2,938 research outputs found
Cancer cell-secreted IGF2 instigates fibroblasts and bone marrow-derived vascular progenitor cells to promote cancer progression
published_or_final_versio
The Nonlinear Meissner Effect in Unconventional Superconductors
We examine the long-wavelength current response in anisotropic
superconductors and show how the field-dependence of the Meissner penetration
length can be used to detect the structure of the order parameter. Nodes in the
excitation gap lead to a nonlinear current-velocity constitutive equation at
low temperatures which is distinct for each symmetry class of the order
parameter. The effective Meissner penetration length is linear in and
exhibits a characteristic anisotropy for fields in the -plane that is
determined by the positions of the nodes in momentum space. The nonlinear
current-velocity relation also leads to an intrinsic magnetic torque for
in-plane fields that are not parallel to a nodal or antinodal direction. The
torque scales as for and has a characteristic angular
dependence. We analyze the effects of thermal excitations, impurity scattering
and geometry on the current response of a superconductor, and
discuss our results in light of recent measurements of the low-temperature
penetration length and in-plane magnetization of single-crystals of
and .Comment: 30 pages, RevTeX file with 16 postscript figures. Submitted to Phys.
Rev.
Influence of Natural Organic Matter Fouling and Osmotic Backwash on Pressure Retarded Osmosis Energy Production from Natural Salinity Gradients
Pressure retarded osmosis (PRO) has the potential to produce clean, renewable energy from natural salinity gradients. However, membrane fouling can lead to diminished water flux productivity, thus reducing the extractable energy. This study investigates organic fouling and osmotic backwash cleaning in PRO and the resulting impact on projected power generation. Fabricated thin-film composite membranes were fouled with model river water containing natural organic matter. The water permeation carried foulants from the feed river water into the membrane porous support layer and caused severe water flux decline of ∼46%. Analysis of the water flux behavior revealed three phases in membrane support layer fouling. Initial foulants of the first fouling phase quickly adsorbed at the active-support layer interface and caused a significantly greater increase in hydraulic resistance than the subsequent second and third phase foulants. The water permeability of the fouled membranes was lowered by ∼39%, causing ∼26% decrease in projected power density. A brief, chemical-free osmotic backwash was demonstrated to be effective in removing foulants from the porous support layer, achieving ∼44% recovery in projected power density. The substantial performance recovery after cleaning was attributed to the partial restoration of the membrane water permeability. This study shows that membrane fouling detrimentally impacts energy production, and highlights the potential strategies to mitigate fouling in PRO power generation with natural salinity gradients
The globalization strategies of five Asian tobacco companies: : An analytical framework
With 30% of the world\u27s smokers, two million deaths annually from tobacco use, and rising levels of tobacco consumption, the Asian region is recognised as central to the future of global tobacco control. There is less understanding, however, of how Asian tobacco companies with regional and global aspirations are contributing to the global burden of tobacco-related disease and death. This introductory article sets out the background and rationale for this special issue on \u27The Emergence of Asian Tobacco Companies: Implications for Global Health Governance\u27. The article discusses the core questions to be addressed and presents an analytical framework for assessing the globalisation strategies of Asian tobacco firms. The article also discusses the selection of the five case studies, namely as independent companies in Asia which have demonstrated concerted ambitions to be a major player in the world market
Influence of impurity-scattering on tunneling conductance in d-wave superconductors with broken time reversal symmetry
Effects of impurity scattering on tunneling conductance in dirty
normal-metal/insulator/superconductor junctions are studied based on the Kubo
formula and the recursive Green function method. The zero-bias conductance peak
(ZBCP) is a consequence of the unconventional pairing symmetry in
superconductors. The impurity scattering in normal metals suppresses the
amplitude of the ZBCP. The degree of the suppression agrees well with results
of the quasiclassical Green function theory. When superconductors have
+is-wave pairing symmetry, the time-reversal symmetry is broken in
superconductors and the ZBCP splits into two peaks. The random impurity
scattering reduces the height of the two splitting peaks. The position of the
splitting peaks, however, almost remains unchanged even in the presence of the
strong impurity scattering. Thus the two splitting peaks never merge into a
single ZBCP.Comment: 12 pages, 5 figures, using jpsj2.cls and overcite.st
B Physics at the Tevatron: Run II and Beyond
This report provides a comprehensive overview of the prospects for B physics
at the Tevatron. The work was carried out during a series of workshops starting
in September 1999. There were four working groups: 1) CP Violation, 2) Rare and
Semileptonic Decays, 3) Mixing and Lifetimes, 4) Production, Fragmentation and
Spectroscopy. The report also includes introductory chapters on theoretical and
experimental tools emphasizing aspects of B physics specific to hadron
colliders, as well as overviews of the CDF, D0, and BTeV detectors, and a
Summary.Comment: 583 pages. Further information on the workshops, including
transparencies, can be found at the workshop's homepage:
http://www-theory.lbl.gov/Brun2/. The report is also available in 2-up
http://www-theory.lbl.gov/Brun2/report/report2.ps.gz or chapter-by-chapter
http://www-theory.lbl.gov/Brun2/report
Surface modes of ultracold atomic clouds with very large number of vortices
We study the surface modes of some of the vortex liquids recently found by
means of exact diagonalizations in systems of rapidly rotating bosons. In
contrast to the surface modes of Bose condensates, we find that the surface
waves have a frequency linear in the excitation angular momentum, . Furthermore, in analogy with the edge waves of electronic quantum Hall
states, these excitations are {\it chiral}, that is, they can be excited only
for values of that increase the total angular momentum of the vortex
liquid. However, differently from the quantum Hall phenomena for electrons, we
also find other excitations that are approximately degenerate in the laboratory
frame with the surface modes, and which decrease the total angular momentum by
quanta. The surface modes of the Laughlin, as well as other scalar and
vector boson states are analyzed, and their {\it observable} properties
characterized. We argue that measurement of the response of a vortex liquid to
a weak time-dependent potential that imparts angular momentum to the system
should provide valuable information to characterize the vortex liquid. In
particular, the intensity of the signal of the surface waves in the dynamic
structure factor has been studied and found to depend on the type of vortex
liquid. We point out that the existence of surface modes has observable
consequences on the density profile of the Laughlin state. These features are
due to the strongly correlated behavior of atoms in the vortex liquids. We
point out that these correlations should be responsible for a remarkable
stability of some vortex liquids with respect to three-body losses.Comment: 28 pages + 6 EPS figures. Final version as accepted for publication
in Phys. Rev.
Examining patient-reported late toxicity and its association with quality of life and unmet need for symptom management among nasopharyngeal cancer survivors: a cross-sectional survey
IntroductionAlongside the improved survival of nasopharyngeal cancer (NPC), late radiation toxicities are alarmingly hampering survivors’ quality of life. A patient-reported symptom burden survey is lacking to address the unmet need for symptom management among local NPC survivors.MethodsA single-center cross-sectional survey was conducted on 211 NPC survivors who had completed radiation therapy for three to 120 months. We employed the Chinese version M. D. Anderson Symptom Inventory - Head & Neck Module (MDASI-HN-C), Functional Assessment of Cancer Therapy - Head & Neck (FACT-HN-C), and a question extracted from the Cancer Survivors’ Unmet Needs Measure (CaSUN).ResultsTwo hundred valid responses were collected. Participants suffered from at least four moderate to severe symptoms (mean = 4.84, SD = 4.99). The top five severe symptoms were dry mouth, mucus problems, difficulty swallowing or chewing, teeth or gum problems, and memory problems. MDASI-HN-C subscales were negatively correlated with the physical, emotional, functional, and HN-specific domains of the FACT-HN-C. The unmet need for symptom management was positively associated with symptom burden, either general symptoms (Adjusted odds ratio [ORadj] = 1.566, 95% CI = 1.282 – 1.914, p < 0.001) or top-5 symptoms (ORadj = 1.379, 95% CI = 1.185 – 1.604, p < 0.001), while negatively associated with post-RT time (ORadj = 0.981, 95% CI [0.972, 0.991], p < 0.001).ConclusionVirtually all NPC survivors suffer from late toxicities, which interplay with survivors’ perceptions intricately to affect their unmet needs for symptom management. Personalized supportive care strategies with regular assessments and stratifications are warranted
Low Frequency Nonlinear Magnetic Response of an Unconventional Superconductor
We consider an unconventional superconductor in a low frequency harmonic
magnetic field. In the Meissner regime at low T a nonlinear magnetic response
arises from quasiparticle excitations near minima in the energy gap. Various
physical quantities then acquire higher harmonics of the frequency of the
applied field. We discuss how examination of the field and angular dependence
of these harmonics allows determination of the structure of the energy gap. We
show how to distinguish nodes from small finite minima ("quasinodes"). Gaps
with nodal lines give rise to universal power law field dependences for the
nonlinear magnetic moment and the nonlinear torque. They both have separable
temporal and angular dependences. In contrast, when there are quasinodes these
quantities have more complicated and nonseparable field, temporal, and angular
dependences. We illustrate this on the example of an s+id gap. We discuss how
to perform measurements so as to maximize the nonlinear signal and how to
investigate in detail the properties of the superconducting minima, thus
determining the gap function symmetry.Comment: To appear in Phys Rev B. Ten figures, 13 text page
Magnetic Properties in Non-centrosymmetric Superconductors with and without Antiferromagnetic Order
The paramagnetic properties in non-centrosymmetric superconductors with and
without antiferromagnetic (AFM) order are investigated with focus on the heavy
Fermion superconductors, CePt_3Si, CeRhSi_3 and CeIrSi_3. First, we investigate
the spin susceptibility in the linear response regime and elucidate the role of
AFM order. The spin susceptibility at T=0 is independent of the pairing
symmetry and increases in the AFM state. Second, the non-linear response to the
magnetic field are investigated on the basis of an effective model for CePt_3Si
which may be also applicable to CeRhSi_3 and CeIrSi_3. The role of
antisymmetric spin-orbit coupling (ASOC), helical superconductivity,
anisotropic Fermi surfaces and AFM order are examined in the dominantly s-, p-
and d-wave states. We emphasize the qualitatively important role of the mixing
of superconducting (SC) order parameters in the p-wave state which enhances the
spin susceptibility and suppresses paramagnetic depairing effect in a
significant way. Therefore, the dominantly p-wave superconductivity admixed
with the s-wave order parameter is consistent with the paramagnetic properties
of CePt_3Si at ambient pressure. We propose some experiments which can
elucidate the novel pairing states in CePt_3Si as well as CeRhSi_3 and
CeIrSi_3.Comment: To appear in J. Phys. Soc. Jpn. (2007) No.1
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