148 research outputs found
The evolving role of the Federal Home Loan Banks in mortgage markets
The Federal Home Loan Banks are part of a system created by the federal government to promote home ownership. This Commentary looks at new initiatives undertaken by these government-sponsored enterprises to expand their role in financial markets-and the attendant implications for their balance sheets.Federal home loan banks ; Mortgages ; Housing - Finance
Graviton 1-loop partition function for 3-dimensional massive gravity
The graviton 1-loop partition function in Euclidean topologically massive
gravity (TMG) is calculated using heat kernel techniques. The partition
function does not factorize holomorphically, and at the chiral point it has the
structure expected from a logarithmic conformal field theory. This gives strong
evidence for the proposal that the dual conformal field theory to TMG at the
chiral point is indeed logarithmic. We also generalize our results to new
massive gravity.Comment: 19 pages, v2: major revision, considerably stronger conclusions,
added comparison with LCFT partition function, confirmation of LCFT
conjecture, added autho
de Sitter Supersymmetry Revisited
We present the basic superconformal field theories in
four-dimensional de Sitter space-time, namely the non-abelian super Yang-Mills
theory and the chiral multiplet theory with gauge interactions or cubic
superpotential. These theories have eight supercharges and are invariant under
the full group of conformal symmetries, which includes the de Sitter
isometry group as a subgroup. The theories are ghost-free and the
anti-commutator is positive. SUSY
Ward identities uniquely select the Bunch-Davies vacuum state. This vacuum
state is invariant under superconformal transformations, despite the fact that
de Sitter space has non-zero Hawking temperature. The theories
are classically invariant under the superconformal group, but this
symmetry is broken by radiative corrections. However, no such difficulty is
expected in the theory, which is presented in appendix B.Comment: 21 pages, 2 figure
Gravity duals for logarithmic conformal field theories
Logarithmic conformal field theories with vanishing central charge describe
systems with quenched disorder, percolation or dilute self-avoiding polymers.
In these theories the energy momentum tensor acquires a logarithmic partner. In
this talk we address the construction of possible gravity duals for these
logarithmic conformal field theories and present two viable candidates for such
duals, namely theories of massive gravity in three dimensions at a chiral
point.Comment: 15 pages, 1 figure, invited plenary talk at the First Mediterranean
Conference on Classical and Quantum Gravity, v2: published version, corrected
typo in left eq. (5
All stationary axi-symmetric local solutions of topologically massive gravity
We classify all stationary axi-symmetric solutions of topologically massive
gravity into Einstein, Schr\"odinger, warped and generic solutions. We
construct explicitly all local solutions in the first three sectors and present
an algorithm for the numerical construction of all local solutions in the
generic sector. The only input for this algorithm is the value of one constant
of motion if the solution has an analytic centre, and three constants of motion
otherwise. We present several examples, including soliton solutions that
asymptote to warped AdS.Comment: 42 pages, 9 figures. v2: Changed potentially confusing labelling of
one sector, added references. v3: Minor changes, matches published versio
Short-cut to new anomalies in gravity duals to logarithmic conformal field theories
Various massive gravity theories in three dimensions are conjecturally dual
to logarithmic conformal field theories (LCFTs). We summarise the status of
these conjectures. LCFTs are characterised by the values of the central charges
and the so-called "new anomalies". We employ a short-cut to calculate these new
anomalies in generalised massive gravity and in the recently proposed
higher-derivative gravity theories with holographic c-theorem. Both cases
permit LCFTs exhibiting intriguing features, like rank three Jordan cells or
non-zero central charges. Finally, as an example we discuss in some detail the
partially massless version of new massive gravity, a theory with several
special properties that we call "partially massless gravity".Comment: 34 pages, 2 figures; v2: added references; v3: Several rewordings in
the introduction and section 2, added references. Matches published versio
Recency of Faulting and Subsurface Architecture of the San Diego Bay Pull-Apart Basin, California, USA
In Southern California, plate boundary motion between the North American and Pacific plates is distributed across several sub-parallel fault systems. The offshore faults of the California Continental Borderland (CCB) are thought to accommodate ∼10–15% of the total plate boundary motion, but the exact distribution of slip and the mechanics of slip partitioning remain uncertain. The Newport-Inglewood-Rose Canyon fault is the easternmost fault within the CCB whose southern segment splays out into a complex network of faults beneath San Diego Bay. A pull-apart basin model between the Rose Canyon and the offshore Descanso fault has been used to explain prominent fault orientations and subsidence beneath San Diego Bay; however, this model does not account for faults in the southern portion of the bay or faulting east of the bay. To investigate the characteristics of faulting and stratigraphic architecture beneath San Diego Bay, we combined a suite of reprocessed legacy airgun multi-channel seismic profiles and high-resolution Chirp data, with age and lithology controls from geotechnical boreholes and shallow sub-surface vibracores. This combined dataset is used to create gridded horizon surfaces, fault maps, and perform a kinematic fault analysis. The structure beneath San Diego Bay is dominated by down-to-the-east motion on normal faults that can be separated into two distinct groups. The strikes of these two fault groups can be explained with a double pull-apart basin model for San Diego Bay. In our conceptual model, the western portion of San Diego Bay is controlled by a right-step between the Rose Canyon and Descanso faults, which matches both observations and predictions from laboratory models. The eastern portion of San Diego Bay appears to be controlled by an inferred step-over between the Rose Canyon and San Miguel-Vallecitos faults and displays distinct fault strike orientations, which kinematic analysis indicates should have a significant component of strike-slip partitioning that is not detectable in the seismic data. The potential of a Rose Canyon-San Miguel-Vallecitos fault connection would effectively cut the stepover distance in half and have important implications for the seismic hazard of the San Diego-Tijuana metropolitan area (population ∼3 million people)
AdS_3/LCFT_2 - Correlators in Cosmological Topologically Massive Gravity
For cosmological topologically massive gravity at the chiral point we
calculate momentum space 2- and 3-point correlators of operators in the
postulated dual CFT on the cylinder. These operators are sourced by the bulk
and boundary gravitons. Our correlators are fully consistent with the proposal
that cosmological topologically massive gravity at the chiral point is dual to
a logarithmic CFT. In the process we give a complete classification of
normalizable and non-normalizeable left, right and logarithmic solutions to the
linearized equations of motion in global AdS_3.Comment: 39 pages + appendices, 1 eps figure, v2: minor changes in text in
4.1.2, corrected typo in (2.31
The malaria testing and treatment landscape in mainland Tanzania, 2016
Abstract Background Understanding the key characteristics of malaria testing and treatment is essential to the control of a disease that continues to pose a major risk of morbidity and mortality in mainland Tanzania, with evidence of a resurgence of the disease in recent years. The introduction of artemisinin combination therapy (ACT) as the first-line treatment for malaria, alongside policies to promote rational case management following testing, highlights the need for evidence of anti-malarial and testing markets in the country. The results of the most recent mainland Tanzania ACTwatch outlet survey are presented here, including data on the availability, market share and price of anti-malarials and malaria diagnosis in 2016. Methods A nationally-representative malaria outlet survey was conducted between 18th May and 2nd July, 2016. A census of public and private outlets with potential to distribute malaria testing and/or treatment was conducted among a representative sample of administrative units. An audit was completed for all anti-malarials, malaria rapid (RDT) diagnostic tests and microscopy. Results A total of 5867 outlets were included in the nationally representative survey, across both public and private sectors. In the public sector, availability of malaria testing was 92.3% and quality-assured (QA) ACT was 89.1% among all screened outlets. Sulfadoxine–pyrimethamine (SP) was stocked by 51.8% of the public sector and injectable artesunate was found in 71.4% of all screened public health facilities. Among anti-malarial private-sector stockists, availability of testing was 15.7, and 65.1% had QA ACT available. The public sector accounted for 83.4% of the total market share for malaria diagnostics. The private sector accounted for 63.9% of the total anti-malarial market, and anti-malarials were most commonly distributed through accredited drug dispensing outlets (ADDOs) (39.0%), duka la dawa baridi (DLDBs) (13.3%) and pharmacies (6.7%). QA ACT comprised 33.1% of the national market share (12.2% public sector and 20.9% private sector). SP accounted for 53.3% of the total market for anti-malarials across both private and public sectors (31.3 and 22.0% of the total market, respectively). The median price per adult equivalent treatment dose (AETD) of QA ACT in the private sector was 1.05). In the private sector, 79.3% of providers perceived ACT to be the most effective treatment for uncomplicated malaria for adults and 88.4% perceived this for children. Conclusions While public sector preparedness for appropriate malaria testing and case management is showing encouraging signs, QA ACT availability and market share in the private sector continues to be sub-optimal for most outlet types. Furthermore, it is concerning that SP continues to predominate in the anti-malarial market. The reasons for this remain unclear, but are likely to be in part related to price, availability and provider knowledge or preferences. Continued efforts to implement government policy around malaria diagnosis and case management should be encouraged
(De)Constructing a Natural and Flavorful Supersymmetric Standard Model
Using the framework of deconstruction, we construct simple, weakly-coupled
supersymmetric models that explain the Standard Model flavor hierarchy and
produce a flavorful soft spectrum compatible with precision limits. Electroweak
symmetry breaking is fully natural; the mu-term is dynamically generated with
no B mu-problem and the Higgs mass is easily raised above LEP limits without
reliance on large radiative corrections. These models possess the distinctive
spectrum of superpartners characteristic of "effective supersymmetry": the
third generation superpartners tend to be light, while the rest of the scalars
are heavy.Comment: 36 pages, 4 figures ; v2: references added, expanded discussion of
FCNC
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