236 research outputs found
Bosonizations of and Integrable Hierarchies
We construct embeddings of in lattice vertex
algebras by composing the Wakimoto realization with the
Friedan-Martinec-Shenker bosonization. The Kac-Wakimoto hierarchy then gives
rise to two new hierarchies of integrable, non-autonomous, non-linear partial
differential equations. A new feature of our construction is that it works for
any value of the central element of ; that is, the
level becomes a parameter in the equations
Acetic Acid Aldol Reactions in the Presence of Trimethylsilyl Trifluoromethanesulfonate
In the presence of TMSOTf and a trialkylamine base, acetic acid undergoes aldol addition to non-enolizable aldehydes under exceptionally mild conditions. Acidic workup yields the β-hydroxy carboxylic acid. The reaction appears to proceed via a three-step, one-pot process, including in situ trimethylsilyl ester formation, bis-silyl ketene acetal formation, and TMSOTf-catalyzed Mukaiyama aldol addition. Independently synthesized TMSOAc also undergoes aldol additions under similar conditions
Fine structure and optical pumping of spins in individual semiconductor quantum dots
We review spin properties of semiconductor quantum dots and their effect on
optical spectra. Photoluminescence and other types of spectroscopy are used to
probe neutral and charged excitons in individual quantum dots with high
spectral and spatial resolution. Spectral fine structure and polarization
reveal how quantum dot spins interact with each other and with their
environment. By taking advantage of the selectivity of optical selection rules
and spin relaxation, optical spin pumping of the ground state electron and
nuclear spins is achieved. Through such mechanisms, light can be used to
process spins for use as a carrier of information
Intensity of Th and Pa scavenging partitioned by particle chemistry in the North Atlantic Ocean
Author Posting. © The Author(s), 2015. This is the author's version of the work. It is posted here by permission of Elsevier for personal use, not for redistribution. The definitive version was published in Marine Chemistry 170 (2015): 49-60, doi:10.1016/j.marchem.2015.01.006.The natural radionuclides 231Pa and 230Th are incorporated into the marine sediment record by
scavenging, or adsorption to various particle types, via chemical reactions that are not fully
understood. Because these isotopes have potential value in tracing several oceanographic
processes, we investigate the nature of scavenging using trans-Atlantic measurements of
dissolved (<0.45 μm) and particulate (0.8-51 μm) 231Pa and 230Th, together with major particle
composition. We find widespread impact of intense scavenging by authigenic Fe/Mn
(hydr)oxides, in the form of hydrothermal particles emanating from the Mid-Atlantic ridge and
particles resuspended from reducing conditions near the seafloor off the coast of West Africa.
Biogenic opal was not found to be a significant scavenging phase for either element in this
sample set, essentially because of its low abundance and small dynamic range at the studied
sites. Distribution coefficients in shallow (< 200 m) depths are anomalously low which suggests
either the unexpected result of a low scavenging intensity for organic matter or that, in water
masses containing abundant organic-rich particles, a greater percentage of radionuclides exist in
the colloidal or complexed phase. In addition to particle concentration, the oceanic distribution
of particle types likely plays a significant role in the ultimate distribution of sedimentary 230Th
and 231Pa.Cruise management for GA03 was funded by the U. S. National Science Foundation to W.
Jenkins (OCE-0926423), E. Boyle (OCE-0926204), and G. Cutter (OCE-0926092). Radionuclide
studies were supported by NSF (OCE-0927064 to LDEO, OCE-0926860 to WHOI, OCE-
0927757 to URI, and OCE-0927754 to UMN). Additional support came from the European
Research Council (278705) to LFR and the Ford Foundation Predoctoral Fellowship to SMV.
Particle studies were supported by NSF OCE-0963026 to PJL
The Impossibility of a Perfectly Competitive Labor Market
Using the institutional theory of transaction cost, I demonstrate that the assumptions of the competitive labor market model are internally contradictory and lead to the conclusion that on purely theoretical grounds a perfectly competitive labor market is a logical impossibility. By extension, the familiar diagram of wage determination by supply and demand is also a logical impossibility and the neoclassical labor demand curve is not a well-defined construct. The reason is that the perfectly competitive market model presumes zero transaction cost and with zero transaction cost all labor is hired as independent contractors, implying multi-person firms, the employment relationship, and labor market disappear. With positive transaction cost, on the other hand, employment contracts are incomplete and the labor supply curve to the firm is upward sloping, again causing the labor demand curve to be ill-defined. As a result, theory suggests that wage rates are always and everywhere an amalgam of an administered and bargained price. Working Paper 06-0
Resistance to autosomal dominant Alzheimer's disease in an APOE3 Christchurch homozygote: a case report.
We identified a PSEN1 (presenilin 1) mutation carrier from the world's largest autosomal dominant Alzheimer's disease kindred, who did not develop mild cognitive impairment until her seventies, three decades after the expected age of clinical onset. The individual had two copies of the APOE3 Christchurch (R136S) mutation, unusually high brain amyloid levels and limited tau and neurodegenerative measurements. Our findings have implications for the role of APOE in the pathogenesis, treatment and prevention of Alzheimer's disease
Impact of Conditional Cash Transfers on Maternal and Newborn Health
Maternal and newborn health (MNH) is a high priority for global health
and is included among the Millennium Development Goals (MDGs). However,
the slow decline in maternal and newborn mortality jeopardizes
achievements of the targets of MDGs. According to UNICEF, 60 million
women give birth outside of health facilities, and family planning
needs are satisfied for only 50%. Further, skilled birth attendance and
the use of antenatal care are most inequitably distributed in maternal
and newborn health interventions in low- and middle-income countries.
Conditional cash transfer (CCT) programmes have been shown to increase
health service utilization among the poorest but little is written on
the effects of such programmes on maternal and newborn health. We
carried out a systematic review of studies on CCT that report maternal
and newborn health outcomes, including studies from 8 countries. The
CCT programmes have increased antenatal visits, skilled attendance at
birth, delivery at a health facility, and tetanus toxoid vaccination
for mothers and reduced the incidence of low birthweight. The
programmes have not had a significant impact on fertility while the
impact on maternal and newborn mortality has not been welldocumented
thus far. Given these positive effects, we make the case for further
investment in CCT programmes for maternal and newborn health, noting
gaps in knowledge and providing recommendations for better design and
evaluation of such programmes. We recommend more rigorous impact
evaluations that document impact pathways and take factors, such as
cost-effectiveness, into account
The Non-existence of the Labor Demand/Supply Diagram, and Other Theorems of Institutional Economics
The most famous and influential diagram in modern (neoclassical) labor economics is the model of wage determination by supply and demand. Using concepts and ideas from institutional economics, I argue that the theory of a perfectly competitive labor market is logically contradictory and, hence, the demand/supply diagram cannot exist on the plane of pure theory. Four other fundamental theorems concerning labor markets are also derived, as are implications about the theoretical foundation of the field of industrial relations and the economic evaluation of labor and employment policy. In this article I accomplish four things of significance. The first is to demonstrate that the core diagram of neoclassical labor economics - the diagram of wage determination by demand and supply (D/S) - does not have logical coherence and thus has no existence on the plane of pure theory. The second is to deduce this conclusion using a core concept of institutional economics (i.e., transaction cost), thus demonstrating that the institutional approach to labor economics has theoretical explanatory power. The third is to use the transaction cost idea to also deduce four fundamental theorems concerning labor markets and wage determination. The fourth is to identify the core theoretical foundation of the field of industrial relations. This discussion also yields important implications for the economic evaluation of labor and employment policy, as well as interesting insights on the history of thought in labor economics. Working Paper 07-2
Impact of Conditional Cash Transfers on Maternal and Newborn Health
Maternal and newborn health (MNH) is a high priority for global health and is included among the Millennium Development Goals (MDGs). However, the slow decline in maternal and newborn mortality jeopardizes achievements of the targets of MDGs. According to UNICEF, 60 million women give birth outside of health facilities, and family planning needs are satisfied for only 50%. Further, skilled birth attendance and the use of antenatal care are most inequitably distributed in maternal and newborn health interventions in low- and middle-income countries. Conditional cash transfer (CCT) programmes have been shown to increase health service utilization among the poorest but little is written on the effects of such programmes on maternal and newborn health. We carried out a systematic review of studies on CCT that report maternal and newborn health outcomes, including studies from 8 countries. The CCT programmes have increased antenatal visits, skilled attendance at birth, delivery at a health facility, and tetanus toxoid vaccination for mothers and reduced the incidence of low birthweight. The programmes have not had a significant impact on fertility while the impact on maternal and newborn mortality has not been well-documented thus far. Given these positive effects, we make the case for further investment in CCT programmes for maternal and newborn health, noting gaps in knowledge and providing recommendations for better design and evaluation of such programmes. We recommend more rigorous impact evaluations that document impact pathways and take factors, such as cost-effectiveness, into account
- …