464 research outputs found
Estimates of scale and cost efficiency for Federal Reserve currency operations
Meeting the currency demands of depository institutions, businesses, and consumers costs the Federal Reserve more than half a billion dollars each year, yet, very little research has been devoted to understanding what factors affect such costs. The authors estimate a cost function in order to obtain estimates of scale and cost efficiency for this service. They find that as in other paper-based technologies, such as checks, scale economies are achieved at a relatively low level of output, implying that currency services are not a natural monopoly. They also provide estimates of facility-specific marginal costs and returns to scale measures that could be used to improve resource allocations. Lastly, they find that the average processing facility operates at more 80 percent of the efficiency of the “best practice” facility, comparable to cost efficiency estimates that have been reported elsewhere for private-sector financial institutions.Federal Reserve banks - Costs ; Payment systems
A Simple Quantum Model of Ultracold Polar Molecule Collisions
We present a unified formalism for describing chemical reaction rates of
trapped, ultracold molecules. This formalism reduces the scattering to its
essential features, namely, a propagation of the reactant molecules through a
gauntlet of long-range forces before they ultimately encounter one another,
followed by a probability for the reaction to occur once they do. In this way,
the electric-field dependence should be readily parametrized in terms of a pair
of fitting parameters (along with a coefficient) for each asymptotic
value of partial wave quantum numbers . From this, the electric
field dependence of the collision rates follows automatically. We present
examples for reactive species such as KRb, and non-reactive species, such as
RbCs
Controversy between Puritans and Quakers to 1660
The Quaker-Puritan controversy began as soon as George Fox started
preaching, in 1647, but the major part of the polemical writings date
from 1653. All of the early Quaker leaders were engaged In the disputes, and all but the radical left wing of Puritan thought is represented. Host of the anti-Quaker writers can he classified as Congregationalists, Baptists, or Presbyterians. The basic Issues under dispute centered on theological and ecclesiological differences, but these
were complicated by political and social conflicts. The Quaker refusal
to pay tithes, to take oaths, or to give magistrates and others the
customary tokens of respect, caused the Qua leers to be frequently regarded as enemies to the State
Reconstruction of eye movements during blinks
In eye movement research in reading, the amount of data plays a crucial role
for the validation of results. A methodological problem for the analysis of the
eye movement in reading are blinks, when readers close their eyes. Blinking
rate increases with increasing reading time, resulting in high data losses,
especially for older adults or reading impaired subjects. We present a method,
based on the symbolic sequence dynamics of the eye movements, that reconstructs
the horizontal position of the eyes while the reader blinks. The method makes
use of an observed fact that the movements of the eyes before closing or after
opening contain information about the eyes movements during blinks. Test
results indicate that our reconstruction method is superior to methods that use
simpler interpolation approaches. In addition, analyses of the reconstructed
data show no significant deviation from the usual behavior observed in readers
Recommended from our members
Molecular Aspects of Transport in Thin Films of Controlled Architecture
Our laboratory focuses on developing spatially localized chemistries which can produce structures of controlled architecture on the supermolecular length scale -- structures which allow us to control the motion of molecular species with high spatial resolution, ultimately on nanometer length scales. Specifically, nanocapillary array membranes (NCAMs) contain an array of nanometer diameter pores connecting vertically separated microfluidic channels. NCAMs can manipulate samples with sub-femtoliter characteristic volumes and attomole sample amounts and are opening the field of chemical analysis of mass-limited samples, because they are capable of digital control of fluid switching down to sub-attoliter volumes; extension of analytical “unit operations” down to sub-femtomole sample sizes; and exerting spatiotemporal control over fluid mixing to enable studies of reaction dynamics. Digital flow switching mediated by nanocapillary array membranes can be controlled by bias, ionic strength, or pore diameter and is being studied by observing the temporal characteristics of transport across a single nanopore in thin PMMA membranes. The control of flow via nanopore surface characteristics, charge density and functional group presentation, is being studied by coupled conductivity and laser-induced fluorescence (LIF) measurements. Reactive mixing experiments previously established low millisecond mixing times for NCAM-mediated fluid transfer, and this has been exploited to demonstrate capture of mass-limited target species by Au colloids. Voltage and thermally-activated polymer switches have been developed for active control of transport in NCAMs. Thermally-switchable and size-selective transport was achieved by grafting poly(N-isopropylacrylamide) brushes onto the exterior surface of a Au-coated polycarbonate track-etched membrane, while the voltage-gated properties of poly(hydroxyethylmethacrylate) were characterized dynamically. Electrophoretic separations have been coupled to analyte sampling both by LIF and mass spectrometry. Detection of electrophoresis separation products by electrospray mass spectrometry was achieved through direct interfacing to an electrospray mass spectrometer. Pb(II) interactions with the DNAzyme have been realized in an NCAM-coupled integrated microfluidic structure allowing cation separations to be coupled to molecular beacon detection motifs for the determination of Pb(II) in an electroplating sludge reference material. By changing the DNAzyme to select for other compounds of interest, it is possible to incorporate multiple sensing systems within a single device, thereby achieving great flexibility
Inhibition of VEGF and Angiopoietin-2 to Reduce Brain Metastases of Breast Cancer Burden
For metastases in the central nervous system, angiogenesis enhances metastatic potential and promotes progression. Primary factors which drive vessel growth are vascular endothelial growth factor (VEGF) and angiopoietin-2. Preclinical models show inhibition of either factor reduces metastases spread and inhibits growth. This work sets out to answer two questions in a preclinical mouse model. First, whether the combined inhibition of VEGF and angiopoietin-2, reduces passive permeability and limits drug uptake into brain metastases; and second, whether this inhibition reduces metastases burden in brain. We observed combinatorial inhibition of VEGF and angiopoietin-2, decreased (p \u3c 0.05) angiogenesis and vascular branching in an aortic ring assay and decreased (p \u3c 0.05) endothelial wound closure times. Using a brain metastases of breast cancer model (induced by intracardiac injections of brain seeking MDA-MB-231Br cells or 4T1Br cells), we observed, similar to VEGF, angiopoetin-2 expression correlates to increased angiogenesis (p \u3c 0.05) and increased lesion permeability. To determine efficacy, animals were administered bevacizumab plus L1-10 (angiopoietin inhibitor) twice per week until neurological symptoms developed. Lesion permeability significantly decreased by ∼50% (p \u3c 0.05) compared to untreated lesions, but remained ∼25% greater (p \u3c 0.0%) than brain. In subsequent experiments, animals were administered similar regimens but sacrificed on day 32. The number of metastatic lesions developed was significantly (p \u3c 0.001) reduced in the bevacizumab group (56%) and combination group (86%). Lesions’ size was reduced in bevacizumab treated lesions (∼67%) and bevacizumab and L1-10 treated lesions (∼78%) developing area \u3c 0.5 mm2. In summary, combinatorial inhibition of VEGF and angiopoietin reduces lesion permeability and brain metastatic burden
Corticosterone Regulates Both Naturally Occurring and Cocaine‐Induced Dopamine Signaling by Selectively Decreasing Dopamine Uptake
Stressful and aversive events promote maladaptive reward‐seeking behaviors such as drug addiction by acting, in part, on the mesolimbic dopamine system. Using animal models, data from our laboratory and others show that stress and cocaine can interact to produce a synergistic effect on reward circuitry. This effect is also observed when the stress hormone corticosterone is administered directly into the nucleus accumbens (NAc), indicating that glucocorticoids act locally in dopamine terminal regions to enhance cocaine\u27s effects on dopamine signaling. However, prior studies in behaving animals have not provided mechanistic insight. Using fast‐scan cyclic voltammetry, we examined the effect of systemic corticosterone on spontaneous dopamine release events (transients) in the NAc core and shell in behaving rats. A physiologically relevant systemic injection of corticosterone (2 mg/kg i.p.) induced an increase in dopamine transient amplitude and duration (both voltammetric measures sensitive to decreases in dopamine clearance), but had no effect on the frequency of transient release events. This effect was compounded by cocaine (2.5 mg/kg i.p.). However, a second experiment indicated that the same injection of corticosterone had no detectable effect on the dopaminergic encoding of a palatable natural reward (saccharin). Taken together, these results suggest that corticosterone interferes with naturally occurring dopamine uptake locally, and this effect is a critical determinant of dopamine concentration specifically in situations in which the dopamine transporter is pharmacologically blocked by cocaine
Three Dimensional Molecular Imaging for Lignocellulosic Materials
The development of high efficiency, inexpensive processing protocols to render biomass components into fermentable substrates for the sequential processing of cell wall components into fuels and important feedstocks for the biorefinery of the future is a key goal of the national roadmap for renewable energy. Furthermore, the development of such protocols depends critically on detailed knowledge of the spatial and temporal infiltration of reagents designed to remove and separate the phenylpropenoid heteropolymer (lignin) from the processable sugar components sequestered in the rigid cell walls of plants. A detailed chemical and structural understanding of this pre-enzymatic processing in space and time was the focus of this program. We worked to develop new imaging strategies that produce real-time molecular speciation information in situ; extract sub-surface information about the effects of processing; and follow the spatial and temporal characteristics of the molecular species in the matrix and correlate this complex profile with saccharification. Spatially correlated SIMS and Raman imaging were used to provide high quality, high resolution subcellular images of Miscanthus cross sections. Furthermore, the combination of information from the mass spectrometry and Raman scattering allows specific chemical assignments of observed structures, difficult to assign from either imaging approach alone and lays the foundation for subsequent heterocorrelated imaging experiments targeted at more challenging biological systems, such as the interacting plant-microbe systems relevant to the rhizosphere
- …