bluuebunny/crossref_metadata_2025 huggingface dataset:
High-Speed Dry Tribological Behaviors of CrNiMo Steel in Nitrogen and Oxygen Atmospheres
Authors: Du San Ming , Zhang Yong Zhen , Shangguan Bao
Published: December 2011

Abstract: In this article, the high-speed dry sliding tribological behaviors of CrNiMo steel against brass in nitrogen and oxygen atmospheres are investigated using a pin-on-disc tribometer. The worn surface is characterized by scanning electron microscopy and electron dispersion spectrums analysis. The wear mechanisms of CrNiMo steel are also analyzed. The results indicate that the tribological properties of CrNiMo steel are coincidental with the law of dry sliding of metal, where the friction coefficients decreases with an increase in sliding speed and with normal load. However, the atmosphere has obvious effects on the tribological properties of CrNiMo steel. In the sliding process, friction heat plays an important role on the tribological properties of materials in high-speed dry friction. The high-speed wear mechanism of CrNiMo steel varies at different atmospheres. In a nitrogen atmosphere, the wear mechanism of CrNiMo steel is mainly characterized by adhesion at a lower speed and load. When the speed and load are increased, melting trace is found in the worn surface accompanied by an abrasive wear. In an oxygen atmosphere, the mechanism is characterized by adhesion at a lower speed and load; with an increase in speed and load, it gradually transformed into oxidation wear and abrasive wear. The difference of the wear mechanisms in the different atmospheres and test parameters is primarily due to the transfer films formed on the contact surfaces of the sliding pairs. In our experimental conditions, the surface film is mainly the metal film in nitrogen, whereas, it is the oxide film in oxygen.
A Study on High Temperature Mechanical Properties of HRB335C Steel
Authors: Wang Biao , Wu Chun Xiang , Ma Jiao Cheng
Published: December 2011

By means of Gleeble-1500 dynamic thermo mechanical simulator using solidifying method, the simulation of continuous casting process for HRB335C steel was carried out and hot ductility and strength were determined. The test results indicate that there were three temperature areas of brittleness for billet produced by HRB335C within 700°C to solidification point, the first temperature area of brittleness was 1300°C to solidification point of the billet, the second temperature area of brittleness was 1200～1000°C, the third temperature area of brittleness was 700～850°C, the steel was plastic within 850～1000°C. The fractographs and micrographs were observed by optical microscope. The reason of embrittlement was analyzed. The cracking sensitivity studied under the different the temperature zone of the fragility for steel HRB335C was found out. The appropriate surface temperature (over 1000°C) of continuous cast billet during bending and straightening was beneficial to avoid and reduce surface cracks and the quality of billet was obviously improved. Key words: Brittle temperature zone; Tensile strength; Microstructure; High temperature mechanical properties; Continuous casting billet
Microstructure Evolution of Undercooled Austenite during Deformation for Medium-Carbon Si-Mn Steel
Authors: Feng Yun Li , Yuan Shao Qiang , Song Meng
Published: December 2011

The microstructure evolution of a medium-carbon Si-Mn steel during deformation of undercooled austenite at different degree of deformation, temperatures and strain rates has been investigated by means of a hot compression simulation test, metallographic microscope, scanning electron microscope and transmission electron microscopy. Also, the mechanism of carbide spheroidized during deformed process has been discussed. The experiment results demonstrate that the process of evolution experienced three stages: that is, strain-induced transformation, austenite eutectoid decomposed to carbides and ferrite matrix, and spheroidization of pearlite at the range of A3-Ar3. The austenitic grains would be refined for the extra-product of ferrite above the Ar3. The eutectoid reaction was induced on the grain boundaries of ferrite and non-transformed austenite and deformation bands with the increasing volume of deformation. An optimum combination of deformation temperature and strain rate is important to obtian the dulplex microstructure consisting of ultrafine ferrites and dispersed carbide particles. The fine spheroidized microstructures are obtained while the deformed temperature reaches 650°C with ≥1.0, meanwhile, The carbides precipate in globular and shot-rod shapes. Keywords: Medium-carbon Si-Mn steel, Undercooled austentite, Microstructure evolution, Deformation induced transformation, Carbide spheroidization
Temperature and Strain-Rate Effect to Mechanical Behavior of Mo-Cr Alloy Cast Iron
Authors: Ruan Jing Kui , Hu Ming Mao
Published: December 2011

Mo-Cr alloy cast iron is the most important material often used to make auto panel dies. To study high-speed machining process of auto panel dies, the material’s elastic modulus and fracture critical values of Mo-Cr alloy iron at 20°C-800°C were studied based on the high temperature elongation test. The material’s stress-strain relation curves at various temperatures (20°C-500°C) and various strain-rates (500/s-5000/s) were studied and the dynamic tensile yield strength values were obtained by dynamic SHPB(Split Hopkinson Pressure Bar) high-speed compression test. The test observation showed that Mo-Cr alloy iron has heat resistance and its behavior is between toughness and brittleness materials. Its toughness is enhanced with temperature increasing. At 20°C-500°C and strain-rates (500/s-5000/s) the dynamic tensile yield strength is decreased about 17％-24％ by temperature softening effect and is increased about 56％-70％ by strain-rate strengthening effect. The strain-rate strengthening effect prevails over temperature softening effect. Keywords: Auto panel die; Mo-Cr alloy cast iron; SHPB; Temperature softening effect; Strain-rate strengthening effect
Numerical Simulation of the Effects of Different Coatings on Graphite Susceptor for the Induction Process of Polycrystalline Silicon
Authors: Lian K.L. , Lian S.S. , Tsao S.
Published: December 2011

The vacuum induction melting and control solidification is a new developed process for the manufacture of polycrystalline silicon with the advantage of quick heating rate compared to the traditional resistance heating method. The graphite susceptor of the induction furnace plays a key role in controlling the temperature of the melt of polycrystal silicon for solar cells. This paper investigates how different coatings painted on the susceptor would influence the heating efficiency and the temperature distribution of the silicon melt. A graphite susceptor is usually coated with a thin film of insulating material to reduce heat losses and to prevent vapors such as SiO to contaminate the susceptor. Numerical simulations show that the coating material at the outer surface of the susceptor should be the one with low thermal conductivity to prevent heat loss. On the other hand, the coating on the inner surface should be the material with high thermal conductivity to allow easy heat transfer.
Microbial Infection-Induced Expansion of Effector T Cells Overcomes the Suppressive Effects of Regulatory T Cells via an IL-2 Deprivation Mechanism
Authors: Benson Alicia , Murray Sean , Divakar Prashanthi , Burnaevskiy Nikolay , Pifer Reed , Forman James , Yarovinsky Felix
Published: December 2011

Foxp3+ regulatory T (Treg) cells are a critical cell population that suppresses T cell activation in response to microbial and viral pathogens. We identify a cell-intrinsic mechanism by which effector CD4+ T cells overcome the suppressive effects of Treg cells in the context of three distinct infections: Toxoplasma gondii, Listeria monocytogenes, and vaccinia virus. The acute responses to the parasitic, bacterial, and viral pathogens resulted in a transient reduction in frequency and absolute number of Treg cells. The infection-induced partial loss of Treg cells was essential for the initiation of potent Th1 responses and host protection against the pathogens. The observed disappearance of Treg cells was a result of insufficiency in IL-2 caused by the expansion of pathogen-specific CD4+ T cells with a limited capacity of IL-2 production. Exogenous IL-2 treatment during the parasitic, bacterial, and viral infections completely prevented the loss of Treg cells, but restoration of Treg cells resulted in a greatly enhanced susceptibility to the pathogens. These results demonstrate that the transient reduction in Treg cells induced by pathogens via IL-2 deprivation is essential for optimal T cell responses and host resistance to microbial and viral pathogens.
Processing of emotional faces in social phobia
Authors: Staugaard Søren Risløv , Rosenberg Nicole Kristjansen
Published: December 2011

Previous research has found that individuals with social phobia differ from controls in their processing of emotional faces. For instance, people with social phobia show increased attention to briefly presented threatening faces. However, when exposure times are increased, the direction of this attentional bias is more unclear. Studies investigating eye movements have found both increased as well as decreased attention to threatening faces in socially anxious participants. The current study investigated eye movements to emotional faces in eight patients with social phobia and 34 controls. Three different tasks with different exposure durations were used, which allowed for an investigation of the time course of attention. At the early time interval, patients showed a complex pattern of both vigilance and avoidance of threatening faces. At the longest time interval, patients avoided the eyes of sad, disgust, and neutral faces more than controls, whereas there were no group differences for angry faces.
The influence of episodic mood disorders on length of stay among patients admitted to private and non-profit hospitals with alcohol dependence syndrome
Authors: Dickerson Justin B.
Published: December 2011

Episodic mood disorders are often associated with alcohol dependence. Few studies have explored the contribution of episodic mood disorders to length of stay among those hospitalized with alcohol dependence syndrome. Filling this research gap could improve care for patients while minimizing hospital utilization costs. This study was a cross-sectional analysis of the National Hospital Discharge Survey. ICD-9-CM diagnosis codes were used to identify those admitted to a private or non-profit hospital with alcohol dependence syndrome, and a co-morbid diagnosis of an episodic mood disorder (n=358). Descriptive statistics were used to highlight differences in key demographic and hospital variables between those with and without episodic mood disorders. Negative binomial regression was used to associate episodic mood disorders with hospital length of stay. Incidence rate ratios were calculated. Co-morbid episodic mood disorders ([.beta]=0.31, P=0.001), referral to a hospital by a physician ([.beta]=0.35, P=0.014), and increasing age ([.beta]= 0.01, P=0.001) were associated with longer hospital stays. Hospital patients with an admitting diagnosis of alcohol dependence syndrome were 36% more likely to have a longer hospital stay if they also had a co-morbid diagnosis of an episodic mood disorder (IRR=1.36, CI=1.14-1.62). Patients admitted to a hospital with alcohol dependence syndrome should be routinely screened for episodic mood disorders. Opportunities exist for enhanced transitional care between acute, ambulatory, and community-based care settings to lower hospital utilization.
King Saul�s mustering of all Israel (1 Sm 11:6�7): An idealised leadership
Authors: Kim Jeong Bong
Published: December 2011

1 Samuel 11:6�7 report the beginning of Saul�s public life and demonstrate his leadership over Israel. However, the verses do not clearly indicate his role in the specific events related in verses 1�11. This article clarifies Saul�s idealised kingly leadership by examining some of the literary-critical issues of 1 Samuel 11:1�11 in their broader context. Saul�s leadership was then considered against its larger ancient Near Eastern context. The article aimed to show that both Saul�s religious authority and also his political ability were welcomed in his emerging kingship.
Expression of the Androgen Receptor and its Correlation with Molecular Subtypes in 980 Chinese Breast Cancer Patients
Authors: Qi Ji-ping , Yang You-lin , Zhu Hong , Wang Jianmin , Jia Ying , Liu Na , Song Yue-jia , Zan Li-kun , Zhang Xu , Zhou Min , Gu Yun-he , Liu Tao , Hicks David G. , Tang Ping
Published: December 2011

Background

Recent studies have shown that androgen displays an inhibitory effect on breast cancer cell lines that express androgen receptor (AR) but not estrogen receptor (ER) and progesterone receptor (PR). We have previously reported that approximately 1/3 of ER negative high grade invasive ductal carcinomas express AR. Thus, AR can serve as a potential therapeutic target for this group of patients.

Aim

Here we investigated AR expression patterns in 980 consecutive breast carcinomas.

Results

We found that (1) AR was expressed more frequently (77%) than ER (61%) and PR (60%) in breast carcinomas; (2) AR expression was associated with ER and PR expression ( P < 0.0001), small tumor size ( P = 0.0324) and lower Ki-67 expression ( P = 0.0013); (3) AR expression was found in 65% of ER negative tumors; (4) AR expression was associated with PR and Ki-67 in ER negative tumors, but not in ER positive tumors; (5) AR expression was higher in ER positive subtypes (Luminal A, Luminal B and Luminal HER2 subtypes, 80%-86%) and lower in ER negative subtypes [HER2, triple negative (TN), and TN EFGR positive subtypes; 52%-66%], with over 50% of TN tumors expressing AR.

Conclusion

More breast carcinomas express AR than ER and PR, including significant numbers of ER negative and TN tumors, for which AR could serve as a potential therapeutic target.
Factors Predicting Coronary Sinus Rupture following Cannula Insertion for Retrograde Cardioplegia
Authors: Sabzi Feridoun , Zokaei Abdolhamid
Published: December 2011

Background

Coronary sinus rupture (CSR) is a rare preventable complication of cannula insertion for retrograde cardioplegia. In the hands of an inexperienced surgeon, this complication has the risk of potential mortality and morbidity, and its repair is technically challenging. Techniques for repairing CSR have been reported previously. In this study, we determined predictors of CSR following coronary artery bypass graft (CABG) surgery.

Methods

Over a four-year period, we retrospectively analyzed 1500 patients in whom a retrograde coronary sinus catheter was used to administer cardioplegic solution. CSR occurred in 15 patients. (12 women and 3 men). Variables such as age, weight, body mass index, gender, aortic clamp time, pump time, cardiomegaly, ejection fraction, and number of grafts were determined for each patient. Factors correlated with CSR were analyzed using multiple regression analysis, and odd ratios of significant variables were determined.

Results

In multiple regression analysis, factors such as female gender, age, weight, and body mass index showed a significant correlation with CSR, and their odd ratios were 4.2, 1.0, 0.96, and 2.2, respectively.

Conclusion

In all 15 cases, a retrograde cannula with a self-inflatable balloon was used and 12 patients were woman with low body mass index. Forceful insertion due to coronary sinus web, fragility of arteries in thin patients, or a small coronary sinus caused CSR in the hands of an inexperienced surgeon.
Clinical Features and Differential Diagnoses in Laryngeal Mucoepidermoid Carcinoma
Authors: Mokhtari Sepideh , Mokhtari Saeedeh
Published: December 2011

Mucoepidermoid carcinoma is the most common malignant tumor of salivary glands. However, it is a rare entity in larynx. Laryngeal cases are frequently misdiagnosed with other malignancies and they are under-reported. So, recognizing the clinical and histological features of this tumor is essential. Laryngeal mucoepidermoid carcinoma can arise in supraglottis, glottis and subglottis. Generally, it presents as a submucosal mass; therefore, progressive symptoms without any identifiable lesion in laryngoscopy must be well considered. The prognosis is somehow dependent on the histological features. In high-grade tumors, recurrence is more common and radical surgery with radiotherapy is recommended. In this paper, we provide a thorough literature review on mucoepidermoid carcinoma in the larynx. The most important distinguishing features of mucoepidermoid carcinoma and its two major differential diagnoses (squamous cell carcinoma and adenosquamous carcinoma) are clearly stated and pitfalls in true diagnosis of this tumor are discussed.
A Finished Dietary Supplement Stimulates Lipolysis and Metabolic Rate in Young Men and Women
Authors: McCarthy Cameron G. , Farney Tyler M. , Canale Robert E. , Alleman Rick J. , Bloomer Richard J.
Published: December 2011

Background

Dietary supplements are often marketed to increase lipolysis and thermogenesis, with the proposed end result being weight loss and body fat reduction. It was the purpose of the present investigation to study the acute effects of a weight/fat loss supplement within a sample of healthy human subjects.

Methods

Twelve subjects (men 24.8 ± 4.3 yrs; women 22.8 ± 0.4 yrs) ingested a dietary supplement (OxyELITE Pro™) or a placebo, on two separate days in a double-blind, cross-over design. Blood samples were collected immediately before ingestion, and at 60 and 120 minutes post ingestion, and analyzed for plasma glycerol and free fatty acids (FFA). Breath samples were collected immediately before ingestion and at 30, 60, 90, and 120 minutes post ingestion, for a measure of kilocalorie expenditure using indirect calorimetry. Area under the curve (AUC) was calculated. Heart rate and blood pressure were recorded at all times and rate pressure product (RPP) was calculated.

Results

AUC was greater for supplement compared to placebo for glycerol (22.74 ± 1.98 μg · mL-1 · 2 hr-1 vs. 15.76 ± 1.36 μg · mL-1 · 2 hr-1; P = 0.001), FFA(1.62 ± 0.07 mmol · L-1 · 2 hr-1 vs. 0.78 ± 0.12 mmol · L-1 · 2 hr-1; P < 0.0001), and kilocalorie expenditure (149 ± 7 kcal · 2 hr-1 vs. 122 ± 8 kcal · 2 hr-1; P = 0.005). Heart rate ( P = 0.02), systolic blood pressure ( P < 0.0001), and RPP ( P = 0.002) were higher for supplement compared to placebo.

Conclusion

Ingestion of OxyELITE Pro™ resulted in an increase in blood markers of lipolysis, as well as metabolic rate, during a two-hour post ingestion time period. An increase in hemodynamic variables was also observed. These findings are in reference to a sample of healthy men and women who were naïve to treatment with the dietary supplement. Additional work is needed to determine if the acute changes observed here would persist with chronic use of the supplement and possibly lead to weight/body fat loss over time.
Subnormal operators of Xia's model and real algebraic curves in $\mathbb C^2$
Authors: Yakubovich Dmitry V.
Published: December 2011

Xia proves in [9] that a pure subnormal operator

S

is completely determined by its self-commutator

C = S^*S – SS^*

, restricted to the closure

M

of its range and the operator

\Lambda = (S^*|M)^*

. In [9–11] he constructs a model for

S

that involves these two operators and the so-called mosaic which is a projection-valued function, analytic outside the spectrum of the minimal normal extension of

S

. He finds all pure subnormals

S

with rank

C=2

. We will give a complete description of pairs of matrices

(C, \Lambda)

that correspond to some

S

for the case of the self-commutator

C

of arbitrary finite rank. It is given in terms of a topological property of a certain algebraic curve, associated with

C

and

\Lambda

. We also give a new explicit formula for Xia's mosaic.
Weighted Weyl estimates near an elliptic trajectory
Authors: Paul Thierry , Uribe Alejandro
Published: December 2011

Let

\psi^\hbar_j

and

E^\hbar_j

denote the eigenfunctions and eigenvalues of a Schrödinger type operator

H_\hbar

with discrete spectrum. Let

\psi_{(x, \xi)}

be a coherent state centered at a point

(x, \xi)

belonging to an elliptic periodic orbit,

\gamma

of action

S\gamma

and Maslov index

\sigma_\gamma

. We consider “weighted Weyl estimates” of the following form: we study the asymptotics, as

\hbar \longrightarrow 0

along any sequence

\hbar = \frac {S_\gamma} {2\pi l – \alpha + \sigma_\gamma},

l \in \mathbb N, \alpha \in \mathbb R

fixed, of

\sum_{|Ej–E|≤c\hbar} | (\psi_{(x, \xi)}, \psi^h_j) |^2.

We prove that the asymptotics depend strongly on

\alpha

-dependent arithmetical properties of

c

and on the angles

\theta

of the Poincaré mapping of

\gamma

. In particular, under irrationality assumptions on the angles, the limit exists for a non-open set of full measure of

c

's. We also study the regularity of the limit as a function of

c

.
On Bernoulli identities and applications
Authors: Eie Minking , Lai King F.
Published: December 2011

Bernoulli numbers appear as special values of zeta functions at integers and identities relating the Bernoulli numbers follow as a consequence of properties of the corresponding zeta functions. The most famous example is that of the special values of the Riemann zeta function and the Bernoulli identities due to Euler. In this paper we introduce a general principle for producing Bernoulli identities and apply it to zeta functions considered by Shintani, Zagier and Eie. Our results include some of the classical results of Euler and Ramanujan. Kummers congruences play important roles in the investigation of

p

-adic interpolation of the classical Riemann zeta function.
Hölder quasicontinuity of Sobolev functions on metric spaces
Authors: Hajłasz Piotr , Kinnunen Juha
Published: December 2011

We prove that every Sobolev function defined on a metric space coincides with a Hölder continuous function outside a set of small Hausdorff content or capacity. Moreover, the Hölder continuous function can be chosen so that it approximates the given function in the Sobolev norm. This is a generalization of a result of Maly [Ma1] to the Sobolev spaces on metric spaces [H1].
Subnormal operators of finite type II. Structure theorems
Authors: Yakubovich Dmitry V.
Published: December 2011

This paper concerns pure subnormal operators with finite rank self-commutator, which we call subnormal operators of finite type. We analyze Xia's theory of these operators [21–23] and give its alternative exposition. Our exposition is based on the explicit use of a certain algebraic curve in

\mathbb C^2

, which we call the discriminant curve of a subnormal operator, and the approach of dual analytic similarity models of [26]. We give a complete structure result for subnormal operators of finite type which corrects and strenghtens the formulation that Xia gave in [23]. Xia claimed that each subnormal operator of finite type is unitarily equivalent to the operator of multiplication by

z

on a weighted vector

H^2

-space over a “quadrature Riemann surface” (with a finite rank perturbation of the norm. We explain how this formulation can be corrected and show that, conversely, every “quadrature Riemann surface” gives rise to a family of subnormal operators. We prove that this family is parametrized by the so-called characters. As a departing point of our study, we formulate a kind of scattering scheme for normal operators, which includes Xia's model as a particular case.
Harnack inequalities on a manifold with positive or negative Ricci curvature
Authors: Bakry Dominique , Qian Zhongmin M.
Published: December 2011

Several new Harnack estimates for positive solutions of the heat equation on a complete Riemannian manifold with Ricci curvature bounded below by a positive or a negative constant are established. These estimates are sharp both for small time for large time and for large distance and lead to new estimates for the heat kernel of a manifold with Ricci curvature bounded below.
Parabolic Harnack inequality and estimates of Markov chains on graphs
Authors: Delmotte Thierry
Published: December 2011

On a graph, we give a characterization of a parabolic Harnack inequality and Gaussian estimates for reversible Markov chains by geometric properties (volume regularity and Poincarà inequality).
On radial behaviour and balanced Bloch functions
Authors: Donaire Juan J. , Pommerenke Christian
Published: December 2011

A Bloch function

g

is a function analytic in the unit disk such that

(1–|z|^2)|g' (z)|

is bounded. First we generalize the theorem of Rohde that, for every "bad" Bloch function,

g(r \zeta) (r \longrightarrow 1)

follows any prescribed curve at a bounded distance for

\zeta

in a set of Hausdorff dimension almost one. Then we introduce balanced Bloch functions. They are characterized by the fact that

|g'(z)|

does not vary much on each circle

\lbrace |z| = r\rbrace

except for small exceptional arcs. We show e.g. that

\int^1_0|g'(r \zeta)|dr< \infty

holds either for all

\zeta \in \mathbb T

or for none.
Newtonian spaces: An extension of Sobolev spaces to metric measure spaces
Authors: Shanmugalingam Nageswari
Published: December 2011

This paper studies a possible definition of Sobolev spaces in abstract metric spaces and answers in the affirmative the question whether this definition yields a Banach space. The paper also explores the relationship between this definition and the Hajlasz spaces. For specialized metric spaces the Sobolev embedding theorems are proven. Different versions of capacities are also explored and these various definitions are compared. The main tool used in this paper is the concept of moduli of path families.
Measure-preserving quality within mappings
Authors: Semmes Stephen
Published: December 2011

In [6], Guy David introduced some methods for finding controlled behavior in Lipschitz mappings with substantial images (in terms of measure). Under suitable conditions, David produces subsets on which the given mapping is bilipschitz with uniform bounds for the bilipschitz constant and the size of the subset. This has applications for boundedness of singular integral operators and "uniform rectifiability" of sets as in [6, 7, 11, 13]. Some special cases of David's results, concerning projections of subsets of Euclidean spaces of codimension 1, or mappings defined on Euclidean spaces (rather than sets or metric spaces of less simple nature), have been given alternate and much simpler proofs, as in [8, 9, 10]. In general this has not occurred.

Here we shall present a variation on David's method which breaks down into simpler pieces. We shall also take advantage of some components of the work of Peter Jones [19]. Jones' approach uses some Littlewood–Paley theory, and one of the important features of David's method was to avoid this, operating in a more directly geometric way which could be applied more broadly. To some extent, the present organization gives a reconciliation between the two, and between David's stopping-time argument and techniques related to Carleson measures and Carleson's Corona construction.
On the generalized Bernoulli numbers that belong to unequal characters
Authors: Slavutskii Ilya Sh.
Published: December 2011

The study of class number invariants of absolute abelian fields, the investigation of congruences for special values of

L

-functions, Fourier coefficients of half-integral weight modular forms, Rubin's congruences involving the special values of

L

-functions of elliptic curves with complex multiplication, and many other problems require congruence properties of the generalized Bernoulli numbers (see [16-18, 12, 29, 3], etc.). The first steps in this direction can be found in the papers of H. W. Leopoldt (see [15]) and L. Carlitz (see [5]). For further studies, see [22, 24, 29]. This paper presents some new examples extending both old author's results and recent investigations of H. Lang (see [14]), A. Balog, H. Darmon, K. Ono (see [3]), etc. On the whole the proved results are consequence of congruences connecting the generalized Bernoulli numbers that belong to unequal characters.
Morera type problems in Clifford analysis
Authors: Marmolejo Olea Emilio
Published: December 2011

The Pompeiu and the Morera problems have been studied in many contexts and generality. For example in different spaces with different groups locally without an invariant measure etc. The variations obtained exhibit the fascination of these problems. In this paper we present a new aspect: we study the case in which the functions have values over a Clifford Algebra. We show that in this context it is completely natural to consider the Morera problem and its variations. Specically we show the equivalence between the Morera problem in Clifford analysis and Pompeiu problem for surfaces in

\mathbb R^n

. We also show an invariance theorem. The noncommutativity of the Clifford algebras brings in some peculiarities. Our main result is a theorem showing that the vanishing of the first moments of a Clifford valued function implies Clifford analyticity. The proof depends on results which show that a particular matrix system of convolution equations admits spectral synthesis.
Non-symmetric hitting distributions on the hyperbolic half-plane and subordinated perpetuities
Authors: Baldi Paolo , Cassadio Tarabusi Enrico , Figà-Talamanca Alessandro , Yor Marc
Published: December 2011

We study the law of functionals whose prototype is

\int_0^{+\infty}

e^{B{_s}^{(\nu)}} dW{_s}{^{(\mu)}}

, where

B^{(\nu)}

,

W^{(\mu)}

are independent Brownian motions with drift. These functionals appear naturally in risk theory as well as in the study of invariant diffusions on the hyperbolic halfplane. Emphasis is put on the fact that the results are obtained in two independent, very different fashions (invariant diffusions on the hyperbolic halfplane and Bessel processes).
A uniform estimate for quartile operators
Authors: Thiele Christoph
Published: December 2011

There is a one parameter family of bilinear Hilbert transforms. Recently, some progress has been made to prove

L^p

estimates for these operators uniformly in the parameter. In the current article we present some of these techniques in a simplified model: we prove the estimate

L^2\times L^2\to L^{1,\infty}

uniformly for a discrete family of model operators for the bilinear Hilbert transform.
Constant scalar curvature hypersurfaces with spherical boundary in Euclidean space
Authors: Alías Luis J. , Malacarne J. Miguel
Published: December 2011

It is still an open question whether a compact embedded hypersurface in the Euclidean space with constant mean curvature and spherical boundary is necessarily a hyperplanar ball or a spherical cap, even in the simplest case of a compact constant mean curvature surface in

\mathbb{R}^3

bounded by a circle. In this paper we prove that this is true for the case of the scalar curvature. Specifically we prove that the only compact embedded hypersurfaces in the Euclidean space with constant scalar curvature and spherical boundary are the hyperplanar round balls (with zero scalar curvature) and the spherical caps (with positive constant scalar curvature). The same applies in general to the case of embedded hypersurfaces with constant

r

-mean curvature, with

r \geq 2

.
Non-rectifiable limit sets of dimension one
Authors: Bishop Christopher J.
Published: December 2011

We construct quasiconformal deformations of convergence type Fuchsian groups such that the resulting limit set is a Jordan curve of Hausdorff dimension 1, but having tangents almost nowhere. It is known that no divergence type group has such a deformation. The main tools in this construction are (1) a characterization of tangent points in terms of Peter Jones'

\beta

's, (2) a result of Stephen Semmes that gives a Carleson type condition on a Beltrami coefficient which implies rectifiability and (3) a construction of quasiconformal deformations of a surface which shrink a given geodesic and whose dilatations satisfy an exponential decay estimate away from the geodesic.
Minimal Resolutions of Lattice Ideals and Integer Linear Programming
Authors: Briales-Morales Emilio , Campillo-López Antonio , Pisón-Casares Pilar , Vigneron-Tenorio Alberto
Published: December 2011

A combinatorial description of the minimal free resolution of a lattice ideal allows us to the connection of Integer Linear Programming and Algebra. The non null reduced homology spaces of some simplicial complexes are the key. The extremal rays of the associated cone reduce the number of variables.
Graphs associated with nilpotent Lie algebras of maximal rank
Authors: Diáz Eduardo , Fernández-Mateos Rafael , Fernández-Ternero Desemparados , Núñez Juan
Published: December 2011

In this paper, we use the graphs as a tool to study nilpotent Lie algebras. It implies to set up a link between graph theory and Lie theory. To do this, it is already known that every nilpotent Lie algebra of maximal rank is associated with a generalized Cartan matrix

A

and it is isomorphic to a quotient of the positive part

\mathfrak{n}_+

of the Kac-Moody algebra

\mathfrak{g}(A)

. Then, if

A

is affine, we can associate

\mathfrak{n}_+

with a directed graph (from now on, we use the term digraph) and we can also associate a subgraph of this digraph with every isomorphism class of nilpotent Lie algebras of maximal rank and of type

A

. Finally, we show an algorithm which obtains these subgraphs and also groups them in isomorphism classes.
Computation of Centralizers in Braid groups and Garside groups
Authors: Franco Nuno , González-Meneses Juan
Published: December 2011

We give a new method to compute the centralizer of an element in Artin braid groups and, more generally, in Garside groups. This method, together with the solution of the conjugacy problem given by the authors in [9], are two main steps for solving conjugacy systems, thus breaking recently discovered cryptosystems based in braid groups [2]. We also present the result of our computations, where we notice that our algorithm yields surprisingly small generating sets for the centralizers.
Explicit models for perverse sheaves
Authors: Gudiel Rodríguez Félix , Narváez Macarro Luis
Published: December 2011

We consider categories of generalized perverse sheaves, with relaxed constructibility conditions, by means of the process of gluing

t

-structures and we exhibit explicit abelian categories defined in terms of standard sheaves categories which are equivalent to the former ones. In particular, we are able to realize perverse sheaves categories as non full abelian subcategories of the usual bounded complexes of sheaves categories. Our methods use induction on perversities. In this paper, we restrict ourselves to the two-strata case, but our results extend to the general case.
Noncommutative algebraic geometry
Authors: Laudal Olav Arnfinn
Published: December 2011

The need for a noncommutative algebraic geometry is apparent in classical invariant and moduli theory. It is, in general, impossible to find commuting parameters parametrizing all orbits of a Lie group acting on a scheme. When one orbit is contained in the closure of another, the orbit space cannot, in a natural way, be given a scheme structure.

In this paper we shall show that one may overcome these difficulties by introducing a noncommutative algebraic geometry, where affine “schemes” are modeled on associative algebras. The points of such an affine scheme are the simple modules of the algebra, and the local structure of the scheme at a finite family of points, is expressed in terms of a noncommutative deformation theory proposed by the author in [10].

More generally, the geometry in the theory is represented by a
swarm
, i.e. a diagram (finite or infinite) of objects (and if one wants, arrows) in a given

k

-linear Abelian category (

k

a field), satisfying some reasonable conditions. The noncommutative deformation theory refered to above, permits the construction of a presheaf of associative

k

-algebras, locally
parametrizing
the diagram. It is shown that this theory, in a natural way, generalizes the classical scheme theory. Moreover it provides a promising framework for treating problems of invariant theory and moduli problems. In particular it is shown that many moduli spaces in classical algebraic geometry are commutativizations of noncommutative schemes containing additional information.
La théorie des équations différentielles $p$-adiques et le Théorème de la monodromie $p$-adique
Authors: Mebkhout Zoghman
Published: December 2011

In this lecture we introduce the reader to the proof of the

p

-adic monodromy theorem linking the

p

-adic differential equations theory and the local Galois

p

-adic representations theory.
An Application of Algebraic Geometry to Encryption: Tame Transformation Method
Authors: Moh T.T.
Published: December 2011

Let

K

be a finite field of

2^{\ell}

elements. Let

\phi_4,\phi_3, \phi_2,\phi_1

be tame mappings of the

n\!+r

-dimensional affine space

K^{n+r}

. Let the composition

\phi_4\phi_3\phi_2\phi_1

be

\pi

. The mapping

\pi

and the

\phi_i

's will be hidden. Let the component expression of

\pi

be

(\pi_1(x_1,\dots,x_{n+r}),\dots \pi_{n+r}(x_1,\dots,x_{n+r}))

. Let the restriction of

\pi

to a subspace be

\hat\pi

as

\hat\pi=(\pi_1(x_1,\dots,x_n,0,\dots,0),\dots,\pi_{n+r}(x_1,\dots, x_n,0,\dots,0))=(f_1,\dots,f_{n+r}) : K^n\ mapsto K^{n+r}

. The field

K

and the polynomial map (

f_1,\dots,f_{n+r}

) will be announced as the public key. Given a plaintext

(x'_1,\dots,x'_n)\in K^n

, let

y'_i=f_i(x'_1,\dots,x'_n)

, then the ciphertext will be

(y'_1,\dots,y'_{n+r})\in K^{n+r}

. Given

\phi_i

and (

y'_1,\dots,y'_{n+r}

), it is easy to find

\phi_i^{-1}(y'_1,\dots,y'_{n+r})

. Therefore the plaintext can be recovered by

(x'_1,\dots,x'_n,0,\dots,0) = \phi_1^{-1}\phi_2^{-1} \phi_3^{-1}\phi_4^{-1}\,\hat\pi\,(x'_1,\dots,x'_n)=\phi_1^{-1} \phi_2^{-1}\phi_3^{-1}\phi_4^{-1}(y'_1,\dots, y'_{n+r})

. The private key will be the set of maps

\{\phi_1,\phi_2,\phi_3,\phi_4\}

. The security of the system rests in part on the difficulty of finding the map

\pi

from the partial informations provided by the map

\hat\pi

and the factorization of the map

\pi

into a product (i.e., composition) of tame transformations

\phi_i

's.
Some geometric aspects of Puiseux surfaces
Authors: Tornero José M.
Published: December 2011

This paper is part of the author's thesis, recently presented, where the following problem is treated: Characterizing the tangent cone and the equimultiple locus of a Puiseux surface (that is, an algebroid embedded surface admitting an equation whose roots are Puiseux power series), using a set of exponents appearing in a root of an equation. The aim is knowing to which extent the well-known results for the quasi-ordinary case can be extended to this much wider family.
Periodic Quasiregular Mappings of Finite Order
Authors: Drasin David , Sastry Swati
Published: December 2011

The authors construct a periodic quasiregular function of any finite order

\rho

,

1\leq\rho < \infty

. This completes earlier work of O. Martio and U. Srebro.
Kinetic equilibration rates for granular media and related equations: entropy dissipation and mass transportation estimates
Authors: Carrillo José A. , McCann Robert J. , Villani Cédric
Published: December 2011

The long-time asymptotics of certain nonlinear, nonlocal, diffusive equations with a gradient flow structure are analyzed. In particular, a result of Benedetto, Caglioti, Carrillo and Pulvirenti [BCCP98] guaranteeing eventual relaxation to equilibrium velocities in a spatially homogeneous model of granular flow is extended and quantified by computing explicit relaxation rates. Our arguments rely on establishing generalizations of logarithmic Sobolev inequalities and mass transportation inequalities, via either the Bakry-Emery method or the abstract approach of Otto and Villani [OV00].
Critical nonlinear elliptic equations with singularities and cylindrical symmetry
Authors: Badiale Marino , Serra Enrico
Published: December 2011

Motivated by a problem arising in astrophysics we study a nonlinear elliptic equation in

\mathbb{R}^{N}

with cylindrical symmetry and with singularities on a whole subspace of

\mathbb{R}^{N}

. We study the problem in a variational framework and, as the nonlinearity also displays a critical behavior, we use some suitable version of the Concentration-Compactness Principle. We obtain several results on existence and nonexistence of solutions.
Isometries between C*-algebras
Authors: Chu Cho-Ho J. , Wong Ngai-Ching
Published: December 2011

Let

A

and

B

be C*-algebras and let

T

be a linear isometry from

A

into

B

. We show that there is a largest projection

p

in

B^{**}

such that

T(\cdot)p : A \longrightarrow B^{**}

is a Jordan triple homomorphism and

T(a b^* c + c b^* a) p= T(a) T(b)^* T(c) p + T(c) T(b)^* T(a) p

for all

a

,

b

,

c

in

A

. When

A

is abelian, we have

\|T(a)p\|=\|a\|

for all

a

in

A

. It follows that a (possibly non-surjective) linear isometry between any C*-algebras reduces
locally
to a Jordan triple isomorphism, by a projection.
Transitive flows on manifolds
Authors: Jiménez López Víctor , Soler López Gabriel
Published: December 2011

In this paper we characterize manifolds (topological or smooth, compact or not, with or without boundary) which admit flows having a dense orbit (such manifolds and flows are called transitive) thus fully answering some questions by Smith and Thomas. Namely, it is shown that a surface admits a transitive flow (which can be got smooth) if and only if it is connected and it is neither homeomorphic to the sphere nor the projective plane nor embeddable in the Klein bottle (or, alternatively, if it is connected and includes two orientable topological circles intersecting transversally at exactly one point). We also prove that any (connected) manifold with dimension at least 3 admits a transitive flow, which can be got smooth if the manifold admits a smooth structure. In particular, this allows us to characterize

\omega

-limit sets with nonempty interior for flows in a given

n

-manifold (as they can be described by the property of being the closure of its transitive

n

-submanifolds).
Levi equation for almost complex structures
Authors: Citti Giovanna , Tomassini Giuseppe
Published: December 2011

In this paper we are dealing with the boundary problem for Levi flat graphs in the space

\mathbb{R}^4

, endowed with an almost complex structure

J

. This problem can be formalized as a Dirichlet problem for a quasilinear degenerate elliptic equation, called Levi equation. The Levi equation has the form

D_1^2 + D^2_2 - D_1f = 0,

where

D_1

and

D_2

are nonlinear vector fields. Under geometrical assumptions on the boundary a lipschitz continuous viscosity solution is found. The regularity of the viscosity solution is studied in suitable anisotropical Sobolev spaces, and it is proved that the solution has derivatives of any order in the direction of the vectors

D_1

and

D_2

i.e. it is of class

C^\infty

in these directions, but not necessary regular in the third direction of the space. Finally, after proving a weak version of the Frobenius theorem, we show that the graph of the solution is foliated in holomorphic curves.
Abelian integrals in holomorphic foliations
Authors: Movasati Hossein
Published: December 2011

The aim of this paper is to introduce the theory of Abelian integrals for holomorphic foliations in a complex manifold of dimension two. We will show the importance of Picard-Lefschetz theory and the classification of relatively exact 1-forms in this theory. As an application we identify some irreducible components of the space of holomorphic foliations of a fixed degree and with a center singularity in the projective space of dimension two. Also we calculate higher Melnikov functions under some generic conditions.
A characterization of isochronous centres in terms of symmetries
Authors: Freire Emilio , Gasull Armengol , Guillamon Antoni
Published: December 2011

We present a description of isochronous centres of planar vector fields

X

by means of their groups of symmetries. More precisely, given a normalizer

U

of

X

(i.e.,

[X,U]=\mu X

, where

\mu

is a scalar function), we provide a necessary and sufficient isochronicity condition based on

\mu

. This criterion extends the result of Sabatini and Villarini that establishes the equivalence between isochronicity and the existence of commutators (

[X,U]= 0

). We put also special emphasis on the mechanical aspects of isochronicity; this point of view forces a deeper insight into the potential and quadratic-like Hamiltonian systems. For these families we provide new ways to find isochronous centres, alternative to those already known from the literature.
Meromorphic functions of the form $f(z) = \sum_{n=1}^\infty a_n/(z - z_n)$
Authors: Langley James K. , Rossi John
Published: December 2011

We prove some results on the zeros of functions of the form

f(z) = \sum_{n=1}^\infty \frac{a_n}{z - z_n}

, with complex

a_n

, using quasiconformal surgery, Fourier series methods, and Baernstein's spread theorem. Our results have applications to fixpoints of entire functions.
Polynomial growth harmonic functions on complete Riemannian manifolds
Authors: Lee Yong Hah
Published: December 2011

In this paper, we give a sharp estimate on the dimension of the space of polynomial growth harmonic functions with fixed degree on a complete Riemannian manifold, under various assumptions.
$(n,2)$-sets have full Hausdorff dimension
Authors: Mitsis Themis
Published: December 2011

We prove that a set containing translates of every 2-plane must have full Hausdorff dimension.
On some permutable products of supersoluble groups
Authors: Alejandre Manuel J. , Ballester-Bolinches Adolfo , Cossey John , Pedraza-Aguilera Mari Carmen
Published: December 2011

It is well known that a group

G = AB

which is the product of two supersoluble subgroups

A

and

B

is not supersoluble in general. Under suitable permutability conditions on

A

and

B

, we show that for any minimal normal subgroup

N

both

AN

and

BN

are supersoluble. We then exploit this to establish some sufficient conditions for

G

to be supersoluble.
On the product theory of singular integrals
Authors: Nagel Alexander , Stein Elias M.
Published: December 2011

We establish

L^p

-boundedness for a class of product singular integral operators on spaces

\widetilde{M} = M_1 \times M_2\times \cdots \times M_n

. Each factor space

M_i

is a smooth manifold on which the basic geometry is given by a control, or Carnot-Caratheodory, metric induced by a collection of vector fields of finite type. The standard singular integrals on

M_i

are non-isotropic smoothing operators of order zero. The boundedness of the product operators is then a consequence of a natural Littlewood-Paley theory on

\widetilde M

. This in turn is a consequence of a corresponding theory on each factor space. The square function for this theory is constructed from the heat kernel for the sub-Laplacian on each factor.
Existence of H-bubbles in a perturbative setting
Authors: Caldiroli Paolo , Musina Roberta
Published: December 2011

Given a

C^{1}

function

H: \mathbb{R}^3 \to \mathbb{R}

, we look for

H

-bubbles, i.e., surfaces in

\mathbb{R}^3

parametrized by the sphere

\mathbb{S}^2

with mean curvature

H

at every regular point. Here we study the case

H(u)=H_{0}(u)+\epsilon H_{1}(u)

where

H_{0}

is some “good” curvature (for which there exist

H_{0}

-bubbles with minimal energy, uniformly bounded in

L^{\infty}

),

\epsilon

is the smallness parameter, and

H_{1}

is
any

C^{1}

function.