bluuebunny/crossref_metadata_2025 huggingface dataset:
Measuring How Fiscal Shocks Affect Durable Spending in Recessions and Expansions
Authors: Berger David , Vavra Joseph
Published: May 2014

We estimate how durable expenditures respond to government spending shocks at different points in the business cycle using a nonlinear VAR approach that allows for the durable multiplier to vary smoothly with the state of the economy. We find strong evidence that the aggregate durable spending response to fiscal shocks is substantially larger during expansions than during recessions, in contrast to what has been has been observed for the aggregate multiplier. We argue that these results are consistent with the theoretical predictions of the fixed cost model of durable demand in Berger and Vavra (2012).
Health, Human Capital, and Life Cycle Labor Supply
Authors: Hokayem Charles , Ziliak James P.
Published: May 2014

We use new PSID data on consumption and health, along with information on annual sick time, to estimate a structural labor supply model that incorporates a health capital stock with the traditional human capital learning-by-doing model. The estimates show strong evidence of learning by doing as well as strong persistence in health. However, the estimates reveal that time and money seem to have little effect on health consistent with 'flat of the curve' medicine. We find strong evidence that consumption and leisure are direct substitutes in preferences, and consumption and leisure are each utility complements with good health.
The Intergenerational Correlation of Consumption Expenditures
Authors: Charles Kerwin Kofi , Danziger Sheldon , Li Geng , Schoeni Robert
Published: May 2014

Using data recently collected by the Panel Study of Income Dynamics, we find that the intergenerational correlation in expenditures is no larger than that in income, suggesting limited intra-family risk-sharing. On the other hand, even after controlling for the intergenerational correlation in income, the expenditures correlation remains significant. This suggests that other factors such as preferences, access to credit, and non-pecuniary inter vivos transfers potentially played a role in consumption smoothing across generations within a family. We also find that the correlation coefficients estimated using food and imputed total expenditures are smaller than that estimated using the measured total expenditures.
How Risky Are Recessions for Top Earners?
Authors: Guvenen Fatih , Kaplan Greg , Song Jae
Published: May 2014

How sensitive to business cycles are the earnings of top earners? And, how does the business cycle sensitivity of top earners vary by industry? We use a confidential dataset on earnings histories of US males from the Social Security Administration. On average, individuals in the top 1 percent of the earnings distribution are slightly more cyclical than the population average. But there are large differences across sectors; top earners in Finance, Insurance, and Real Estate (FIRE) and Construction face substantial business cycle volatility, whereas those in Services (who make up 40 percent of individuals in the top 1 percent) have earnings that are less cyclical than the average worker.
Agricultural Productivity Differences across Countries
Authors: Gollin Douglas , Lagakos David , Waugh Michael E.
Published: May 2014

Recent studies argue that cross-country labor productivity differences are much larger in agriculture than in the aggregate. We reexamine the agricultural productivity data underlying this conclusion using new evidence from disaggregate sources. We find that for the world's staple grains-maize, rice, and wheat-cross-country differences in the quantity of grain produced per worker are enormous according to both micro- and macrosources. Our findings validate the idea that understanding agricultural productivity is at the heart of understanding world income inequality.
Physician Payment Reform and Hospital Referrals
Authors: Ho Kate , Pakes Ariel
Published: May 2014

Commercial health insurers in California use provider capitation payments to different extents. These are similar to arrangements introduced by the recent health reforms to give physicians incentives to control costs. In a previous paper we showed that patients whose insurers used capitation incentives traveled further to access lower-priced, similar-quality hospitals than other same-severity patients. This paper predicts the implied effects of a move to widespread capitation. We show that, if the introduction of capitation prompted low-capitation insurers to act like high-capitation insurers, this would generate a 4-5 percent cost saving with some reduction in patient convenience but no reduction in quality.
The Determinants of the Macroeconomic Implications of Aging
Authors: Sheiner Louise
Published: May 2014

The aging of the US population undoubtedly will be associated with macroeconomic changes. In particular, some combination of lower consumption growth and increased labor input will ultimately be required. But, the timing of these changes can have important effects on variables like the rate of return to capital and wages. If the adjustment to consumption is slow, which would be the case if budget deficits were allowed to rise significantly as the population ages, then aging is likely to be associated with an increase in the return to capital and a reduction in wages.
Aging in Europe: Reforms, International Diversification, and Behavioral Reactions
Authors: Börsch-Supan Axel , Härtl Klaus , Ludwig Alexander
Published: May 2014

The extent of demographic changes in Europe is much more drastic than in the United States. This paper studies the effects of population aging on the interactions between economic growth and living standards in Europe with labor market and pension reform, behavioral adaptations, and international capital flows. Our analysis is based on an overlapping generations model with behavioral reactions to reform which is extended to the multi-country situation typical for Europe. While the negative effects of population aging on growth in Europe can in principle be compensated by reforms and economic adaptation mechanisms, they may be partially offset by behavioral reactions.
Does the US Labor Market Reward International Experience?
Authors: Pozo Susan
Published: May 2014

A typical strategy for measuring the returns to international experience--comparing the earnings of returning migrants to comparable non-migrants--has been criticized for not adequately accounting for self-selection. I suggest an alternative, testing whether individuals born beyond US borders, but into US citizenship, earn more in US labor markets relative to counterparts born on US soil. Those born abroad to US citizens did not self-select an international experience. Using the ACS, I find that the US market rewards international experience, especially in occupations that value creativity and innovation. Women, in particular, are handsomely rewarded for international human capital.
Rainfall Forecasts, Weather, and Wages over the Agricultural Production Cycle
Authors: Rosenzweig Mark R. , Udry Christopher
Published: May 2014

We look at the effects of rainfall forecasts and realized rainfall on equilibrium agricultural wages over the course of the agricultural production cycle. We show theoretically that a forecast of good weather can lower wages in the planting stage, by lowering ex ante out-migration, and can exacerbate the negative impact of adverse weather on harvest-stage wages. Using Indian household panel data describing early-season migration and district-level planting- and harvest-stage wages over the period 2005-2010, we find results consistent with the model, indicating that rainfall forecasts improve labor allocations on average but exacerbate wage volatility because they are imperfect.
Dynamics of Demand for Index Insurance: Evidence from a Long-Run Field Experiment
Authors: Cole Shawn , Stein Daniel , Tobacman Jeremy
Published: May 2014

This paper estimates how experimentally-manipulated experiences with a novel financial product, rainfall index insurance, affect subsequent insurance demand. Using a seven-year panel, we develop three main findings. First, recent experience matters for demand, consistent with overinference from small samples. Second, spillovers also matter, in the sense that the recent payout experience of village co-residents affects insurance demand about as much as one's own recent payout experience. Third, the spillover effect decays as time passes while the effect of one's own experience does not. We discuss implications of this analysis for commercial sustainability of this complicated but promising risk management technology.
Together at Last: Trade Costs, Demand Structure, and Welfare
Authors: Mrázová Monika , Neary J. Peter
Published: May 2014

We show that relaxing the assumption of CES preferences in monopolistic competition has surprising implications when trade is restricted. Integrated and segmented markets behave differently, the latter typically exhibiting reciprocal dumping. Globalization and lower trade costs have different effects. The former reduces spending on all existing varieties, the latter switches spending from home to imported varieties; when demands are less convex than CES, globalization raises whereas lower trade costs reduce firm output. Finally, calibrating gains from trade is harder. Many more parameters are needed, while import demand elasticities typically overestimate the true elasticities, and so underestimate the gains from trade.
The Impact of Medicaid on Labor Market Activity and Program Participation: Evidence from the Oregon Health Insurance Experiment
Authors: Baicker Katherine , Finkelstein Amy , Song Jae , Taubman Sarah
Published: May 2014

In 2008, a group of uninsured low-income adults in Oregon was selected by lottery for the chance to apply for Medicaid. Using this randomized design and 2009 administrative data, we find no significant effect of Medicaid on employment or earnings. Our 95 percent confidence intervals allow us to reject that Medicaid causes a decline in employment of more than 4.4 percentage points, or an increase of more than 1.2 percentage points. Medicaid increases food stamps receipt, but has little, if any, impact on receipt of other measured government benefits, including SSDI.
Trends in Earnings Differentials across College Majors and the Changing Task Composition of Jobs
Authors: Altonji Joseph G. , Kahn Lisa B. , Speer Jamin D.
Published: May 2014

We show that, among college graduates, earnings differentials across field of study have increased substantially since the early 1990s. We study the degree to which this increase can be accounted for by changes in the labor market return to skills associated with a major. To do so, we define major-specific measures of the relative importance of abstract, routine, and manual tasks on the job, by linking majors to the occupations they typically lead to. Changes in the relationship between earnings and these measures can account for about two-thirds of the rise in inequality.
Implementation Details for Frequent Batch Auctions: Slowing Down Markets to the Blink of an Eye
Authors: Budish Eric , Cramton Peter , Shim John
Published: May 2014

Our recent research (Budish, Cramton, and Shim 2013) proposes frequent batch auctions - uniform-price sealed-bid double auctions conducted at frequent but discrete time intervals - as a market design alternative to continuous-time trading in financial markets. This short paper discusses the implementation details of frequent batch auctions. We outline the process flow for frequent batch auctions, discuss a modification to the market design that accommodates market fragmentation and Reg NMS, and discuss the engineering and economic considerations relevant for determining the batch interval. Open questions are discussed throughout.
Getting More Organs for Transplantation
Authors: Kessler Judd B. , Roth Alvin E.
Published: May 2014

Organs for transplantation are a scarce resource. Paying to increase the supply of organs is illegal in much of the world. We review efforts to increase transplantation by increasing the supply of available organs from living and deceased donors. Progress has been made in increasing the availability of living donor kidneys through kidney exchange. Recent legislation in Israel aims at encouraging deceased donation by awarding priority for receiving organs to registered donors. We also explore the manner in which organ donation is solicited and present evidence to suggest that some recent movement towards 'mandated choice' may be counterproductive.
Growth, Adoption, and Use of Mobile E-Commerce
Authors: Einav Liran , Levin Jonathan , Popov Igor , Sundaresan Neel
Published: May 2014

We document some early effects of how mobile devices might change Internet and retail commerce. We present three main findings based on an analysis of eBay's mobile shopping application and core Internet platform. First, early adopters of mobile e-commerce applications appear to be people who already were relatively heavy Internet commerce users. Second, adoption of the mobile shopping application is associated with both an immediate and sustained increase in total platform purchasing, with little evidence of substitution from the core platform. Third, differences in user behavior across the mobile applications and the regular Internet site are not yet so dramatic.
The Economics of Online Postsecondary Education: MOOCs, Nonselective Education, and Highly Selective Education
Authors: Hoxby Caroline M.
Published: May 2014

I consider economically sustainable online postsecondary education, including massive open online courses (MOOCs). The analysis suggests that MOOCs will be financially sustainable substitutes for some non-selective postsecondary education, but there are substantial risks. The analysis suggests that MOOCs will be financially sustainable substitutes for only a small share of highly selective postsecondary education (HSPE) and are likely to collapse the economic model that allows HSPE institutions to invest in advanced education and research. I outline a non-MOOC model of online education that may allow HSPE institutions to sustain their distinctive activities and to reach a larger number of students.
Declining Discount Rates
Authors: Cropper Maureen L. , Freeman Mark C. , Groom Ben , Pizer William A.
Published: May 2014

We ask whether the US government should replace its current discounting practices with a declining discount rate schedule, as the United Kingdom and France have done, or continue to discount the future at a constant exponential rate. We present the theoretical basis for a declining discount rate (DDR) schedule, but focus on how, in practice, a DDR could be estimated for use by policy analysts. We discuss the empirical approaches in the literature and review how the United Kingdom and France estimated their DDR schedules. We conclude with advice on how the United States might proceed to consider modifying its current discounting practices.
On Not Revisiting Official Discount Rates: Institutional Inertia and the Social Cost of Carbon
Authors: Sunstein Cass R.
Published: May 2014

Within the federal government, official decisions are a product of both substantive judgments and institutional constraints. With respect to discounting, current practice is governed by OMB Circular A-4 and the 2010 and 2013 technical support documents of the Interagency Working Group on the Social Cost of Carbon. Reconsideration of existing judgments must be subjected to a demanding process of internal review (and potentially to external review as well). Institutional constraints, including the need to obtain consensus, can impose obstacles to efforts to rethink existing practices, especially in an area like discounting, which is at once technical and highly controversial. Both decisions costs and error costs must be considered.
The Economic Cost of Global Fuel Subsidies
Authors: Davis Lucas W.
Published: May 2014

By 2015, global oil consumption will reach 90 million barrels per day. In part, this high level of consumption reflects the fact that many countries provide subsidies for gasoline and diesel. This paper examines global fuel subsidies using the latest available data from the World Bank, finding that road-sector subsidies for gasoline and diesel totaled $110 billion in 2012. Pricing fuels below cost is inefficient because it leads to overconsumption. Under baseline assumptions about supply and demand elasticities, the total annual deadweight loss worldwide is $44 billion. Incorporating external costs increases the economic costs substantially.
Why Are Power Plants in India Less Efficient than Power Plants in the United States?
Authors: Chan Hei Sing (Ron) , Cropper Maureen L. , Malik Kabir
Published: May 2014

India's coal-fired generating capacity doubled between 1990 and 2010 and currently accounts for 70 percent of electricity produced. Despite this, thermal efficiency at state-owned coal-fired power plants in India is significantly lower than at plants in the United States. When matched on age and capacity, heat input per kWh was 8 percent higher at Indian plants between 1997 and 2009. This can only partly be explained by the lower heat content of Indian coal. Electricity sector restructuring in the United States improved thermal efficiency at investor-owned plants; however, electricity sector restructuring in India has yet to improve thermal efficiency at state-owned coal-fired power plants.
Mandated Risk Retention in Mortgage Securitization: An Economist's View
Authors: Willen Paul
Published: May 2014

I evaluate the empirical premise and the economic logic of the Dodd-Frank Act's requirement that issuers of asset-backed securities retain credit risk.
Is It Too Late to Bail Out the Troubled Countries in the Eurozone?
Authors: Conesa Juan Carlos , Kehoe Timothy J.
Published: May 2014

In January 1995, US President Bill Clinton organized a bailout for Mexico that imposed penalty interest rates and induced the Mexican government to reduce its debt, ending the debt crisis. Can the Troika (European Commission, European Central Bank, and International Monetary Fund) organize similar bailouts for the troubled countries in the eurozone? Our analysis suggests that debt levels are so high that bailouts with penalty interest rates could induce the eurozone governments to default rather than reduce their debt. A resumption of economic growth is one of the few ways that the eurozone crises can end.
Study to find the Optimal Purification Processing Conditions of Anthocyanin from Bokbunja Byproducts
Authors: Kim Hee-Sun , Kang Eun-Jin , Kim Won-Suk , Kim Myung-Hwan
Published: May 2014

This study was performed to determine the purification yield, color value, and total anthocyanin content of purified anthocyanins from Bokbunja byproducts for analyzing the optimal conditions of purification processing by response surface methodology (RSM) based on HCl or trifluoroacetic acid (TFA) concentration as an acidulent and ethanol concentration as an eluent. From the results of purification yield, color value, and total anthocyanin content of the purified anthocyanins, it was shown that HCl was better than TFA for purification processing from Bokbunja byproducts and the optimal concentration range of ethanol was 60-75%. The optimal purification conditions for HCl or TFA, ethanol concentration, and overall desirability by analysis of multiple response surface methodology with the same weighed value for each dependent variable were 0.84%, 73.12% and 0.77 for HCl acidulent and 1.00%, 60.75%, and 0.96 for TFA acidulent, respectively.
Quality and Antioxidant Property of Gelatin Jelly Incorporated with Jujube Concentrate
Authors: Choi Ji Eun , Lee Jun Ho
Published: May 2014

The feasibility of incorporating jujube concentrate (JC) as a value-added food ingredient in convenience food products was investigated using a model system of gelatin jelly. With an increasing level of JC added, the pH, moisture content, and lightness gradually decreased while the soluble solids content increased (p < 0.05). Hardness and total polyphenol content also increased significantly with a higher amount of JC in the formulation (p < 0.05). A consumer acceptance test indicated that the addition of JC had a favorable effect on consumer preferences in all attributes. Jelly with 20% JC is recommended (with respect to the overall preference score) for taking advantage of the functional properties of JC without sacrificing consumer acceptability.
Development and Validation of a New HPV Genotyping Assay Based on Next-Generation Sequencing
Authors: Yi Xin , Zou Jing , Xu Jiajia , Liu Tao , Liu Tengfei , Hua Sang , Xi Feng , Nie Xifang , Ye Lili , Luo Yufen , Xu Lin , Du Hui , Wu Ruifang , Yang Ling , Liu Ren , Yang Bin , Wang Jian , Belinson Jerome L.
Published: May 2014

Objectives:

We developed a new human papillomavirus (HPV) genotyping assay based on multiplex polymerase chain reaction and next-generation sequencing (NGS) methods for large-scale cervical cancer screening.

Methods:

We first trained the assay on 1,170 self-collected samples, balancing the cutoff points for high-risk types. Then using 4,262 separate self-collected specimens, we compared concordance, sensitivity, and specificity for cervical intraepithelial neoplasia type 2 (CIN2) or higher and CIN type 3 (CIN3) or higher of the HPV sequencing assay with that of Hybrid Capture 2 (HC2) direct samples and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry assay self-samples.

Results:

All assays had a good agreement. The sensitivity for CIN2 or higher and CIN3 or higher of the self-sampling specimens tested with the sequencing assay run on both MiSeq and Ion Torrent Personal Genome Machine sequencer was similar to that of direct-sampling specimens tested with HC2 (P > .05), but the specificity of the sequencing assay for CIN2 or higher and CIN3 or higher was significantly higher than that of HC2 (P < .01).

Conclusions:

This population-based study has demonstrated the applicability of a new NGS high-risk HPV assay for primary cervical cancer screening based on self-collection.
Evaluation of CITED1, SIX1, and CD56 Protein Expression for Identification of Blastemal Elements in Wilms Tumor
Authors: Sehic Daniel , Ciornei Cristina D. , Gisselsson David
Published: May 2014

Objectives:

Successful further treatment of Wilms tumors (WTs) after preoperative chemotherapy and surgery depends on correct histopathologic risk stratification, including quantification of remaining blastemal elements. In the present study, we assessed the usefulness of protein markers for the detection of WT blastema.

Methods:

Expression of the candidate blastemal protein markers CITED1, SIX1, and CD56 was evaluated by immunofluorescence regarding sensitivity and specificity for staining blastema in a tissue microarray containing cores from 30 WTs, a small number of rarer pediatric renal neoplasms, and normal postnatal kidney.

Results:

CITED1, SIX1, and CD56 were expressed in blastema in 100%, 89%, and 74%, respectively, of the WTs with this component present. However, they were also expressed in 64%, 25%, and 79%, respectively, of epithelial WT elements and 48%, 52%, and 62%, respectively, of stromal WT elements.

Conclusions:

SIX1 showed the highest specificity, CITED1 the highest sensitivity, and CD56 low specificity and sensitivity for detection of postchemotherapy WT blastema. Cytokeratin staining proved to be a useful way to determine rudimentary tubular elements not readily recognized by routine staining.
The role of intermediaries in sectoral innovation system: The case of Thailand’s food industry
Authors: Chunhavuthiyanon Manunya , Intarakumnerd Patarapong
Published: May 2014

Unlike previous snapshot studies, this research traces ‘historical learning events’ to enable us to examine the evolution of roles and underpinning capabilities of intermediaries in an innovation system. By following this approach, the rationale, obstacles and lessons learned of intermediaries in performing their roles and building up required capabilities can be vividly illustrated. The National Food Institute (NFI) of Thailand was selected as the case study. As an intermediary organization, NFI has enhanced its capabilities step by step in analysing and disseminating information, training, testing policy development and consultancies through major ‘learning events’ that provide NFI with learning opportunities. As a result, over time it can perform its intermediary roles better by reducing ‘systemic failures’ in the Thai food industry’s sectoral innovation system. Recently, however, due to the lack of an official mandate, continuous government budgetary support and organizational lock-in problems, NFI’s role has not evolved with the changes in strategies and capability needs of Thai food exporters as these firms change from OEM to OBM manufacturers.
Understanding development trajectories for biotechnology governance frameworks in Sub-Saharan Africa: The policy kinetics model
Authors: Mugwagwa Julius , Kingiri Ann , Muraguri Lois
Published: May 2014

Using case studies on development and implementation of biotechnology governance frameworks in four African countries, we introduce and build the case for a policy kinetics (PK) approach to analysing and unpacking complex policy processes. The PK approach proposes a comprehensive approach to understanding how various ‘pieces of the policy puzzle’ interact in arenas to facilitate or constrain attainment of desired outputs. Borrowing from reaction kinetics in chemistry, which is the study of rates of chemical processes, our argument is that complex policy processes can indeed be broken down into reactants, processes, catalysts and outputs, all interacting at various levels in space and time. We also bring attention to the presence of various intermediate outputs of processes with the potential to facilitate or constrain the process, including bringing a shift to the direction, duration and pace of the overall process. The presence or potential emergence of components that mimic process catalysts is another area that this approach brings to the attention of policy actors. By engaging with what happens at the level where the various components of a policy process interface with each other, we argue that this model is a useful tool for unpacking, understanding and influencing not only the development and implementation of biotechnology governance mechanisms in Africa, but other policy arenas elsewhere.
Diffusion of solar innovations in Ethiopia: Exploring systemic problems
Authors: Kebede Kassahun Y. , Mitsufuji Toshio
Published: May 2014

Previous studies have shown that the global diffusion of renewable energy technologies has been rather slow. The challenges facing the diffusion of renewables in developing countries, in particular, have been complex, even though such nations are generally known to be richly endowed with renewable resources. For instance, Ethiopia, one of the highest solar radiation-endowed countries in sub-Saharan Africa, has a huge renewable potential that has yet to be exploited through the application of appropriate renewable energy technologies. This study is an attempt to explore the systemic problems and barriers affecting the diffusion of solar (energy) innovations in Ethiopia. The Innovation Systems (IS) framework is used for the analysis of this embryonic solar market and the overall diffusion of solar innovations. Data for the study were collected from the relevant stakeholders through semi-structured interviews, observations and archival document reviews. The study identified that there are known diffusion barriers and systemic problems that have constrained the diffusion of solar innovations in the country. The lack of integration among solar actors and the financial problem facing both sides of the supply chain have been identified as critical factors behind the slow rate of diffusion. This article makes recommendations for solar actors to identify faster diffusion mechanisms and for further research on how to build a well-functioning IS in the country.
Lessons learned from extracorporeal membrane oxygenation as a bridge to lung transplantation
Authors: Shumaster Vladimir , Jawitz Oliver K. , Yuh David , Bonde Pramod
Published: May 2014

Extracorporeal membrane oxygenation (ECMO) has been used infrequently as a bridge to lung transplantation due to lack of consensus and data regarding the benefits of such a strategy. We present data from the United Network of Organ Sharing (UNOS) database on the outcomes of patients bridged to lung transplantation with ECMO. We used the UNOS database to analyze data between January 1, 2000 and December 31, 2011. During this time 14,263 lung transplants were performed, of which 143 (1.0%) were bridged using ECMO. Patients on ECMO as a bridge to lung transplantation were compared to those transplanted without prior ECMO support. Demographics, survival rates, complications, and rejection episodes were compared between the two groups. The 30-day, 6-month, 1-year, 3-year, and 5-year survival rates were 69%, 56%, 48%, 26%, and 11%, respectively, for the ECMO bridge group and 95%, 88%, 81%, 58%, and 38% respectively, for the control group (p ≤ 0.01). The ECMO group incurred higher rate of postoperative complications, including airway dehiscence (4% vs. 1%, p ≤ 0.01), stroke (3% vs. 2%, p ≤ 0.01), infection (56% vs. 42%, p ≤ 0.01), and pulmonary embolism (10% vs. 0.6%, p ≤ 0.01). The length of hospital stay was longer for the ECMO group (41 vs. 25 days, p ≤ 0.01), and they were treated for rejection more often (49% vs. 36%, p = 0.02). The use of ECMO as a bridge to lung transplantation is associated with significantly worse survival and more frequent postoperative complications. Therefore, we advocate very careful patient selection and cautious use of ECMO.
The algebra and model theory of tame valued fields
Authors: Kuhlmann Franz-Viktor
Published: May 2014

A henselian valued field K is called a tame field if its algebraic
closure

K
~

${\tilde{K}}$

is a tame extension, that is, the ramification field
of the normal extension

K
~

|
K

${\tilde{K}|K}$

is algebraically closed. Every
algebraically maximal Kaplansky field is a tame field, but not
conversely. We develop the algebraic theory of tame fields and then
prove Ax–Kochen–Ershov Principles for tame fields. This
leads to model completeness and completeness results
relative to value group and residue field. As the maximal immediate
extensions of tame fields will in general not be unique, the proofs
have to use much deeper valuation theoretical results than those
for other classes of valued fields which have already been shown to
satisfy Ax–Kochen–Ershov Principles. The results of this paper have
been applied to gain insight in the Zariski space of places of an
algebraic function field, and in the model theory of large fields.
The least common multiple of consecutive quadratic progression terms
Authors: Hong Shaofang , Qian Guoyou
Published: May 2014

Let k be an arbitrary positive integer and let

f
(
x
)
∈
ℤ
[
x
]

${f(x)\in {\mathbb {Z}}[x]}$

be a quadratic polynomial with a and D as its
leading coefficient and discriminant, respectively. Associated to
the least common multiple

lcm

0
≤
i
≤
k

{
f

(
n
+
i
)

}

${\operatorname{lcm}_{0\le i\le k}\lbrace f(n+i)\rbrace }$

of any

k
+
1

${k+1}$

consecutive terms in the quadratic progression

{
f

(
n
)

}

n
∈

ℕ
*

${\lbrace f(n)\rbrace _{n\in \mathbb {N}^*}}$

, we define the function

g

k
,
f

(
n
)

:
=

∏

i
=
0

k

|
f

(
n
+
i
)

|

1

lcm

0
≤
i
≤
k

{
f

(
n
+
i
)

}

$
{g_{k, f}(n):= \Biggl (\prod _{i=0}^{k}|f(n+i)|\Biggr )
\frac{1}{\operatorname{lcm}_{0\le i\le k}\lbrace f(n+i)\rbrace }}
$

for all

n
∈

ℕ
*

∖

Z

k
,
f

${n\in \mathbb {N}^*\setminus Z_{k, f}}$

, where

Z

k
,
f

:
=

⋃

i
=
0

k

{
n
∈

ℕ
*

:
f

(
n
+
i
)

=
0
}

${Z_{k,f}:= \bigcup _{i=0}^k\lbrace n\in \mathbb {N}^*: f(n+i)=0\rbrace }$

.
In this paper, we first show that g

k,f
is eventually periodic
if and only if

D
≠

a
2

i
2

${D\ne a^2i^2}$

for all integers i with

1
≤
i
≤
k

${1\le i\le k}$

.
Consequently, we develop a detailed p-adic analysis of g

k,f
and
determine its smallest period. Finally, we obtain asymptotic formulas of

log

lcm

0
≤
i
≤
k

{
f

(
n
+
i
)

}

${\log \operatorname{lcm}_{0\le i\le k}\lbrace f(n+i)\rbrace }$

for all quadratic polynomials
f as n goes to infinity.
Influence of carboxylic group content on the solution behavior of carboxymethylated lignin (CML) in water
Authors: Gan Linhuo , Zhou Mingsong , Qiu Xueqing
Published: May 2014

Carboxymethylated lignin (CML) is well suited as a dispersant or natural adsorbent applied in ceramics, gypsum paste, graphite suspension, and water treatment. In this paper, the effects of COOH content in CML on its behavior in water and the dispersion stability of aqueous graphite suspension has been investigated by means of viscosimetry, surface tension measurement, fluorescence spectrometry, dynamic light scattering (DLS), Turbiscan Lab Expert (TLE) stability analysis, and ζ potential measurement. Viscosimetry clearly revealed the polyelectrolyte effect in diluted aqueous solution of CML. With a higher COOH content of CML, the surface tension of water is reduced. Moreover, the aggregation behavior of CML was strengthened with increasing COOH content, leading to a more compact molecular structure of the aggregates. Based on the results, an aggregation model was proposed to illustrate the variations in the solution behavior of CML with different COOH contents at various concentrations. The dispersion stability of aqueous graphite suspension was improved by adding CML with high COOH content.
On the Correction of the Asymptotic Distribution of the Likelihood Ratio Statistic If Nuisance Parameters Are Estimated Based on an External Source
Authors: Jonker Marianne , Van der Vaart Aad
Published: May 2014

In practice, nuisance parameters in statistical models are often replaced by estimates based on an external source, for instance if estimates were published before or a second dataset is available. Next these estimates are assumed to be known when the parameter of interest is estimated, a hypothesis is tested or confidence intervals are constructed. By this assumption, the level of the test is, in general, higher than supposed and the coverage of the confidence interval is too low. In this article, we derive the asymptotic distribution of the likelihood ratio statistic if the nuisance parameters are estimated based on a dataset that is independent of the data used for estimating the parameter of interest. This distribution can be used for correctly testing hypotheses and constructing confidence intervals. Four theoretical and practical examples are given as illustration.
A Comparative Study of Mathematical Modeling of Photovoltaic Array
Authors: Anurag Anup , Bal Satarupa , Sourav Suman
Published: May 2014

This paper provides a detailed and comprehensive study of various models of photovoltaic (PV) array which have been formulated previously in the literature, using the datasheet parameters. In this paper, comparisons of the models have been made on basis of the MPP tracking, the root mean square deviation (RMSD) from the experimental data, the Fill Factor (FF), the efficiency of the model and the time required for simulation. Further, the resemblance with the actual P–V and I–V curves, as obtained on the basis of experimental data, has also been included in this analysis. On the basis of all these, the best model that can be used for simulation purposes, keeping in mind the necessary factors for a particular application, can be selected. It is envisaged that the work can be very useful for professionals who require simple and accurate PV simulators for their design. This paper is also intended to be a useful tool for the beginners who require a clear and logical insight regarding the working and modeling of PV cells. All the systems here are modeled and simulated in MATLAB/Simulink environment.
Performance Analysis of the Water Supply System of a Dairy Company by Means of an Advanced Simulation Tool
Authors: Marchini Davide , Rinaldi Marta , Montanari Roberto , Bottani Eleonora , Solari Federico
Published: May 2014

This work presents the result of a research project, concerning the development of a simulation model for a water supply system of a dairy company, located in Parma, Italy. The approach developed allows investigating, through process simulation, the plant areas where the efficiency of the water supply system can be significantly improved by means of some simple interventions. The final objective is to reduce the water consumption of the plant; this represents a relevant issue to the dairy industry. In line with this goal, at first the simulation model was used to reproduce the current (AS IS) system, so as to reach a precise knowledge of the water flows in the plant. In the second part of the work, a series of alternative (TO BE) scenarios was investigated, and the related performance was assessed, thus identifying the best plant configuration. The process simulator was designed under Microsoft Excel, programmed with Visual Basic for Applications. Thanks to the study implemented, an optimal scenario of the water supply system was finally identified, which allows savings up to 7.2% of water compared to the original configuration.
Middlemen in the Shapley-Shubik Competitive Markets for Indivisible Goods
Authors: Oishi Takayuki , Sakaue Shin
Published: May 2014

We generalize the Shapley-Shubik market model for indivisible goods by
considering the case where agents need middlemen to exchange their
indivisible goods. In this model, there always exist competitive equilibria
in which transaction takes place directly between sellers and buyers or
indirectly through the middlemen. Furthermore, the incentives of middlemen
to enter the market exist. We derive these results from the existence of an
integral solution for a partitioning linear program.
Crowned Dens Syndrome
Authors: Koyfman Anna , Yaffe Daniel
Published: May 2014

Crystal deposition in the cervical spine around the odontoid process may lead to acute neck pain. This rare condition is called crowned dens syndrome and should be considered in the differential diagnosis of a possible etiology for fever, headache and cervical pain of unknown origin. The syndrome is often overlooked, thus leading to misdiagnosis, invasive and useless investigations (lumbar puncture, biopsy), inappropriate treatment (steroids, antibiotics, antiviral drugs) and prolonged hospitalization. This can be prevented by imaging, based on a cervical CT scan that allows an accurate diagnosis. The disease has a good prognosis and symptoms usually subside within a few weeks. We describe a patient with crowned dens syndrome which manifested with clinical (acute occipital headache) and radiographic (calcium deposits in the alar ligament) features. Our patient recovered in four days with symptomatic therapy.
A Powerful and Adaptive Association Test for Rare Variants
Authors: Pan Wei , Kim Junghi , Zhang Yiwei , Shen Xiaotong , Wei Peng
Published: May 2014

This article focuses on conducting global testing for association between a binary trait and a set of rare variants (RVs), although its application can be much broader to other types of traits, common variants (CVs), and gene set or pathway analysis. We show that many of the existing tests have deteriorating performance in the presence of many nonassociated RVs: their power can dramatically drop as the proportion of nonassociated RVs in the group to be tested increases. We propose a class of so-called sum of powered score (SPU) tests, each of which is based on the score vector from a general regression model and hence can deal with different types of traits and adjust for covariates, e.g., principal components accounting for population stratification. The SPU tests generalize the sum test, a representative burden test based on pooling or collapsing genotypes of RVs, and a sum of squared score (SSU) test that is closely related to several other powerful variance component tests; a previous study (Basu and Pan 2011) has demonstrated good performance of one, but not both, of the Sum and SSU tests in many situations. The SPU tests are versatile in the sense that one of them is often powerful, although its identity varies with the unknown true association parameters. We propose an adaptive SPU (aSPU) test to approximate the most powerful SPU test for a given scenario, consequently maintaining high power and being highly adaptive across various scenarios. We conducted extensive simulations to show superior performance of the aSPU test over several state-of-the-art association tests in the presence of many nonassociated RVs. Finally we applied the SPU and aSPU tests to the GAW17 mini-exome sequence data to compare its practical performance with some existing tests, demonstrating their potential usefulness.
Study of grain growth and defect formation in Ag thin films by planar TEM with in-situ heating
Authors: Brossard S. , Martin F. , Bourgon J.
Published: May 2014

Silver thin films are used as a functional layer in many applications such as low-emissivity and solar control coatings on glass for insulating windows, as well as transparent conducting electrodes for OLEDs and PV. For these applications, the conductivity of the film is critical; it is linked to the crystallinity and the grain size of silver layers which thickness ranges from 5 to 15nm. Such coatings often undergo thermal treatments up to 700°C aimed at toughening the glass substrate or improving the coating itself by promoting grain growth and curing point defects. This treatment can however dramatically damage the silver layer by inducing the formation of defects in the layer, such as holes or silver domes, decreasing both conductivity and light transmission of the coatings. Because of the extreme thinness of the films (less than 15 nm), the investigation of these phenomena requires in situ imaging at the nanoscale. In this study, grain growth and defects formation were observed in 15 nm-thick Ag films encapsulated with zinc oxide and silicon nitride using Transmission Electron Microscopy with in-situ heating from ambient temperature to 600°C. Significant grain growth was found to occur only from 400°C, and from 500°C holes in the silver layer started to form and grow, as well as thick silver domes formed by dewetting. Irradiation by the electron beam was also found to cause grain growth.
Effect of strain rate on splitting tensile strength of geopolymer concrete
Authors: Feng Ke Nan , Ruan Dong , Pan Zhu , Collins Frank , Bai Yu , Wang Chien Ming , Duan Wen Hui
Published: May 2014

The splitting tensile strengths of geopolymer concrete and geopolymer mortar under strain rates from 10−7 s−1 to 25 s−1 were investigated. Five mixes – one ordinary Portland cement (OPC) concrete, three geopolymer concrete and one geopolymer mortar – were considered. A Shimadzu AG-X 300 kN testing machine and a split Hopkinson pressure bar were used to conduct the tests. The dynamic increase factors of the splitting tensile strength (DIFft) of the geopolymer concretes were measured and compared with modified CEB recommendations. The results show that alkaline activators have a significant influence on the quasi-static splitting tensile strength of geopolymer concrete. For low strain rate loadings, the geopolymer concrete with low compressive strength had a larger DIFft and the viscous effect was found to be the main cause for an increase in DIFft. With high strain rate loadings, crack inertia was found to be responsible for the improvement in DIFft of geopolymer concretes. The existing formula for OPC concrete underestimates the DIFft of geopolymer concrete and therefore new empirical equations are proposed. In addition, the failure modes under various strain rate loadings were found to be similar due to the confinement of splitting tensile test on the crack path.
Behaviour of full-scale two-way simply supported concrete slabs in fire
Authors: Zhang Da-shan , Dong Yu-li , Fang Yuan-yuan
Published: May 2014

This paper presents two tests of full-scale simply supported two-way concrete slabs in a high-temperature environment, based on the standard temperature–time curve (ISO 834). Details of the support conditions, the reinforcement arrangements and the positions of displacement transducers and thermocouple trees are given. Crack development, the temperature distribution, central vertical deflection and edge horizontal deflection of the concrete slabs were recorded during the tests. It was observed that, despite large deflection, neither slab collapsed; this was due to the significant influence of tensile membrane effects on maintaining the structural stability of the floor slabs under fire conditions. Based on the experimental results, an energy-based model to determine the limit load-carrying capacity of concrete slabs at elevated temperatures is verified and discussed. A comparison of the energy-based model results and the test results showed good agreement, while conventional yield theory provides conservative critical reinforcement temperatures in the slabs.
Association of Untreated Metabolic Syndrome With Moderate to Severe Periodontitis in Thai Population
Authors: Thanakun Supanee , Watanabe Hisashi , Thaweboon Sroisiri , Izumi Yuichi
Published: May 2014

Background: Metabolic syndrome (MetS) correlates with systemic inflammation. A relation of MetS to periodontitis has been reported. This study aims to evaluate whether periodontitis is associated with untreated MetS, plasma adiponectin, and leptin among Thai people.

Methods: One hundred twenty‐five participants (aged 35 to 76 years) were recruited. Demographic and biologic data, bleeding on probing (BOP), probing depth (PD), and clinical attachment level (CAL) of all teeth were examined. Plasma adiponectin and leptin levels were measured.

Results: Forty‐four participants (35.2%) were healthy, and 81 (64.8%) had MetS. All periodontal conditions (BOP, PD, and CAL) were significantly worse in patients with MetS than healthy participants. After adjustment for confounders, MetS was strongly associated with severe periodontitis (odds ratio [OR] = 3.60, 95% confidence interval [CI]: 1.34 to 9.65). MetS with four to five components had a higher association with periodontitis than did MetS with three components (OR = 5.49, 95% CI: 1.75 to 17.19), whereas each separate component had no association with periodontitis, except for high diastolic blood pressure. Periodontitis was also associated with age (OR = 1.08, 95% CI: 1.01 to 1.14) and education (OR = 3.76, 95% CI: 1.05 to 13.40). The risk of MetS was predicted by body mass index and plasma adiponectin (OR = 1.90, 95% CI: 1.24 to 2.92 and OR = 0.93, 95% CI: 0.88 to 0.98, respectively).

Conclusions: There may be a relationship between untreated MetS and periodontitis in Thai people. Periodontal diagnosis should be regularly conducted in patients with MetS.