bluuebunny/crossref_metadata_2025 huggingface dataset:
Teacher Incentives
Authors: Glewwe Paul , Ilias Nauman , Kremer Michael
Published: July 2010

We analyze a randomized trial of a program that rewarded Kenyan primary school teachers based on student test scores, with penalties for students not taking the exams. Scores increased on the formula used to reward teachers, and program school students scored higher on the exams linked to teacher incentives. Yet most of the gains were focused on the teacher reward formula. The dropout rate was unchanged. Instead, exam participation increased among enrolled students. Test scores increased on exams linked to the incentives, but not on other, unrelated exams. Teacher attendance and homework assignment were unaffected, but test preparation sessions increased. (JEL I21, I28, J13, O15)
Freedom Fries
Authors: Michaels Guy , Zhi Xiaojia
Published: July 2010

Do firms always choose the cheapest suitable inputs, or can group attitudes affect their choices? To investigate this question, we examine the deterioration of relations between the United States and France from 2002–2003, when France's favorability rating in the US fell by 48 percentage points. We estimate that the worsening attitudes reduced bilateral trade by about 9 percent and that trade in inputs probably declined similarly, by about 8 percent. We use these estimates to calculate the average decrease in firms' willingness to pay for French (or US) commodities when attitudes worsened. (JEL D24, F13, F14, L14, L21)
Information from Markets Near and Far: Mobile Phones and Agricultural Markets in Niger
Authors: Aker Jenny C
Published: July 2010

Price dispersion across markets is common in developing countries. Using novel market and trader-level data, this paper provides estimates of the impact of mobile phones on price dispersion across grain markets in Niger. The introduction of mobile phone service between 2001 and 2006 explains a 10 to 16 percent reduction in grain price dispersion. The effect is stronger for market pairs with higher transport costs. (JEL O13, O33, Q11, Q13)
Do Temporary-Help Jobs Improve Labor Market Outcomes for Low-Skilled Workers? Evidence from “Work First”
Authors: Autor David H , Houseman Susan N
Published: July 2010

Temporary-help jobs offer rapid entry into paid employment, but they are typically brief and it is unknown whether they foster longer term employment. We utilize the unique structure of Detroit's welfare-to-work program to identify the effect of temporary-help jobs on labor market advancement. Exploiting the rotational assignment of welfare clients to numerous nonprofit contractors with differing job placement rates, we find that temporary-help job placements do not improve and may diminish subsequent earnings and employment outcomes among participants. In contrast, job placements with direct-hire employers substantially raise earnings and employment over a seven quarter follow-up period. (JEL J22, J23, J24, J31, J68)
Amplification Mechanisms in Liquidity Crises
Authors: Krishnamurthy Arvind
Published: July 2010

I describe two amplifications mechanisms that operate during crises and discuss the benefits of policy given each mechanism. The first mechanism involves asset prices and balance sheets. A negative shock to agents' balance sheets causes them to liquidate assets, lowering prices, further deteriorating balance sheets and amplifying the shock. The second mechanism involves investors' Knightian uncertainty. Unusual shocks to untested financial innovations increase agents' uncertainty about their investments, causing them to disengage from markets and amplifying the crisis. Liquidity provision by the central bank alleviates the crisis in both mechanisms. Ex ante policies such as liquidity/capital requirements may also be beneficial. (JEL E32, E44, G01, G21, G32)
Relative Goods' Prices, Pure Inflation, and The Phillips Correlation
Authors: Reis Ricardo , Watson Mark W
Published: July 2010

This paper uses a dynamic factor model for the quarterly changes in consumption goods' prices in the United States since 1959 to separate them into three independent components: idiosyncratic relative-price changes, a low-dimensional index of aggregate relative-price changes, and an index of equiproportional changes in all inflation rates that we label “pure” inflation. We use the estimates to answer two questions. First, what share of the variability of inflation is associated with each component, and how are they related to conventional measures of monetary policy and relative-price shocks? Second, what drives the Phillips correlation between inflation and measures of real activity? (JEL E21, E23, E31, E52)
Financiers versus Engineers: Should the Financial Sector be Taxed or Subsidized?
Authors: Philippon Thomas
Published: July 2010

I study the allocation of human capital in an economy with production externalities, financial constraints, and career choices. Agents choose to become entrepreneurs, workers, or financiers. Entrepreneurship has positive externalities but requires the services of financiers. In the second best solution, the financial sector should be taxed in exactly the same way as the nonfinancial sector. When direct subsidies to investment and scientific education are not feasible, subsidizing the financial sector increases growth if externalities are driven by physical capital as in Paul M. Romer (1986), and decreases growth if externalities are driven by human capital as in Robert E. Lucas, Jr. (1988). (JEL E44, H21, H25, L26, O41)
Do Expectations Matter? The Great Moderation Revisited
Authors: Canova Fabio , Gambetti Luca
Published: July 2010

We examine the role of expectations in the Great Moderation episode. We derive theoretical restrictions in a New-Keynesian model and test them using measures of expectations obtained from survey data, the Greenbook and bond markets. Expectations explain the dynamics of inflation and interest rates but their importance is roughly unchanged over time. Systems with and without expectations display similar reduced form characteristics. Results are robust to changes in the structure of the empirical model. (JEL E23, E24, E31, E32)
The Effect of Corporate Taxes on Investment and Entrepreneurship
Authors: Djankov Simeon , Ganser Tim , McLiesh Caralee , Ramalho Rita , Shleifer Andrei
Published: July 2010

We present new data on effective corporate income tax rates in 85 countries in 2004. The data come from a survey, conducted jointly with PricewaterhouseCoopers, of all taxes imposed on “the same” standardized mid-size domestic firm. In a cross-section of countries, our estimates of the effective corporate tax rate have a large adverse impact on aggregate investment, FDI, and entrepreneurial activity. Corporate tax rates are correlated with investment in manufacturing but not services, as well as with the size of the informal economy. The results are robust to the inclusion of many controls. (JEL E22, F23, G31, H25, H32, L26)
Labor Contracts, Equal Treatment, and Wage-Unemployment Dynamics
Authors: Snell Andy , Thomas Jonathan P
Published: July 2010

This paper analyses a model in which firms cannot pay discriminate based on year of entry. It is assumed that workers can costlessly quit at any time, while firms are committed to contracts. We solve for the dynamics of wages and unemployment, and show that real wages display a degree of downward rigidity and do not necessarily clear the labor market. Using sectoral productivity data from the post-war US economy, we assess the ability of the model to match the actual unemployment series. We also show that equal treatment follows from the assumption of at-will employment contracting in our model. (JEL E24, E32, J31, J41)
Optimized single electroencephalogram channel sleep staging in rats
Authors: Fang Guangzhan , Xia Yang , Zhang Chunpeng , Liu Tiejun , Yao Dezhong
Published: July 2010

Most studies of sleep staging in rats use both multichannels electroencephalogram (EEG) and electromyogram (EMG), so it would be convenient and meaningful in some fields if sleep staging in rats could be realized using a single EEG channel. In this study, we used a single bipolar cortical EEG electrode at the frontal–parietal location with a 0.5–30 Hz filter band and a clustering sleep-staging algorithm including seven classification parameters. The agreements between the computer and two independent raters were 96.9 ± 1.1% for Wake, 97.1 ± 1.4% for non-rapid eye movement (NREM) sleep, and 91.4 ± 2.5% for rapid eye movement (REM) sleep, and the overall agreement was 96.7 ± 0.7%. These results indicate that the accuracies of sleep staging remain high even though only a single EEG channel was used and that a system based on this scheme would be suitable for realtime and long-term studies of sleep.
Lane-Exchange Mechanisms for Truckload Carrier Collaboration
Authors: Özener Okan Örsan , Ergun Özlem , Savelsbergh Martin
Published: July 2010

Because of historically high fuel prices, the trucking industry's operating expenses are higher than ever and thus profit margins are lower than ever. To cut costs, the trucking industry is searching for and exploring new ideas. We investigate the potential of collaborative opportunities in truckload transportation. When carriers serve transportation requests from many shippers, they may be able to reduce their repositioning costs by exchanging one or more of them. We develop optimization models to determine the maximum benefit that can be derived from collaborating. We also develop various exchange mechanisms which differ in terms of information sharing requirements and side payment options that allow carriers to realize some or all of the costs savings opportunities.
Small maximal partial spreads in classical finite polar spaces
Authors: Klein Andreas , Metsch Klaus , Storme Leo
Published: July 2010

We prove lower bounds on the size of small maximal partial spreads in Q
+(4n + 1, q), W(2n + 1, q), and H(2n + 1, q
2). This research on the size of smallest maximal partial spreads in classical finite polar spaces is part of a detailed study on small and large maximal partial ovoids and spreads in classical finite polar spaces, performed in [De Beule, Klein, Metsch, Storme, Des. Codes Cryptogr 47: 21–34, 2008, De Beule, Klein, Metsch, Storme, European J. Combin 29: 1280–1297, 2008].
Generalized polygons with non-discrete valuation defined by two-dimensional affine ℝ-buildings
Authors: Struyve Koen , Van Maldeghem Hendrik
Published: July 2010

In this paper, we show that the building at infinity of a two-dimensional affine ℝ-building is a generalized polygon endowed with a valuation satisfying some specific axioms. Specializing to the discrete case of affine buildings, this solves part of a long standing conjecture about affine buildings of type , and it reproves the results obtained mainly by the second author for types and . The techniques are completely different from the ones employed in the discrete case, but they are considerably shorter, and general (i.e., independent of the type of the two-dimensional ℝ-building).
Tropical enumerative invariants of 𝔽0 and 𝔽2
Authors: Franz Marina , Markwig Hannah
Published: July 2010

There is an equation relating numbers of curves on satisfying incidence conditions and numbers of curves on 𝔽2 satisfying incidence conditions. The purpose of this paper is to give a tropical proof of this equation in the case of rational curves. We use induction on the degree and two Kontsevich-type formulas for curves on 𝔽0 and on 𝔽2. The formula for 𝔽2 was not known before and is proved using tropical geometry.
The Lerch zeta function II. Analytic continuation
Authors: Lagarias Jeffrey C. , Winnie Li Wen-Ching
Published: July 2010

This is the second of four papers that study algebraic
and analytic structures associated with the Lerch zeta function.
The Lerch zeta function

(
s
,
a
,
c
)

:
=

n
=
0

e

2

i
n
a

(
n
+
c
)

s

$
\zeta (s,a,c) := \sum _{n=0}^\infty \frac{e^{2 \pi in a}}{ (n+c)^{s}}
$

was introduced by Lipschitz in 1857,
and is named after Lerch, who showed in 1887 that it satisfied
a functional equation. Here we analytically continue

(
s
,
a
,
c
)

$\zeta (s, a, c)$
as a function of three complex variables.
We show that it is well-defined as a multivalued function
on the manifold

:
=

(
s
,
a
,
c
)

(

)

(

)

,

${\mathcal {M}}:= \lbrace (s, a, c) \in {\mathbb {C}}\times ( {\mathbb {C}}\setminus {\mathbb {Z}}) \times ( {\mathbb {C}}\setminus {\mathbb {Z}}) \rbrace ,$
and that
this analytic continuation becomes single-valued on the maximal abelian cover of

${\mathcal {M}}$
.
We compute the monodromy functions describing the multivalued
nature of this function on

${\mathcal {M}}$
, and determine various of
its properties.
Manifolds associated with (2)n+1$(\mathbb {Z}_2)^{n+1}$-colored regular graphs
Authors: Bao Zhiqiang , Lü Zhi
Published: July 2010

In this article we describe a canonical way to expand a certain kind
of

(

2

)

n
+
1

$(\mathbb {Z}_2)^{n+1}$
-colored regular graphs into closed

n

$n$
-manifolds by adding cells determined by the edge-colorings
inductively. We show that every closed combinatorial

n

$n$
-manifold
can be obtained in this way. When

n

3

$n\le 3$
, we give simple
equivalent conditions for a colored graph to admit an expansion. In
addition, we show that if a

(

2

)

n
+
1

$(\mathbb {Z}_2)^{n+1}$
-colored regular
graph admits an

n

$n$
-skeletal expansion, then it is realizable as the
induced graph of an

(
n
+
1
)

$(n+1)$
-dimensional closed

(

2

)

n
+
1

$(\mathbb {Z}_2)^{n+1}$
-manifold.
A Steinness criterion for Stein fibrations
Authors: Vâjâitu Viorel
Published: July 2010

Let

X

$X$
be a complex space and

k

$k$
be a positive integer such
the cohomology groups

H
1

(
X
,

)

,
...
,

H
k

(
X
,

)

$H^1(X,{\cal O}), \ldots , H^{k}(X,{\cal O})$
are of finite dimension.
If there is a holomorphic map

f
:
X

k

$f:X \longrightarrow ^k $
with fibres Stein, then

X

$X$
is Stein.
Side reactions of 4-acetamido-TEMPO as the catalyst in cellulose oxidation systems
Authors: Patel Ilabahen , Opietnik Martina , Böhmdorfer Stefan , Becker Manuel , Potthast Antje , Saito Tsuguyuki , Isogai Akira , Rosenau Thomas
Published: July 2010

TEMPO/hypochlorite oxidation of cellulosics are frequently used to obtain water-soluble polyglucuronates or nano-disperse materials. The reaction under neutral conditions offers a big advantage over hitherto applied alkaline systems as base-induce β-elimination reactions causing severe cellulose degradation are suppressed. Although 4-acetamido-TEMPO seems to offer high initial activities in cellulose oxidation, the TEMPO derivative is irreversibly converted into species with much lower reactivity. The degradation pathways and the chemical structure of the 4-acetamido-TEMPO-derived (by)products have been clarified. Degradation is strongly dependent on the pH value of the reaction mixture. In acidic conditions (pH<5), 4-oxo-TEMPO is formed by an oxidative deamination process, the 4-oxo-derivative still being capable of performing cellulose oxidation. In alkaline media, a similar process proceeds, but is immediately followed by a Favorskij rearrangement to a pyrrolidine-3-carboxylic acid (PROXYL) derivative. In both cases, the released acetamido moiety is slowly converted into methylamine by a decarboxylative rearrangement (Hofmann degradation). The results suggest that the instability and the chemical fate of 4-acetamido-TEMPO needs to be considered when cellulose oxidations and their kinetics are addressed: the recyclability of the 4-acetamido-TEMPO catalyst is rather limited.
Infinitely Often Dense Bases for the Integers with a Prescribed Representation Function
Authors: Lee Jaewoo
Published: July 2010

Nathanson constructed asymptotic bases for the integers with prescribed representation functions, then asked how dense they can be. We can easily obtain an upper bound using a simple argument. In this paper, we will see this is indeed the best bound when we prescribe an arbitrary representation function.
On Vanishing Sums of Distinct Roots of Unity
Authors: Sivek Gary
Published: July 2010

We show that for any integers
Gender-Specific Effects of Smoking and Alcohol Consumption on the Risk of Falling in Downhill Skiers
Authors: Burtscher M. , Pühringer R. , Werner I. , Ruedl G. , Sommersacher R. , Woldrich T. , Nachbauer W.
Published: July 2010

More than 90 % of all accidents on ski slopes are caused by falls without other skiers involved. Only little information is available about causes of falling. Recently, we identified several risk factors and triggers, including alcohol consumption and smoking, associated with an increased fall risk. The main goal of the present study was to focus on gender-specific effects of smoking and alcohol consumption on the risk of falling in downhill skiers. Randomized inquiries were performed on five occasions in five ski areas where 1607 downhill skiers, 928 males and 679 females, were interviewed by a standardized questionnaire. Data were collected on demographic characteristics, smoking habits, regular physical activity, skiing skills, preferred slopes, alcohol consumption, snow and weather conditions, and the number of preceding falls on the day of the inquiry. Conditional logistic-regression analysis was used to estimate adjusted odds ratios for fall outcome. Logistic-regression analysis revealed that the fall risk during skiing was increased only in males that are 30 years of age or older: 1.6-fold when they were non-smokers but drank alcohol and 2.2-fold when they were smokers and drank alcohol on the skiing day. In female skiers, this risk was increased in the age groups below 30 and those 30 years and older: 1.9- and 2.2-fold for smokers who did not drink alcohol, 2.2- and 2.8-fold when they were non-smokers but consumed alcohol, and 3.4- and 5.1-fold when they were smokers and drank alcohol on the skiing day. These findings demonstrate that being a smoker or drinking alcohol on the skiing day increases the risk of falling especially in female downhill skiers. The combination of both factors results in an additive risk increase. The avoidance of these risk factors could help to reduce the frequency of falls and probably also that of injuries particularly in female skiers.
Temperature Distribution during Friction Stir Spot Welding of Magnesium Alloy AM60B
Authors: Li Bo , Kang Hong-Tae
Published: July 2010

This study investigated the effects of welding parameters on temperature distribution of magnesium alloy AM60B during Friction Stir Spot Welding (FSSW). The welding parameters included tool rotational velocity, plunge depth, and holding time. These parameters were selected from previous test results. The temperature distributions were measured with type-K thermocouples during FSSW with various welding parameter combinations. The measurement locations were placed along the centerline in longitudinal direction of the coupons. The temperature distributions during FSSW were also calculated with finite element analysis (FEA) for each combination of the welding parameters. The experimental results were compared with those obtained from FEA.
Small-Scale Mechanical Characterization of Aluminum and Titanium Alloys
Authors: Sanders Matthew , Di Bella Frank , Liang Hong
Published: July 2010

A Small Punch Test method with 3 mm diameter and 0.5 mm thick specimens was utilized to characterize 3003-H14 aluminum, 2618-T61 aluminum, and Ti-6Al-4V alloys. The method was found to be repeatable and the effect of surface roughness negligible within the range of 0.450–3.011 μm. In addition, the titanium has shown higher strength and elastic modulus than the aluminum specimens. The addition of iron, copper, and nickel elements to Al makes the alloy stronger and more ductile. The research shows that the Small Punch Test can be used to qualitatively compare such mechanical properties as surface hardness, ductility, toughness, yield strength, and ultimate tensile strength of small volume test specimens in aluminum and titanium alloys. The advantage of such a method is its ability to obtain consistent evaluation of mechanical properties from small specimen volumes effectively.
Selected trace and minor elements in sandstones from Paraguay
Authors: Facetti-Masulli J. F. , Kump P. , González E.
Published: July 2010

Selected trace and minor elements analyzed by XRF in sandstone samples were Rb-Sr-Zr-Nb-Ba-La-Ce-Nd as well as Ti-Mn-Fe with which they are often correlated. Refractory elements like REE are considered useful indicators of geochemical processes and, in this case, of provenance . Usually they maintain their original relationships and are transferred almost directly into sediments. The values here found, absolute and normalized, show correlations among the samples, allowing the establishment of their origin. Most of them in the spidergram patterns display positive spikes of Zr, and negative anomalies at Nb, Sr, Ti: differences in their height/depth could be in relation with the different Series or Formations. Strikingly, spidergrams of samples collected from the Patiño Formation show marked negative anomalies interalia of Ba, as well as positive spikes of Nb and Zr, very similar to those found in magmatic specimens from Misiones, Carapeguá-Acahay and Alto Paraguay Province and quite different from the other analyzed samples. In addition a remarkable presence of Precambrian signatures were found in the analyzed sandstones from the Paleozoic.
Redox behavior of Ce(IV)/Ce(III) in the presence of nitrilotriacetic acid: A surrogate study for An(IV)/An(III) redox behavior
Authors: Suzuki Yoshinori , Nankawa T. , Francis Arokiasamy J. , Ohnuki T.
Published: July 2010

Using cyclic voltammetry, we investigated the redox behavior of Ce(IV)/Ce(III), which is a surrogate for An(IV)/An(III) (An=actinides), in a solution of nitrilotriacetic acid (NTA) at 25 °C. The cyclic voltammogram of Ce in a 0.1 M NTA solution at pH 6 showed a reversible one-electron redox reaction for Ce(IV)/Ce(III) at 0.51 Vvs.Ag/AgCl. This redox potential was much lower than that obtained in 1 M nitric acid, indicating that Ce(IV) was preferentially stabilized by complexation with NTA. The redox potential in the NTA solution was independent of the Ce concentration from 2 to 20 mM, NTA concentration from 5 to 200 mM and pH between 3 and 7. These results indicated that no polymerization and no additional coordination of NTA and OH−to the Ce(III)-NTA complex took place during the redox reaction. As the speciation calculation of Ce(III) in the NTA solution showed that the predominant species was CeIII(nta)23−(H3nta=NTA), the redox reaction of the Ce-NTA complex was expressed by the following: CeIV(nta)22−+e−⇋CeIII(nta)23−. The logarithm of the stability constant of CeIV(nta)22−was calculated to be 38.6±0.8 forI=0 from the redox potential shift of Ce(IV)/Ce(III) in the NTA solution. The value was in good accordance with the stability constant of the NpIV(nta)22−complex, demonstrating that the aqueous coordination chemistry of Ce(IV) with NTA is quite similar to that of An(IV). These results strongly suggest that a negative shift of the Pu(IV)/Pu(III) redox potential in the NTA solution should make Pu(IV) more stable than Pu(III) even in a reducing environment.
Supercritical carbon dioxide extraction of uranium from acidic medium employing crown ethers
Authors: Rao Ankita , Kumar Pradeep , Ramakumar K. L.
Published: July 2010

Supercritical carbon dioxide (SC CO2) extraction of uranium from nitric acid medium employing various crown ethers was studied. CO2-phillic C–F bonds in pentadecafluoro-n-octanic acid (HPFOA) counter ion enhanced the extraction efficiency. Pressure (100−300 atm) and temperature (323−353 K) were found to influence extraction efficiency by affecting SC CO2 density as well as due to large size cluster formation of supercritical fluid near critical point thereby resulting in reduced interaction with solute. Pressure of 200 atm and temperature of 323 K were found to be optimum. The trend in efficiency for benzo substituted crown ethers was due to the combined effect of cavity size and number of ether oxygen atoms. The extraction efficiency among 18-crown-6 series is influenced by the extent of basicity of ether oxygen, which in turn is dictated by the substituent group. Efficiency also decreased beyond 2 M nitric acid due to co-extraction of crown-nitric acid complex. Uranium: crown: HPFOA mole ratio influenced extraction efficiency, having optimum value at 1:10:100. Under optimized conditions with ditertiarybutyldicyclohexano-18-crown-6 the efficiency was found to be (86±5) %.
Miniature Inverted-Repeat Transposable Elements ofStowawayAre Active in Potato
Authors: Momose Masaki , Abe Yutaka , Ozeki Yoshihiro
Published: July 2010

Miniature inverted-repeat transposable elements (MITEs) are dispersed in large numbers within the genomes of eukaryotes although almost all are thought to be inactive. Plants have two major groups of such MITEs: Tourist and Stowaway. Mobile MITEs have been reported previously in rice but no active MITEs have been found in dicotyledons. Here, we provide evidence that Stowaway MITEs can be mobilized in the potato and that one of them causes a change of tuber skin color as an obvious phenotypic variation. In an original red-skinned potato clone, the gene encoding for a flavonoid 3′,5′-hydroxylase, which is involved in purple anthocyanin synthesis, has been inactivated by the insertion of a Stowaway MITE named dTstu1 within the first exon. However, dTstu1 is absent from this gene in a purple somaclonal variant that was obtained as a regenerated plant from a protoplast culture of the red-skinned potato. The color change was attributed to reversion of flavonoid 3′,5′-hydroxylase function by removal of dTstu1 from the gene. In this purple variant another specific transposition event has occurred involving a MITE closely related to dTstu1. Instead of being fossil elements, Stowaway MITEs, therefore, still have the ability to become active under particular conditions as represented by tissue culturing.
Optimal Neutrality Tests Based on the Frequency Spectrum
Authors: Ferretti Luca , Perez-Enciso Miguel , Ramos-Onsins Sebastian
Published: July 2010

The ascertainment of the demographic and selective history of populations has been a major research goal in genetics for decades. To that end, numerous statistical tests have been developed to detect deviations between expected and observed frequency spectra, e.g., Tajima's D, Fu and Li's F and D tests, and Fay and Wu's H. Recently, Achaz developed a general framework to generate tests that detect deviations in the frequency spectrum. In a further development, we argue that the results of these tests should be as independent on the sample size as possible and propose a scale-free form for them. Furthermore, using the same framework as that of Achaz, we develop a new family of neutrality tests based on the frequency spectrum that are optimal against a chosen alternative evolutionary scenario. These tests maximize the power to reject the standard neutral model and are scalable with the sample size. Optimal tests are derived for several alternative evolutionary scenarios, including demographic processes (population bottleneck, expansion, contraction) and selective sweeps. Within the same framework, we also derive an optimal general test given a generic evolutionary scenario as a null model. All formulas are relatively simple and can be computed very fast, making it feasible to apply them to genome-wide sequence data. A simulation study showed that, generally, the tests proposed are more consistently powerful than standard tests like Tajima's D. We further illustrate the method with real data from a QTL candidate region in pigs.
Direct Evidence for Postmeiotic Transcription During Drosophila melanogaster Spermatogenesis
Authors: Vibranovski Maria D , Chalopin Domitille S , Lopes Hedibert F , Long Manyuan , Karr Timothy L
Published: July 2010

Extensive gene expression during meiosis is a hallmark of spermatogenesis. Although it was generally accepted that RNA transcription ceases during meiosis, recent observations suggest that some transcription occurs in postmeiosis. To further resolve this issue, we provide direct evidence for the de novo transcription of RNA during the postmeiotic phases. These results strengthen the newly emerging notion that postmeiotic transcription is dynamic and integral to the overall process of spermatogenesis.
Reproductive Isolation in Hybrid Mice Due to Spermatogenesis Defects at Three Meiotic Stages
Authors: Oka Ayako , Mita Akihiko , Takada Yuki , Koseki Haruhiko , Shiroishi Toshihiko
Published: July 2010

Early in the process of speciation, reproductive failures occur in hybrid animals between genetically diverged populations. The sterile hybrid animals are often males in mammals and they exhibit spermatogenic disruptions, resulting in decreased number and/or malformation of mature sperms. Despite the generality of this phenomenon, comparative study of phenotypes in hybrid males from various crosses has not been done, and therefore the comprehensive genetic basis of the disruption is still elusive. In this study, we characterized the spermatogenic phenotype especially during meiosis in four different cases of reproductive isolation: B6-ChrXMSM, PGN-ChrXMSM, (B6 × Mus musculus musculus-NJL/Ms) F1, and (B6 × Mus spretus) F1. The first two are consomic strains, both bearing the X chromosome of M. m. molossinus; in B6-ChrXMSM, the genetic background is the laboratory strain C57BL/6J (predominantly M. m. domesticus), while in PGN-ChrXMSM the background is the PGN2/Ms strain purely derived from wild M. m. domesticus. The last two cases are F1 hybrids between mouse subspecies or species. Each of the hybrid males exhibited cell-cycle arrest and/or apoptosis at either one or two of three distinct meiotic stages: premeiotic stage, zygotene-to-pachytene stage of prophase I, and metaphase I. This study shows that the sterility in hybrid males is caused by spermatogenic disruptions at multiple stages, suggesting that the responsible genes function in different cellular processes. Furthermore, the stages with disruptions are not correlated with the genetic distance between the respective parental strains.
A Strategy for Direct Mapping and Identification of Mutations by Whole-Genome Sequencing
Authors: Zuryn Steven , Le Gras Stéphanie , Jamet Karine , Jarriault Sophie
Published: July 2010

Mutant screens have proven powerful for genetic dissection of a myriad of biological processes, but subsequent identification and isolation of the causative mutations are usually complex and time consuming. We have made the process easier by establishing a novel strategy that employs whole-genome sequencing to simultaneously map and identify mutations without the need for any prior genetic mapping.
Global Genetic Robustness of the Alternative Splicing Machinery in Caenorhabditis elegans
Authors: Li Yang , Breitling Rainer , Snoek L Basten , van der Velde K Joeri , Swertz Morris A , Riksen Joost , Jansen Ritsert C , Kammenga Jan E
Published: July 2010

Alternative splicing is considered a major mechanism for creating multicellular diversity from a limited repertoire of genes. Here, we performed the first study of genetic variation controlling alternative splicing patterns by comprehensively identifying quantitative trait loci affecting the differential expression of transcript isoforms in a large recombinant inbred population of Caenorhabditis elegans, using a new generation of whole-genome very-high-density oligonucleotide microarrays. Using 60 experimental lines, we were able to detect 435 genes with substantial heritable variation, of which 36% were regulated at a distance (in trans). Nonetheless, we find only a very small number of examples of heritable variation in alternative splicing (22 transcripts), and most of these genes colocalize with the associated genomic loci. Our findings suggest that the regulatory mechanism of alternative splicing in C. elegans is robust toward genetic variation at the genome-wide scale, which is in striking contrast to earlier observations in humans.
Phosphorus turnover characteristics of soils: Comparison of pot experiment results and modelling by stepwise regression analyses
Authors: Sárdi K. , Csathó P.
Published: July 2010

The phosphorus retention ability of soils depends on several factors and influences the effectiveness of fertilization as well as the release of P from soil to water. In the present study the phosphorus supplying and/or retention ability of soils were estimated by two approaches: biological approach (pot experiments) and modelling (by regression analyses). In the course of the biological approach pot experiments were carried out with soils showing significant differences in total and available P contents. Soil samples were collected from selected plots of 9 sites of the National Long-Term Fertilization Trials (NLFT) after 20 years of fertilization, which represents different agro-ecological regions of Hungary. Site characteristics covered a wide range in pH, carbonate and P content, representing typical soil types of the country. With the statistical approach (modelling), the most important soil properties were included and the role of these factors was evaluated by stepwise regression analyses. From the equations, the contribution of important soil parameters to phosphorus supplying and retention ability could be quantified. The objective of the present study was to find a simple way to compare and evaluate the two approaches in P nutrient turnover of soils. Results of the two approaches were correlated. From these results, a rank correlation was also made from the experimental and calculated results. A very close relationship was observed for the P supply and retention of soils (r value was 0.918 for the N
0
P
0
K
0
unfertilized control and 0.927 for the N
200
P
200
K
100
fertilization level). Values obtained with rank correlation were 0.87 and 0.866, respectively, verifying that both methodologies are reliable for estimating the nutrient dynamics in soils and to predict P dynamics in a diverse range of soils.
Characterization of dissolved organic matter (DOM) extracted from soils by hot water percolation (HWP)
Authors: Takács M. , Füleky Gy.
Published: July 2010

The Hot Water Percolation (HWP) technique for preparing soil extracts has several advantages: it is easily carried out, fast, and several parameters can be measured from the same solution. The object of this study was to examine the possible use of HWP extracts for the characterization of soil organic matter. The HPLC-SEC chromatograms, UV-VIS and fluorescence properties of the HWP extracts were studied and the results were compared with those of the International Humic Substances Society (IHSS) Soil Humic Acid (HA), IHSS Soil Fulvic Acid (FA) and IHSS Suwannee Natural Organic Matter (NOM) standards as well as their HA counterparts isolated by traditional extraction methods from the original soil samples. The DOM of the HWP solution is probably a mixture of organic materials, which have some characteristics similar to the Soil FA fractions and NOM. The HWP extracted organic material can be studied and characterized using simple techniques, like UV-VIS and fluorescence spectroscopy.
Relations between soil properties and the 1 M NH 4 NO 3 soluble mobile element fraction
Authors: Rékási M. , Filep T.
Published: July 2010

The aim of the present study was to establish whether the 1MNH4NO3extraction is a suitable method for determining the background concentrations of mobile element fractions in soils and for describing the relations among mobile element fractions and soil properties. The 1MNH4NO3extraction resulted As, Cr and Pb concentrations below the detection limit in 90% of the investigated soils. This shows that the mobile element content determined simply in 1MNH4NO3solution is probably inadequate for the determination of the mobile background concentrations of these elements. Therefore, in the risk assessment of soil contamination other soil properties and element fractions – like “total” (cc. HNO3+H2O2soluble) – should also be taken into consideration. The mobile Al concentration increased exponentially below pH 4. No correlation was found among 1MNH4NO3soluble mobile As, Cr, Cu and Pb element concentrations and any investigated soil property. Mobile Co, Mn, Al, Ni and Zn concentrations were determined mainly by soil pH. Soil colloid content correlated particularly with mobile Sr and B contents.
Increasing importance of the water storage function of soils under changing climate
Authors: Várallyay Gy.
Published: July 2010

There are many uncertainties in “global” climate changes (direction, rate, seasonal and geographical distribution) and in the prediction of their environmental, ecological, economical and even social consequences. All prognoses, however, forecast the increasing risk, frequency, duration and intensity (seriousness) of irregular, extreme climatic and hydrological events and moisture situations. In their prevention or reduction the
water storage function of soil
has special significance. Consequently, all efforts have to be taken for its more efficient use: helping the infiltration and storage of water in soils. Permanent
soil moisture control
may help to
prevent,
or at least reduce undesirable soil processes and their harmful economical/ecological/environmental/social consequences; and may fulfil the conditions of the “quality maintenance” of soil, this “conditionally renewable” natural resource, which is an important element of sustainable development, including the adaption to and mitigation of climate changes.
Effect of bentonite and zeolite on some characteristics of acidic sandy soil and on the biomass of a test plant
Authors: Kátai J. , Tállai M. , Sándor Zs. , Oláh Zsuposné Á.
Published: July 2010

In a pot experiment the effect of bentonite and zeolite doses [0; 5; 10; 15 and 20 g·kg soil
-1
] was studied on some chemical properties and ten soil microbiological and enzymological properties of an acidic [pH(H
2
O) = 5.65] humic sandy soil [WRB: Lamellic Arenosol (Dystric)], as well as on the biomass of perennial ryegrass (
Lolium perenne
L.), as test plant. The pot experiment was set up in 2007 and 2008 at the Department of Agrochemistry and Soil Science of the Debrecen University in three replications. The average results of the two year experiment can be summarized as follows: The pH increased due to the effect of small and medium amendment doses. The bentonite treatments proved to be more effective than the zeolite doses. As the pH increased, the hydrolytic acidity – in case of the bentonite treatments significantly – decreased. Concerning the easily available nutrient content of soil, the small and medium amendment doses turned out to be effective. The large bentonite doses reduced the nitrate-N content, the easily available phosphorus and potassium contents of soil. Large dose zeolite treatments decreased the nitrate-N content, but increased both the phosphorus and potassium content of soil, in most cases significantly. Regarding the measured soil microbial parameters, the small and medium amendment doses were the most effective. The bentonite and zeolite treatments increased the biomass of perennial ryegrass, especially the small and medium doses of bentonite and the large dose of zeolite brought about significant increases. According to the statistical analyses moderate and close correlations were found between the parameters studied. In the bentonite treatments a close correlation was established between the aerobic cellulose decomposing bacteria and saccharase enzyme activity (r = 0.864) of soil. In the case of zeolite treatments, a close correlation was found between the number of nitrifying bacteria and microbial biomass C (r = 0.911) of soil.
Long-term effect of heavy metal loads on the mycorrhizal colonization and metal uptake of barley
Authors: Biró B. , Füzy A. , Posta K.
Published: July 2010

A pot experiment was designed to study the colonization of indigenous arbuscular mycorrhizal fungi (AMF) on barley (
Hordeum vulgare
L.) host plant. Soils of the pots were collected from a long-term field microelement loading experiment on calcareous chernozem soil twelve years after 13 heavy metals (Al, As, Ba, Cd, Cr, Cu, Hg, Mo, Ni, Pb, Se, Sr and Zn) were applied once in four doses (0, 30, 90 and 270 mg element·kg
-1
d.w.). The biomass production and element accumulation of the host plant, the various colonization values of the arbuscular mycorrhiza fungi (AMF) – such as colonization intensity (M %), arbusculum richness (A %) in the root system and the sporulation intensity (g
-1
dry soil) in the rhizosphere – were measured. When considering the twelve-year adaptation process of the AM fungal populations at the various metal loads, a relatively balanced inside mycorrhiza colonization was found, suggesting the potentials for the selection of tolerant fungi in metal contaminated soils. The balanced infection intensity (M %) of the AM fungi and their common strategies with the host plant have resulted a nonsignificant shoot and root biomass production of barley in general. Mycorrhiza sporulation in the root system proved to be much variable and indicated the toxicity of metals and metal rates. Cd, Pb and Sr elements significantly reduced spore numbers, while a value of 34 spores·g
-1
soil was counted in the case of Ni in comparison to the control’s 22 spores·g
-1
soil value. Stress-defending strategies of the fungal–plant symbiosis, such as the increased arbusculum richness (A %) could be established for the Hg and Pb rates. In the case of Cd an increased root biomass production became a tool for stress alleviation and reduced the metal allocation towards the shoots. Mycorrhiza fungi are part of the common plant–microbe interactions and appropriate defending mechanisms in metal contaminated soils.
Taxonomic distance measurements applied for soil correlation
Authors: Láng V. , Fuchs M. , Waltner I. , Michéli E.
Published: July 2010

The development of the recent European and global initiatives resulted in an increasing demand for harmonized digital soil information. One of the major limitations of harmonization is the great variation of field and analytical methods and classification systems. Since 1998, the World Reference Base for Soil Resources (WRB) is the global correlation scheme for soil classification and international communication. The one to one correlation of units, however, is difficult, if not impossible. Another problem is that the correct correlation of national units to WRB units might have spatial consequences. If the original map units need to be maintained, it is important to express the extent to which certain national units match with the WRB units. Taxonomic distance measurements were applied successfully to express numerically the correlation between the brown forest soil types (BFS) of the Hungarian Soil Classification System (HSCS) and WRB Reference Soil Groups (RSGs).
Phosphate sorption capacity of European volcanic soils
Authors: Füleky Gy.
Published: July 2010

The aim of the presented study was to prepare the phosphate sorption isotherms of 20 European volcanic soil profiles and some other Hungarian and German volcanic soils (n = 114) used in the experiment and to establish the soil characteristics determining the phosphate sorption capacity of these soils. The Langmuir isotherm well describes the phosphate sorption of European volcanic soils at bright concentration interval 0–600 mg·dm
-3
P. The calculated phosphate adsorption maximum (P
max
) is an excellent soil property for characterizing the surface activity of soils developed on volcanic parent material. The calculated phosphate sorption maxima of soils included in the experiment ranged from 0 to 10.000 mg P·kg
-1
. Some of the volcanic soils sorbed a high ratio of the added phosphate at low concentrations, while others sorbed somewhat less. The difference in the phosphate binding affinity of soils caused the differences in the shape of the Langmuir adsorption isotherms. P retention % is a WRB diagnostic requirement of andic soil horizon. It was supposed that the phosphate sorption maximum (P
max
) gives a better characterization of the surface reactivity of volcanic soils. As it was predicted, oxalate soluble Al is the most important soil property, which dominantly (in 73%) explained the phosphate sorption ability of European volcanic soils.
Níveis de energia digestível sobre os desempenhos reprodutivo e zootécnico e a deposição de lipídios nos hepatócitos de machos de tilápia-do-nilo
Authors: Bombardelli Robie Allan , Hayashi Carmino , Natali Maria Raquel Marçal , Sanches Eduardo Antônio , Piana Pitágoras Augusto
Published: July 2010

O experimento foi conduzido com o objetivo de avaliar o desempenho reprodutivo e zootécnico e a deposição de lipídios no tecido hepático de machos de tilápia-do-nilo alimentados com rações contendo diferentes níveis de energia digestível, obtidos com a inclusão de óleo de soja. Foram utilizados 400 reprodutores (300 fêmeas e 100 machos) distribuídos em delineamento inteiramente casualizado, composto de cinco níveis de energia digestível (2.700, 2.950, 3.200, 3.450 e 3.700 kcal.kg de ração-1) e quatro repetições. Os reprodutores foram alimentados com rações contendo 35% de proteína bruta e submetidos ao manejo reprodutivo em hapas por 101 dias. O melhor resultado de concentração espermática e percentual de espermatozoides normais foram obtidos para reprodutores alimentados com rações contendo 3.465,56 e 3.443,43 kcal. kg de ração-1, que produziram 7,98 × 10(9) espermatozoides.mL de sêmen-1 e 38,98% de espermatozoides normais, respectivamente. A produção de sêmen, o pH seminal, o índice de sobrevivência espermática e o tempo de ativação espermática não foram afetados pelos níveis energéticos das rações. Os níveis de energia das rações não influenciaram o desempenho zootécnico dos peixes, mas promoveram aumento linear na deposição de lipídios nos hepatócitos e afetaram a qualidade seminal, estimulando a produção de espermatozoides e a melhora dos índices de normalidade da morfologia espermática em níveis energéticos próximos a 3.450 kcal. kg de ração-1.
Evaluation of HDR tone‐mapping algorithms using a high‐dynamic‐range display to emulate real scenes
Authors: Kuang Jiangtao , Heckaman Rodney , Fairchild Mark D.
Published: July 2010

Abstract— Current HDR display technology approaches the dynamic‐range capabilities of the fully adapted human visual system. As such, this technology has potential for performing as a surrogate for real‐world scenes in the perceptual evaluation of high‐dynamic‐range (HDR) image‐reproduction algorithms that aim to map HDR scenes to the limited dynamic ranges available in typical display and print technology. Compared with direct image assessment in comparison with real‐world scenes, it is clear that use of HDR display technology has the benefit of simplicity in experimental design while maintaining the HDR of the original scene. To evaluate this potential application of HDR display technology, seven published versions of well‐known HDR tone‐mapping algorithms were benchmarked for perceptual rendering accuracy against each of four real‐world scenes constructed in the laboratory and against corresponding images on an HDR display. The results illustrate that visual assessments obtained from the HDR display and those obtained from real‐world scenes are in good agreement, validating the potential for HDR display technology as an evaluation tool in this context.