Fusion at deep subbarrier energies: potential inversion revisited

For a single potential barrier, the barrier penetrability can be inverted based on the WKB approximation to yield the barrier thickness. We apply this method to heavy-ion fusion reactions at energies well below the Coulomb barrier and directly determine the inter-nucleus potential between the colliding nuclei. To this end, we assume that fusion cross sections at deep subbarrier energies are governed by the lowest barrier in the barrier distribution. The inverted inter-nucleus potentials for the $^{16}$O +$^{144}$Sm and $^{16}$O +$^{208}$Pb reactions show that they are much thicker than phenomenological potentials. We discuss a consequence of such thick potential by fitting the inverted potentials with the Bass function.Comment: 8 pages, 5 figures. Uses aipxfm.sty. A talk given at the FUSION08: New Aspects of Heavy Ion Collisions Near the Coulomb Barrier, September 22-26, 2008, Chicago, US

Organizational citizenship behavior, identification, psychological contract and leadership frames : the example of primary school teachers in Taiwan

Purpose (mandatory) The study examines organizational citizenship behavior (OCB) by combining two heterogeneous perspectives, integrating OCB-related factors at work using both personal and organizational perspectives, thus contributing to our knowledge of OCB. . . Design/methodology/approach (mandatory) Two studies are conducted using surveys in Taiwan with a snowball sampling technique to enlarge participation. Study 1 analyzes the relationships between organizational identification, expected psychological contract, perceived psychological contract and OCB. Study 2 analyzes the relationship between OCB and principals’ (or head teachers’) leadership frames. . . Findings (mandatory) Study 1 finds that organizational identification is an antecedent of OCB and that expected psychological contract moderates the organizational identification-OCB relationship. Study 2 finds that the symbolic leadership frame is the only antecedent of OCB and that different leadership frames influence each other in predicting OCB. Expected psychological contract is found to moderate the organizational identification-OCB relationship, indicating that primary school teachers’ with higher levels of expected psychological contract are more likely to demonstrate OCB at school. Interestingly, perceived psychological contract did not demonstrate such a moderating effect. . . Originality/value (mandatory) The study makes three contributions. First, we analyze composite OCB via Identity and Psychological Contract theories (Study 1). Second, we scrutinize specific aspects of OCB via Leader-Member-Exchange and Leadership Frame theories. These aspects include assisting colleagues, job commitment, working morale and non-selfish behavior (Study 2). Third, we increase understanding of primary school teachers' OCB, discussing important implications for school principals and human resource managers as well as perhaps others in similar sectors. . . Key words: Organizational Citizenship Behavior; Leadership; Identification; Psychological Contract; Primary School Teachers; Principals

The BSL Sentence Reproduction Test: Exploring age of acquisition effects in British deaf adults

Here we present initial findings from a BSL sentence reproduction test, adapted from a test originally created for ASL (Hauser et al., 2008), with the aim of creating a screen that can be used to distinguish signers with native-like vs. non-native-like skills. The stimulus items, based on a set of 49 sentences from Hauser et al. (2008), included 40 BSL sentences varying in length and complexity, presented on video by a deaf native BSL signer. Participants were instructed to copy the signed sentence to camera, exactly as they saw it, regardless of phonological or lexical variants for the same concepts that they might prefer. Participants were 20 deaf adults: 10 deaf native signers, 5 deaf early learners first exposed to BSL between ages 2 and 6, and 5 late learners first exposed to BSL at age 11 or later. Responses were scored by a team of deaf and hearing sign language researchers. Responses which were agreed by all scorers as identical to the stimulus were given a score of 1; responses which included any phonological, morphological, lexical or syntactic deviations were given a score of 0 (except for a few specific, agreed-upon acceptable deviations). Results indicate that native signers scored significantly higher than non-native signers. For non-native signers there was no significant differences between early and late learners. We explore implications of these findings for use of the BSL-SRT as a screening test for assessing fluency in deaf adults and for exploring age-of-acquisition effects more generally. Hauser, P., Paludneviciene, R., Supalla, T., & Bavelier, D. (2008). American Sign Language – Sentence Reproduction Test: Development & Implications. In R. M. d. Quadros (Ed.), Sign Languages: Spinning and Unraveling the Past, Present and Future. TISLR 9, Forty-five Papers and Three Posters from the 9th Theoretical Issues in Sign Language Research Conference (pp. 155-167). Petrópolis/RJ. Brazil: Editora Arara Azul

Fusion barrier distributions in systems with finite excitation energy

Eigen-channel approach to heavy-ion fusion reactions is exact only when the excitation energy of the intrinsic motion is zero. In order to take into account effects of finite excitation energy, we introduce an energy dependence to weight factors in the eigen-channel approximation. Using two channel problem, we show that the weight factors are slowly changing functions of incident energy. This suggests that the concept of the fusion barrier distribution still holds to a good approximation even when the excitation energy of the intrinsic motion is finite. A transition to the adiabatic tunneling, where the coupling leads to a static potential renormalization, is also discussed.Comment: 9 pages, 4 figures, Submitted to Physical Review

A reconsideration of the measurements with the O ring stack

The measurements made this year of Rn entry to the O ring stack were interpreted to be diffusion through the urethane O rings; however the alternative hypothesis is that Rn was mainly entering the stack by leakage through a small hole. This note presents a calculation of diffusion from first principles and rederives the diffusion constant for the O ring stack measurements

A Cretaceous‐Eocene depositional age for the Fenghuoshan Group, Hoh Xil Basin: Implications for the tectonic evolution of the northern Tibet Plateau

The Fenghuoshan Group marks the initiation of terrestrial deposition in the Hoh Xil Basin and preserves the first evidence of uplift above sea level of northern Tibet. The depositional age of the Fenghuoshan Group is debated as are the stratigraphic relationships between the Fenghuoshan Group and other terrestrial sedimentary units in the Hoh Xil Basin. We present new radiometric dates and a compilation of published biostratigraphic data which are used to reinterpret existing magnetostratigraphic data from the Fenghuoshan Group. From these data, we infer an 85–51 Ma depositional age range for the Fenghuoshan Group. U‐Pb detrital zircon age spectra from this unit are compared to age spectra from Tibetan terranes and Mesozoic sedimentary sequences to determine a possible source terrane for Fenghuoshan Group strata. We propose that these strata were sourced from the Qiangtang Terrane and may share a common sediment source with Cretaceous sedimentary rocks in Nima Basin. Field relationships and compiled biostratigraphic data indicate that the Fenghuoshan and Tuotuohe Groups are temporally distinct units. We report late Oligocene ages for undeformed basalt flows that cap tilted Fenghuoshan Group strata. Together, our age constraints and field relationships imply exhumation of the central Qiangtang Terrane from the Late Cretaceous to earliest Eocene, followed by Eocene‐Oligocene deformation, and shortening of the northern Qiangtang and southern Songpan‐Ganzi terranes. Crustal shortening within the Hoh Xil Basin ceased by late Oligocene time as is evident from flat‐lying basaltic rocks, which cap older, deformed strata. Key Points The Fenghuoshan Group was deposited from late Cretaceous to early Eocene time The Fenghuoshan Group was likely sourced from the central Qiangtang Terrane Crustal shortening of the Hoh Xil Basin occurred from Eocene to Oligocene timePeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106814/1/ts02.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/106814/2/fs02.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/106814/3/tect20113.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/106814/4/ts06.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/106814/5/fs06.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/106814/6/ts03.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/106814/7/fs03.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/106814/8/ts07.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/106814/9/fs07.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/106814/10/fs04.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/106814/11/ts04.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/106814/12/fs01.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/106814/13/ts08.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/106814/14/ts01.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/106814/15/fs05.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/106814/16/ts05.pd

Dating of the oldest continental sediments from the Himalayan foreland basin

A detailed knowledge of Himalayan development is important for our wider understanding of several global processes, ranging from models of plateau uplift to changes in oceanic chemistry and climate(1-4). Continental sediments 55 Myr old found in a foreland basin in Pakistan(5) are, by more than 20 Myr, the oldest deposits thought to have been eroded from the Himalayan metamorphic mountain belt. This constraint on when erosion began has influenced models of the timing and diachrony of the India-Eurasia collision(6-8), timing and mechanisms of exhumation(9,10) and uplift(11), as well as our general understanding of foreland basin dynamics(12). But the depositional age of these basin sediments was based on biostratigraphy from four intercalated marl units(5). Here we present dates of 257 detrital grains of white mica from this succession, using the Ar-40-(39) Ar method, and find that the largest concentration of ages are at 36-40 Myr. These dates are incompatible with the biostratigraphy unless the mineral ages have been reset, a possibility that we reject on the basis of a number of lines of evidence. A more detailed mapping of this formation suggests that the marl units are structurally intercalated with the continental sediments and accordingly that biostratigraphy cannot be used to date the clastic succession. The oldest continental foreland basin sediments containing metamorphic detritus eroded from the Himalaya orogeny therefore seem to be at least 15-20 Myr younger than previously believed, and models based on the older age must be re-evaluated

Building a Spiking Neural Network Model of the Basal Ganglia on SpiNNaker

We present a biologically-inspired and scalable model of the Basal Ganglia (BG) simulated on the SpiNNaker machine, a biologically-inspired low-power hardware platform allowing parallel, asynchronous computing. Our BG model consists of six cell populations, where the neuro-computational unit is a conductance-based Izhikevich spiking neuron; the number of neurons in each population is proportional to that reported in anatomical literature. This model is treated as a single-channel of action-selection in the BG, and is scaled-up to three channels with lateral cross-channel connections. When tested with two competing inputs, this three-channel model demonstrates action-selection behaviour. The SpiNNaker-based model is mapped exactly on to SpineML running on a conventional computer; both model responses show functional and qualitative similarity, thus validating the usability of SpiNNaker for simulating biologically-plausible networks. Furthermore, the SpiNNaker-based model simulates in real time for time-steps 1 ms; power dissipated during model execution is & #x2248;1.8 W

SU(16) grandunification: breaking scales, proton decay and neutrino magnetic moment

We give a detailed renormalization group analysis for the SU(16) grandunified group with general breaking chains in which quarks and leptons transform separately at intermediate energies. Our analysis includes the effects of Higgs bosons. We show that the grandunification scale could be as low as $\sim 10^{8.5}$ GeV and give examples where new physics could exist at relatively low energy ($\sim 250$ GeV). We consider proton decay in this model and show that it is consistent with a low grandunification scale. We also discuss the possible generation of a neutrino magnetic moment in the range of $10^{-11}$ to $10^{-10}\mu_B$ with a very small mass by the breaking of the embedded SU(2)$_\nu$ symmetry at a low energy.Comment: (16 pages in REVTEX + 6 figures not included) OITS-49