9,867 research outputs found
From Divergence to Convergence: Re-evaluating the History Behind China's Economic Boom
China's long-term economic dynamics pose a formidable challenge to economic historians. The Qing Empire (1644-1911), the world's largest national economy prior to the 19th century, experienced a tripling of population during the 17th and 18th centuries with no signs of diminishing per capita income. In some regions, the standard of living may have matched levels recorded in advanced regions of Western Europe. However, with the Industrial Revolution a vast gap emerged between newly rich industrial nations and China's lagging economy. Only with an unprecedented growth spurt beginning in the late 1970s has the gap separating China from the global leaders been substantially diminished, and China regained its former standing among the world's largest economies. This essay develops an integrated framework for understanding this entire history, including both the long period of divergence and the more recent convergent trend. The analysis sets out to explain how deeply embedded political and economic institutions that had contributed to a long process of extensive growth subsequently prevented China from capturing the benefits associated with new technologies and information arising from the Industrial Revolution. During the 20th century, the gradual erosion of these historic constraints and of new obstacles created by socialist planning eventually opened the door to China's current boom. Our analysis links China's recent economic development to important elements of its past, while using the success of the last three decades to provide fresh perspectives on the critical obstacles undermining earlier modernization efforts, and their removal over the last century and a half.
Scaling and exact solutions for the flux creep problem in a slab superconductor
The flux creep problem for a superconductor slab placed in a constant or
time-dependent magnetic field is considered. Logarithmic dependence of the
activation energy on the current density is assumed, U=U0 ln(J/Jc), with a
field dependent Jc. The density B of the magnetic flux penetrating into the
superconductor, is shown to obey a scaling law, i.e., the profiles B(x) at
different times can be scaled to a function of a single variable. We found
exact solution for the scaling function in some specific cases, and an
approximate solution for a general case. The scaling also holds for a slab
carrying transport current I resulting in a power-law V(I) with exponent p~1.
When the flux fronts moving from two sides of the slab collapse at the center,
the scaling is broken and p crosses over to U0/kT.Comment: RevTex, 10 pages including 6 figures, submitted to Phys.Rev.
A catalog of Kazarian galaxies
The entire Kazarian galaxies (KG) catalog is presented which combines
extensive new measurements of their optical parameters with a literature and
database search. The measurements were made using images extracted from the
STScI Digitized Sky Survey (DSS) of Jpg(blue), Fpg(red) and Ipg(NIR) band
photographic sky survey plates obtained by the Palomar and UK Schmidt
telescopes. We provide accurate coordinates, morphological type, spectral and
activity classes, blue apparent diameters, axial ratios, position angles, red,
blue and NIR apparent magnitudes, as well as counts of neighboring objects in a
circle of radius 50 kpc from centers of KG. Special attention was paid to the
individual descriptions of the galaxies in the original Kazarian lists, which
clarified many cases of misidentifications of the objects, particularly among
interacting systems. The total number of individual Kazarian objects in the
database is now 706. We also include the redshifts which are now available for
404 galaxies and the 2MASS infrared magnitudes for 598 KG. The database also
includes extensive notes, which summarize information about the membership of
KG in different systems of galaxies, and about revised activity classes and
redshifts. An atlas of several interesting subclasses of KG is also presented.Comment: 15 pages, 5 figures, 1 table, Accepted in Astrophysics, Vol. 53, No.
1, 2010 (English translation of Astrofizika
Critical Buckling Load for Lattice Column Elements with Variable Dimensions
Lattice structures are used in a variety of high-value engineering applications; for example, in automobile, aerospace and biomedical applications, due to their light weight, high specific strength, stiffness, heat transfer control and energy absorption. Additive Manufacturing (AM) technologies, such as Selective Laser Melting (SLM), offer radical net-shape manufacturing solutions for metallic structures directly from digital data. The prediction of AM lattice structure mechanical properties prior to manufacture is both cost and time-consuming; particularly as existing models do not readily accommodate the effects of manufacturing defects and lattice node geometry on column buckling. The critical buckling load of columns was algebraically and numerically simulated for a full Design of Experiments (DOE) of independent variables, including column length, column radius, node radius and material type. This simulation data quantifies the effect of independent variables on critical buckling load and demonstrates the limitations of algebraically prediction. This research can be extended to allow the simulation of the load carrying capacity of entire lattice structures; and to accommodate the effect of manufacturing variation on the associated load carrying capacity of AM lattice structures
Parent formulation at the Lagrangian level
The recently proposed first-order parent formalism at the level of equations
of motion is specialized to the case of Lagrangian systems. It is shown that
for diffeomorphism-invariant theories the parent formulation takes the form of
an AKSZ-type sigma model. The proposed formulation can be also seen as a
Lagrangian version of the BV-BRST extension of the Vasiliev unfolded approach.
We also discuss its possible interpretation as a multidimensional
generalization of the Hamiltonian BFV--BRST formalism. The general construction
is illustrated by examples of (parametrized) mechanics, relativistic particle,
Yang--Mills theory, and gravity.Comment: 26 pages, discussion of the truncation extended, typos corrected,
references adde
First order parent formulation for generic gauge field theories
We show how a generic gauge field theory described by a BRST differential can
systematically be reformulated as a first order parent system whose spacetime
part is determined by the de Rham differential. In the spirit of Vasiliev's
unfolded approach, this is done by extending the original space of fields so as
to include their derivatives as new independent fields together with associated
form fields. Through the inclusion of the antifield dependent part of the BRST
differential, the parent formulation can be used both for on and off-shell
formulations. For diffeomorphism invariant models, the parent formulation can
be reformulated as an AKSZ-type sigma model. Several examples, such as the
relativistic particle, parametrized theories, Yang-Mills theory, general
relativity and the two dimensional sigma model are worked out in details.Comment: 36 pages, additional sections and minor correction
Independent Attacks in Imperfect Settings; A Case for A Two Way Quantum Key Distribution Scheme
We review the study on a two way quantum key distribution protocol given
imperfect settings through a simple analysis of a toy model and show that it
can outperform a BB84 setup. We provide the sufficient condition for this as a
ratio of optimal intensities for the protocols
An Assessment of Funding and Other Capacity Needs for Health Equity Programming Within State-Level Chronic Disease Programs
Background: Chronic diseases are an important contributor to morbidity and mortality among racial/ethnic minority, low-income, and other under-resourced populations. Given that state health departments (and their chronic disease programs) play a significant role in providing population and preventive health services, their capacity to promote health equity is an important consideration in national efforts to address chronic diseases. The purpose of this study was to examine capacity needs of state chronic disease programs with respect to promoting health equity.
Methods: In 2015, the National Association of Chronic Disease Directors (NACDD) conducted a survey of its members that work within a state chronic disease division (CDD) or the larger state health department. The survey was structured to provide information on major funding sources for chronic diseases, the extent to which key funders required a focus on health equity, dedicated staffing for health equity, and training and technical assistance needs of practitioners to support health equity integration in chronic disease programming. All data were analyzed using SPSS 19.0.
Findings: A total of 147 chronic disease directors and practitioners responded to the survey from 43 states, the District of Columbia and three of the U.S. Affiliated Territories and Commonwealths. Forty-two percent (N=25) of the 59 directors of state, territorial and tribal chronic disease programs at the time of the study responded. Only 52% of respondents believed their CDD adequately addressed health inequities. Among the 70 respondents who did not know or did not believe their health departments adequately addressed health inequities, barriers identified include insufficient funding (62%), inadequate training (54%), and health inequities not being a priority (22%). Respondents also identified opportunities to strengthen funding requirements to address health disparities
Conclusions: Overall, the data highlight some opportunities to enhance the capacity of state CDDs to promote health equity, such as through more direct funding requirements for health equity integration, staff training, increased funding, and specialized technical assistance. Because the response rate was less than 100%, we cannot generalize the findings to every state chronic disease program. However, the responses are relatable to their collective experience
Grain refinement of stainless steel in ultrasound-assisted additive manufacturing
Metals and alloys fabricated by fusion-based additive manufacturing (AM), or 3D printing, undergo complex dynamics of melting and solidification, presenting challenges to the effective control of grain structure. Herein, we report on the use of high-intensity ultrasound that controls the process of solidification during AM of 316L stainless steel. We find that the use of ultrasound favours the columnar-to-equiaxed transition, promoting the formation of fine equiaxed grains with random crystallographic texture. Moreover, the use of ultrasound increases the number density of grains from 305 mm−2 to 2748 mm−2 despite an associated decrease in cooling rate and temperature gradient in the melt pool during AM. Our assessment of the relationship between grain size and cooling rate indicates that the formation of crystallites during AM is enhanced by ultrasound. Furthermore, the use of ultrasound increases the amount of constitutional supercooling during solidification by lowering the temperature gradient in the bulk of the melt pool, thus creating an environment that favours nucleation, growth, and survival of grains. This new understanding provides opportunities to better exploit ultrasound to control grain structure in AM-fabricated metal products
Impact of novel psychoactive substances on clinical and forensic toxicology and global public health
Novel psychoactive substances (NPS) have been a part of the landscape of clinical and forensic toxicology for over a century, beginning with the introduction of a few new drugs like heroin, lysergic acid diethylamide (LSD), 3,4-methylenedioxymethamphetamine (MDMA) and gammahydroxybutyric acid (GHB). However, after the appearance of synthetic cannabinoids in the early 2000’s there was a rapid emergence of hundreds of synthetic cathinones, benzodiazepines and opioids. Toxicology laboratories previously focused on a rather narrow range of compounds including amphetamines, cannabinoids, cocaine, opioids, antidepressants, salicylate and acetaminophen. Now potent fentanyl derivatives are mixed with heroin or substituted entirely, killing unsuspecting drug users at an alarming rate. Toxicology laboratories are challenged with detecting potent drug analogs that are only present in blood for a short period of time, urinary metabolites whose chemical formula and structures are initially unknown, and no available reference standards. Here four international experts discuss what fueled the global NPS market, how toxicology laboratories can best address this challenge, and how public health and law enforcement agencies can help reduce the morbidity and mortality associated with NPS
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