6,116 research outputs found
Mott transition, antiferromagnetism, and unconventional superconductivity in layered organic superconductors
The phase diagram of the layered organic superconductor
-(ET)Cu[N(CN)]Cl has been accurately measured from a
combination of H NMR and AC susceptibility techniques under helium gas
pressure. The domains of stability of antiferromagnetic and superconducting
long-range orders in the pressure {\it vs} temperature plane have been
determined. Both phases overlap through a first-order boundary that separates
two regions of inhomogeneous phase coexistence. The boundary curve is found to
merge with another first order line related to the metal-insulator transition
in the paramagnetic region. This transition is found to evolve into a crossover
regime above a critical point at higher temperature. The whole phase diagram
features a point-like region where metallic, insulating, antiferromagnetic and
non s-wave superconducting phases all meet.Comment: 4 pages, 6 figures, Revte
Bankruptcy - Summary Jurisdiction - Filing Proof of Claim as Basis for Money Judgment on a Counterclaim in Favor of the Trustee
Appellant filed a proof of claim with the trustee in bankruptcy for unliquidated damages for an alleged breach of contract by the bankrupt. In response, the trustee filed a petition with the bankruptcy court for an order disallowing the appellant\u27s claim and for a money judgment against appellant for a breach of the same contract. The district court affirmed the referee\u27s denial of appellant\u27s claim and judgment in favor of the trustee. On appeal, held, affirmed. Filing proof of claim gives the bankruptcy court jurisdiction not only to hear, but to grant the trustee\u27s petition for affirmative relief on a counterclaim arising out of the same transaction. Peters v. Lines, 275 F.2d 919 (9th Cir. 1960)
Coexistence of Superconductivity and Spin Density Wave orderings in the organic superconductor (TMTSF)_2PF_6
The phase diagram of the organic superconductor (TMTSF)_2PF_6 has been
revisited using transport measurements with an improved control of the applied
pressure. We have found a 0.8 kbar wide pressure domain below the critical
point (9.43 kbar, 1.2 K) for the stabilisation of the superconducting ground
state featuring a coexistence regime between spin density wave (SDW) and
superconductivity (SC). The inhomogeneous character of the said pressure domain
is supported by the analysis of the resistivity between T_SDW and T_SC and the
superconducting critical current. The onset temperature T_SC is practically
constant (1.20+-0.01 K) in this region where only the SC/SDW domain proportion
below T_SC is increasing under pressure. An homogeneous superconducting state
is recovered above the critical pressure with T_SC falling at increasing
pressure. We propose a model comparing the free energy of a phase exhibiting a
segregation between SDW and SC domains and the free energy of homogeneous
phases which explains fairly well our experimental findings.Comment: 13 pages, 10 figures, revised v: fig.9 added, section 4.2 rewritten,
accepted v: sections 4&5 improve
Ultraviolet Spectra of CV Accretion Disks with Non-Steady T(r) Laws
An extensive grid of synthetic mid- and far-ultraviolet spectra for accretion
disks in cataclysmic variables has been presented by Wade and Hubeny (1998). In
those models, the disk was assumed to be in steady-state, that is T_eff(r) is
specified completely by the mass M_WD and radius R_WD of the accreting white
dwarf star and the mass transfer rate M_dot which is constant throughout the
disk. In these models, T_eff(r) is proportional to r^{-3/4} except as modified
by a cutoff term near the white dwarf.
Actual disks may vary from the steady-state prescription for T_eff(r),
however, e.g. owing to outburst cycles in dwarf novae M_dot not constant with
radius) or irradiation (in which case T_eff in the outer disk is raised above
T_steady). To show how the spectra of such disks might differ from the steady
case, we present a study of the ultraviolet (UV) spectra of models in which
power-law temperature profiles T_eff(r) is proportional to r^{-gamma} with
gamma < 3/4 are specified. Otherwise, the construction of the models is the
same as in the Wade & Hubeny grid, to allow comparison. We discuss both the UV
spectral energy distributions and the appearance of the UV line spectra. We
also briefly discuss the eclipse light curves of the non-standard models.
Comparison of these models with UV observations of novalike variables suggests
that better agreement may be possible with such modified T_eff(r) profiles.Comment: 13 pages, 6 figures (one reduced quality), ApJ in pres
Business as Usual? Brown and the Continuing Conundrum of Race in America
In this article, Professors Robert Chang and Jerome Culp examine the state of race in America in the aftermath of the landmark Supreme Court decision of Brown v. Board of Education, focusing on the ten-year window preceding its fiftieth anniversary. Their findings reveal that while Brown established fundamental precedent in the area of race relations, racial inequality remains entrenched in a number of modern social institutions. Chang and Culp analyze this dilemma by focusing on three distinct trends. First, a cycle of inequality is driven by racial disparities in wealth and perpetuated by interlocking systems of education, housing, family, healthcare, employment, and criminal justice. Second, civil rights activists often fall short of their goals following Brown due to what the authors describe as civil rights myopias. Finally, racial remediation schemes also face major obstacles as White identity has intensified since Brown. As a result, little has changed in the ten-year window preceding Brown\u27s fiftieth anniversary and racial inequality remains a persistent problem in America
From Starburst to Quiescence: Testing AGN feedback in Rapidly Quenching Post-Starburst Galaxies
Post-starbursts are galaxies in transition from the blue cloud to the red
sequence. Although they are rare today, integrated over time they may be an
important pathway to the red sequence. This work uses SDSS, GALEX, and WISE
observations to identify the evolutionary sequence from starbursts to fully
quenched post-starbursts in the narrow mass range , and identifies "transiting" post-starbursts which are intermediate
between these two populations. In this mass range, of galaxies are
starbursts, are quenched post-starbursts, and are the
transiting types in between. The transiting post-starbursts have stellar
properties that are predicted for fast-quenching starbursts and morphological
characteristics that are already typical of early-type galaxies. The AGN
fraction, as estimated from optical line ratios, of these post-starbursts is
about 3 times higher () than that of normal star-forming
galaxies of the same mass, but there is a significant delay between the
starburst phase and the peak of nuclear optical AGN activity (median age
difference of Myr), in agreement with previous studies.
The time delay is inferred by comparing the broad-band near NUV-to-optical
photometry with stellar population synthesis models. We also find that
starbursts and post-starbursts are significantly more dust-obscured than normal
star-forming galaxies in the same mass range. About of the starbursts
and of the transiting post-starbursts can be classified as the
"Dust-Obscured Galaxies" (DOGs), while only of normal galaxies are
DOGs.The time delay between the starburst phase and AGN activity suggests that
AGN do not play a primary role in the original quenching of starbursts but may
be responsible for quenching later low-level star formation during the
post-starburst phase.Comment: 30 pages, 18 figures,accepted to Ap
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