bluuebunny/crossref_metadata_2025 huggingface dataset:
Gender and work–family conflict: Testing the rational model and the gender role expectations model in the Spanish cultural context
Authors: Calvo‐Salguero Antonia , Martínez‐de‐Lecea José‐María Salinas , del Carmen Aguilar‐Luzón María
Published: August 2011

Gutek, Searle, and Klepa (1991) proposed two models to explain the gender differences in work–family conflict: the rational model and the gender role expectations model. Both models have mostly been tested on American and Canadian samples, and have obtained partial support. Given the cultural differences between North American countries and Spain, we should question whether the two models are equally applicable to Spanish society or whether one of them captures Spanish men and women's experience of work–family conflict better than the other. So, the aim of this study is to test which of the models better explains the gender differences in work–family conflict in the Spanish cultural context (or if, indeed, the two models apply equally well). Given the typical cultural dimensions of Spanish society, we expected to find greater support for the gender role expectations model than for the rational model. However, the results obtained in this study indicated that, while the rational model can explain the gender differences that were found, the gender role expectations model cannot capture Spanish people's work–family conflict experiences. The results are interpreted in terms of cultural dimensions characteristic of the Spanish context.
Activity profile and physical demands of male field hockey umpires in international matches
Authors: Sunderland Caroline , Taylor Emily , Pearce Emily , Spice Christopher
Published: August 2011

In this study, we investigated the physical demands and activity profiles of international field hockey umpires during match‐play. We collected GPS data and heart rates from ten umpires over 16 international matches. Total mean distance covered in a full match was 6655±406 m. No differences were observed between mean distances covered in the first and second halves (3390±241 m and 3264±253 m respectively; P =0.093). Hockey umpires spent 2.7±1% of the total match time performing high‐intensity running (>15.5 km · h–1). Paired t‐tests revealed no difference in the distance umpires covered during high‐intensity running in the first versus the second half (339±168 m vs. 285±106 m; P=0.113), or in the number of sprints performed (3.4±2.3 vs. 2.8±2.1; P=0.290). There was large inter‐individual variability in the total distance covered at high intensity (range 274–999 m). No difference in mean heart rates was evident between the first and second half (150±9 and 147±10 beats · min–1 respectively; P =0.055). The results of this study show that the performance of the participating hockey umpires did not decrease from the first to the second half. Training and testing procedures should be updated to reflect the specific role of the hockey umpire.
Self‐reported asthma and respiratory symptoms among Italian amateur athletes
Authors: Tardivo Stefano , Zerman Tamara , Frizzera Sandra , Locatelli Francesca , Ferrari Pietro , Schenk Kai , Bonella Francesco , Tomaello Luca , Posenato Chiara , Meneghello Mara , Ferrari Marcello
Published: August 2011

The prevalence and the factors influencing respiratory symptoms and asthma in recreational athletes are still poorly defined. The aim of the study is to estimate the prevalence of self‐reported asthma and respiratory symptoms in a sample of Italian amateur athletes compared with the general population. We also intend to estimate the association between asthma, the type of exercise and the environment where it was practised. The study population included athletes (A) practising sports in the city of Bozen (northern Italy) (n = 1022). A random sample from the general population (GP) (n = 2166) was used as the control group. All participants filled in a questionnaire including items regarding asthma, respiratory symptoms and type of sporting activities. Associations between exposure variables and outcomes, adjusted for potential confounding factors, were estimated using logistic regression. Our findings revealed that the prevalence of asthma (“Have you ever had asthma?”) was lower among A (4.0%) than in the GP (11.0%, P < 0.001). Similar figures were recorded for current asthma (asthma in the past plus an asthma attack or wheezing in the last 12 months and/or current use of medication for asthma) (A 3.0%, GP 4.8%, P = 0.044) and for respiratory symptoms (A 3.9%, GP 18.9%, P < 0.001). Comparisons within the sample of athletes, taking indoor sports as a reference category, revealed that performing outdoor sports in spring and summer was associated with a higher risk of asthma, the same however was not true for outdoor sports performed in winter (adjusted OR = 2.8, 95% CI = 1.1–7.5). Where OR = Odds Ratio and CI = Confidence Interval. The risk of developing symptoms after exercise was higher for outdoor sports practised in the mild or cold seasons (adjusted OR = 4.6, 95% CI = 1.0–21.3 and adjusted OR = 11.9, 95% CI = 2.5–56.1, respectively). Training for more than five hours a week was associated with a lower prevalence of asthma than training for less (adjusted OR = 0.45, 95% CI = 0.2–0.9). Finally, no relationship emerged between type of exercise, asthma and respiratory symptoms. The results of this study indicate that asthma is less common in amateur athletes than in the general population and that the risk of asthma and respiratory symptoms is associated more with outdoor than with indoor sports, but not with any particular type of exercise.
Shifting Attention among Working Memory Representations: Testing Cue Type, Awareness, and Strategic Control
Authors: Berryhill Marian E. , Richmond Lauren L. , Shay Cara S. , Olson Ingrid R.
Published: August 2011

It is well known that visual working memory (VWM) performance is modulated by attentional cues presented during encoding. Interestingly, retrospective cues presented after encoding, but prior to the test phase also improve performance. This improvement in performance is termed the retro-cue benefit. We investigated whether the retro-cue benefit is sensitive to cue type, whether participants were aware of their improvement in performance due to the retro-cue, and whether the effect was under strategic control. Experiment 1 compared the potential cueing benefits of abrupt onset retro-cues relying on bottom-up attention, number retro-cues relying on top-down attention, and arrow retro-cues, relying on a mixture of both. We found a significant retro-cue effect only for arrow retro-cues. In Experiment 2, we tested participants' awareness of their use of the informative retro-cue and found that they were aware of their improved performance. In Experiment 3, we asked whether participants have strategic control over the retro-cue. The retro-cue was difficult to ignore, suggesting that strategic control is low. The retro-cue effect appears to be within conscious awareness but not under full strategic control.
Influence of annealing time on structural and magnetic properties of rapid thermally annealed FePt films
Authors: Brombacher C , Schubert C , Neupert K , Kehr M , Donges J , Albrecht M
Published: August 2011

L10 ordered FePt films with (0 0 1) texture and out-of-plane magnetic easy axis were fabricated by rapid thermal annealing of chemically disordered FePt thin films grown on amorphous SiO2 substrates. While keeping the annealing temperature fixed at 800 °C, the influence of the annealing time was investigated in the regime between 5 and 300 s. The evolution of the a and c lattice parameters indicates that the in-plane strain is a key factor for the formation of the (0 0 1) texture. A large tetragonal distortion is found after an annealing time of 5 s whereas a relaxation of the lattice parameters towards bulk values is found for longer annealing times. The dependence of the magnetic properties on the annealing time will be discussed with respect to the observed variation of the structure and morphology of the annealed FePt films.
Ion emission in collisions between two laser-produced plasmas
Authors: Hough P , Hayden P , Fallon C , Kelly T J , McLoughin C , Yeates P , Mosnier J P , Kennedy E T , Harilal S S , Costello J T
Published: August 2011

Measurements of the total ion emission from a pair of colliding laser-produced aluminium plasmas were obtained with the aid of a Faraday cup detector. The energy profile width at half height of the kinetic energy distribution for ions emitted normal to the target was found to be 30% narrower for colliding plasmas compared with a single plasma. Similar to ion emission from single plumes, the mean ion kinetic energy is observed to increase with the energy of the incident laser pulse. However, the width of the ion energy distribution increases at a significantly slower rate than in the single plume case.
Thermal conductivity measurement of porous silicon by the pulsed-photothermal method
Authors: Amin-Chalhoub E , Semmar N , Coudron L , Gautier G , Boulmer-Leborgne C , Petit A , Gaillard M , Mathias J , Millon E
Published: August 2011

Thermal properties of two types of porous silicon are studied using the pulsed-photothermal method (PPT). This method is based on a pulsed-laser source in the nanosecond regime. A 1D analytical model is coupled with the PPT technique in order to determine thermal properties of the studied samples (thermal conductivity and volumetric heat capacity).

At first, a bulk single crystal silicon sample and a titanium thin film deposited on a single crystal silicon substrate are studied in order to validate the PPT method. Porous silicon samples are elaborated with two different techniques, the sintering technique for macroporous silicon and the electrochemical etching method for mesoporous silicon. Metallic thin films are deposited on these two substrates by magnetron sputtering. Finally, the thermal properties of macroporous (30% of porosity and pores diameter between 100 and 1000 nm) and mesoporous silicon (30% and 15% of porosity and pores diameter between 5 and 10 nm) are determined in this work and it is found that thermal conductivity of macroporous (73 W m−1 K−1) and mesoporous (between 80 and 50 W m−1 K−1) silicon is two times lower than the single crystal silicon (140 W m−1 K−1).
3D electromagnetic optimization of the front face of the ITER ICRF antenna
Authors: Louche F. , Dumortier P. , Messiaen A. , Durodié F.
Published: August 2011

In the framework of the ion cyclotron resonance heating (ICRH) antenna development for ITER, a design based on an external matching concept has been proposed [1]. We present in this work a series of electromagnetic simulations of this design performed with the commercial code CST Microwave Studio [2]. On the one hand, we explore how various geometrical modifications of some parts of the antenna (the straps and the four-port junction) can practically double the RF power coupled to the plasma. This optimization is supported by transmission line analysis. On the other hand, we treat the important question of the opportunity to tilt the straps in the toroidal direction to follow the plasma curvature as close as possible. We show that a configuration with two toroidal segments is sufficient and that further segmentation is not necessary. This work also underlines significant progress in the realism of ICRH antenna modelling and the importance of considering realistic load shaping in the models.
Integrated modelling of steady-state scenarios and heating and current drive mixes for ITER
Authors: Murakami M. , Park J.M. , Giruzzi G. , Garcia J. , Bonoli P. , Budny R.V. , Doyle E.J. , Fukuyama A. , Hayashi N. , Honda M. , Hubbard A. , Ide S. , Imbeaux F. , Jaeger E.F. , Luce T.C. , Na Y.-S. , Oikawa T. , Osborne T.H. , Parail V. , Polevoi A. , Prater R. , Sips A.C.C. , Snipes J. , St. John H.E. , Snyder P.B. , Voitsekhovitch I.
Published: August 2011

Recent progress on ITER steady-state (SS) scenario modelling by the ITPA-IOS group is reviewed. Code-to-code benchmarks as the IOS group's common activities for the two SS scenarios (weak shear scenario and internal transport barrier scenario) are discussed in terms of transport, kinetic profiles, and heating and current drive (CD) sources using various transport codes. Weak magnetic shear scenarios integrate the plasma core and edge by combining a theory-based transport model (GLF23) with scaled experimental boundary profiles. The edge profiles (at normalized radius ρ = 0.8–1.0) are adopted from an edge-localized mode-averaged analysis of a DIII-D ITER demonstration discharge. A fully noninductive SS scenario is achieved with fusion gain Q = 4.3, noninductive fraction f
NI = 100%, bootstrap current fraction f
BS = 63% and normalized beta βN = 2.7 at plasma current I
p = 8 MA and toroidal field B
T = 5.3 T using ITER day-1 heating and CD capability. Substantial uncertainties come from outside the radius of setting the boundary conditions (ρ = 0.8). The present simulation assumed that βN (ρ) at the top of the pedestal (ρ = 0.91) is about 25% above the peeling–ballooning threshold. ITER will have a challenge to achieve the boundary, considering different operating conditions (T
e/T
i ≈ 1 and density peaking). Overall, the experimentally scaled edge is an optimistic side of the prediction. A number of SS scenarios with different heating and CD mixes in a wide range of conditions were explored by exploiting the weak-shear steady-state solution procedure with the GLF23 transport model and the scaled experimental edge. The results are also presented in the operation space for DT neutron power versus stationary burn pulse duration with assumed poloidal flux availability at the beginning of stationary burn, indicating that the long pulse operation goal (3000 s) at I
p = 9 MA is possible. Source calculations in these simulations have been revised for electron cyclotron current drive including parallel momentum conservation effects and for neutral beam current drive with finite orbit and magnetic pitch effects.
A flexible affine 𝑀-sextic which is algebraically unrealizable
Authors: Fiedler-Le Touzé S. , Orevkov S.
Published: August 2011

We prove that the union of a real algebraic curve of degree six and a real line on

R
P

2

\mathbf {RP}^{2}

cannot be isotopic to the arrangement in Figure 1. Previously, the second author realized this arrangement with flexible curves. Here we show that these flexible curves are pseudo-holomorphic in a suitable tame almost complex structure on

C
P

2

\mathbf {CP}^{2}

.

For the proof of the algebraic non-realizability we consider all possible positions of the curve with respect to certain pencils of lines. Using the Murasugi-Tristram inequality for certain links in

S

3

S^{3}

, we show that all the positions but one are unrealizable. Then, we prohibit the last position (the one which is realizable by a flexible curve) by studying its behaviour with respect to an auxiliary pencil of cubics.
Families of singular rational curves
Authors: Kebekus Stefan
Published: August 2011

Let

X
X

be a projective variety which is covered by a family of rational curves of minimal degrees. We give a bound on the dimension of the subfamily of singular rational curves. Among other applications, we will show that this yields a new characterization of the projective space in terms of rational curves.
Un théorème de comparaison entre les faisceaux d’opérateurs différentiels de Berthelot et de Mebkhout-Narváez-Macarro
Authors: Noot-Huyghe Christine
Published: August 2011

In this paper, we compare in one particular case, the arithmetic

D
D

-modules introduced by Berthelot and the arithmetic

D
D

-modules introduced by Mebkhout and Narváez-Macarro. We prove that there exists an equivalence of categories of coherent

D
D

-modules when you consider the arithmetic

D
D

-modules introduced by Berthelot on a projective smooth formal scheme

X

\mathcal {X}

, over some discrete valuation ring

R
R

of mixed characteristics

(
0
,
p
)

(0,p)

, that is endowed with an ample divisor, along which the coefficients of the differential operators are overconvergent. On the side of Mebkhout-Narváez-Macarro, you have to look at differential operators over a smooth, affine, weakly formal scheme over

R
R

, whose

p
p

-adic completion is the complementary of

Z
Z

into

X

\mathcal {X}

. The equivalence of categories is given in one direction by taking global sections of the

D
D

-modules.
A characterization of quasi-homogeneous complete intersection singularities
Authors: Vosegaard Henrik
Published: August 2011

It is well-known that quasi-homogeneity is characterized by equality of the Milnor and Tjurina numbers for isolated complex analytic hypersurface singularities and for certain low-dimensional singularities. We prove that this characterization extends to any complex isolated complete intersection singularity of positive dimension.
Recovering plane curves from their bitangents
Authors: Caporaso Lucia , Sernesi Edoardo
Published: August 2011

We prove that a general complex projective plane quartic curve is uniquely determined by its 28 bitangent lines. A similar property (called theta-property in the paper) is proved for a general singular quartic having

δ
=
1
,
…
,
4

\delta =1,\dots ,4

double points with respect to its set of generalized bitangents (suitably defined). The proofs are by degeneration.
On codimension two subvarieties of 𝑃⁵ and 𝑃⁶
Authors: Ellia Ph. , Franco D.
Published: August 2011

We prove the following:

Theorem. Let

X
⊂

P

5

X\subset \mathbf {P}^5

be a smooth, subcanonical threefold. If

h
0

(

I

X

(
4
)
)
≠
0

h^0(\mathcal {I}_X(4))\ne 0

, then

X
X

is a complete intersection.

Let

X
⊂

P

6

X\subset \mathbf {P}^6

be a smooth, codimension two subvariety, if

h
0

(

I

X

(
5
)
)

≠
0

h^0(\mathcal {I}\!_X(5))\!\ne 0

or

deg
⁡
(
X
)
≤
73

\operatorname {deg}(X)\le 73

, then

X
X

is a complete intersection.

This improves, for

5
≤
n
≤
6

5\le n\le 6

, earlier results on Hartshorne’s conjecture for codimension two subvarieties of

P

n

\mathbf {P}^n

.
Surfaces with triple points
Authors: Endraß Stephan , Persson Ulf , Stevens Jan
Published: August 2011

In this paper we compute upper bounds for the number of ordinary triple points on a hypersurface in

P

3

\mathbb {P}^3

and give a complete classification for degree six (degree four or less is trivial, and five is elementary). However, the real purpose is to point out the intricate geometry of examples with many triple points, and how it fits with the general classification of surfaces.
Local models in the ramified case. I: The EL-case
Authors: Pappas G. , Rapoport M.
Published: August 2011

Local models are schemes defined in linear algebra terms that describe the étale local structure of integral models for Shimura varieties and other moduli spaces. We point out that the flatness conjecture of Rapoport-Zink on local models fails in the presence of ramification and that in that case one has to modify their definition. We study modifications of the local models forG=\textrmRE/F\textrmGL(n)G=\text \textrm {R}_{E/F}\text \textrm {GL}(n), withE/FE/Fa totally ramified extension, and for a maximal parahoric level subgroup. The special fibers of these models are subschemes of the affine Grassmannian. We give applications to the structure of Schubert varieties in the affine Grassmannian and to the calculation of sheaves of nearby cycles and describe a relation with geometric convolution. In the general EL case, we replace the conjecture of Rapoport-Zink with a conjecture about the modified local models.
Stringy invariants of normal surfaces
Authors: Veys Willem
Published: August 2011

The stringy Euler number and

E
E

–function of Batyrev for log terminal singularities in dimension 2 can also be considered for a normal surface singularity with all log discrepancies nonzero in its minimal log resolution. Here we obtain a structure theorem for resolution graphs with respect to log discrepancies, implying that these stringy invariants can be defined in a natural way, even when some log discrepancies are zero, and more precisely for all normal surface singularities which are not log canonical. We also show that the stringy

E
E

–functions of log terminal surface singularities are polynomials (with rational powers) with nonnegative coefficients, yielding well defined (rationally graded) stringy Hodge numbers.
One-motives and a conjecture of Deligne
Authors: Ramachandran Niranjan
Published: August 2011

We introduce new motivic invariants of arbitrary varieties over a perfect field. These cohomological invariants take values in the category of one-motives (considered up to isogeny in positive characteristic). The algebraic definition of these invariants presented here proves a [1] conjecture of Deligne. Other applications include some cases of conjectures of Serre, Katz, and Jannsen on the independence of

ℓ
\ell

of parts of the étale cohomology of arbitrary varieties over number fields and finite [1] fields.
On the moduli space of rank 3 vector bundles on a genus 2 curve and the Coble cubic
Authors: Ortega Angela
Published: August 2011

We prove a conjecture about the moduli space

S
U

C

(
3
)

\mathcal {SU}_C(3)

of semi-stable rank 3 vector bundles with trivial determinant on a genus 2 curve

C
C

, due to I. Dolgachev. Given

C
C

a smooth projective curve of genus 2, and the embedding of the Jacobian

J
C

JC

into

|

3
Θ

|

|3\Theta |

, A. Coble proved, at the beginning of the 20th century, that there exists a unique cubic hypersurface

C

\mathcal {C}

in

|

3
Θ

|

∗

≃

P

8

|3\Theta |^* \simeq \mathbb {P}^8

,

J
C
[
3
]

JC[3]

-invariant and singular along

J
C

JC

. On the other hand, we have a map of degree 2 from

S
U

C

(
3
)

\mathcal {SU}_C(3)

over

|

3
Θ

|

≃

P

8
∗

|3\Theta | \simeq \mathbb {P}^{8*}

, ramified along a sextic hypersurface

B

\mathcal {B}

. Dolgachev’s conjecture affirms that the sextic

B

\mathcal {B}

is the dual variety of Coble’s cubic

C

\mathcal {C}

.
The Hodge-𝒟-conjecture for 𝒦3 and Abelian surfaces
Authors: Chen Xi , Lewis James
Published: August 2011

Let

X
X

be a projective algebraic manifold, and

CH

k

(
X
,
1
)

\text {CH}^{k}(X,1)

the higher Chow group, with corresponding real regulator
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="r Subscript k comma 1 Baseline circled-times double-struck upper R colon CH Superscript k Baseline left-parenthesis upper X comma 1 right-parenthesis circled-times double-struck upper R right-arrow upper H Subscript script upper D Superscript 2 k minus 1 Baseline left-parenthesis upper X comma double-struck upper R left-parenthesis k right-parenthesis right-parenthesis">

r

k
,
1

⊗

R

:

CH
k

(
X
,
1
)
⊗

R

→

H

D

2
k
−
1

(
X
,

R

(
k
)
)

\text {r}_{k,1}\otimes {{\mathbb R}}: \text {CH}^k(X, 1)\otimes {{\mathbb R}} \to H_{\mathcal D}^{2k-1}(X,{{\mathbb R}}(k))

. If

X
X

is a general K3 surface or Abelian surface, and

k
=
2

k=2

, we prove the Hodge-

D

{\mathcal D}

-conjecture, i.e. the surjectivity of

r

2
,
1

⊗

R

\text {r}_{2,1}\otimes {{\mathbb R}}

. Since the Hodge-

D

{\mathcal D}

-conjecture is not true for general surfaces in

P

3

\mathbb {P}^{3}

of degree

≥
5

\geq 5

, the results in this paper provide an effective bound for when this conjecture is true.
Effective divisors on \overline{ℳ}_{ℊ}, curves on 𝒦3 surfaces, and the slope conjecture
Authors: Farkas Gavril , Popa Mihnea
Published: August 2011

We compute the class of the compactification of the divisor of curves sitting on a

K
3

K3

surface and show that it violates the Harris-Morrison Slope Conjecture. We carry this out using the fact that this divisor has four distinct incarnations as a geometric subvariety of the moduli space of curves. We also give a counterexample to a hypothesis raised by Harris and Morrison that the Brill-Noether divisors are essentially the only effective divisors on the moduli space of curves having minimal slope

6
+
12

/

(
g
+
1
)

6+12/(g+1)

.
Multiplier ideals, 𝑉-filtration, and spectrum
Authors: Budur Nero , Saito Morihiko
Published: August 2011

For an effective divisor on a smooth algebraic variety or a complex manifold, we show that the associated multiplier ideals coincide essentially with the filtration induced by the filtration

V
V

constructed by B. Malgrange and M. Kashiwara. This implies another proof of a theorem of L. Ein, R. Lazarsfeld, K.E. Smith, and D. Varolin that any jumping coefficient in the interval

(
0
,
1
]

(0,1]

is a root of the Bernstein-Sato polynomial up to sign. We also give a refinement (using mixed Hodge modules) of the formula for the coefficients of the spectrum for exponents not greater than one or greater than the dimension of the variety minus one.
On the failure of pseudo-nullity of Iwasawa modules
Authors: Hachimori Yoshitaka , Sharifi Romyar
Published: August 2011

Consider the family of CM-fields which are pro-

p
p

p
p

-adic Lie extensions of number fields of dimension at least two, which contain the cyclotomic

Z

p

\mathbf {Z}_p

-extension, and which are ramified at only finitely many primes. We show that the Galois groups of the maximal unramified abelian pro-

p
p

extensions of these fields are not always pseudo-null as Iwasawa modules for the Iwasawa algebras of the given

p
p

-adic Lie groups. The proof uses Kida’s formula for the growth of

λ
\lambda

-invariants in cyclotomic

Z

p

{\mathbf Z}_p

-extensions of CM-fields. In fact, we give a new proof of Kida’s formula which includes a slight weakening of the usual

μ
=
0

\mu = 0

assumption. This proof uses certain exact sequences involving Iwasawa modules in procyclic extensions. These sequences are derived in an appendix by the second author.
Frobenius and monodromy operators in rigid analysis, and Drinfel’d’s symmetric space
Authors: Große-Klönne Elmar
Published: August 2011

We define Frobenius and monodromy operators on the de Rham cohomology of

K
K

-dagger spaces (rigid spaces with overconvergent structure sheaves) with strictly semistable reduction

Y
Y

, over a complete discrete valuation ring

K
K

of mixed characteristic. For this we introduce log rigid cohomology and generalize the so-called Hyodo-Kato isomorphism to versions for non-proper

Y
Y

, for non-perfect residue fields, for non-integrally defined coefficients, and for the various strata of

Y
Y

. We apply this to define and investigate crystalline structure elements on the de Rham cohomology of Drinfel’d’s symmetric space

X
X

and its quotients. Our results are used in a critical way in the recent proof of the monodromy-weight conjecture for quotients of

X
X

given by de Shalit (2005).
A canonical decomposition of generalized theta functions on the moduli stack of Gieseker vector bundles
Authors: Kausz Ivan
Published: August 2011

We use a Gieseker type degeneration of the moduli stack of vector bundles on a curve to prove a decomposition formula for generalized theta functions which is motivated by what in conformal field theory is called the factorization rule.
Toric singularities: Log-blow-ups and global resolutions
Authors: Nizioł Wiesława
Published: August 2011

We prove that singularities of Kato’s log-regular schemes (a base-free analogue of toroidal embeddings) can be resolved globally by a log-blow-up. This is done by showing that the classical desingularization algorithms can be globalized and extended to log-schemes.
Mariño-Vafa formula and Hodge integral identities
Authors: Liu Chiu-Chu Melissa , Liu Kefeng , Zhou Jian
Published: August 2011

We derive some Hodge integral identities by taking various limits of the Mariño-Vafa formula using the cut-and-join equation. These identities include the formula of generalλg\lambda _g-integrals, the formula ofλg−1\lambda _{g-1}-integrals onM¯g,1{\overline {\mathcal {M}}}_{g,1}, the formula of cubicλ\lambdaintegrals onM¯g{\overline {\mathcal {M}}}_g, and the ELSV formula relating Hurwitz numbers and Hodge integrals. In particular, our proof of the MV formula by the cut-and-join equation leads to a new and simple proof of theλg\lambda _gconjecture. We also present a proof of the ELSV formula completely parallel to our proof of the Mariño-Vafa formula.
The Grothendieck-Lefschetz theorem for normal projective varieties
Authors: Ravindra G. , Srinivas V.
Published: August 2011

We prove that for a normal projective variety

X
X

in characteristic

0
0

, and a base-point free ample line bundle

L
L

on it, the restriction map of divisor class groups

Cl
⁡
(
X
)
→
Cl
⁡
(
Y
)

\operatorname {Cl} (X)\to \operatorname {Cl}(Y)

is an isomorphism for a general member

Y
∈

|

L

|

Y\in |L|

provided that

dim
⁡

X

≥
4

\dim {X}\geq 4

. This is a generalization of the Grothendieck-Lefschetz theorem, for divisor class groups of singular varieties.
Numerical bounds for semi-stable families of curves or of certain higher-dimensional manifolds
Authors: Viehweg Eckart , Zuo Kang
Published: August 2011

Given an open subset

U
U

of a projective curve

Y
Y

and a smooth family

f
:
V
→
U

f:V\to U

of curves, with semi-stable reduction over

Y
Y

, we show that for a subvariation

V

\mathbb {V}

of Hodge structures of

R
1

f
∗

C

V

R^1f_*\mathbb {C}_V

with

rank

(

V

)
>
2

\textrm {rank} (\mathbb {V})>2

the Arakelov inequality must be strict. For families of

n
n

-folds we prove a similar result under the assumption that the

(
n
,
0
)

(n,0)

component of the Higgs bundle of

V

\mathbb {V}

defines a birational map.
Vanishing theorems of negative vector bundles on projective varieties and the convexity of coverings
Authors: Bogomolov Fedor , de Oliveira Bruno
Published: August 2011

We give a new proof of the vanishing of

H

1

(
X
,
V
)

H^{1}(X,V)

for negative vector bundles

V
V

on normal projective varieties

X
X

satisfying rank

V
>
dim
⁡
X

V> \dim X

. Our proof is geometric, it uses a topological characterization of the affine bundles associated with nontrivial cocycles

α
∈

H

1

(
X
,
V
)

\alpha \in H^{1}(X,V)

of negative vector bundles. Following the same circle of ideas, we use the analytic characteristics of affine bundles to obtain convexity properties of coverings of projective varieties. We suggest a weakened version of the Shafarevich conjecture: the universal covering

X
~

\tilde X

of a projective manifold

X
X

is holomorphically convex modulo the pre-image

ρ

−
1

(
Z
)

\rho ^{-1}(Z)

of a subvariety

Z
⊂
X

Z \subset X

. We prove this conjecture for projective varieties

X
X

whose pullback map

ρ

∗

\rho ^{*}

identifies a nontrivial extension of a negative vector bundle

V
V

by

O

\mathcal {O}

with the trivial extension.
Lie symmetries of the Chow group of a Jacobian and the tautological subring
Authors: Polishchuk A.
Published: August 2011

Let

J
J

be the Jacobian of a smooth projective curve. We define a natural action of the Lie algebra of polynomial Hamiltonian vector fields on the plane, vanishing at the origin, on the Chow group

CH
⁡
(
J

)

Q

\operatorname {CH}(J)_{\mathbb {Q}}

. Using this action we obtain some relations between tautological cycles in

CH
⁡
(
J

)

Q

\operatorname {CH}(J)_{\mathbb {Q}}

.
Kummer surfaces for the self-product of the cuspidal rational curve
Authors: Schröer Stefan
Published: August 2011

The classical Kummer construction attaches a K3 surface to an abelian surface. As Shioda and Katsura showed, this construction breaks down for supersingular abelian surfaces in characteristic two. Replacing supersingular abelian surfaces by the self-product of the rational cuspidal curve, and the sign involution by suitable infinitesimal group scheme actions, we give the correct Kummer-type construction for this situation. We encounter rational double points of type

D
4

D_4

and

D
8

D_8

instead of type

A
1

A_1

. It turns out that the resulting surfaces are supersingular K3 surfaces with Artin invariant one and two. They lie in a 1-dimensional family obtained by simultaneous resolution, which exists after purely inseparable base change.
Counting elliptic curves in 𝐾3 surfaces
Authors: Lee Junho , Leung Naichung
Published: August 2011

We compute the genus

g
=
1

g=1

family GW-invariants of K3 surfaces for non-primitive classes. These calculations verify the Göttsche-Yau-Zaslow formula for non-primitive classes with index two. Our approach is to use the genus two topological recursion formula and the symplectic sum formula to establish relationships among various generating functions.
Arithmetic properties of projective varieties of almost minimal degree
Authors: Brodmann Markus , Schenzel Peter
Published: August 2011

We study the arithmetic properties of projective varieties of almost minimal degree, that is of non-degenerate irreducible projective varieties whose degree exceeds the codimension by precisely

2
2

. We notably show, that such a variety

X
⊂

P

r

X \subset {\mathbb P}^r

is either arithmetically normal (and arithmetically Gorenstein) or a projection of a variety of minimal degree

X
~

⊂

P

r
+
1

\tilde {X} \subset {\mathbb P}^{r + 1}

from an appropriate point

p
∈

P

r
+
1

∖

X
~

p \in {\mathbb P}^{r + 1} \setminus \tilde {X}

. We focus on the latter situation and study

X
X

by means of the projection

X
~

→
X

\tilde {X} \rightarrow X

.

If

X
X

is not arithmetically Cohen-Macaulay, the homogeneous coordinate ring

B
B

of the projecting variety

X
~

\tilde {X}

is the endomorphism ring of the canonical module

K
(
A
)

K(A)

of the homogeneous coordinate ring

A
A

of

X
.

X.

If

X
X

is non-normal and is maximally Del Pezzo, that is, arithmetically Cohen-Macaulay but not arithmetically normal,

B
B

is just the graded integral closure of

A
.

A.

It turns out, that the geometry of the projection

X
~

→
X

\tilde {X} \rightarrow X

is governed by the arithmetic depth of

X
X

in any case.

We study, in particular, the case in which the projecting variety

X
~

⊂

P

r
+
1

\tilde {X} \subset {\mathbb P}^{r + 1}

is a (cone over a) rational normal scroll. In this case

X
X

is contained in a variety of minimal degree

Y
⊂

P

r

Y \subset {\mathbb P}^r

such that

codim
Y

⁡
(
X
)
=
1

\operatorname {codim}_Y(X) = 1

. We use this to approximate the Betti numbers of

X
X

.

In addition, we present several examples to illustrate our results and we draw some of the links to Fujita’s classification of polarized varieties of

Δ
\Delta

-genus

1
1

.
The tautological rings of the moduli spaces of stable maps to flag varieties
Authors: Oprea Dragos
Published: August 2011

We show that the rational cohomology classes on the moduli spaces of genus zero stable maps to

S
L

SL

flag varieties are tautological.
On the topological index of irregular surfaces
Authors: Barja M. , Naranjo J. , Pirola G.
Published: August 2011

We study the topological index of some irregular surfaces that we call generalized Lagrangian. We show that under certain hypotheses on the base locus of the Lagrangian system the topological index is non-negative. For the minimal surfaces of general type with

q
=
4

q=4

and

p
g

=
5

p_g=5

we prove the same statement without any hypothesis.
A conjecture on rational approximations to rational points
Authors: McKinnon David
Published: August 2011

In this paper, we examine how well a rational point

P
P

on an algebraic variety

X
X

can be approximated by other rational points. We conjecture that if

P
P

lies on a rational curve, then the best approximations to

P
P

on

X
X

can be chosen to lie along a rational curve. We prove this conjecture for a wide range of examples, and for a great many more examples we deduce our conjecture from Vojta’s Main Conjecture.
A study of the Hilbert-Mumford criterion for the stability of projective varieties
Authors: Ross Julius , Thomas Richard
Published: August 2011

We make a systematic study of the Hilbert-Mumford criterion for different notions of stability for polarised algebraic varieties

(
X
,
L
)

(X,L)

; in particular for K- and Chow stability. For each type of stability this leads to a concept of slope

μ
\mu

for varieties and their subschemes; if

(
X
,
L
)

(X,L)

is semistable, then

μ
(
Z
)
≤
μ
(
X
)

\mu (Z)\le \mu (X)

for all

Z
⊂
X

Z\subset X

. We give examples such as curves, canonical models and Calabi-Yaus. We prove various foundational technical results towards understanding the converse, leading to partial results; in particular this gives a geometric (rather than combinatorial) proof of the stability of smooth curves.
On the global quotient structure of the space of twisted stable maps to a quotient stack
Authors: Abramovich Dan , Graber Tom , Olsson Martin , Tseng Hsian-Hua
Published: August 2011

Let

X

{\mathcal {X}}

be a tame proper Deligne-Mumford stack of the form

[
M

/

G
]

[M/G]

where

M
M

is a scheme and

G
G

is an algebraic group. We prove that the stack

K

g
,
n

(

X

,
d
)

{\mathcal {K}} _{g,n}({\mathcal {X}},d)

of twisted stable maps is a quotient stack and can be embedded into a smooth Deligne-Mumford stack. When

G
G

is finite, we give a more precise construction of

K

g
,
n

(

X

,
d
)

{\mathcal {K}}_{g,n}( {\mathcal {X}},d)

using Hilbert schemes and admissible

G
G

-covers.
Comparison of fundamental group schemes of a projective variety and an ample hypersurface
Authors: Biswas Indranil , Holla Yogish
Published: August 2011

Let

X
X

be a smooth projective variety defined over an algebraically closed field, and let

L
L

be an ample line bundle over

X
X

. We prove that for any smooth hypersurface

D
D

on

X
X

in the complete linear system

|

L

⊗
d

|

\vert L^{\otimes d}\vert

, the inclusion map

D
↪
X

D\hookrightarrow X

induces an isomorphism of fundamental group schemes, provided

d
d

is sufficiently large and

dim
⁡
X

≥

3

\dim X \, \geq \, 3

. If

dim
⁡
X

=

2

\dim X \, =\, 2

, and

d
d

is sufficiently large, then the induced homomorphism of fundamental group schemes remains surjective. We give an example to show that the homomorphism of fundamental group schemes induced by the inclusion map of a reduced ample curve in a smooth projective surface is not surjective in general.
Rational surfaces in index-one Fano hypersurfaces
Authors: Beheshti Roya , Starr Jason
Published: August 2011

We give the first evidence for a conjecture that a general, index-one, Fano hypersurface is not unirational: (i) a general point of the hypersurface is contained in no rational surface ruled, roughly, by low-degree rational curves, and (ii) a general point is contained in no image of a Del Pezzo surface.
Modular forms for the even modular lattice of signature (2,10)
Authors: Freitag Eberhard , Manni Riccardo
Published: August 2011

We consider the principal congruence subgroup

Γ
[
2
]

\Gamma [2]

of level two inside the orthogonal group of an even and unimodular lattice of signature

(
2
,
10
)

(2,10)

. Using Borcherds’ additive lifting construction, we construct a

715
715

-dimensional space of singular modular forms. This space is the direct sum of the one-dimensional trivial and a

714
714

-dimensional irreducible representation of the finite group

O
⁡
(

F

2

12

)

\operatorname {O}(\mathbb {F}^{12}_2)

(even type). It generates an algebra whose normalization is the ring of all modular forms. We define a certain ideal of quadratic relations. This system appears as a special member of a whole system of ideals of quadratic relations. At least some of them have geometric meaning. For example, we work out the relation to Kondo’s approach to the modular variety of Enriques surfaces.
Triangulations et cohomologie étale sur une courbe analytique 𝑝-adique
Authors: Ducros Antoine
Published: August 2011

Let

k
k

be a non-Archimedean complete field and let

X
X

be a

k
k

-analytic curve as defined by Berkovich. Let

π
\pi

be the natural map between the étale site and the underlying topological space of

X
X

. This text is devoted to the study of the cohomology of sheaves of the kind

R

q

π

∗

F

\mbox {R}^{q}\pi _{*}\mathscr F

. First of all, we define what a triangulation of a curve is and we prove, using the semi-stable reduction theorem, that any curve whose singular locus is nowhere dense has a triangulation. For given

q
q

and

F

\mathscr F

we associate to any triangulation on

X
X

a two-term complex whose cohomology groups are shown to be precisely those of

R

q

π

∗

F

\mbox {R}^{q} \pi _{*}\mathscr F

.

This allows us to prove a comparison theorem between our groups and their scheme-theoretic counterparts when

X
X

is the analytification of a smooth algebraic

k
k

-curve. After that we assume that

k
k

comes with a dualizing module (e.g.,

k
=

C

(
(
t
)
)

k={\mathbb C} ((t))

or

k
=

Q

p

)
.

k={\mathbb Q}_{p}).

Then we build some pairings between suitable cohomology groups and show that their non-degeneratedness is equivalent to some arithmetic properties of some one-dimensional function fields over

k
~

\widetilde {k}

which are attached to certain points of

X
;

X;

thanks to this equivalence we can prove that we actually have perfect pairings in some cases.

Putting those results all together we recover as corollaries some previous theorems of the author concerning unramified

H

3

\mbox {H}^{3}

with coefficients

μ

n

⊗
2

\mu _{n}^{\otimes 2}

over a

p
p

-adic curve, and also Lichtenbaum’s duality between the Picard group and the Brauer group of such a curve.
The classification of surfaces of general type with nonbirational bicanonical map
Authors: Borrelli Giuseppe
Published: August 2011

We classify surfaces of general type whose bicanonical map factors through a rational map of degree 2 to a rational or ruled surface.

We prove that if such a surface has no pencil of genus 2 curves, then it is the smooth minimal model of a double plane branched along a reduced curve with certain singularities, a configuration already suggested by Du Val in the 1950s. This result allows us to complete the classification of surfaces of general type presenting the nonstandard case, with the possible exception of those with

p
g

=
q
≤
1

p_g=q\le 1

.
Derived and abelian equivalence of K3 surfaces
Authors: Huybrechts Daniel
Published: August 2011

The paper attempts to shed more light on a particular class of stability conditions onK3K3surfaces constructed by Tom Bridgeland. The hearts of the underlying t-structures turn out to be significant invariants of the surface. We prove that twoK3K3surfacesXXandX′X’are derived equivalent if and only if there exist complexified polarizationsB+iωB+i\omegaandB′+iω′B’+i\omega ’such that the associated abelian categoriesA(exp⁡(B+iω))\mathcal {A}(\exp (B+i\omega ))andK(exp⁡(B′+iω′))\mathcal {K}(\exp (B’+i\omega ’))are equivalent. We study in detail the minimal objects ofA(exp⁡(B+iω))\mathcal {A}(\exp (B+i\omega ))and investigate stability under the Fourier–Mukai transform.
Some cases of Vojta’s conjecture on integral points over function fields
Authors: Corvaja Pietro , Zannier Umberto
Published: August 2011

In the present paper we solve, in particular, the function field version of a special case of Vojta’s conjecture for integral points, namely for the variety obtained by removing a conic and two lines from the projective plane. This will follow from a bound for the degree of a curve on such a surface in terms of its Euler characteristic.

This case is special, but significant, because it lies “at the boundary”, in the sense that it represents the simplest case of the conjecture which is still open. Also, it was already studied in the context of Nevanlinna Theory by M. Green in the seventies.

Our general results immediately imply the degeneracy of solutions of Fermat type equations

z
d

=
P
(

x
m

,

y
n

)

z^d=P(x^m,y^n)

for all

d
≥
2

d\ge 2

and large enough

m
,
n

m,n

, also in the case of non-constant coefficients. Such equations fall apparently out of all known treatments.

The methods used here refer to derivations, as is usual in function fields, but contain fundamental new points. One of the tools concerns an estimation for the

gcd
(
1
−
u
,
1
−
v
)

\gcd (1-u,1-v)

for

S
S

-units

u
,
v

u,v

; this had been developed also in the arithmetic case, but for function fields we may obtain a much more uniform quantitative version.

In the Appendix we shall finally point out some other implications of the methods to the problem of torsion-points on curves and related known questions.
Sur certaines singularités d’hypersurfaces 𝐼𝐼
Authors: Barlet Daniel
Published: August 2011

The aim of the present article is to construct analytic invariants for a germ of a holomorphic function having a one-dimensional critical locus

S
S

. This is done for a large class of such germs containing for instance any quasi-homogeneous germ at the origin. More precisely, aside from the Brieskorn

(
a
,
b
)

(a,b)

-module at the origin and a (locally constant along

S
∗

:=
S
∖
{
0
}

S^* : = S \setminus \{0\}

) sheaf

H

n

\mathcal {H}^n

of

(
a
,
b
)

(a,b)

-modules associated with the transversal hypersurface singularities along each connected component of

S
∗

S^*

, we construct also

(
a
,
b
)

(a,b)

-modules “with supports”

E
c

E_c

and

E

c
∩

S

′

E’_{c \cap \, S}

.

An interesting consequence of the local study along

S
∗

S^*

is the corollary showing that for a germ with an isolated singularity, the largest sub-

(
a
,
b
)

(a,b)

-module having a simple pole in its Brieskorn-

(
a
,
b
)

(a,b)

-module is independent of the choice of a reduced equation for the corresponding hypersurface germ.

We also give precise relations between these various

(
a
,
b
)

(a,b)

-modules via an exact commutative diagram. This is an

(
a
,
b
)

(a,b)

-linear version of the tangling phenomenon for consecutive strata we have previously studied in the “topological” setting for the localized Gauss-Manin system of

f
f

.

Finally we show that in our situation there exists a non-degenerate

(
a
,
b
)

(a,b)

-sesquilinear pairing
\[

h
:
E
×

E

c

∩

S

′

⟶
|

Ξ
′

|
2

h : E \times E’_{c\,\cap \, S} \longrightarrow \vert \Xi ’ \vert ^2

\]
where

|

Ξ
′

|
2

\vert \Xi ’ \vert ^2

is the space of formal asymptotic expansions at the origin for fiber integrals. This generalizes the canonical hermitian form defined in 1985 for the isolated singularity case (for the

(
a
,
b
)

(a,b)

-module version see the recent 2005 paper). Its topological analogue (for the eigenvalue

1
1

of the monodromy) is the non-degenerate sesquilinear pairing
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="h colon upper H Subscript c intersection upper S Superscript n Baseline left-parenthesis upper F comma double-struck upper C right-parenthesis Subscript equals 1 Baseline times upper H Superscript n Baseline left-parenthesis upper F comma double-struck upper C right-parenthesis Subscript equals 1 Baseline right-arrow double-struck upper C">

h
:

H

c

∩

S

n

(
F
,

C

)

=
1

×

H
n

(
F
,

C

)

=
1

→

C

h : H^n_{c\,\cap \,S}(F, \mathbb {C})_{=1} \times H^n(F, \mathbb {C})_{=1} \to \mathbb {C}

\]
defined in an earlier paper for an arbitrary germ with a one-dimensional critical locus. Then we show this sesquilinear pairing is related to the non-degenerate sesquilinear pairing introduced on the sheaf

H

n

\mathcal {H}^n

via the canonical Hermitian form of the transversal hypersurface singularities.
Scarcity and abundance of trivial zeros in division towers
Authors: Rohrlich David
Published: August 2011

Explicit formulas and asymptotic estimates are derived for twisted root numbers of elliptic curves in division towers. The key assumption on the elliptic curves considered is that the image of the Galois representation afforded by the first layer of the division tower is contained in a Borel subgroup. In [Math. Research Letters 13 (2006), 359–376], by contrast, the Galois representation was assumed to be surjective.
Birational geometry of quadrics in characteristic 2
Authors: Totaro Burt
Published: August 2011

A conic bundle or quadric bundle in characteristic

2
2

can have generic fiber which is nowhere smooth over the function field of the base variety; in that case, the generic fiber is called a quasilinear quadric. We solve some of the main problems of birational geometry for quasilinear quadrics, which remain open for quadrics in characteristic not

2
2

: when are two quadrics birational, and when is a quadric ruled over the base field? The proofs begin by extending Karpenko and Merkurjev’s theorem on the essential dimension of quadrics to arbitrary quadrics (smooth or not) in characteristic

2
2

.