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A multiscale approach reveals elaborate circulatory system and intermittent heartbeat in velvet worms (Onychophora) (open access)

A multiscale approach reveals elaborate circulatory system and intermittent heartbeat in velvet worms (Onychophora)

Article describes how an antagonistic hemolymph-muscular system is essential for soft-bodied invertebrates. The authors analyzed the entire circulatory system of the peripatopsid Euperipatoides rowelli and claimed they discovered a surprisingly elaborate organization.
Date: April 28, 2023
Creator: Jahn, Henry; Hammel, Jörg U.; Göpel, Torben; Wirkner, Christian S. & Mayer, Georg
System: The UNT Digital Library
Did Anything Good Come Out of the Pandemic? COVID-19-Stress Induced Self-Regulatory Sustainable Apparel Consumption among the Millennials in the U.S. (open access)

Did Anything Good Come Out of the Pandemic? COVID-19-Stress Induced Self-Regulatory Sustainable Apparel Consumption among the Millennials in the U.S.

Authors of the article proposed and tested a conceptual model delineating the relationships between COVID-19 stress, commitment to the environment, and intentions for sustainable apparel consumption in terms of intentions for purchasing sustainable apparel and divesting apparel. The authors recommend the sustainable apparel brands and marketers promote how sustainable apparel consumption can protect the environment to make the environment and human beings less susceptible to the future outbreaks of pandemics.
Date: April 28, 2023
Creator: Chakraborty, Swagata & Sadachar, Amrut
System: The UNT Digital Library
Tuning the temperature range of superelastic Ni-Ti alloys for elastocaloric cooling via thermal processing (open access)

Tuning the temperature range of superelastic Ni-Ti alloys for elastocaloric cooling via thermal processing

Article describes how caloric cooling enlisting solid-state refrigerants is potentially a promising eco-friendly alternative to conventional cooling based on vapor compression. Here, the authors have explored tuning the operation temperature range of Ni50.8Ti49.2 for elastocaloric cooling. In particular, they have studied the effect of thermal treatments (a.k.a. aging) on the transformation temperature, superelasticity, and elastocaloric effects of Ni50.8Ti49.2 shape memory alloy tubes.
Date: April 28, 2023
Creator: Yamazaki, Takahiro; Montagnoli, Andre L.; Young, Marcus L. & Takeuchi, Ichiro
System: The UNT Digital Library
Parental occupation and childhood germ cell tumors: a case–control study in Denmark, 1968–2016 (open access)

Parental occupation and childhood germ cell tumors: a case–control study in Denmark, 1968–2016

This article examines associations between parental occupation and childhood germ cell tumors (GCTs) in offspring while distinguishing by common histologic subtype (i.e., yolk sac tumor and teratoma).
Date: April 28, 2021
Creator: Hall, Clinton; Hansen, Johnni; Olsen, Jørn; He, Di; von Ehrenstein, Ondine S.; Ritz, Beate et al.
System: The UNT Digital Library
A New Detailed Term Accounting Opacity Code: TOPAZ (open access)

A New Detailed Term Accounting Opacity Code: TOPAZ

A new opacity code, TOPAZ, which explicitly includes configuration term structure in the bound-bound transitions is being developed. The goal is to extend the current capabilities of detailed term accounting opacity codes such as OPAL that are limited to lighter elements of astrophysical interest. At present, opacity calculations of heavier elements use statistical methods that rely on the presence of myriad spectral lines for accuracy. However, statistical approaches have been shown to be inadequate for astrophysical opacity calculations. An application of the TOPAZ code will be to study the limits of statistical methods. Comparisons of TOPAZ to other opacity codes as well as experiments are presented.
Date: April 28, 2004
Creator: Iglesias, C A; Chen, M H; Isaacs, W; Sonnad, V & Wilson, B G
System: The UNT Digital Library
Recovery and Visualization of 3D Structure of Chromosomes from Tomographic Reconstruction Images (open access)

Recovery and Visualization of 3D Structure of Chromosomes from Tomographic Reconstruction Images

The objectives of this work include automatic recovery and visualization of a 3D chromosome structure from a sequence of 2D tomographic reconstruction images taken through the nucleus of a cell. Structure is very important for biologists as it affects chromosome functions, behavior of the cell and its state. Chromosome analysis is significant in the detection of deceases and in monitoring environmental gene mutations. The algorithm incorporates thresholding based on a histogram analysis with a polyline splitting algorithm, contour extraction via active contours, and detection of the 3D chromosome structure by establishing corresponding regions throughout the slices. Visualization using point cloud meshing generates a 3D surface. The 3D triangular mesh of the chromosomes provides surface detail and allows a user to interactively analyze chromosomes using visualization software.
Date: April 28, 2004
Creator: Babu, S; Liao, P; Shin, M C & Tsap, L V
System: The UNT Digital Library
Mechanical Design of a Heavy Ion Beam Dump for the RIA Fragmentation Line (open access)

Mechanical Design of a Heavy Ion Beam Dump for the RIA Fragmentation Line

The RIA fragmentation line requires a beam stop for the primary beam downstream of the first dipole magnet. The beam may consist of U, Ca, Sn, Kr, or O ions. with a variety of power densities. The configuration with highest power density is for the U beam, with a spot size of 3 cm x 3 cm and a total power of up to 300 kW. The mechanical design of the dump that meets these criteria consists of a 70 cm diameter aluminum wheel with water coolant channels. A hollow drive shaft supplies the coolant water and connects the wheel to an electrical motor located in an adjacent air space. The beam strikes the wheel along the outer perimeter and passes through a thin window of aluminum where 15% of its power is absorbed and the remainder of the beam is absorbed in flowing water behind the window. Rotation of the wheel at 400 RPM results in maximum aluminum temperatures below 100 C and acceptably low thermal stresses of 3 ksi. Rotating the wheel also results in low radiation damage levels by spreading the damage out over the whole perimeter of the wheel. For some of the other beams, a …
Date: April 28, 2005
Creator: Stein, W.; Ahle, L. E. & Conner, D. L.
System: The UNT Digital Library
A computer-based training system combining virtual reality and multimedia (open access)

A computer-based training system combining virtual reality and multimedia

Training new users of complex machines is often an expensive and time-consuming process. This is particularly true for special purpose systems, such as those frequently encountered in DOE applications. This paper presents a computer-based training system intended as a partial solution to this problem. The system extends the basic virtual reality (VR) training paradigm by adding a multimedia component which may be accessed during interaction with the virtual environment: The 3D model used to create the virtual reality is also used as the primary navigation tool through the associated multimedia. This method exploits the natural mapping between a virtual world and the real world that it represents to provide a more intuitive way for the student to interact with all forms of information about the system.
Date: April 28, 1993
Creator: Stansfield, S. A.
System: The UNT Digital Library
A comparison of driver concepts for heavy-ion fusion. Revision 1 (open access)

A comparison of driver concepts for heavy-ion fusion. Revision 1

The indirect-drive targets being considered for inertial fusion require the driver to deposit 5 MJ on a target in less than 10 ns. This requirement can in principle be met by on beams with particle masses between 120 and 240 amu, an ion kinetic energy in the range of 6--12 GeV, and a total current in excess of 30 kA. Three strategies for generating beams with these parameters are currently being studied. European laboratories are investigating the use of low-current beams from a radio-frequency accelerator. To obtain the needed current density, these beams would be stacked and accumulated in storage rings and then directed simultaneously at the target. American researchers are developing high-current induction accelerators, and the two principal configurations under consideration are the linear driver and the ``recirculator,`` in which ion pulses pass repeatedly through the same accelerator elements. The merits of the three approaches are compared, and key physics uncertainties in each are identified.
Date: April 28, 1994
Creator: Sharp, W. M.
System: The UNT Digital Library
ECH (electron cyclotron heating) in the Microwave Tokamak Experiment (open access)

ECH (electron cyclotron heating) in the Microwave Tokamak Experiment

The Microwave Tokamak Experiment (MTX) at LLNL will investigate electron heating in the MTX tokamak (formerly Alcator-C) at high density (up to 6 x 10/sup 20/ m/sup -3/) and high power by using a free electron laser (FEL). Parameters of the FEL are a peak power up to 8 GW and 50 ns duration, with average power 1 to 2 MW, at a frequency of 250 GHz. The planned input driver for the FEL is a gyrotron oscillator. The FEL output will be transported quasi-optically, inside a 50 cm evacuated pipe, to the input port of the tokamak by means of a four-mirror system. Launch polarization is the ordinary mode. This experiment will test the FEL technology at short wavelength and high peak and average power levels. Important physics issues to be explored are the effects of intense pulse heating (electric field up to 500 kV/cm) on nonlinear wave absorption and bulk heating, plasma confinement, plasma impurities, and parametric instabilities. Because the FEL technology is scalable to higher frequency and power, success of these experiments has importance for next-generation tokamaks.
Date: April 28, 1987
Creator: Stallard, B. W.; Smith, G. R.; James, R. A.; Thomassen, K. I.; Kritz, A. H.; Makowski, M. et al.
System: The UNT Digital Library
Effect of plasma shielding on the fidelity of magnetic probe in a plasma focus environment (open access)

Effect of plasma shielding on the fidelity of magnetic probe in a plasma focus environment

This paper examines the fidelity of a dielectric, encapsulated magnetic probe in the adverse plasma environment encountered in plasma focus experiments. The ionization of the surface of the probe produces a conductive layer that tends to shield it from external magnetic fields. The solution of the wave equation is used to show the allowed regions of conductivity, sigma, and thickness, d, for the ionized layer. The results show that as d approaches the penetration depth, delta = (..omega mu..sigma)/sup /sup 1///sub 2//, severe attenuation and distortion results, rendering the probe useless. When d is much less than delta, we encounter attenuation only, which also may be too severe for use. Finally, an experiment is described, which allows the experimenter to determine the fidelity of the probe.
Date: April 28, 1978
Creator: Zucker, O. S.
System: The UNT Digital Library
Identifying Native and Exotic Predators of Ground-Nesting Songbirds in Subantarctic Forests in Southern Chile (open access)

Identifying Native and Exotic Predators of Ground-Nesting Songbirds in Subantarctic Forests in Southern Chile

This article describes an artificial nest experiment to assess the impact of predators on daily survival rates of artificial bird nests in three different habitat types.
Date: April 28, 2011
Creator: Maley, Brett M.; Anderson, Christopher B.; Stodola, Kirk & Rosemond, Amy D.
System: The UNT Digital Library
Performance of the AFS vertex detector at the CERN ISR (open access)

Performance of the AFS vertex detector at the CERN ISR

The central detector of the Axial Field Spectrometer (AFS) is a cylindrical drift chamber using a bicycle-wheel geometry. Its design has been optimized for jet-like events with high track densities. This is accomplished through a high degree of azimuthal segmentation (4/sup 0/ sectors) with up to 42 space points per track, using measurements of drift time and charge division. Particle identification in the non-relativistic region is obtained by (dE/dx) sampling. The detector is operated in an inhomogeneous magnetic field at event rates of typically 5 x 10/sup 5/ collisions per second. Preliminary results will be presented on the detector performance achieved after one year of operation at the ISR.
Date: April 28, 1981
Creator: Botner, O.; Burkert, V. & Cockerill, D.
System: The UNT Digital Library
Materials processing in space: ICF target fabrication implications (open access)

Materials processing in space: ICF target fabrication implications

During the last quarter of 1982, the Novette laser will become operational at Lawrence Livermore National Laboratory. The primary characteristics of the Novette laser are shown. In many ways, the new laser will serve as a proving ground and test bed for the Nova laser which is also under construction and should be operational in early 1985. Tables provide the Nova operational characteristics. The advent of the two new lasers, Novette and Nova, will make it possible to study many new and exciting aspects of laser-target interactions and of many implosion physics experiments which have previously not been possible. Some of the most interesting and exciting work will be the exploration of the parameters critical to the ignition of a significant thermonuclear burn in the deuterium-tritium fuel in the targets.
Date: April 28, 1982
Creator: Hendricks, C.D.
System: The UNT Digital Library
Probing the Planck Scale with Proton Decay (open access)

Probing the Planck Scale with Proton Decay

We advocate the idea that proton decay may probe physics at the Planck scale instead of the GUT scale. This is possible because supersymmetric theories have dimension-5 operators that can induce proton decay at dangerous rates, even with R-parity conservation. These operators are expected to be suppressed by the same physics that explains the fermion masses and mixings. We present a thorough analysis of nucleon partial lifetimes in models with a string-inspired anomalous U(1)_X family symmetry which is responsible for the fermionic mass spectrum as well as forbidding R-parity violating interactions. Protons and neutrons can decay via R-parity conserving non-renormalizable superpotential terms that are suppressed by the Planck scale and powers of the Cabibbo angle. Many of the models naturally lead to nucleon decay near present limits without any reference to grand unification.
Date: April 28, 2004
Creator: Harnik, Roni; Larson, Daniel T.; Murayama, Hitoshi & Thormeier, Marc
System: The UNT Digital Library
Designing Neutralized Drift Compression for Focusing of Intense Ion Beam Pulses in a Background Plasma (open access)

Designing Neutralized Drift Compression for Focusing of Intense Ion Beam Pulses in a Background Plasma

Neutralized drift compression offers an effective method for particle beam focusing and current amplification. In neutralized drift compression, a linear radial and longitudinal velocity drift is applied to a beam pulse, so that the beam pulse compresses as it drifts in the drift-compression section. The beam intensity can increase more than a factor of 100 in both the radial and longitudinal directions, resulting in more than 10,000 times increase in the beam number density during this process. The self-electric and self-magnetic fields can prevent tight ballistic focusing and have to be neutralized by supplying neutralizing electrons. This paper presents a survey of the present theoretical understanding of the drift compression process and plasma neutralization of intense particle beams. The optimal configuration of focusing and neutralizing elements is discussed in this paper.
Date: April 28, 2009
Creator: Kaganovich, I. D.; Davidson, R. C.; Dorf, M.; Startsev, E. A.; Barnard, J. J.; Friedman, A. et al.
System: The UNT Digital Library
Quantum Phase Extraction in Isospectral Electronic Nanostructures (open access)

Quantum Phase Extraction in Isospectral Electronic Nanostructures

Quantum phase is not a direct observable and is usually determined by interferometric methods. We present a method to map complete electron wave functions, including internal quantum phase information, from measured single-state probability densities. We harness the mathematical discovery of drum-like manifolds bearing different shapes but identical resonances, and construct quantum isospectral nanostructures possessing matching electronic structure but divergent physical structure. Quantum measurement (scanning tunneling microscopy) of these 'quantum drums' [degenerate two-dimensional electron states on the Cu(111) surface confined by individually positioned CO molecules] reveals that isospectrality provides an extra topological degree of freedom enabling robust quantum state transplantation and phase extraction.
Date: April 28, 2010
Creator: Moon, Christopher
System: The UNT Digital Library
ALTERNATE APPROACH TO HAZARD CATEGORIZATION FOR SALTSTONE FACILITY AT SRS (open access)

ALTERNATE APPROACH TO HAZARD CATEGORIZATION FOR SALTSTONE FACILITY AT SRS

The Saltstone Facility at Savannah River Site (SRS) was originally segmented into two segments: the Saltstone Production Facility (SPF) and the Saltstone Disposal Facility (SDF). Based on the inventory of radionuclides available for release the SPF and SDF were categorized as Nonreactor Hazard Category (HC)-3. The hazard categorization recognized the SDF will contain contributions of radionuclides which would exceed the HC-2 Threshold Quantity (TQ) in the form of grout. However it was determined not to impact the facility hazard categorization based on the grout being in a solid, monolithic form which was not easily dispersible. But, the impact of a quantity of unset grout expected to be present at the vault following operation of the process was not addressed. A Potential Inadequacy in Safety Analysis (PISA) was later issued based on the hazard categorization determination for the facility not addressing unset grout. This initiated a re-evaluation of the accident scenarios within the hazards analysis. During this re-evaluation, the segmentation of the facility was challenged based on the potential interaction between facility segments; specifically, the leachate return line and the grout transfer line, which were considered separate segments, are located in close proximity at one point. such that for certain events …
Date: April 28, 2009
Creator: Roy, B.
System: The UNT Digital Library
E10 Orbifolds (open access)

E10 Orbifolds

We study Z2 orbifolds of M-theory in terms of E10. We find a simple relation between the Z2 action on E10 and the imaginary root that corresponds [hep-th/0401053]to the"twisted sector" branes. We discuss the connection between the Kac-Moody algebra DE10 and the"untwisted" sector, and we demonstrate how DE18 can describe both the untwisted and twisted sectors simultaneously.
Date: April 28, 2005
Creator: Brown, Jeffrey; Ganguli, Surya; Ganor, Ori J. & Helfgott, Craig
System: The UNT Digital Library
Quantum Detection and Invisibility in Coherent Nanostructures (open access)

Quantum Detection and Invisibility in Coherent Nanostructures

We address quantum invisibility in the context of electronics in nanoscale quantum structures. In analogy with metamaterials, we use the freedom of design that quantum corrals provide and show that quantum mechanical objects can be hidden inside the corral, with respect to inelastic electron scattering spectroscopy in combination with scanning tunneling microscopy, and we propose a design strategy. A simple illustration of the invisibility is given in terms of an elliptic quantum corral containing a molecule, with a local vibrational mode, at one of the foci. Our work has implications to quantum information technology and presents new tools for nonlocal quantum detection and distinguishing between different molecules.
Date: April 28, 2010
Creator: Fransson, J.
System: The UNT Digital Library
Non-diffusive spin dynamics in a two-dimensional electron gas (open access)

Non-diffusive spin dynamics in a two-dimensional electron gas

We describe measurements of spin dynamics in the two-dimensional electron gas in GaAs/GaAlAs quantum wells. Optical techniques, including transient spin-grating spectroscopy, are used to probe the relaxation rates of spin polarization waves in the wavevector range from zero to 6 x 10{sup 4} cm{sup -1}. We find that the spin polarization lifetime is maximal at nonzero wavevector, in contrast with expectation based on ordinary spin diffusion, but in quantitative agreement with recent theories that treat diffusion in the presence of spin-orbit coupling.
Date: April 28, 2010
Creator: Weber, C.P.
System: The UNT Digital Library
Single-Atom Gating of Quantum State Superpositions (open access)

Single-Atom Gating of Quantum State Superpositions

The ultimate miniaturization of electronic devices will likely require local and coherent control of single electronic wavefunctions. Wavefunctions exist within both physical real space and an abstract state space with a simple geometric interpretation: this state space - or Hilbert space - is spanned by mutually orthogonal state vectors corresponding to the quantized degrees of freedom of the real-space system. Measurement of superpositions is akin to accessing the direction of a vector in Hilbert space, determining an angle of rotation equivalent to quantum phase. Here we show that an individual atom inside a designed quantum corral1 can control this angle, producing arbitrary coherent superpositions of spatial quantum states. Using scanning tunnelling microscopy and nanostructures assembled atom-by-atom we demonstrate how single spins and quantum mirages can be harnessed to image the superposition of two electronic states. We also present a straightforward method to determine the atom path enacting phase rotations between any desired state vectors. A single atom thus becomes a real-space handle for an abstract Hilbert space, providing a simple technique for coherent quantum state manipulation at the spatial limit of condensed matter.
Date: April 28, 2010
Creator: Moon, Christopher
System: The UNT Digital Library
Limits on a muon flux from neutralino annihilations in the Sun with the IceCube 22-string detector (open access)

Limits on a muon flux from neutralino annihilations in the Sun with the IceCube 22-string detector

A search for muon neutrinos from neutralino annihilations in the Sun has been performed with the IceCube 22-string neutrino detector using data collected in 104.3 days of live-time in 2007. No excess over the expected atmospheric background has been observed. Upper limits have been obtained on the annihilation rate of captured neutralinos in the Sun and converted to limits on the WIMP-proton cross-sections for WIMP masses in the range 250-5000 GeV. These results are the most stringent limits to date on neutralino annihilation in the Sun.
Date: April 28, 2009
Creator: Collaboration, IceCube & Klein, Spencer
System: The UNT Digital Library
Measurement of the gamma gamma* to eta_c transition form factor (open access)

Measurement of the gamma gamma* to eta_c transition form factor

The authors study the reaction e{sup +}e{sup -} {yields} e{sup +}e{sup -} {eta}{sub c}, {eta}{sub c} {yields} K{sub S}K{sup {+-}}{pi}{sup {-+}} and obtain {eta}{sub c} mass and width values 2982.2 {+-} 0.4 {+-} 1.6 MeV/c{sup 2} and 31.7 {+-} 1.2 {+-} 0.8 MeV, respectively. They find {Lambda}({eta}{sub c} {yields} {gamma}{gamma}){Beta}({eta}{sub c} {yields} K{bar K}{pi}) = 0.374 {+-} 0.009 {+-} 0.031 keV, and measure the {gamma}{gamma}* {yields} {eta}{sub c} transition form factor in the momentum transfer range from 2 to 50 GeV{sup 2}. The analysis is based on 469 fb{sup -1} of integrated luminosity collected at PEP-II with the BABAR detector at e{sup +}e{sup -} center-of-mass energies near 10.6 GeV.
Date: April 28, 2010
Creator: Lees, J. P.; Poireau, V.; Prencipe, E.; Tisserand, V.; Garra Tico, J.; Grauges, E. et al.
System: The UNT Digital Library