petechiae, livedo reticularis, interdigital intertrigo, paronychia, acquired striae distensae, acral coldness.The most characteristic cutaneous sign of vomiting is Russell's sign (knuckle calluses). Symptoms due to laxative or diuretic abuse include adverse reactions by drugs. Symptoms due to psychiatric morbidity (artefacta) include the consequences of self-induced trauma. The role of the dermatologist in the management of eating disorders is to make an early diagnosis of the "hidden" signs of eating disorders in patients who tend to minimize or deny their disorder. PMID:20808514

  19. Serial position encoding of signs.

    PubMed

    Miozzo, Michele; Petrova, Anna; Fischer-Baum, Simon; Peressotti, Francesca

    2016-09-01

    Reduced short-term memory (STM) capacity has been reported for sign as compared to speech when items have to be recalled in a specific order. This difference has been attributed to a more precise and efficient serial position encoding in verbal STM (used for speech) than visuo-spatial STM (used for sign). We tested in the present investigation whether the reduced STM capacity with signs stems from a lack of positional encoding available in verbal STM. Error analyses reported in prior studies have revealed that positions are defined in verbal STM by distance from both the start and the end of the sequence (both-edges positional encoding scheme). Our analyses of the errors made by deaf participants with finger-spelled letters revealed that the both-edges positional encoding scheme underlies the STM representation of signs. These results indicate that the cause of the STM disadvantage is not the type of positional encoding but rather the difficulties in binding an item in visuo-spatial STM to its specific position in the sequence. Both-edges positional encoding scheme could be specific of sign, since it has not been found in visuo-spatial STM tasks conducted with hearing participants. PMID:27244095

  20. TWO DISTANT HALO VELOCITY GROUPS DISCOVERED BY THE PALOMAR TRANSIENT FACTORY

    SciTech Connect

    Sesar, Branimir; Cohen, Judith G.; Levitan, David; Kirby, Evan N.; Kulkarni, Shrinivas R.; Prince, Thomas A.; Grillmair, Carl J.; Laher, Russ R.; Surace, Jason A.; Juric, Mario; Ofek, Eran O.

    2012-08-20

    We report the discovery of two new halo velocity groups (Cancer groups A and B) traced by eight distant RR Lyrae stars and observed by the Palomar Transient Factory survey at R.A. {approx} 129 Degree-Sign , decl. {approx} 20 Degree-Sign (l {approx} 205 Degree-Sign , b {approx} 32 Degree-Sign ). Located at 92 kpc from the Galactic center (86 kpc from the Sun), these are some of the most distant substructures in the Galactic halo known to date. Follow-up spectroscopic observations with the Palomar Observatory 5.1 m Hale telescope and W. M. Keck Observatory 10 m Keck I telescope indicate that the two groups are moving away from the Galaxy at v-bar{sub gsr}{sup A} = 78.0{+-}5.6 km s{sup -1} (Cancer group A) and v-bar{sub gsr}{sup B} = 16.3{+-}7.1 km s{sup -1} (Cancer group B). The groups have velocity dispersions of {sigma}{sub v{sub g{sub s{sub r}{sup A}}}} = 12.4{+-}5.0 km s{sup -1} and {sigma}B{sub v{sub g{sub s{sub r}{sup B}}}} =14.9{+-}6.2 km s{sup -1} and are spatially extended (about several kpc), making it very unlikely that they are bound systems, and more likely to be debris of tidally disrupted dwarf galaxies or globular clusters. Both groups are metal-poor (median metallicities of [Fe/H]{sup A} = -1.6 dex and [Fe/H]{sup B} = -2.1 dex) and have a somewhat uncertain (due to small sample size) metallicity dispersion of {approx}0.4 dex, suggesting dwarf galaxies as progenitors. Two additional RR Lyrae stars with velocities consistent with those of the Cancer groups have been observed {approx}25 Degree-Sign east, suggesting possible extension of the groups in that direction.

  1. REVERSAL OF FORTUNE: INCREASED STAR FORMATION EFFICIENCIES IN THE EARLY HISTORIES OF DWARF GALAXIES?

    SciTech Connect

    Madau, Piero; Weisz, Daniel R.; Conroy, Charlie

    2014-08-01

    On dwarf galaxy scales, the different shapes of the galaxy stellar mass function and the dark halo mass function require a star-formation efficiency (SFE) in these systems that is currently more than 1 dex lower than that of Milky Way-size halos. Here, we argue that this trend may actually be reversed at high redshift. Specifically, by combining the resolved star-formation histories of nearby isolated dwarfs with the simulated mass-growth rates of dark matter halos, we show that the assembly of these systems occurs in two phases: (1) an early, fast halo accretion phase with a rapidly deepening potential well, characterized by a high SFE; and (2) a late, slow halo accretion phase where, perhaps as a consequence of reionization, the SFE is low. Nearby dwarfs have more old stars than predicted by assuming a constant or decreasing SFE with redshift, a behavior that appears to deviate qualitatively from the trends seen among more massive systems. Taken at face value, the data suggest that at sufficiently early epochs, dwarf galaxy halos above the atomic cooling mass limit can be among the most efficient sites of star formation in the universe.

  2. Jupiter's Main Ring/Ring Halo

    NASA Technical Reports Server (NTRS)

    1997-01-01

    A mosaic of four images taken through the clear filter (610 nanometers) of the solid state imaging (CCD) system aboard NASA's Galileo spacecraft on November 8, 1996, at a resolution of approximately 46 kilometers (28.5 miles) per picture element (pixel) along Jupiter's rings. Because the spacecraft was only about 0.5 degrees above the ring plane, the image is highly foreshortened in the vertical direction. The images were obtained when Galileo was in Jupiter's shadow, peering back toward the Sun; the ring was approximately 2.3 million kilometers (1.4 million miles) away. The arc on the far right of the image is produced when sunlight is scattered by small particles comprising Jupiter's upper atmospheric haze. The ring also efficiently scatters light, indicating that much of its brightness is due to particles that are microns or less in diameter. Such small particles are believed to have human-scale lifetimes, i.e., very brief compared to the solar system's age.

    Jupiter's ring system is composed of three parts - - a flat main ring, a lenticular halo interior to the main ring, and the gossamer ring, outside the main ring. The near and far arms of Jupiter's main ring extend horizontally across the mosaic, joining together at the ring's ansa, on the figure's far left side. The near arm of the ring appears to be abruptly truncated close to the planet, at the point where it passes into Jupiter's shadow. Some radial structure is barely visible across the ring's ansa (top image). A faint mist of particles can be seen above and below the main rings. This vertically extended 'halo' is unusual in planetary rings, and is probably caused by electromagnetic forces pushing the smallest grains out of the ring plane. Because of shadowing, the halo is not visible close to Jupiter in the lower right part of the mosaic. To accentuate faint features in the bottom image of the ring halo, different brightnesses are shown through color. Brightest features are white or yellow and the

  3. GCN: a gaseous Galactic halo stream?

    NASA Astrophysics Data System (ADS)

    Jin, Shoko

    2010-10-01

    We show that a string of HI clouds that form part of the high-velocity cloud complex known as GCN is a probable gaseous stream extending over more than 50° in the Galactic halo. The radial velocity gradient along the stream is used to deduce transverse velocities as a function of distance, enabling a family of orbits to be computed. We find that a direction of motion towards the Galactic disc coupled with a mid-stream distance of ~20kpc provides a good match to the observed sky positions and radial velocities of the HI clouds comprising the stream. With an estimated mass of 105Msolar, its progenitor is likely to be a dwarf galaxy. However, no stellar counterpart has been found amongst the currently known Galactic dwarf spheroidal galaxies or stellar streams and the exact origin of the stream is therefore currently unknown.

  4. The formation of the smooth halo component

    NASA Astrophysics Data System (ADS)

    Peñarrubia, Jorge

    2016-08-01

    The detection and characterization of debris in the integral-of-motion space is a promising avenue to uncover the hierarchical formation of the Milky Way. Yet, the fact that the integrals do not remain constant during the assembly process adds considerable complexity to this approach. Indeed, in time-dependent potentials tidal substructures tend to be effaced from the integral-of-motion space through an orbital diffusion process, which naturally leads to the formation of a `smooth' stellar halo. In this talk I will introduce a new probability theory that describes the evolution of collisionless systems subject to a time-dependent potential. The new theory can be used to reconstruct the hierarchical assembly of our Galaxy through modelling the observed distribution of accreted stars in the integral-of-motion space.

  5. Matter Radii of Light Halo Nuclei

    NASA Astrophysics Data System (ADS)

    Al-Khalili, J. S.; Tostevin, J. A.

    1996-05-01

    We reexamine the matter radii of diffuse halo nuclei, as deduced from reaction cross section measurements at high energy. Careful consideration is given to the intrinsic few-body structure of these projectiles and the adiabatic nature of the projectile-target interaction. Using 11Li, 11Be, and 8B as examples we show that data require significantly larger matter radii than previously reported. The revised value for 11Li of 3.55 fm is consistent with three-body models with significant 1s-intruder state components, which reproduce experimental 9Li momentum distributions following 11Li breakup, but were hitherto thought to be at variance with cross section data.

  6. Solitonic axion condensates modeling dark matter halos

    SciTech Connect

    Castañeda Valle, David Mielke, Eckehard W.

    2013-09-15

    Instead of fluid type dark matter (DM), axion-like scalar fields with a periodic self-interaction or some truncations of it are analyzed as a model of galaxy halos. It is probed if such cold Bose–Einstein type condensates could provide a viable soliton type interpretation of the DM ‘bullets’ observed by means of gravitational lensing in merging galaxy clusters. We study solitary waves for two self-interacting potentials in the relativistic Klein–Gordon equation, mainly in lower dimensions, and visualize the approximately shape-invariant collisions of two ‘lump’ type solitons. -- Highlights: •An axion model of dark matter is considered. •Collision of axion type solitons are studied in a two dimensional toy model. •Relations to dark matter collisions in galaxy clusters are proposed.

  7. Reflection halo twins: subsun and supersun.

    PubMed

    Können, Gunther P; van der Werf, Siebren Y

    2011-10-01

    From an aircraft, a short distinct vertical structure is sometimes seen above the setting sun. Such a feature can be understood as a halo, which is the counterpart of the well-known subsun. Whereas the latter arises from reflections off basal faces of plate-oriented ice crystals illuminated from above, what we call the supersun emerges when these crystals are illuminated from below. The supersun occurs when the sun is below the true horizon and is only visible from elevated positions. The curvature of the Earth causes the ensemble of reflecting crystal faces to act as a hollow mirror and the supersun appears as a vertical band of uniform width, extending from the sun upwards to its supersolar point. We discuss the geometrical properties of the phenomenon and simulate its shape and radiance distribution with an extended version of an atmospheric ray-tracing program. PMID:22016250

  8. Halo Substructure and the Power Spectrum

    NASA Astrophysics Data System (ADS)

    Zentner, Andrew R.; Bullock, James S.

    2003-11-01

    We present a semianalytic model to investigate the merger history, destruction rate, and survival probability of substructure in hierarchically formed dark matter halos and use it to study the substructure content of halos as a function of input primordial power spectrum. For a standard cold dark matter ``concordance'' cosmology (ΛCDM n=1, σ8=0.95) we successfully reproduce the subhalo velocity function and radial distribution profile seen in N-body simulations and determine that the rate of merging and disruption peaks ~10-12 Gyr in the past for Milky Way-like halos, while surviving substructures are typically accreted within the last ~0-8 Gyr. We explore power spectra with normalizations and spectral ``tilts'' spanning the ranges σ8~=1-0.65 and n~=1-0.8, and include a ``running-index'' model with dn/dlnk=-0.03 similar to the best-fit model discussed in the first-year Wilkinson Microwave Anisotropy Probe (WMAP) report. We investigate spectra with truncated small-scale power, including a broken-scale inflation model and three warm dark matter cases with mW=0.75-3.0 keV. We find that the mass fraction in substructure is relatively insensitive to the tilt and overall normalization of the primordial power spectrum. All of the CDM-type models yield projected substructure mass fractions that are consistent with, but on the low side, of published estimates from strong lens systems: f9=0.4%-1.5% (64th percentile) for subhalos smaller than 109 Msolar within projected cylinders of radius r<10 kpc. Truncated models produce significantly smaller fractions, f9=0.02%-0.2% for mW~=1 keV, and are disfavored by lensing estimates. This suggests that lensing and similar probes can provide a robust test of the CDM paradigm and a powerful constraint on broken-scale inflation/warm particle masses, including masses larger than the ~1 keV upper limits of previous studies. We compare our predicted subhalo velocity functions with the dwarf satellite population of the Milky Way. Assuming

  9. Ivy Sign in Moyamoya Disease

    PubMed Central

    Sivrioglu, Ali Kemal; Saglam, Muzaffer; Yildiz, Bulent; Anagnostakou, Vania; Kizilkilic, Osman

    2016-01-01

    Moyamoya disease is an idiopathic disease characterized by the progressive stenosis and collateral development of the distal internal carotid arteries. In this disease, several collateral vascular structures develop following stenosis and occlusion. The ivy sign is a characteristic Magnetic rezonance imaging (MRI) finding frequently encountered in patients with moyamoya. It can be observed both in post contrast T1-weighted images and Fluid attenuated inversion recovery (FLAIR) images. While this sign manifests in the form of contrasting on the cortical surfaces due to the formation of leptomeningeal collateral development and increased numbers of pial vascular webs on post contrast images, in FLAIR images it originates from the slow arterial flow in the leptomeningeal collateral vascular structures. In this case, we presented the Digital subtraction angiography (DSA) signs of moyamoya disease and “ivy sign” in MRI and its development mechanism in a 16 years old female patient. PMID:27026766

  10. Column density profiles of multiphase gaseous haloes

    NASA Astrophysics Data System (ADS)

    Liang, Cameron J.; Kravtsov, Andrey V.; Agertz, Oscar

    2016-05-01

    We analyse circumgalactic medium (CGM) in a suite of high-resolution cosmological re-simulations of a Milky Way size galaxy and show that CGM properties are quite sensitive to details of star formation-feedback loop modelling. The simulation that produces a realistic late-type galaxy, fails to reproduce existing observations of the CGM. In contrast, simulation that does not produce a realistic galaxy has the predicted CGM in better agreement with observations. This illustrates that properties of galaxies and properties of their CGM provide strong complementary constraints on the processes governing galaxy formation. Our simulations predict that column density profiles of ions are well described by an exponential function of projected distance d: N ∝ e^{-d/h_s}. Simulations thus indicate that the sharp drop in absorber detections at larger distances in observations does not correspond to a `boundary' of an ion, but reflects the underlying steep exponential column density profile. Furthermore, we find that ionization energy of ions is tightly correlated with the scaleheight hs: h_s ∝ E_ion^{0.74}. At z ≈ 0, warm gas traced by low-ionization species (e.g. Mg II and C IV) has hs ≈ 0.03 - 0.07Rvir, while higher ionization species (O VI and Ne VIII) have hs ≈ 0.32 - 0.45Rvir. Finally, the scaleheights of ions in our simulations evolve slower than the virial radius for z ≤ 2, but similarly to the halo scale radius, rs. Thus, we suggest that the column density profiles of galaxies at different redshifts should be scaled by rs rather than the halo virial radius.

  11. Solar wind halo electrons from 1-4 AU

    NASA Technical Reports Server (NTRS)

    Mccomas, D. J.; Bame, S. J.; Feldman, W. C.; Gosling, J. T.; Phillips, J. L.

    1992-01-01

    Observations from the Ulysses solar wind electron spectrometer are used to make a first examination of the evolution of the solar wind suprathermal or halo electron population as a function of heliocentric distance beyond 1 AU. As the core population cools with increasing heliocentric distance, no gap is formed between the core and halo populations. Rather, the halo electrons extend to increasingly lower energies. As predicted previously on theoretical grounds, the ratio of the core electron temperature to the low energy cutoff of the halo population appears to be roughly constant with a value of about 7.5. The total integrated heat flux drops rapidly with increasing heliocentric distance; a best fit power law of R exp -2.36 is found. In addition, it is found that the ratio of the halo to core densities is roughly constant over heliocentric distance with the halo representing 4 percent of the total electron distribution. These results suggest that the halo population may not consist of truly noninteractive test particles over the heliocentric range of 1-4 AU.

  12. Optimal linear reconstruction of dark matter from halo catalogues

    SciTech Connect

    Cai, Yan -Chuan; Bernstein, Gary; Sheth, Ravi K.

    2011-04-01

    The dark matter lumps (or "halos") that contain galaxies have locations in the Universe that are to some extent random with respect to the overall matter distributions. We investigate how best to estimate the total matter distribution from the locations of the halos. We derive the weight function w(M) to apply to dark-matter haloes that minimizes the stochasticity between the weighted halo distribution and its underlying mass density field. The optimal w(M) depends on the range of masses of halos being used. While the standard biased-Poisson model of the halo distribution predicts that bias weighting is optimal, the simple fact that the mass is comprised of haloes implies that the optimal w(M) will be a mixture of mass-weighting and bias-weighting. In N-body simulations, the Poisson estimator is up to 15× noisier than the optimal. Optimal weighting could make cosmological tests based on the matter power spectrum or cross-correlations much more powerful and/or cost effective.

  13. Optimal linear reconstruction of dark matter from halo catalogues

    DOE PAGESBeta

    Cai, Yan -Chuan; Bernstein, Gary; Sheth, Ravi K.

    2011-04-01

    The dark matter lumps (or "halos") that contain galaxies have locations in the Universe that are to some extent random with respect to the overall matter distributions. We investigate how best to estimate the total matter distribution from the locations of the halos. We derive the weight function w(M) to apply to dark-matter haloes that minimizes the stochasticity between the weighted halo distribution and its underlying mass density field. The optimal w(M) depends on the range of masses of halos being used. While the standard biased-Poisson model of the halo distribution predicts that bias weighting is optimal, the simple factmore » that the mass is comprised of haloes implies that the optimal w(M) will be a mixture of mass-weighting and bias-weighting. In N-body simulations, the Poisson estimator is up to 15× noisier than the optimal. Optimal weighting could make cosmological tests based on the matter power spectrum or cross-correlations much more powerful and/or cost effective.« less

  14. The Role of Sign Phonology and Iconicity during Sign Processing: The Case of Deaf Children

    ERIC Educational Resources Information Center

    Ormel, Ellen; Hermans, Daan; Knoors, Harry; Verhoeven, Ludo

    2009-01-01

    To investigate the influence of sign phonology and iconicity during sign processing in deaf children, the roles of these sign features were examined using an experimental sign-picture verification paradigm. Participants had to make decisions about sign-picture pairs, manipulated according to phonological sign features (i.e., hand shape, movement,…

  15. Lévy-Student distributions for halos in accelerator beams.

    PubMed

    Cufaro Petroni, Nicola; De Martino, Salvatore; De Siena, Silvio; Illuminati, Fabrizio

    2005-12-01

    We describe the transverse beam distribution in particle accelerators within the controlled, stochastic dynamical scheme of stochastic mechanics (SM) which produces time reversal invariant diffusion processes. This leads to a linearized theory summarized in a Schrödinger-like (SL) equation. The space charge effects have been introduced in recent papers by coupling this S-L equation with the Maxwell equations. We analyze the space-charge effects to understand how the dynamics produces the actual beam distributions, and in particular we show how the stationary, self-consistent solutions are related to the (external and space-charge) potentials both when we suppose that the external field is harmonic (constant focusing), and when we a priori prescribe the shape of the stationary solution. We then proceed to discuss a few other ideas by introducing generalized Student distributions, namely, non-Gaussian, Lévy infinitely divisible (but not stable) distributions. We will discuss this idea from two different standpoints: (a) first by supposing that the stationary distribution of our (Wiener powered) SM model is a Student distribution; (b) by supposing that our model is based on a (non-Gaussian) Lévy process whose increments are Student distributed. We show that in the case (a) the longer tails of the power decay of the Student laws and in the case (b) the discontinuities of the Lévy-Student process can well account for the rare escape of particles from the beam core, and hence for the formation of a halo in intense beams. PMID:16486070

  16. Bar formation and evolution in disc galaxies with gas and a triaxial halo: morphology, bar strength and halo properties

    NASA Astrophysics Data System (ADS)

    Athanassoula, E.; Machado, Rubens E. G.; Rodionov, S. A.

    2013-03-01

    We follow the formation and evolution of bars in N-body simulations of disc galaxies with gas and/or a triaxial halo. We find that both the relative gas fraction and the halo shape play a major role in the formation and evolution of the bar. In gas-rich simulations, the disc stays near-axisymmetric much longer than in gas-poor ones, and, when the bar starts growing, it does so at a much slower rate. Because of these two effects combined, large-scale bars form much later in gas-rich than in gas-poor discs. This can explain the observation that bars are in place earlier in massive red disc galaxies than in blue spirals. We also find that the morphological characteristics in the bar region are strongly influenced by the gas fraction. In particular, the bar at the end of the simulation is much weaker in gas-rich cases. The quality of our simulations is such as to allow us to discuss the question of bar longevity because the resonances are well resolved and the number of gas particles is sufficient to describe the gas flow adequately. In no case did we find a bar which was destroyed. Halo triaxiality has a dual influence on bar strength. In the very early stages of the simulation it induces bar formation to start earlier. On the other hand, during the later, secular evolution phase, triaxial haloes lead to considerably less increase of the bar strength than spherical ones. The shape of the halo evolves considerably with time. We confirm previous results of gas-less simulations that find that the inner part of an initially spherical halo can become elongated and develop a halo bar. However we also show that, on the contrary, in gas-rich simulations, the inner parts of an initially triaxial halo can become rounder with time. The main body of initially triaxial haloes evolves towards sphericity, but in initially strongly triaxial cases it stops well short of becoming spherical. Part of the angular momentum absorbed by the halo generates considerable rotation of the halo

  17. The halo model in a massive neutrino cosmology

    SciTech Connect

    Massara, Elena; Villaescusa-Navarro, Francisco; Viel, Matteo E-mail: villaescusa@oats.inaf.it

    2014-12-01

    We provide a quantitative analysis of the halo model in the context of massive neutrino cosmologies. We discuss all the ingredients necessary to model the non-linear matter and cold dark matter power spectra and compare with the results of N-body simulations that incorporate massive neutrinos. Our neutrino halo model is able to capture the non-linear behavior of matter clustering with a ∼20% accuracy up to very non-linear scales of k = 10 h/Mpc (which would be affected by baryon physics). The largest discrepancies arise in the range k = 0.5 – 1 h/Mpc where the 1-halo and 2-halo terms are comparable and are present also in a massless neutrino cosmology. However, at scales k < 0.2 h/Mpc our neutrino halo model agrees with the results of N-body simulations at the level of 8% for total neutrino masses of < 0.3 eV. We also model the neutrino non-linear density field as a sum of a linear and clustered component and predict the neutrino power spectrum and the cold dark matter-neutrino cross-power spectrum up to k = 1 h/Mpc with ∼30% accuracy. For masses below 0.15 eV the neutrino halo model captures the neutrino induced suppression, casted in terms of matter power ratios between massive and massless scenarios, with a 2% agreement with the results of N-body/neutrino simulations. Finally, we provide a simple application of the halo model: the computation of the clustering of galaxies, in massless and massive neutrinos cosmologies, using a simple Halo Occupation Distribution scheme and our halo model extension.

  18. THE GROWTH OF GALAXY STELLAR MASS WITHIN DARK MATTER HALOS

    SciTech Connect

    Zehavi, Idit; Patiri, Santiago; Zheng Zheng

    2012-02-20

    We study the evolution of stellar mass in galaxies as a function of host halo mass, using the 'MPA' and 'Durham' semi-analytic models, implemented on the Millennium Run simulation. For both models, the stellar mass of the central galaxies increases rapidly with halo mass at the low-mass end and more slowly in halos of larger masses at the three redshifts probed (z {approx} 0, 1, 2). About 45% of the stellar mass in central galaxies in present-day halos less massive than {approx}10{sup 12} h{sup -1} M{sub Sun} is already in place at z {approx} 1, and this fraction increases to {approx}65% for more massive halos. The baryon conversion efficiency into stars has a peaked distribution with halo mass, and the peak location shifts toward lower mass from z {approx} 1 to z {approx} 0. The stellar mass in low-mass halos grows mostly by star formation since z {approx} 1, while in high-mass halos most of the stellar mass is assembled by mergers, reminiscent of 'downsizing'. We compare our findings to empirical results from the Sloan Digital Sky Survey and DEEP2 surveys utilizing galaxy clustering measurements to study galaxy evolution. The theoretical predictions are in qualitative agreement with these phenomenological results, but there are large discrepancies. The most significant one concerns the number of stars already in place in the progenitor galaxies at z {approx} 1, which is about a factor of two larger in both semi-analytic models. We demonstrate that methods studying galaxy evolution from the galaxy-halo connection are powerful in constraining theoretical models and can guide future efforts of modeling galaxy evolution. Conversely, semi-analytic models serve an important role in improving such methods.

  19. A halo bias function measured deeply into voids without stochasticity

    NASA Astrophysics Data System (ADS)

    Neyrinck, Mark C.; Aragón-Calvo, Miguel A.; Jeong, Donghui; Wang, Xin

    2014-06-01

    We study the relationship between dark-matter haloes and matter in the MIP (multum in parvo) N-body simulation ensemble, which allows precision measurements of this relationship, even deeply into voids. What enables this is a lack of discreteness, stochasticity, and exclusion, achieved by averaging over hundreds of possible sets of initial small-scale modes, while holding fixed large-scale modes that give the cosmic web. We find (i) that dark-matter-halo formation is greatly suppressed in voids; there is an exponential downturn at low densities in the otherwise power-law matter-to-halo density bias function. Thus, the rarity of haloes in voids is akin to the rarity of the largest clusters, and their abundance is quite sensitive to cosmological parameters. The exponential downturn appears both in an excursion-set model, and in a model in which fluctuations evolve in voids as in an open universe with an effective Ωm proportional to a large-scale density. We also find that (ii) haloes typically populate the average halo-density field in a super-Poisson way, i.e. with a variance exceeding the mean; and (iii) the rank-order-Gaussianized halo and dark-matter fields are impressively similar in Fourier space. We compare both their power spectra and cross-correlation, supporting the conclusion that one is roughly a strictly increasing mapping of the other. The MIP ensemble especially reveals how halo abundance varies with `environmental' quantities beyond the local matter density; (iv) we find a visual suggestion that at fixed matter density, filaments are more populated by haloes than clusters.

  20. A New Model for Dark Matter Halos Hosting Quasars

    NASA Astrophysics Data System (ADS)

    Cen, Renyue; Safarzadeh, Mohammadtaher

    2015-01-01

    A new model for quasar-hosting dark matter halos, meeting two physical conditions, is put forth. First, significant interactions are taken into consideration to trigger quasar activities. Second, satellites in very massive halos at low redshift are removed from consideration due to their deficiency in cold gas. We analyze the Millennium Simulation to find halos that meet these two conditions and simultaneously match two-point auto-correlation functions of quasars and cross-correlation functions between quasars and galaxies at z = 0.5-3.2. The masses of the quasar hosts found decrease with decreasing redshift, with the mass thresholds being [(2-5) × 1012, (2-5) × 1011, (1-3) × 1011] M ⊙ for median luminosities of ~[1046, 1046, 1045] erg s-1 at z = (3.2, 1.4, 0.53), respectively, an order of magnitude lower than those inferred based on halo occupation distribution modeling. In this model, quasar hosts are primarily massive central halos at z >= 2-3 but increasingly dominated by lower mass satellite halos experiencing major interactions toward lower redshift. However, below z = 1, satellite halos in groups more massive than ~2 × 1013 M ⊙ do not host quasars. Whether for central or satellite halos, imposing the condition of significant interactions substantially boosts the clustering strength compared to the total population with the same mass cut. The inferred lifetimes of quasars at z = 0.5-3.2 of 3-30 Myr are in agreement with observations. Quasars at z ~ 2 would be hosted by halos of mass ~5 × 1011 M ⊙ in this model, compared to ~3 × 1012 M ⊙ previously thought, which would help reconcile with the observed, otherwise puzzling high covering fractions for Lyman limit systems around quasars.

  1. Core-halo issues for a very high intensity beam

    SciTech Connect

    Nghiem, P. A. P.; Chauvin, N.; Uriot, D.

    2014-02-17

    The relevance of classical parameters like beam emittance and envelope used to describe a particle beam is questioned in case of a high intensity accelerator. In the presence of strong space charge effects that affect the beam differently following its density, the much less dense halo part behaves differently from the much denser core part. A method for precisely determining the core-halo limit is proposed, that allows characterizing the halo and the core independently. Results in 1D case are given and discussed. Expected developments extending the method to 2D, 4D, or 6D phase spaces are examined.

  2. Halo current diagnostic system of experimental advanced superconducting tokamak.

    PubMed

    Chen, D L; Shen, B; Granetz, R S; Sun, Y; Qian, J P; Wang, Y; Xiao, B J

    2015-10-01

    The design, calibration, and installation of disruption halo current sensors for the Experimental Advanced Superconducting Tokamak are described in this article. All the sensors are Rogowski coils that surround conducting structures, and all the signals are analog integrated. Coils with two different cross-section sizes have been fabricated, and their mutual inductances are calibrated. Sensors have been installed to measure halo currents in several different parts of both the upper divertor (tungsten) and lower divertor (graphite) at several toroidal locations. Initial measurements from disruptions show that the halo current diagnostics are working well. PMID:26520954

  3. Connecting Galaxies, Halos, and Star Formation Rates Across Cosmic Time

    SciTech Connect

    Conroy, Charlie; Wechsler, Risa H.

    2008-06-02

    A simple, observationally-motivated model is presented for understanding how halo masses, galaxy stellar masses, and star formation rates are related, and how these relations evolve with time. The relation between halo mass and galaxy stellar mass is determined by matching the observed spatial abundance of galaxies to the expected spatial abundance of halos at multiple epochs--i.e. more massive galaxies are assigned to more massive halos at each epoch. This 'abundance matching' technique has been shown previously to reproduce the observed luminosity- and scale-dependence of galaxy clustering over a range of epochs. Halos at different epochs are connected by halo mass accretion histories estimated from N-body simulations. The halo-galaxy connection at fixed epochs in conjunction with the connection between halos across time provides a connection between observed galaxies across time. With approximations for the impact of merging and accretion on the growth of galaxies, one can then directly infer the star formation histories of galaxies as a function of stellar and halo mass. This model is tuned to match both the observed evolution of the stellar mass function and the normalization of the observed star formation rate--stellar mass relation to z {approx} 1. The data demands, for example, that the star formation rate density is dominated by galaxies with M{sub star} {approx} 10{sup 10.0-10.5} M{sub {circle_dot}} from 0 < z < 1, and that such galaxies over these epochs reside in halos with M{sub vir} {approx} 10{sup 11.5-12.5} M{sub {circle_dot}}. The star formation rate--halo mass relation is approximately Gaussian over the range 0 < z < 1 with a mildly evolving mean and normalization. This model is then used to shed light on a number of issues, including (1) a clarification of 'downsizing', (2) the lack of a sharp characteristic halo mass at which star formation is truncated, and (3) the dominance of star formation over merging to the stellar build-up of galaxies

  4. Testing gravity using the environmental dependence of dark matter halos.

    PubMed

    Zhao, Gong-Bo; Li, Baojiu; Koyama, Kazuya

    2011-08-12

    In this Letter, we investigate the environmental dependence of dark matter halos in theories which attempt to explain the accelerated expansion of the Universe by modifying general relativity (GR). Using high-resolution N-body simulations in f(R) gravity models which recover GR in dense environments by virtue of the chameleon mechanism, we find a significant difference, which depends on the environment, between the lensing and dynamical masses of dark matter halos. This environmental dependence of the halo properties can be used as a smoking gun to test GR observationally. PMID:21902382

  5. Stellar halos: a rosetta stone for galaxy formation and cosmology

    NASA Astrophysics Data System (ADS)

    Inglis Read, Justin

    2015-08-01

    Stellar halos make up about a percent of the total stellar mass in galaxies. Yet their old age and long phase mixing times make them living fossil records of galactic history. In this talk, I review the latest simulations of structure formation in our standard Lambda Cold Dark Matter cosmology. I discuss the latest predictions for stellar halos and the relationship between the stellar halo light and the underlying dark matter. Finally, I discuss how these simulations compare to observations of the Milky Way and Andromeda and, ultimately, what this means for our cosmological model and the formation history of the Galaxy.

  6. Halo current diagnostic system of experimental advanced superconducting tokamak

    SciTech Connect

    Chen, D. L.; Shen, B.; Sun, Y.; Qian, J. P. Wang, Y.; Xiao, B. J.; Granetz, R. S.

    2015-10-15

    The design, calibration, and installation of disruption halo current sensors for the Experimental Advanced Superconducting Tokamak are described in this article. All the sensors are Rogowski coils that surround conducting structures, and all the signals are analog integrated. Coils with two different cross-section sizes have been fabricated, and their mutual inductances are calibrated. Sensors have been installed to measure halo currents in several different parts of both the upper divertor (tungsten) and lower divertor (graphite) at several toroidal locations. Initial measurements from disruptions show that the halo current diagnostics are working well.

  7. CONNECTING GALAXIES, HALOS, AND STAR FORMATION RATES ACROSS COSMIC TIME

    SciTech Connect

    Conroy, Charlie; Wechsler, Risa H.

    2009-05-01

    A simple, observationally motivated model is presented for understanding how halo masses, galaxy stellar masses, and star formation rates are related, and how these relations evolve with time. The relation between halo mass and galaxy stellar mass is determined by matching the observed spatial abundance of galaxies to the expected spatial abundance of halos at multiple epochs, i.e., more massive galaxies are assigned to more massive halos at each epoch. This 'abundance matching' technique has been shown previously to reproduce the observed luminosity and scale dependence of galaxy clustering over a range of epochs. Halos at different epochs are connected by halo mass accretion histories estimated from N-body simulations. The halo-galaxy connection at fixed epochs in conjunction with the connection between halos across time provides a connection between observed galaxies across time. With approximations for the impact of merging and accretion on the growth of galaxies, one can then directly infer the star formation histories of galaxies as a function of stellar and halo mass. This model is tuned to match both the observed evolution of the stellar mass function and the normalization of the observed star formation rate (SFR)-stellar mass relation to z {approx} 1. The data demands, for example, that the star formation rate density is dominated by galaxies with M {sub star} {approx} 10{sup 10.0-10.5} M {sub sun} from 0 < z < 1, and that such galaxies over these epochs reside in halos with M {sub vir} {approx} 10{sup 11.5-12.5} M {sub sun}. The SFR-halo mass relation is approximately Gaussian over the range 0 < z < 1 with a mildly evolving mean and normalization. This model is then used to shed light on a number of issues, including (1) a clarification of {sup d}ownsizing{sup ,} (2) the lack of a sharp characteristic halo mass at which star formation is truncated, and (3) the dominance of star formation over merging to the stellar buildup of galaxies with M {sub star

  8. Beam-halo measurements in high-current proton beams

    SciTech Connect

    Allen, C.K.; Chan, K.C.D.; Colestock, P.L.; Crandall, K.R.; Garnett, R.W.; Gilpatrick, J.D.; Lysenko, W.; Qiang, J.; Schneider, J.D.; Schulze, M.E.; Sheffield, R.L.; Smith, H.V.; Wangler, T.P.

    2002-01-11

    We present results from an experimental study of the beam halo in a high-current 6.7-MeV proton beam propagating through a 52-quadrupole periodic-focusing channel. The gradients of the first four quadrupoles were independently adjusted to match or mismatch the injected beam. Emittances and beamwidths were obtained from measured profiles for comparisons with maximum emittance-growth predictions of a free-energy model and maximum halo-amplitude predictions of a particle-core model. The experimental results support both models and the present theoretical picture of halo formation.

  9. Los Alamos beam halo experiment: comparing theory, simulation and experiment.

    SciTech Connect

    Wangler, Thomas P.,; Qiang, J.

    2002-01-01

    We compare macroparticle simulations with measurements from a proton beam-halo experiment in a 52-quadrupole periodic-focusing channel. Three different initial distributions with the same Courant-Snyder parameters and emittances, but different shapes, predict different beam profiles in the transport system. Input distributions with greater population in the tails produce larger rates of emittance growth, a result that is qualitatively consistent with the particle-core model of halo formation in mismatched beams. The simulations underestimate the growth rate of halo and emittance for mismatched beams. Better agreement between simulations and experiment may require an input distribution that represents more accurately the tails of the real input beam.

  10. DUST-SCATTERED ULTRAVIOLET HALOS AROUND BRIGHT STARS

    SciTech Connect

    Murthy, Jayant; Henry, Richard Conn

    2011-06-10

    We have discovered ultraviolet (UV) halos extending as far as 5 deg. around four (of six) bright UV stars using data from the Galaxy Evolution Explorer satellite. These halos are due to scattering of the starlight from nearby thin, foreground dust clouds. We have placed limits of 0.58 {+-} 0.12 and 0.72 {+-} 0.06 on the phase function asymmetry factor (g) in the FUV (1521 A) and NUV (2320 A) bands, respectively. We suggest that these halos are a common feature around bright stars and may be used to explore the scattering function of interstellar grains at small angles.

  11. Using accurate phase space coordinates of ~100,00 halo field stars to constrain the Milky Way halo

    NASA Astrophysics Data System (ADS)

    Valluri, Monica

    2015-08-01

    The current cosmological paradigm predicts that dark matter halos are triaxial overall, but oblate in regions where baryons dominate. However recent measurements of the shape of the Milky Way dark matter halo find it to be very triaxial with a shape and orientation that are significantly at odds with theoretical predictions. The ESA’s Gaia satellite will soon map the entire Milky Way giving us six phase-space coordinates, ages and abundances for hundreds of thousands of halo stars. I will report progress on a new code based on the Schwarzschild orbit superposition method and orbital frequency mapping, to determine the global shape of the Milky Way's dark matter halo using field stars from Gaia. This technique will simultaneously yield the self-consistent phase-space distribution function of the stellar halo in the inner 20-30kpc region. Detailed analysis of correlations between the chemical abundances, ages and orbits of halo stars in this distribution function will enable us to extract clues to the formation history of the Milky Way that are encoded in orbital properties of halo stars.

  12. HaloSat: A CubeSat to Map the Distribution of Baryonic Matter in the Galactic Halo

    NASA Astrophysics Data System (ADS)

    Miles, Drew M.

    2016-04-01

    Approximately half of predicted baryonic matter in the Milky Way remains unidentified. One possible explanation for the location of this missing matter is in an extended Galactic halo. HaloSat is a CubeSat that aims to constrain the mass and distribution of the halo’s baryonic matter by obtaining an all-sky map of O VII and O VIII emission in the hot gas associated with the halo of the Milky Way. HaloSat offers an improvement in the quality of measurements of oxygen line emission over existing X-ray observatories and an observation plan dedicated to mapping the hot gas in the Galactic halo. In addition to the missing baryon problem, HaloSat will assign a portion of its observations to the solar wind charge exchange (SWCX) in order to calibrate models of SCWX emission. We present here the current status of HaloSat and the progression of instrument development in anticipation of a 2018 launch.

  13. The Sociolinguistics of Sign Languages.

    ERIC Educational Resources Information Center

    Lucas, Ceil, Ed.

    This collection of papers examines how sign languages are distributed around the world; what occurs when they come in contact with spoken and written languages, and how signers use them in a variety of situations. Each chapter introduces the key issues in a particular area of inquiry and provides a comprehensive review of the literature. The seven…

  14. The HyperSign Project.

    ERIC Educational Resources Information Center

    Abdulezer, Susan

    This report describes ongoing activities and results of the HyperSign Immersion Project developed at the Public School for the Deaf in New York City, New York. The project's objectives were to: (1) provide a means to enable Deaf students to assume a self-directed role in education; (2) provide an on-site prototype of a technologically supportive…

  15. Pronouns in Mexican Sign Language.

    ERIC Educational Resources Information Center

    Plumlee, Marilyn

    This paper provides an analysis of the manual and non-manual pronouns identified in Mexican Sign Language (MSL) used by a female speaker in 1993, discusses syntactic uses of each type, and examines pronoun deletion. MSL has two distinct modes of expressing pronominal relationships: manual pronouns (including indexical, incorporated, classifiers,…

  16. Library Signs and the Disabled.

    ERIC Educational Resources Information Center

    Benedict, Marjorie A.

    This essay outlines general criteria for evaluating the effectiveness of an existing or proposed sign system for libraries with respect to the needs of physically disabled library users, specifically the deaf, the blind, and those confined to wheelchairs. The function of the International Symbol of Access is described, and design considerations…

  17. Lexical Frequency in Sign Languages

    ERIC Educational Resources Information Center

    Johnston, Trevor

    2012-01-01

    Measures of lexical frequency presuppose the existence of corpora, but true machine-readable corpora of sign languages (SLs) are only now being created. Lexical frequency ratings for SLs are needed because there has been a heavy reliance on the interpretation of results of psycholinguistic and neurolinguistic experiments in the SL research…

  18. Signing Shakespeare: Romeo Loves Juliet.

    ERIC Educational Resources Information Center

    Goldfarb, Liz; Cambridge, Terry

    1995-01-01

    A language arts teacher of junior high students with deafness or hearing impairments familiarized her students with "Romeo and Juliet" by telling the story in speech and signs, exploring the characters's personalities, reviewing vocabulary, putting the characters into contemporary situations, and directing the students in a full-scale production…

  19. Eye Gaze in Creative Sign Language

    ERIC Educational Resources Information Center

    Kaneko, Michiko; Mesch, Johanna

    2013-01-01

    This article discusses the role of eye gaze in creative sign language. Because eye gaze conveys various types of linguistic and poetic information, it is an intrinsic part of sign language linguistics in general and of creative signing in particular. We discuss various functions of eye gaze in poetic signing and propose a classification of gaze…

  20. 13 CFR 305.12 - Project sign.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false Project sign. 305.12 Section 305... WORKS AND ECONOMIC DEVELOPMENT INVESTMENTS Requirements for Approved Projects § 305.12 Project sign. The... the construction period of a sign or signs at a conspicuous place at the Project site indicating...

  1. 13 CFR 305.12 - Project sign.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 13 Business Credit and Assistance 1 2014-01-01 2014-01-01 false Project sign. 305.12 Section 305... WORKS AND ECONOMIC DEVELOPMENT INVESTMENTS Requirements for Approved Projects § 305.12 Project sign. The... the construction period of a sign or signs at a conspicuous place at the Project site indicating...

  2. 13 CFR 305.12 - Project sign.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 13 Business Credit and Assistance 1 2011-01-01 2011-01-01 false Project sign. 305.12 Section 305... WORKS AND ECONOMIC DEVELOPMENT INVESTMENTS Requirements for Approved Projects § 305.12 Project sign. The... the construction period of a sign or signs at a conspicuous place at the Project site indicating...

  3. 13 CFR 305.12 - Project sign.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 13 Business Credit and Assistance 1 2013-01-01 2013-01-01 false Project sign. 305.12 Section 305... WORKS AND ECONOMIC DEVELOPMENT INVESTMENTS Requirements for Approved Projects § 305.12 Project sign. The... the construction period of a sign or signs at a conspicuous place at the Project site indicating...

  4. Tactile Signing with One-Handed Perception

    ERIC Educational Resources Information Center

    Mesch, Johanna

    2013-01-01

    Tactile signing among persons with deaf-blindness is not homogenous; rather, like other forms of language, it exhibits variation, especially in turn taking. Early analyses of tactile Swedish Sign Language, tactile Norwegian Sign Language, and tactile French Sign Language focused on tactile communication with four hands, in which partially blind or…

  5. 46 CFR 154.1830 - Warning sign.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Warning sign. 154.1830 Section 154.1830 Shipping COAST... SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Operations § 154.1830 Warning sign. (a) The master... a warning sign: (1) At the gangway facing the shore so that the sign may be seen from the shore;...

  6. 49 CFR 195.434 - Signs.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Signs. 195.434 Section 195.434 Transportation... PIPELINE Operation and Maintenance § 195.434 Signs. Each operator must maintain signs visible to the public around each pumping station and breakout tank area. Each sign must contain the name of the operator and...

  7. Numeral Incorporation in Japanese Sign Language

    ERIC Educational Resources Information Center

    Ktejik, Mish

    2013-01-01

    This article explores the morphological process of numeral incorporation in Japanese Sign Language. Numeral incorporation is defined and the available research on numeral incorporation in signed language is discussed. The numeral signs in Japanese Sign Language are then introduced and followed by an explanation of the numeral morphemes which are…

  8. 49 CFR 195.434 - Signs.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Signs. 195.434 Section 195.434 Transportation... PIPELINE Operation and Maintenance § 195.434 Signs. Each operator must maintain signs visible to the public around each pumping station and breakout tank area. Each sign must contain the name of the operator and...

  9. 46 CFR 154.1830 - Warning sign.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Warning sign. 154.1830 Section 154.1830 Shipping COAST... SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Operations § 154.1830 Warning sign. (a) The master... a warning sign: (1) At the gangway facing the shore so that the sign may be seen from the shore;...

  10. 49 CFR 193.2917 - Warning signs.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Warning signs. 193.2917 Section 193.2917...: FEDERAL SAFETY STANDARDS Security § 193.2917 Warning signs. (a) Warning signs must be conspicuously placed along each protective enclosure at intervals so that at least one sign is recognizable at night from...

  11. 36 CFR 1001.10 - Symbolic signs.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... signs. (a) The signs pictured in 36 CFR 1.10 provide general information and regulatory guidance in the area administered by the Presidio Trust. Certain of the signs designate activities that are either... 36 Parks, Forests, and Public Property 3 2013-07-01 2012-07-01 true Symbolic signs....

  12. 36 CFR 1.10 - Symbolic signs.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 36 Parks, Forests, and Public Property 1 2012-07-01 2012-07-01 false Symbolic signs. 1.10 Section... PROVISIONS § 1.10 Symbolic signs. (a) The signs pictured below provide general information and regulatory guidance in park areas. Certain of the signs designate activities that are either allowed or...

  13. 49 CFR 195.434 - Signs.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Signs. 195.434 Section 195.434 Transportation... PIPELINE Operation and Maintenance § 195.434 Signs. Each operator must maintain signs visible to the public around each pumping station and breakout tank area. Each sign must contain the name of the operator and...

  14. 36 CFR 1.10 - Symbolic signs.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false Symbolic signs. 1.10 Section... PROVISIONS § 1.10 Symbolic signs. (a) The signs pictured below provide general information and regulatory guidance in park areas. Certain of the signs designate activities that are either allowed or...

  15. 46 CFR 154.1830 - Warning sign.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Warning sign. 154.1830 Section 154.1830 Shipping COAST... SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Operations § 154.1830 Warning sign. (a) The master... a warning sign: (1) At the gangway facing the shore so that the sign may be seen from the shore;...

  16. 49 CFR 193.2917 - Warning signs.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Warning signs. 193.2917 Section 193.2917...: FEDERAL SAFETY STANDARDS Security § 193.2917 Warning signs. (a) Warning signs must be conspicuously placed along each protective enclosure at intervals so that at least one sign is recognizable at night from...

  17. 46 CFR 154.1830 - Warning sign.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Warning sign. 154.1830 Section 154.1830 Shipping COAST... SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Operations § 154.1830 Warning sign. (a) The master... a warning sign: (1) At the gangway facing the shore so that the sign may be seen from the shore;...

  18. 36 CFR 1001.10 - Symbolic signs.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... signs. (a) The signs pictured in 36 CFR 1.10 provide general information and regulatory guidance in the area administered by the Presidio Trust. Certain of the signs designate activities that are either... 36 Parks, Forests, and Public Property 3 2012-07-01 2012-07-01 false Symbolic signs....

  19. 49 CFR 195.434 - Signs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Signs. 195.434 Section 195.434 Transportation... PIPELINE Operation and Maintenance § 195.434 Signs. Each operator must maintain signs visible to the public around each pumping station and breakout tank area. Each sign must contain the name of the operator and...

  20. 46 CFR 154.1830 - Warning sign.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Warning sign. 154.1830 Section 154.1830 Shipping COAST... SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Operations § 154.1830 Warning sign. (a) The master... a warning sign: (1) At the gangway facing the shore so that the sign may be seen from the shore;...

  1. 49 CFR 193.2917 - Warning signs.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Warning signs. 193.2917 Section 193.2917...: FEDERAL SAFETY STANDARDS Security § 193.2917 Warning signs. (a) Warning signs must be conspicuously placed along each protective enclosure at intervals so that at least one sign is recognizable at night from...

  2. 36 CFR 1.10 - Symbolic signs.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Symbolic signs. 1.10 Section... PROVISIONS § 1.10 Symbolic signs. (a) The signs pictured below provide general information and regulatory guidance in park areas. Certain of the signs designate activities that are either allowed or...

  3. 36 CFR 1.10 - Symbolic signs.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Symbolic signs. 1.10 Section... PROVISIONS § 1.10 Symbolic signs. (a) The signs pictured below provide general information and regulatory guidance in park areas. Certain of the signs designate activities that are either allowed or...

  4. 36 CFR 1001.10 - Symbolic signs.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... signs. (a) The signs pictured in 36 CFR 1.10 provide general information and regulatory guidance in the area administered by the Presidio Trust. Certain of the signs designate activities that are either... 36 Parks, Forests, and Public Property 3 2014-07-01 2014-07-01 false Symbolic signs....

  5. 36 CFR 1001.10 - Symbolic signs.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... signs. (a) The signs pictured in 36 CFR 1.10 provide general information and regulatory guidance in the area administered by the Presidio Trust. Certain of the signs designate activities that are either... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Symbolic signs....

  6. 49 CFR 195.434 - Signs.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Signs. 195.434 Section 195.434 Transportation... PIPELINE Operation and Maintenance § 195.434 Signs. Each operator must maintain signs visible to the public around each pumping station and breakout tank area. Each sign must contain the name of the operator and...

  7. 36 CFR 1.10 - Symbolic signs.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 36 Parks, Forests, and Public Property 1 2013-07-01 2013-07-01 false Symbolic signs. 1.10 Section... PROVISIONS § 1.10 Symbolic signs. (a) The signs pictured below provide general information and regulatory guidance in park areas. Certain of the signs designate activities that are either allowed or...

  8. 13 CFR 305.12 - Project sign.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 13 Business Credit and Assistance 1 2012-01-01 2012-01-01 false Project sign. 305.12 Section 305... WORKS AND ECONOMIC DEVELOPMENT INVESTMENTS Requirements for Approved Projects § 305.12 Project sign. The... the construction period of a sign or signs at a conspicuous place at the Project site indicating...

  9. 49 CFR 193.2917 - Warning signs.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Warning signs. 193.2917 Section 193.2917...: FEDERAL SAFETY STANDARDS Security § 193.2917 Warning signs. (a) Warning signs must be conspicuously placed along each protective enclosure at intervals so that at least one sign is recognizable at night from...

  10. 49 CFR 193.2917 - Warning signs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Warning signs. 193.2917 Section 193.2917...: FEDERAL SAFETY STANDARDS Security § 193.2917 Warning signs. (a) Warning signs must be conspicuously placed along each protective enclosure at intervals so that at least one sign is recognizable at night from...

  11. 36 CFR 1001.10 - Symbolic signs.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... signs. (a) The signs pictured in 36 CFR 1.10 provide general information and regulatory guidance in the area administered by the Presidio Trust. Certain of the signs designate activities that are either... 36 Parks, Forests, and Public Property 3 2011-07-01 2011-07-01 false Symbolic signs....

  12. Systematics of reactions with 4,6He: Static and dynamic halo effects and evidence for core-halo decoupling

    NASA Astrophysics Data System (ADS)

    Aguilera, E. F.; Martel, I.; Sánchez-Benítez, A. M.; Acosta, L.

    2011-02-01

    Experimental reaction cross sections for He6 and He4 projectiles are reduced and are shown to follow well-defined trajectories that can be characterized by respective Wong-type curves. The strong enhancement observed for the He6 data is interpreted as caused by two separate halo effects: a size effect, which affects the whole energy region, and a dynamic effect, important only near and below the barrier. Evidence for a core-halo decoupling is presented for the 6He+64Zn system, which further supports the hypothesis that the decoupling is a characteristic feature of true halo systems.

  13. Possible existence of wormholes in the central regions of halos

    SciTech Connect

    Rahaman, Farook; Salucci, P.; Kuhfittig, P.K.F.; Ray, Saibal; Rahaman, Mosiur

    2014-11-15

    An earlier study (Rahaman, et al., 2014 and Kuhfittig, 2014) has demonstrated the possible existence of wormholes in the outer regions of the galactic halo, based on the Navarro–Frenk–White (NFW) density profile. This paper uses the Universal Rotation Curve (URC) dark matter model to obtain analogous results for the central parts of the halo. This result is an important compliment to the earlier result, thereby confirming the possible existence of wormholes in most of the spiral galaxies. - Highlights: • Earlier we showed possible existence of wormholes in the outer regions of halo. • We obtain here analogous results for the central parts of the galactic halo. • Our result is an important compliment to the earlier result. • This confirms possible existence of wormholes in most of the spiral galaxies.

  14. DIAGNOSTIC TOOLS FOR BEAM HALO INVESTIGATION IN SNS LINAC

    SciTech Connect

    Aleksandrov, Alexander V; Blokland, Willem; Liu, Yun; Long, Cary D; Zhukov, Alexander P

    2012-01-01

    Uncontrolled beam loss is a major concern in the operation of a high intensity hadron linac. A low density cloud of particles with large oscillation amplitudes, so called halo, can form around the dense regular beam core. This halo can be a direct or indirect cause of beam loss. There is experimental evidence of halo growing in the SNS linac and limiting the further reduction of beam loss. A set of tools is being developed for detecting of the halo and investigating its origin and dynamics. The set includes high resolution emittance measurements in the injector, laser based emittance measurements at 1 GeV, and high resolution profile measurements along the linac. We will present our experience with useful measurement techniques and data analysis algorithms.

  15. Halo Orbit Mission Correction Maneuvers Using Optimal Control

    NASA Technical Reports Server (NTRS)

    Lo, M.; Serban, R.; Petzold, L.; Koon, W.; Ross, S.; Marsden, J.; Wilson, R.

    2000-01-01

    This paper addresses the computation of the required trajectory correction maneuvers (TCM) for a halo orbit space mission to compensate for the launch velocity errors introduced by inaccuracies of the launch vehicle.

  16. BEAM HALO FORMATION IN HIGH-INTENSITY BEAMS.

    SciTech Connect

    FEDOTOV, A.V.

    2005-03-18

    Studies of beam halo became unavoidable feature of high-intensity machines where uncontrolled beam loss should be kept to extremely small level. For a well controlled stable beam such a loss is typically associated with the low density halo surrounding beam core. In order to minimize uncontrolled beam loss or improve performance of an accelerator, it is very important to understand what are the sources of halo formation in a specific machine of interest. The dominant mechanisms are, in fact, different in linear accelerators, circular machines or Energy Recovering Linacs (ERL). In this paper, we summarize basic mechanisms of halo formation in high-intensity beams and discuss their application to various types of accelerators of interest, such as linacs, rings and ERL.

  17. Lithium in halo stars from standard stellar evolution

    NASA Technical Reports Server (NTRS)

    Deliyannis, Constantine P.; Demarque, Pierre; Kawaler, Steven D.

    1990-01-01

    A grid has been constructed of theoretical evolution sequences of models for low-metallicity stars from the premain-sequence to the giant branch phases. The grid is used to study the history of surface Li abundance during standard stellar evolution. The Li-7 observations of halo stars by Spite and Spite (1982) and subsequent observations are synthesized to separate the halo stars by age. The theory of surface Li abundance is illustrated by following the evolution of a reference halo star model from the contracting fully convective premain sequence to the giant branch phase. The theoretical models are compared with observed Li abundances. The results show that the halo star lithium abundances can be explained in the context of standard stellar evolution theory using completely standard assumptions and physics.

  18. Building Blocks of the Milky Way's Stellar Halo

    NASA Astrophysics Data System (ADS)

    van Oirschot, Pim; Starkenburg, Else; Helmi, Amina; Nelemans, Gijs

    2016-08-01

    We study the assembly history of the stellar halo of Milky Way-like galaxies using the six high-resolution Aquarius dark matter simulations combined with the Munich-Groningen semi-analytic galaxy formation model. Our goal is to understand the stellar population contents of the building blocks of the Milky Way halo, including their star formation histories and chemical evolution, as well as their internal dynamical properties. We are also interested in how they relate or are different from the surviving satellite population. Finally, we will use our models to compare to observations of halo stars in an attempt to reconstruct the assembly history of the Milky Way's stellar halo itself.

  19. ADP study of the structure of the IUE halo

    NASA Technical Reports Server (NTRS)

    Massa, Derck

    1992-01-01

    Results of a two year ADP study of gas in the Galactic halo are presented. This is partly a summary of 2 papers which were published in referred journals and partly a discussion of work currently underway.

  20. EFFECT OF DARK MATTER HALO SUBSTRUCTURES ON GALAXY ROTATION CURVES

    SciTech Connect

    Roy, Nirupam

    2010-11-01

    In this paper, the effect of halo substructures on galaxy rotation curves is investigated using a simple model of dark matter clustering. A dark matter halo density profile is developed based only on the scale-free nature of clustering that leads to a statistically self-similar distribution of the substructures at the galactic scale. A semi-analytical method is used to derive rotation curves for such a clumpy dark matter density profile. It is found that the halo substructures significantly affect the galaxy velocity field. Based on the fractal geometry of the halo, this self-consistent model predicts a Navarro-Frenk-White-like rotation curve and a scale-free power spectrum of the rotation velocity fluctuations.

  1. Effective Dark Matter Halo Catalog in f(R) Gravity.

    PubMed

    He, Jian-Hua; Hawken, Adam J; Li, Baojiu; Guzzo, Luigi

    2015-08-14

    We introduce the idea of an effective dark matter halo catalog in f(R) gravity, which is built using the effective density field. Using a suite of high resolution N-body simulations, we find that the dynamical properties of halos, such as the distribution of density, velocity dispersion, specific angular momentum and spin, in the effective catalog of f(R) gravity closely mimic those in the cold dark matter model with a cosmological constant (ΛCDM). Thus, when using effective halos, an f(R) model can be viewed as a ΛCDM model. This effective catalog therefore provides a convenient way for studying the baryonic physics, the galaxy halo occupation distribution and even semianalytical galaxy formation in f(R) cosmologies. PMID:26317711

  2. Detection of ultraviolet halos around highly inclined galaxies

    SciTech Connect

    Hodges-Kluck, Edmund; Bregman, Joel N.

    2014-07-10

    We report the discovery of diffuse ultraviolet light around late-type galaxies out to 5-20 kpc from the midplane using Swift and GALEX images. The emission is consistent with the stellar outskirts in the early-type galaxies but not in the late-type galaxies, where the emission is quite blue and consistent with a reflection nebula powered by light escaping from the galaxy and scattering off dust in the halo. Our results agree with expectations from halo dust discovered in extinction by Ménard et al. to within a few kpc of the disk and imply a comparable amount of hot and cold gas in galaxy halos (a few× 10{sup 8} M{sub ☉} within 20 kpc) if the dust resides primarily in Mg II absorbers. The results also highlight the potential of UV photometry to study individual galaxy halos.

  3. Spherical collapse and halo mass function in the symmetron model

    NASA Astrophysics Data System (ADS)

    Taddei, Laura; Catena, Riccardo; Pietroni, Massimo

    2014-01-01

    We study the gravitational clustering of spherically symmetric overdensities and the statistics of the resulting dark matter halos in the "symmetron model," in which a new long range force is mediated by a Z2 symmetric scalar field. Depending on the initial radius of the overdensity, we identify two distinct regimes: for small initial radii the symmetron mediated force affects the spherical collapse at all redshifts; for initial radii larger than some critical size this force vanishes before collapse because of the symmetron screening mechanism. As a consequence, halos with initial radii smaller than some critical value collapse earlier than in the ΛCDM and statistically tend to form more massive dark matter halos. Regarding the halo mass function of these objects, we observe departures from standard ΛCDM predictions at the few percent level. The formalism developed here can be easily applied to other models where fifth forces participate to the dynamics of the gravitational collapse.

  4. Summary of the 2014 Beam-Halo Monitoring Workshop

    SciTech Connect

    Fisher, Alan

    2015-09-25

    Understanding and controlling beam halo is important for high-intensity hadron accelerators, for high-brightness electron linacs, and for low-emittance light sources. This can only be achieved by developing suitable diagnostics. The main challenge faced by such instrumentation is the high dynamic range needed to observe the halo in the presence of an intense core. In addition, measurements must often be made non-invasively. This talk summarizes the one-day workshop on Beam-Halo Monitoring that was held at SLAC on September 19 last year, immediately following IBIC 2014 in Monterey. Workshop presentations described invasive techniques using wires, screens, or crystal collimators, and non-invasive measurements with gas or scattered electrons. Talks on optical methods showed the close links between observing halo and astronomical problems like observing the solar corona or directly observing a planet orbiting another star.

  5. Halo formation and evolution: unification of structure and physical properties

    NASA Astrophysics Data System (ADS)

    Ernest, Allan D.; Collins, Matthew P.

    2016-08-01

    The assembly of matter in the universe proliferates a wide variety of halo structures, often with enigmatic consequences. Giant spiral galaxies, for example, contain both dark matter and hot gas, while dwarf spheroidal galaxies, with weaker gravity, contain much larger fractions of dark matter, but little gas. Globular clusters, superficially resembling these dwarf spheroidals, have little or no dark matter. Halo temperatures are also puzzling: hot cluster halos contain cooler galaxy halos; dwarf galaxies have no hot gas at all despite their similar internal processes. Another mystery is the origin of the gas that galaxies require to maintain their measured star formation rates (SFRs). We outline how gravitational quantum theory solves these problems, and enables baryons to function as weakly-interacting-massive-particles (WIMPs) in Lambda Cold Dark Matter (LCDM) theory. Significantly, these dark-baryon ensembles may also be consistent with primordial nucleosynthesis (BBN) and cosmic microwave background (CMB) anisotropies.

  6. Spontaneous Involution of Congenital Melanocytic Nevus With Halo Phenomenon

    PubMed Central

    Lee, Noo Ri; Chung, Hee-Chul; Hong, Hannah; Lee, Jin Wook

    2015-01-01

    Abstract: Congenital melanocytic nevus (CMN) is a neural crest-derived hamartoma, which appear at or soon after birth. CMN has a dynamic course and may show variable changes over time, including spontaneous involution. Spontaneous involution of CMN is a rare phenomenon and is often reported in association with halo phenomenon or vitiligo. The mechanism of halo phenomenon is yet to be investigated but is suggested to be a destruction of melanocytes by immune responses of cytotoxic T cells or IgM autoantibodies. Here, the authors report an interesting case of spontaneously regressed medium-sized CMN with halo phenomenon and without vitiligo, which provides evidence that cytotoxic T cells account for the halo formation and pigmentary regression of CMN. PMID:26588343

  7. Recent results in analysis and simulation of beam halo

    SciTech Connect

    Ryne, Robert D.; Wangler, Thomas P.

    1995-09-15

    Understanding and predicting beam halo is a major issue for accelerator driven transmutation technologies. If strict beam loss requirements are not met, the resulting radioactivation can reduce the availability of the accelerator facility and may lead to the necessity for time-consuming remote maintenance. Recently there has been much activity related to the core-halo model of halo evolution [1-5]. In this paper we will discuss the core-halo model in the context of constant focusing channels and periodic focusing channels. We will present numerical results based on this model and we will show comparisons with results from large scale particle simulations run on a massively parallel computer. We will also present results from direct Vlasov simulations.

  8. Recent results in analysis and simulation of beam halo

    SciTech Connect

    Ryne, R.D.; Wangler, T.P.

    1994-09-01

    Understanding and predicting beam halo is a major issue for accelerator driven transmutation technologies. If strict beam loss requirements are not met, the resulting radioactivation can reduce the availability of the accelerator facility and may lead to the necessity for time-consuming remote maintenance. Recently there has been much activity related to the core-halo model of halo evolution. In this paper the authors will discuss the core-halo model in the context of constant focusing channels and periodic focusing channels. They will present numerical results based on this model and they will show comparisons with results from large scale particle simulations run on a massively parallel computer. They will also present results from direct Vlasov simulations.

  9. Dark matter annihilation in the first galaxy haloes

    NASA Astrophysics Data System (ADS)

    Schön, S.; Mack, K. J.; Avram, C. A.; Wyithe, J. S. B.; Barberio, E.

    2015-08-01

    We investigate the impact of energy released from self-annihilating dark matter (DM) on heating of gas in the small, high-redshift DM haloes thought to host the first stars. A supersymmetric (SUSY)-neutralino-like particle is implemented as our DM candidate. The PYTHIA code is used to model the final, stable particle distributions produced during the annihilation process. We use an analytic treatment in conjunction with the code MEDEA2 to find the energy transfer and subsequent partition into heating, ionizing and Lyman α photon components. We consider a number of halo density models, DM particle masses and annihilation channels. We find that the injected energy from DM exceeds the binding energy of the gas within a 105-106 M⊙ halo at redshifts above 20, preventing star formation in early haloes in which primordial gas would otherwise cool. Thus we find that DM annihilation could delay the formation of the first galaxies.

  10. Visibility of stars, halos, and rainbows during solar eclipses.

    PubMed

    Können, Gunther P; Hinz, Claudia

    2008-12-01

    The visibility of stars, planets, diffraction coronas, halos, and rainbows during the partial and total phases of a solar eclipse is studied. The limiting magnitude during various stages of the partial phase is presented. The sky radiance during totality with respect to noneclipse conditions is revisited and found to be typically 1/4000. The corresponding limiting magnitude is +3.5. At totality, the signal-to-background ratio of diffraction coronas, halos, and rainbows has dropped by a factor of 250. It is found that diffraction coronas around the totally eclipsed Sun may nevertheless occur. Analyses of lunar halo observations during twilight indicate that bright halo displays may also persist during totality. Rainbows during totality seem impossible. PMID:19037334

  11. The "guitar pick" sign: a novel sign of retrobulbar hemorrhage.

    PubMed

    Theoret, Jonathan; Sanz, Geoffrey E; Matero, David; Guth, Todd; Erickson, Catherine; Liao, Michael M; Kendall, John L

    2011-05-01

    Retrobulbar hemorrhage is a rare complication of blunt ocular trauma. Without prompt intervention, permanent reduction in visual acuity can develop in as little as 90 minutes. We report a novel bedside ultrasound finding of conical deformation of the posterior ocular globe: the "guitar pick" sign. In our elderly patient, the ocular globe shape normalized post-lateral canthotomy and inferior cantholysis. Identifying this sonographic finding may add to the clinical examination when deciding whether to perform decompression. PMID:21524372

  12. REVISITING SCALING RELATIONS FOR GIANT RADIO HALOS IN GALAXY CLUSTERS

    SciTech Connect

    Cassano, R.; Brunetti, G.; Venturi, T.; Kale, R.; Pratt, G. W.; Markevitch, M.

    2013-11-10

    Many galaxy clusters host megaparsec-scale radio halos, generated by ultrarelativistic electrons in the magnetized intracluster medium. Correlations between the synchrotron power of radio halos and the thermal properties of the hosting clusters were established in the last decade, including the connection between the presence of a halo and cluster mergers. The X-ray luminosity and redshift-limited Extended GMRT Radio Halo Survey provides a rich and unique dataset for statistical studies of the halos. We uniformly analyze the radio and X-ray data for the GMRT cluster sample, and use the new Planck Sunyaev-Zel'dovich (SZ) catalog to revisit the correlations between the power of radio halos and the thermal properties of galaxy clusters. We find that the radio power at 1.4 GHz scales with the cluster X-ray (0.1-2.4 keV) luminosity computed within R{sub 500} as P{sub 1.4}∼L{sup 2.1±0.2}{sub 500}. Our bigger and more homogenous sample confirms that the X-ray luminous (L{sub 500} > 5 × 10{sup 44} erg s{sup –1}) clusters branch into two populations—radio halos lie on the correlation, while clusters without radio halos have their radio upper limits well below that correlation. This bimodality remains if we excise cool cores from the X-ray luminosities. We also find that P{sub 1.4} scales with the cluster integrated SZ signal within R{sub 500}, measured by Planck, as P{sub 1.4}∼Y{sup 2.05±0.28}{sub 500}, in line with previous findings. However, contrary to previous studies that were limited by incompleteness and small sample size, we find that 'SZ-luminous' Y{sub 500} > 6 × 10{sup –5} Mpc{sup 2} clusters show a bimodal behavior for the presence of radio halos, similar to that in the radio-X-ray diagram. Bimodality of both correlations can be traced to clusters dynamics, with radio halos found exclusively in merging clusters. These results confirm the key role of mergers for the origin of giant radio halos, suggesting that they trigger the relativistic particle

  13. Revisiting Scaling Relations for Giant Radio Halos in Galaxy Clusters

    NASA Technical Reports Server (NTRS)

    Cassano, R.; Ettori, S.; Brunetti, G.; Giacintucci, S.; Pratt, G. W.; Venturi, T.; Kale, R.; Dolag, K.; Markevitch, Maxim L.

    2013-01-01

    Many galaxy clusters host megaparsec-scale radio halos, generated by ultrarelativistic electrons in the magnetized intracluster medium. Correlations between the synchrotron power of radio halos and the thermal properties of the hosting clusters were established in the last decade, including the connection between the presence of a halo and cluster mergers. The X-ray luminosity and redshift-limited Extended GMRT Radio Halo Survey provides a rich and unique dataset for statistical studies of the halos. We uniformly analyze the radio and X-ray data for the GMRT cluster sample, and use the new Planck Sunyaev-Zel'dovich (SZ) catalog to revisit the correlations between the power of radio halos and the thermal properties of galaxy clusters. We find that the radio power at 1.4 GHz scales with the cluster X-ray (0.1-2.4 keV) luminosity computed within R(sub 500) as P(sub 1.4) approx. L(2.1+/-0.2) - 500). Our bigger and more homogenous sample confirms that the X-ray luminous (L(sub 500) > 5 × 10(exp 44) erg/s)) clusters branch into two populations-radio halos lie on the correlation, while clusters without radio halos have their radio upper limits well below that correlation. This bimodality remains if we excise cool cores from the X-ray luminosities. We also find that P(sub 1.4) scales with the cluster integrated SZ signal within R(sub 500), measured by Planck, as P(sub 1.4) approx. Y(2.05+/-0.28) - 500), in line with previous findings. However, contrary to previous studies that were limited by incompleteness and small sample size, we find that "SZ-luminous" Y(sub 500) > 6×10(exp -5) Mpc(exp 2) clusters show a bimodal behavior for the presence of radio halos, similar to that in the radio-X-ray diagram. Bimodality of both correlations can be traced to clusters dynamics, with radio halos found exclusively in merging clusters. These results confirm the key role of mergers for the origin of giant radio halos, suggesting that they trigger the relativistic particle acceleration.

  14. Halo-independent direct detection analyses without mass assumptions

    NASA Astrophysics Data System (ADS)

    Anderson, Adam J.; Fox, Patrick J.; Kahn, Yonatan; McCullough, Matthew

    2015-10-01

    Results from direct detection experiments are typically interpreted by employing an assumption about the dark matter velocity distribution, with results presented in the mχ-σn plane. Recently methods which are independent of the DM halo velocity distribution have been developed which present results in the vmin-tilde g plane, but these in turn require an assumption on the dark matter mass. Here we present an extension of these halo-independent methods for dark matter direct detection which does not require a fiducial choice of the dark matter mass. With a change of variables from vmin to nuclear recoil momentum (pR), the full halo-independent content of an experimental result for any dark matter mass can be condensed into a single plot as a function of a new halo integral variable, which we call tilde h(pR). The entire family of conventional halo-independent tilde g(vmin) plots for all DM masses are directly found from the single tilde h(pR) plot through a simple rescaling of axes. By considering results in tilde h(pR) space, one can determine if two experiments are inconsistent for all masses and all physically possible halos, or for what range of dark matter masses the results are inconsistent for all halos, without the necessity of multiple tilde g(vmin) plots for different DM masses. We conduct a sample analysis comparing the CDMS II Si events to the null results from LUX, XENON10, and SuperCDMS using our method and discuss how the results can be strengthened by imposing the physically reasonable requirement of a finite halo escape velocity.

  15. Halo and space charge issues in the SNS Ring

    SciTech Connect

    Fedotov, A.V.; Abell, D.T.; Beebe-Wang, J.; Lee, Y.Y.; Malitsky, N.; Wei, J.; Gluckstern, R.L.

    2000-06-30

    The latest designs for high-intensity proton rings require minimizing beam-induced radioactivation of the vacuum chamber. Although the tune depression in the ring is much smaller than in high-intensity linacs, space-charge contributions to halo formation and, hence, beam loss may be significant. This paper reviews our current understanding of halo formation issues for the Spallation Neutron Source (SNS) accumulator ring.

  16. STELLAR POPULATION VARIATIONS IN THE MILKY WAY's STELLAR HALO

    SciTech Connect

    Bell, Eric F.; Xue Xiangxiang; Rix, Hans-Walter; Ruhland, Christine; Hogg, David W.

    2010-12-15

    If the stellar halos of disk galaxies are built up from the disruption of dwarf galaxies, models predict highly structured variations in the stellar populations within these halos. We test this prediction by studying the ratio of blue horizontal branch stars (BHB stars; more abundant in old, metal-poor populations) to main-sequence turn-off stars (MSTO stars; a feature of all populations) in the stellar halo of the Milky Way using data from the Sloan Digital Sky Survey. We develop and apply an improved technique to select BHB stars using ugr color information alone, yielding a sample of {approx}9000 g < 18 candidates where {approx}70% of them are BHB stars. We map the BHB/MSTO ratio across {approx}1/4 of the sky at the distance resolution permitted by the absolute magnitude distribution of MSTO stars. We find large variations of the BHB/MSTO star ratio in the stellar halo. Previously identified, stream-like halo structures have distinctive BHB/MSTO ratios, indicating different ages/metallicities. Some halo features, e.g., the low-latitude structure, appear to be almost completely devoid of BHB stars, whereas other structures appear to be rich in BHB stars. The Sagittarius tidal stream shows an apparent variation in the BHB/MSTO ratio along its extent, which we interpret in terms of population gradients within the progenitor dwarf galaxy. Our detection of coherent stellar population variations between different stellar halo substructures provides yet more support to cosmologically motivated models for stellar halo growth.

  17. Galaxy disruption in a halo of dark matter.

    PubMed

    Forbes, Duncan A; Beasley, Michael A; Bekki, Kenji; Brodie, Jean P; Strader, Jay

    2003-08-29

    The relics of disrupted satellite galaxies have been found around the Milky Way and Andromeda, but direct evidence of a satellite galaxy in the early stages of disruption has remained elusive. We have discovered a dwarf satellite galaxy in the process of being torn apart by gravitational tidal forces as it merges with a larger galaxy's dark matter halo. Our results illustrate the morphological transformation of dwarf galaxies by tidal interaction and the continued buildup of galaxy halos. PMID:12907809

  18. Unraveling the History of the Milky Way's Halo

    NASA Astrophysics Data System (ADS)

    Valluri, Monica; Debattista, V. P.

    2010-01-01

    One of the key predictions of Lambda-CDM cosmological simulations is that the dark matter halos of galaxies, such as the Milky Way, are strongly prolate or triaxial. However simulations with gas show that both the shapes and density profiles of dark matter halos can be dramatically altered by the condensation of baryons into a disk or spheroidal component. Current and future astrometric mission (e.g. RAVE, Segue, Gaia and NASA's SIM Lite Astrometric Observatory) are expected to obtain the full 6 dimensional phase space information of several thousands of halo stars. We describes a novel method to analyze this phase-space information that be used to set constrains, not just on the present shape and phase space distribution of the Milky Way halo, but also on its past shape history. We exploit a technique for revealing the phase space structure and orbital content of galaxies: "The Laskar Frequency Map". The power of this technique is demonstrated by applying it to a series of controlled simulations in which dynamically realistic disks are grown in isolated triaxial dark matter halos. We show that even when the growth of a baryonic disk causes the halo's shape to become oblate or close to spherical, it is possible to determine if it was originally prolate or triaxial as predicted by cosmological N-body simulations. It is also possible to determine if the original halo's major axis was perpendicular to the major axis or the minor axis of the disk. The technique can yield valuable information on the shape history of the halo form as few as a 1000- 5000 orbits.

  19. Flattened halos in a nontopological soliton model of dark matter

    NASA Astrophysics Data System (ADS)

    Mielke, Eckehard W.; Peralta, Humberto H.

    2004-12-01

    Soliton type solutions of a scalar model with a Φ6 self-interaction are analyzed for their density profiles as toy model of dark matter halos. We construct exact solutions with nontrivial ellipticity due to angular momentum and propose a “nonlinear superposition” of round and flattened halos in order to improve the scaling relations and the correspondence of the predicted rotation curves to the empirical Burkert fit.

  20. Vaporization in comets - The icy grain halo of Comet West

    NASA Technical Reports Server (NTRS)

    Ahearn, M. F.; Cowan, J. J.

    1980-01-01

    The variation with heliocentric distance of the production rates of various species in Comet West (1975n = 1976 VI) is explained with a cometary model consisting of a CO2 dominated nucleus plus a halo of icy grains of H2O or clathrate hydrate. It is concluded that the parents of CN and C3 are released primarily from the nucleus but that the parent of C2 is released primarily from the halo of icy grains.

  1. Non-Gaussianity and Excursion Set Theory: Halo Bias

    SciTech Connect

    Adshead, Peter; Baxter, Eric J.; Dodelson, Scott; Lidz, Adam

    2012-09-01

    We study the impact of primordial non-Gaussianity generated during inflation on the bias of halos using excursion set theory. We recapture the familiar result that the bias scales as $k^{-2}$ on large scales for local type non-Gaussianity but explicitly identify the approximations that go into this conclusion and the corrections to it. We solve the more complicated problem of non-spherical halos, for which the collapse threshold is scale dependent.

  2. An Improved Catalog of Halo Wide Binary Candidates

    NASA Astrophysics Data System (ADS)

    Allen, Christine; Monroy-Rodríguez, Miguel A.

    2014-08-01

    We present an improved catalog of halo wide binaries compiled from an extensive literature search. Most of our binaries stem from the common proper motion binary catalogs by Allen et al. and Chanamé & Gould, but we have also included binaries from the lists of Ryan and Zapatero-Osorio & Martín. All binaries were carefully checked and their distances and systemic radial velocities are included when available. Probable membership to the halo population was tested by means of reduced proper motion diagrams for 251 candidate halo binaries. After eliminating obvious disk binaries, we ended up with 211 probable halo binaries, 150 of which have radial velocities available. We compute galactic orbits for these 150 binaries and calculate the time they spend within the galactic disk. Considering the full sample of 251 candidate halo binaries as well as several subsamples, we find that the distribution of angular separations (or expected major semiaxes) follows a power law f(a) ~ a -1 (Oepik's relation) up to different limits. For the 50 most disk-like binaries, those that spend their entire lives within z = ±500 pc, this limit is found to be 19,000 AU (0.09 pc), while for the 50 most halo-like binaries, those that spend on average only 18% of their lives within z = ±500 pc, the limit is 63,000 AU (0.31 pc). In a companion paper, we employ this catalog to establish limits on the masses of the halo massive perturbers (massive compact halo objects).

  3. The SEGUE K Giant Survey. III. Quantifying Galactic Halo Substructure

    NASA Astrophysics Data System (ADS)

    Janesh, William; Morrison, Heather L.; Ma, Zhibo; Rockosi, Constance; Starkenburg, Else; Xue, Xiang Xiang; Rix, Hans-Walter; Harding, Paul; Beers, Timothy C.; Johnson, Jennifer; Lee, Young Sun; Schneider, Donald P.

    2016-01-01

    We statistically quantify the amount of substructure in the Milky Way stellar halo using a sample of 4568 halo K giant stars at Galactocentric distances ranging over 5-125 kpc. These stars have been selected photometrically and confirmed spectroscopically as K giants from the Sloan Digital Sky Survey’s Sloan Extension for Galactic Understanding and Exploration project. Using a position-velocity clustering estimator (the 4distance) and a model of a smooth stellar halo, we quantify the amount of substructure in the halo, divided by distance and metallicity. Overall, we find that the halo as a whole is highly structured. We also confirm earlier work using blue horizontal branch (BHB) stars which showed that there is an increasing amount of substructure with increasing Galactocentric radius, and additionally find that the amount of substructure in the halo increases with increasing metallicity. Comparing to resampled BHB stars, we find that K giants and BHBs have similar amounts of substructure over equivalent ranges of Galactocentric radius. Using a friends-of-friends algorithm to identify members of individual groups, we find that a large fraction (˜33%) of grouped stars are associated with Sgr, and identify stars belonging to other halo star streams: the Orphan Stream, the Cetus Polar Stream, and others, including previously unknown substructures. A large fraction of sample K giants (more than 50%) are not grouped into any substructure. We find also that the Sgr stream strongly dominates groups in the outer halo for all except the most metal-poor stars, and suggest that this is the source of the increase of substructure with Galactocentric radius and metallicity.

  4. One dark matter mystery: halos in the cosmic web

    NASA Astrophysics Data System (ADS)

    Gaite, Jose

    2015-01-01

    The current cold dark matter cosmological model explains the large scale cosmic web structure but is challenged by the observation of a relatively smooth distribution of matter in galactic clusters. We consider various aspects of modeling the dark matter around galaxies as distributed in smooth halos and, especially, the smoothness of the dark matter halos seen in N-body cosmological simulations. We conclude that the problems of the cold dark matter cosmology on small scales are more serious than normally admitted.

  5. Halo-independent direct detection analyses without mass assumptions

    SciTech Connect

    Anderson, Adam J.; Fox, Patrick J.; Kahn, Yonatan; McCullough, Matthew

    2015-10-06

    Results from direct detection experiments are typically interpreted by employing an assumption about the dark matter velocity distribution, with results presented in the m{sub χ}−σ{sub n} plane. Recently methods which are independent of the DM halo velocity distribution have been developed which present results in the v{sub min}−g-tilde plane, but these in turn require an assumption on the dark matter mass. Here we present an extension of these halo-independent methods for dark matter direct detection which does not require a fiducial choice of the dark matter mass. With a change of variables from v{sub min} to nuclear recoil momentum (p{sub R}), the full halo-independent content of an experimental result for any dark matter mass can be condensed into a single plot as a function of a new halo integral variable, which we call h-til-tilde(p{sub R}). The entire family of conventional halo-independent g-tilde(v{sub min}) plots for all DM masses are directly found from the single h-tilde(p{sub R}) plot through a simple rescaling of axes. By considering results in h-tilde(p{sub R}) space, one can determine if two experiments are inconsistent for all masses and all physically possible halos, or for what range of dark matter masses the results are inconsistent for all halos, without the necessity of multiple g-tilde(v{sub min}) plots for different DM masses. We conduct a sample analysis comparing the CDMS II Si events to the null results from LUX, XENON10, and SuperCDMS using our method and discuss how the results can be strengthened by imposing the physically reasonable requirement of a finite halo escape velocity.

  6. An improved catalog of halo wide binary candidates

    SciTech Connect

    Allen, Christine; Monroy-Rodríguez, Miguel A.

    2014-08-01

    We present an improved catalog of halo wide binaries compiled from an extensive literature search. Most of our binaries stem from the common proper motion binary catalogs by Allen et al. and Chanamé and Gould, but we have also included binaries from the lists of Ryan and Zapatero-Osorio and Martín. All binaries were carefully checked and their distances and systemic radial velocities are included when available. Probable membership to the halo population was tested by means of reduced proper motion diagrams for 251 candidate halo binaries. After eliminating obvious disk binaries, we ended up with 211 probable halo binaries, 150 of which have radial velocities available. We compute galactic orbits for these 150 binaries and calculate the time they spend within the galactic disk. Considering the full sample of 251 candidate halo binaries as well as several subsamples, we find that the distribution of angular separations (or expected major semiaxes) follows a power law f(a) ∼ a {sup –1} (Oepik's relation) up to different limits. For the 50 most disk-like binaries, those that spend their entire lives within z = ±500 pc, this limit is found to be 19,000 AU (0.09 pc), while for the 50 most halo-like binaries, those that spend on average only 18% of their lives within z = ±500 pc, the limit is 63,000 AU (0.31 pc). In a companion paper, we employ this catalog to establish limits on the masses of the halo massive perturbers (massive compact halo objects).

  7. Halo-independent direct detection analyses without mass assumptions

    SciTech Connect

    Anderson, Adam J.; Fox, Patrick J.; Kahn, Yonatan; McCullough, Matthew

    2015-10-06

    Results from direct detection experiments are typically interpreted by employing an assumption about the dark matter velocity distribution, with results presented in the mχ – σn plane. Recently methods which are independent of the DM halo velocity distribution have been developed which present results in the vmin – g~ plane, but these in turn require an assumption on the dark matter mass. Here we present an extension of these halo-independent methods for dark matter direct detection which does not require a fiducial choice of the dark matter mass. With a change of variables from vmin to nuclear recoil momentum (pR), the full halo-independent content of an experimental result for any dark matter mass can be condensed into a single plot as a function of a new halo integral variable, which we call tilde h(pR). The entire family of conventional halo-independent tilde g~(vmin) plots for all DM masses are directly found from the single tilde h~(pR) plot through a simple rescaling of axes. By considering results in tildeh~(pR) space, one can determine if two experiments are inconsistent for all masses and all physically possible halos, or for what range of dark matter masses the results are inconsistent for all halos, without the necessity of multiple tilde g~(vmin) plots for different DM masses. As a result, we conduct a sample analysis comparing the CDMS II Si events to the null results from LUX, XENON10, and SuperCDMS using our method and discuss how the results can be strengthened by imposing the physically reasonable requirement of a finite halo escape velocity.

  8. Halo-independent direct detection analyses without mass assumptions

    DOE PAGESBeta

    Anderson, Adam J.; Fox, Patrick J.; Kahn, Yonatan; McCullough, Matthew

    2015-10-06

    Results from direct detection experiments are typically interpreted by employing an assumption about the dark matter velocity distribution, with results presented in the mχ – σn plane. Recently methods which are independent of the DM halo velocity distribution have been developed which present results in the vmin – g~ plane, but these in turn require an assumption on the dark matter mass. Here we present an extension of these halo-independent methods for dark matter direct detection which does not require a fiducial choice of the dark matter mass. With a change of variables from vmin to nuclear recoil momentum (pR),more » the full halo-independent content of an experimental result for any dark matter mass can be condensed into a single plot as a function of a new halo integral variable, which we call tilde h(pR). The entire family of conventional halo-independent tilde g~(vmin) plots for all DM masses are directly found from the single tilde h~(pR) plot through a simple rescaling of axes. By considering results in tildeh~(pR) space, one can determine if two experiments are inconsistent for all masses and all physically possible halos, or for what range of dark matter masses the results are inconsistent for all halos, without the necessity of multiple tilde g~(vmin) plots for different DM masses. As a result, we conduct a sample analysis comparing the CDMS II Si events to the null results from LUX, XENON10, and SuperCDMS using our method and discuss how the results can be strengthened by imposing the physically reasonable requirement of a finite halo escape velocity.« less

  9. Star Streams in Triaxial Isochrone Potentials with Sub-halos

    NASA Astrophysics Data System (ADS)

    Carlberg, R. G.

    2015-07-01

    The velocity, position, and action variable evolutions of a tidal stream drawn out of a star cluster in a triaxial isochrone potential, containing a sub-halo population, reproduces many of the orbital effects of more general cosmological halos but allows for the easy calculation of orbital actions. We employ a spherical shell code, which we show accurately reproduces the results of a tree gravity code for a collisionless star cluster. Streams from clusters on high eccentricity orbits, e≳ 0.6, can spread out so much that the amount of material at high enough surface density to stand out on the sky may be only a few percent of the stream’s total mass. Low eccentricity streams remain more spatially coherent, but sub-halos both broaden the stream and displace the centerline with details depending on the orbits allowed within the potential. Overall, the majority of stream particles have changes in their total actions of only 1%-2%, leaving the mean stream relatively undisturbed. A halo with 1% of the mass in sub-halos typically spreads the velocity distribution about a factor of two wider than would be expected for a smooth halo. Strong density variations, “gaps,” along with mean velocity offsets, are clearly detected in low eccentricity streams for even a 0.2% sub-halo mass fraction. Around one hundred velocity measurements per kiloparsec of stream will enable tests for the presence of a local sub-halo density as small as 0.2%-0.5% of the local mass density, with about 1% predicted for 30 kpc orbital radii streams.

  10. Old Signs, New Signs, Whose Signs? Sociolinguistic Variation in the NZSL Lexicon

    ERIC Educational Resources Information Center

    McKee, Rachel; McKee, David

    2011-01-01

    Lexicographers, teachers and interpreters of New Zealand Sign Language (NZSL) are challenged by the degree of lexical variation that exists in this young language. For instance, most numerals between one and twenty have two or more variants in common use (McKee, McKee, and Major 2008), a situation that contrasts with most established spoken…

  11. Highly ionized gas in the Galactic halo

    NASA Technical Reports Server (NTRS)

    Shull, J. Michael; Slavin, Jonathan D.

    1994-01-01

    We reexamine the values of electron density n(sub e) and gas pressure P/k in the interstellar medium (ISM) of the Galactic halo, as inferred from C IV emission and absorption lines and using current C IV atomic data. In a homogeneous model with 4.7 less than or equal to log T less than or equal to 5.3, the data are consistent with 0.01 less than or equal to n(sub e) less than or equal to 0.02/cu cm and 2200 less than or equal to P/k less than or equal to 3700/cu cm K, a factor of 2-3 higher than advocated by Martin & Bowyer (1990) and comparable to the thermal pressure in the disk. If some of the C IV absorption arises from nonemitting, photoionized gas, then the inferred density and pressure will increase accordingly. The volume filling factor for homogeneous models ranges from 0.5% to 5%. Because of the constraints arising from filling factor and radiated power, most of the C IV must arise from gas near the peak of the cooling curve, at log t less than or equal to 5.6. We relate both emission-line and absorption-line observations to recent models in which turbulent mixing layers and isobarically cooling supernova remnants (SNRs) provide significant amounts of halo gas at approximately 10(exp 5.3) K and process 20-40 solar mass/yr with a power of approximately 10(exp 41) ergs/sec. Since the observed C IV and N V absorption scale heights have been reported to differ, at 4.9 kpc and 1.6 kpc, respectively, we examine inhomogeneous models with different exponential scale heights of T, P, and SN energy input. The ISM may change its character with distance above the Galactic plane, as superbubbles and mixing layers dominate over isolated SNRs as the source of the C IV. For appropiate scale heights, the midplane pressure is twice the homogeneous values quoted above. The O IV lambda 1034 diffuse emission line, which can be used as a temperature diagnostic of the hot gas, is predicted to be comparable in strength to that of C IV lambda 1549 (approximately 6000 photons

  12. Evolution of Extended Satellites in Massive Halos

    NASA Astrophysics Data System (ADS)

    Gravel, Pierre

    The evolution of extended satellites in massive halos is studied in the weak and the strong regimes of satellite deformation. In the first part of the thesis we follow the dynamics of a spherical region evolving locally as an Einstein-de Sitter universe ( qo=0.5,W=1 ) and containing overdensities acting as seeds for the formation of a satellite and its future host. We study the dynamics of forming satellites when their hosts are still unvirialized, accreting material, and generating time-varying gravitational potentials (TVGP). The three main dynamical processes affecting the satellite are dynamical friction, the TVGP, and tidal disruption. The internal flow of energy inside a satellite and across its boundary is analyzed with specialized local and global methods, providing information on the nature, the magnitude and the timing of the individual processes. A strongly deformed satellite able to survive a few galaxy crossings forms a compact core from which dynamical friction extracts energy, while its halo is tidally disrupted by the ``slingshot'' effect. This leads to the formation of systems of external stellar shells and internal energy shells. Their origins and appearances are closely related. Satellite self-gravity and phase wrapping control the emergence of both types of shells from the satellite inner regions once non-linear effects set in. In the second part of the thesis, we analyze the combined effects of dynamical friction, tidal stripping, and internal and external two-body heating on satellites moving inside massive hosts. External two-body heating is a stochastic process that occurs inside a satellite as a back reaction to the scattering of inhomogeneous material in the surrounding stellar system. This type of heating accelerates the evolution of less bound objects by increasing their rate of evaporation. The heating becomes important at low satellite velocities, and when the masses of the perturbing objects are comparable to or greater than the

  13. Subhalo statistics of galactic haloes: beyond the resolution limit

    NASA Astrophysics Data System (ADS)

    Cautun, Marius; Hellwing, Wojciech A.; van de Weygaert, Rien; Frenk, Carlos S.; Jones, Bernard J. T.; Sawala, Till

    2014-12-01

    We study the substructure population of Milky Way (MW)-mass haloes in the Λ cold dark matter (ΛCDM) cosmology using a novel procedure to extrapolate subhalo number statistics beyond the resolution limit of N-body simulations. The technique recovers the mean and the variance of the subhalo abundance, but not its spatial distribution. It extends the dynamic range over which precise statistical predictions can be made by the equivalent of performing a simulation with 50 times higher resolution, at no additional computational cost. We apply this technique to MW-mass haloes, but it can easily be applied to haloes of any mass. We find up to 20 per cent more substructures in MW-mass haloes than found in previous studies. Our analysis lowers the mass of the MW halo required to accommodate the observation that the MW has only three satellites with a maximum circular velocity Vmax ≥ 30 km s- 1 in the ΛCDM cosmology. The probability of having a subhalo population similar to that in the MW is 20 per cent for a virial mass, M200 = 1 × 1012 M⊙ and practically zero for haloes more massive than M200 = 2 × 1012 M⊙.

  14. QUANTIFYING KINEMATIC SUBSTRUCTURE IN THE MILKY WAY'S STELLAR HALO

    SciTech Connect

    Xue Xiangxiang; Zhao Gang; Luo Ali; Rix, Hans-Walter; Bell, Eric F.; Koposov, Sergey E.; Kang, Xi; Liu, Chao; Yanny, Brian; Beers, Timothy C.; Lee, Young Sun; Bullock, James S.; Johnston, Kathryn V.; Morrison, Heather; Rockosi, Constance

    2011-09-01

    We present and analyze the positions, distances, and radial velocities for over 4000 blue horizontal-branch (BHB) stars in the Milky Way's halo, drawn from SDSS DR8. We search for position-velocity substructure in these data, a signature of the hierarchical assembly of the stellar halo. Using a cumulative 'close pair distribution' as a statistic in the four-dimensional space of sky position, distance, and velocity, we quantify the presence of position-velocity substructure at high statistical significance among the BHB stars: pairs of BHB stars that are close in position on the sky tend to have more similar distances and radial velocities compared to a random sampling of these overall distributions. We make analogous mock observations of 11 numerical halo formation simulations, in which the stellar halo is entirely composed of disrupted satellite debris, and find a level of substructure comparable to that seen in the actually observed BHB star sample. This result quantitatively confirms the hierarchical build-up of the stellar halo through a signature in phase (position-velocity) space. In detail, the structure present in the BHB stars is somewhat less prominent than that seen in most simulated halos, quite possibly because BHB stars represent an older sub-population. BHB stars located beyond 20 kpc from the Galactic center exhibit stronger substructure than at r{sub gc} < 20 kpc.

  15. The age of the Milky Way inner halo.

    PubMed

    Kalirai, Jason S

    2012-06-01

    The Milky Way galaxy has several components, such as the bulge, disk and halo. Unravelling the assembly history of these stellar populations is often restricted because of difficulties in measuring accurate ages for low-mass, hydrogen-burning stars. Unlike these progenitors, white dwarf stars, the 'cinders' of stellar evolution, are remarkably simple objects and their fundamental properties can be measured with little ambiguity. Here I report observations of newly formed white dwarf stars in the halo of the Milky Way, and a separate analysis of archival data in the well studied 12.5-billion-year-old globular cluster Messier 4. I measure the mass distribution of the remnant stars and invert the stellar evolution process to develop a mathematical relation that links this final stellar mass to the mass of their immediate progenitors, and therefore to the age of the parent population. By applying this technique to a small sample of four nearby and kinematically confirmed halo white dwarf stars, I calculate the age of local field halo stars to be 11.4 ± 0.7 billion years. The oldest globular clusters formed 13.5 billion years ago. Future observations of newly formed white dwarf stars in the halo could be used to reduce the uncertainty, and to probe relative differences between the formation times of the youngest globular clusters and the inner halo. PMID:22678285

  16. The abundance and environment of dark matter haloes

    NASA Astrophysics Data System (ADS)

    Metuki, Ofer; Libeskind, Noam I.; Hoffman, Yehuda

    2016-04-01

    An open question in cosmology and the theory of structure formation is to what extent does environment affect the properties of galaxies and haloes. The present paper aims at shedding light on this problem. The paper focuses on the analysis of a dark matter only simulation and it addresses the issue of how the environment affects the abundance of haloes, which are are assigned four attributes: their virial mass, an ambient density calculated with an aperture that scales with Rvir (ΔM), a fixed-aperture (ΔR) ambient density, and a cosmic web classification (i.e. voids, sheets, filaments, and knots, as defined by the V-web algorithm). ΔM is the mean density around a halo evaluated within a sphere of a radius of 5Rvir, where Rvir is the virial radius. ΔR is the density field Gaussian smoothed with R=4{ {h}^{-1}Mpc}, evaluated at the center of the halo. The main result of the paper is that the difference between haloes in different web elements stems from the difference in their mass functions, and does not depend on their adaptive-aperture ambient density. A dependence on the fixed-aperture ambient density is induced by the cross correlation between the mass of a halo and its fixed-aperture ambient density.

  17. Stellar Haloes with the Illustris Simulation: Mock Observations and Assembly

    NASA Astrophysics Data System (ADS)

    Pillepich, Annalisa; Torrey, Paul; Nelson, Dylan; Snyder, Greg; Rodriguez-Gomez, Vicente; Genel, Shy; Vogelsberger, Mark; Hernquist, Lars

    2015-08-01

    Illustris is a state-of-the-art simulation which combines the statistical power of a ˜106 Mpc-side cosmological volume with gasdynamics, prescriptions for star formation, feedback, and kpc resolution. It allows us to analyze about ˜5,000 well-resolved galaxies spanning a variety of morphologies, environments, and halo masses (3×10^11 < Mvir < 10^14 Msun). Illustris therefore provides the most realistic and richest sample of simulated galactic stellar haloes available up to date. Based on the properties of the stellar particles in each simulated galaxy/halo, we have produced synthetic images in different luminosity bands and extracted information about the mass distribution, smoothness, and phase-space structures up to large galactocentric distances at different limits of surface brightness. We can therefore gain insight and provide theoretically-motivated expectations for the build-up and properties of the stellar haloes, and their relation to the underlying DM haloes, their central galaxies, and their halo assembly histories.

  18. The gamma-ray-flux PDF from galactic halo substructure

    NASA Astrophysics Data System (ADS)

    Lee, Samuel K.; Ando, Shin'ichiro; Kamionkowski, Marc

    2009-07-01

    One of the targets of the recently launched Fermi Gamma-ray Space Telescope is a diffuse gamma-ray background from dark-matter annihilation or decay in the Galactic halo. N-body simulations and theoretical arguments suggest that the dark matter in the Galactic halo may be clumped into substructure, rather than smoothly distributed. Here we propose the gamma-ray-flux probability distribution function (PDF) as a probe of substructure in the Galactic halo. We calculate this PDF for a phenomenological model of halo substructure and determine the regions of the substructure parameter space in which the PDF may be distinguished from the PDF for a smooth distribution of dark matter. In principle, the PDF allows a statistical detection of substructure, even if individual halos cannot be detected. It may also allow detection of substructure on the smallest microhalo mass scales, ~ M⊕, for weakly-interacting massive particles (WIMPs). Furthermore, it may also provide a method to measure the substructure mass function. However, an analysis that assumes a typical halo substructure model and a conservative estimate of the diffuse background suggests that the substructure PDF may not be detectable in the lifespan of Fermi in the specific case that the WIMP is a neutralino. Nevertheless, for a large range of substructure, WIMP annihilation, and diffuse background models, PDF analysis may provide a clear signature of substructure.

  19. The abundance and environment of dark matter haloes

    NASA Astrophysics Data System (ADS)

    Metuki, Ofer; Libeskind, Noam I.; Hoffman, Yehuda

    2016-07-01

    An open question in cosmology and the theory of structure formation is to what extent does environment affect the properties of galaxies and haloes. The present paper aims at shedding light on this problem. The paper focuses on the analysis of a dark matter only simulation and it addresses the issue of how the environment affects the abundance of haloes, which are assigned four attributes: their virial mass, an ambient density calculated with an aperture that scales with Rvir (ΔM), a fixed-aperture (ΔR) ambient density, and a cosmic web classification (i.e. voids, sheets, filaments, and knots, as defined by the V-web algorithm). ΔM is the mean density around a halo evaluated within a sphere of a radius of 5Rvir, where Rvir is the virial radius. ΔR is the density field Gaussian smoothed with R = 4 h-1 Mpc, evaluated at the centre of the halo. The main result of the paper is that the difference between haloes in different web elements stems from the difference in their mass functions, and does not depend on their adaptive-aperture ambient density. A dependence on the fixed-aperture ambient density is induced by the cross-correlation between the mass of a halo and its fixed-aperture ambient density.

  20. DUAL HALOS AND FORMATION OF EARLY-TYPE GALAXIES

    SciTech Connect

    Park, Hong Soo; Lee, Myung Gyoon E-mail: mglee@astro.snu.ac.kr

    2013-08-20

    We present a determination of the two-dimensional shape parameters of the blue and red globular cluster systems (GCSs) in a large number of elliptical galaxies and lenticular galaxies (early-type galaxies, called ETGs). We use a homogeneous data set of the globular clusters in 23 ETGs obtained from the HST/ACS Virgo Cluster Survey. The position angles of both blue and red GCSs show a correlation with those of the stellar light distribution, showing that the major axes of the GCSs are well aligned with those of their host galaxies. However, the shapes of the red GCSs show a tight correlation with the stellar light distribution as well as with the rotation property of their host galaxies, while the shapes of the blue GCSs do much less. These provide clear geometric evidence that the origins of the blue and red globular clusters are distinct and that ETGs may have dual halos: a blue (metal-poor) halo and a red (metal-rich) halo. These two halos show significant differences in metallicity, structure, and kinematics, indicating that they are formed in two distinguishable ways. The red halos might have formed via dissipational processes with rotation, while the blue halos are through accretion.