bluuebunny/crossref_metadata_2025_split huggingface dataset:
Free β-Subunit of Human Chorionic Gonadotropin in Serum Is a Diagnostically Sensitive Marker of Seminomatous Testicular Cancer
Authors: Lempiäinen Anna , Stenman Ulf-Håkan , Blomqvist Carl , Hotakainen Kristina 
Published: September 2008

Abstract
Background: We studied whether measurement of the free β subunit of human chorionic gonadotropin (hCGβ) in serum offers additional diagnostic information compared to determination of intact hCG alone in testicular cancer.
Methods: We determined hCG and hCGβ with ultrasensitive assays in 94 serum samples obtained preoperatively, 22 samples obtained during relapse, and 3687 samples obtained during routine follow-up of 351 patients with testicular tumors.
Results: In preoperative samples, isolated increases of hCGβ were seen in 40% of the samples from seminoma patients (n = 42) and in 8% of those from patients with nonseminomatous testicular cancer (NSGCT) (n = 51). Both markers were increased in 12% of the seminoma and 71% of the NSGCT patients and were within reference intervals in 43% of the seminoma and 20% of the NSGCT patients. Specific determination of hCGβ increased the frequency of marker-positive seminomas from 17% to 57% and of marker-positive relapses from 32% to 59% (n = 22). Theoretically, about 40% of marker-positive seminomas and relapses would have been missed with an assay measuring hCG and hCGβ together. Preoperative hCG and hCGβ concentrations correlated with stage, tumor histology, and disease-related mortality. Additionally, hCGβ correlated with tumor size.
Conclusions: hCGβ is a diagnostically sensitive marker for testicular cancer. In patients with seminomatous testicular cancer, hCGβ is superior to hCG, and in some NSGCT patients it provides additional information.
A rigidity result for domains with a locally strictly convex point
Authors: Jo Kyeonghee 
Published: September 2008

Abstract
In this article, we investigate projective domains with a strictly convex point in the boundary and their automorphisms. We prove that ellipsoids can be characterized as follows: A domain Ω is an ellipsoid if and only if ∂Ω is locally strongly convex at some boundary point where an Aut(Ω)-orbit accumulates. We also show that every quasi-homogeneous projective domain in an affine space which is locally strictly convex at a boundary point, is the universal covering of a closed projective manifold.
Projective models of K3 surfaces with an even set
Authors: Garbagnati Alice , Sarti Alessandra 
Published: September 2008

Abstract
The aim of this paper is to describe algebraic K3 surfaces with an even set of rational curves or of nodes. Their minimal possible Picard number is nine. We completely classify these K3 surfaces and after a careful analysis of the divisors contained in the Picard lattice we study their projective models, giving necessary and sufficient conditions to have an even set. Moreover we investigate their relation with K3 surfaces with a Nikulin involution.
Principal bundles over a smooth real projective curve of genus zero
Authors: Biswas Indranil , Huisman Johannes 
Published: September 2008

Abstract
Let H
0 denote the kernel of the endomorphism, defined by , of the real algebraic group given by the Weil restriction of . Let X be a nondegenerate anisotropic conic in . The principal -bundle over the complexification defined by the ample generator of Pic(), gives a principal H
0-bundle over X through a reduction of structure group. Given any principal G-bundle EG
over X, where G is any connected reductive linear algebraic group defined over ℝ, we prove that there is a homomorphism such that EG
is isomorphic to the principal G-bundle obtained by extending the structure group of using .
The tautological line bundle over the real projective line and the principal -bundle together give a principal -bundle F on , Given any principal G-bundle EG
over , where G is any connected reductive linear algebraic group defined over ℝ, we prove that there is a homomorphism such that EG
is isomorphic to the principal G-bundle obtained by extending the structure group of F using .
Nitric oxide and sphingolipids: mechanisms of interaction and role in cellular pathophysiology
Authors: Perrotta Cristiana , De Palma Clara , Clementi Emilio 
Published: September 2008

AbstractNitric oxide is a short-lived messenger with pleiotropic roles in the regulation of cell patho-physiological processes, including survival, death, proliferation and differentiation. Increasing evidence over the last few years has shown that nitric oxide effects in apoptosis, growth and differentiation originate in significant part from its interplay with signalling members of the sphingolipid family. In many cell types belonging to different lineages, nitric oxide and sphingolipids interact in two-way pathways leading to regulation of the activity and expression of enzymes involved in each other's signalling events. These crosstalk signalling events involve various sphingolipids, with key roles for ceramide and sphingosine-1-phosphate, and signal transduction molecules downstream of nitric oxide, with cyclic GMP as a main player. The biological implications of some of these interactions are now being understood. The best-characterised so far, the mutual regulation of sphingomyelinases and endothelial nitric oxide synthase, acts as a tuning system in crucial patho-physiological processes such as inflammation, proliferation and cell death.
Regulation of human tissue kallikrein-related peptidase expression by steroid hormones in 32 cell lines
Authors: Shaw Julie L.V. , Diamandis Eleftherios P. 
Published: September 2008

AbstractHuman tissue kallikrein-related peptidases (KLK), which are secreted serine proteases, are encoded by 15 genes located on chromosome 19q13.4. Previous studies have shown thatKLKexpression is regulated by steroid hormones and many KLKs are dysregulated in hormone-dependent malignancies. Some KLKs are proposed biomarkers for these cancers. We have characterized KLK hormonal regulation patterns using a large number of human cell lines. KLK levels were quantified in supernatants from 32 cell lines, each subjected to four hormonal stimulations (dexamethasone, norgestrel, dihydrotestosterone or estradiol), using ELISAs. Cell lines included breast, prostate, ovarian, lung, pancreatic, colon, and cervical cancer cells, T-lymphocytes, keratinocytes and a non-cancerous epithelial breast cell line. KLKs were regulated in several cell lines not previously studied, such as keratinocytes (KLK5, 6, and 7), ovarian cancer (KLK5 and 9) and cervical cancer (KLK3, 5, 6, 7, 8, 10, 11, and 13) cells. Many KLKs were regulated by the synthetic glucocorticoid dexamethasone; specifically, KLK5, 6, 8, 10 and 11 were upregulated in several breast cancer cell lines and downregulated in several cervical cancer cell lines. Knowledge of KLK hormonal regulation patterns will help to shed further light on their potential use as biomarkers and therapeutic targets for hormone-related malignancies.
Ceramide in bacterial infections and cystic fibrosis
Authors: Grassmé Heike , Becker Katrin Anne , Zhang Yang , Gulbins Erich 
Published: September 2008

Abstract
Ceramide is formed by the activity of sphingomyelinases, by degradation of complex sphingolipids, reverse ceramidase activity or de novo synthesized. The formation of ceramide within biological membranes results in the formation of large ceramide-enriched membrane domains. These domains serve the spatial and temporal organization of receptors and signaling molecules. The acid sphingomyelinase-ceramide system plays an important role in the infection of mammalian host cells with bacterial pathogens such as Neisseria gonorrhoeae, Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, Salmonella typhimurium and Pseudomonas aeruginosa. Ceramide and ceramide-enriched membrane platforms are also involved in the induction of apoptosis in infected cells, such as in epithelial and endothelial cells after infection with Pseudomonas aeruginosa and Staphylococcus aureus, respectively. Finally, ceramide-enriched membrane platforms are critical regulators of the release of pro-inflammatory cytokines upon infection. The diverse functions of ceramide in bacterial infections suggest that ceramide and ceramide-enriched membrane domains are key players in host responses to many pathogens and thus are potential novel targets to treat infections.
Effect of Wettability on High-Velocity Coefficient in Two-Phase Gas/Liquid Flow
Authors: Noh Myeong , Firoozabadi Abbas 
Published: September 2008

Summary
Gas-well productivity is affected by two distinct mechanisms: liquid blocking and high-velocity flow in two-phase flow. The former has been studied extensively recently, but the understanding of the latter is limited. High-velocity gas flow in single phase has been studied thoroughly by a large number of authors. Despite the fact that high-velocity coefficient in the presence of an immobile and a mobile liquid phase is much higher than that in single phase, only a handful of studies have been made on the subject. In this work, we have measured the high-velocity coefficient, A in steady-state two-phase gas/liquid flow. The results are presented as a function of liquid relative permeability and liquid saturation. In our measurements, the wetting state is varied by the treatment with a fluorochemical compound. Then, the effect of wettability on the high-velocity coefficient in two-phase flow is investigated. Results show that when the liquid is strongly wetting, the high-velocity coefficient increases approximately 270-fold in water/gas two-phase flow. However, our data show a systematic reduction of high-velocity coefficients for the altered wetting state in two-phase flow. We present measurements of the velocity coefficients in single-phase flow and two-phase flow, for both oil/gas and water/gas flow and strong liquid-wetting and altered-wetting states. On the basis of our measurements, we conclude that the treatment of the wellbore region can result in significant improvement in well deliverability from the large reduction of high-velocity coefficients.
A Permeability Model for Coal and Other Fractured, Sorptive-Elastic Media
Authors: Robertson Eric P. , Christiansen Richard L. 
Published: September 2008

Summary
This paper describes the derivation of a new equation that can be used to model the permeability behavior of a fractured, sorptive-elastic medium, such as coal, under variable stress conditions. The equation is applicable to confinement pressure schemes commonly used during the collection of permeability data in the laboratory. The model is derived for cubic geometry under biaxial or hydrostatic confining pressures. The model is designed to handle changes in permeability caused by adsorption and desorption of gases onto and from the matrix blocks in fractured media. The model equations can be used to calculate permeability changes caused by the production of methane (CH4) from coal as well as the injection of gases, such as carbon dioxide, for sequestration in coal. Sensitivity analysis of the model found that each of the input variables can have a significant impact on the outcome of the permeability forecast as a function of changing pore pressure; thus, accurate input data are essential. The permeability model also can be used as a tool to determine input parameters for field simulations by curve fitting laboratory-generated permeability data. The new model is compared to two other widely used coal-permeability models using a hypothetical coal with average properties.
A New Model of Trapping and Relative Permeability Hysteresis for All Wettability Characteristics
Authors: Spiteri Elizabeth J. , Juanes Ruben , Blunt Martin J. , Orr Franklin M. 
Published: September 2008

Summary
The complex physics of multiphase flow in porous media are usually modeled at the field scale using Darcy-type formulations. The key descriptors of such models are the relative permeabilities to each of the flowing phases. It is well known that, whenever the fluid saturations undergo a cyclic process, relative permeabilities display hysteresis effects.
In this paper, we investigate hysteresis in the relative permeability of the hydrocarbon phase in a two-phase system. We propose a new model of trapping and waterflood relative permeability, which is applicable for the entire range of rock wettability conditions. The proposed formulation overcomes some of the limitations of existing trapping and relative permeability models. The new model is validated by means of pore-network simulation of primary drainage and waterflooding. We study the dependence of trapped (residual) hydrocarbon saturation and waterflood relative permeability on several fluid/rock properties, most notably the wettability and the initial water saturation. The new model is able to capture two key features of the observed behavior: (1) non-monotonicity of the initial-residual curves, which implies that waterflood relative permeabilities cross; and (2) convexity of the waterflood relative permeability curves for oil-wet media caused by layer flow of oil.
Growth and Inequality in Closed and Open Economies: The Role of the Product Cycle
Authors: Ranjan Priya 
Published: September 2008

Abstract
The product cycle literature suggests that new goods have a higher skill intensity in the early phase of production, which declines once the production process becomes standardized. Using this insight it is shown how an increase in the rate of neutral technological progress, which frees up resources tied in the production of existing goods, leads to increased production of skill intensive new goods and consequently an increase in wage inequality. When technological progress is exogenous, a decrease in skill endowment or trade liberalization with a skill scarce country increases wage inequality but leaves the composition of production between new and standardized goods unaltered. When the rate of technological progress depends on research effort, trade between a skill-abundant Northern economy and a skill-scarce Southern economy can raise wage inequality in both countries and increase productivity growth in the latter. North-North trade increases both wage inequality and productivity growth.
Uses and misuses of progress curve analysis in enzyme kinetics
Authors: Nikolova Natalia , Tenekedjiev Kiril , Kolev Krasimir 
Published: September 2008

Abstract
Progress curve analysis is a convenient tool for the characterization of enzyme action: a single reaction mixture provides multiple experimental measured points for continuously varying amounts of substrates and products with exactly the same enzyme and modulator concentrations. The determination of kinetic parameters from the progress curves, however, requires complex mathematical evaluation of the time-course data. Some freely available programs (e.g. FITSIM, DYNAFIT) are widely applied to fit kinetic parameters to user-defined enzymatic mechanisms, but users often overlook the stringent requirements of the analytic procedures for appropriate design of the input experiments. Flaws in the experimental setup result in unreliable parameters with consequent misinterpretation of the biological phenomenon under study. The present commentary suggests some helpful mathematical tools to improve the analytic procedure in order to diagnose major errors in concept and design of kinetic experiments.
The current analysis of the effect of hyperbaric oxygen therapy on the frostbitten tissue: Experimental study in rabbits
Authors: Uygur Fatih , Noyan Nurettin , Sever Celalettin , Gümüş Tuna 
Published: September 2008

Abstract
Many experimental studies have been performed and the mechanism of hyperbaric oxygen therapy on the frostbitten tissue has not been elucidated. In this study, we evaluated the effect of hyperbaric oxygen therapy on the frostbitten ears of rabbits in an experimental animal model by examining the concentrations of thromboxane A2 (as thromboxane B2-Tx B2) and of prostaglandin I2 (PG I2) (as 6-keto-prostaglandin F1α-PG F1α) in tissues, and by counting the numbers of inflammatory cells (neutrophils and mast cells-MC) Hyperbaric oxygen therapy (HBO) at 2.5 ATA for 90 minutes twice daily for fourteen days to rabbits, the ears of which were subjected to frostbite, decreased presence of inflammatory cells (mast cells −75%; neutrophils −40%) and increased prostaglandin I2 (PG I2) (as 6-Keto-PGF1α) in the involved skin. Thromboxane A2 (TxA2) (as Tx B2) was unaffected. Our results revealed that an inflammatory process was the underlying cause of frostbite injury and that hyperbaric oxygen therapy was active in pathological situations involving an inflammatory process in frostbite.
External cavity wavelength tunable semiconductor lasers - a review
Authors: Mroziewicz B. 
Published: September 2008

AbstractExternal cavity tunable lasers have been around for many years and now constitute a large group of semiconductor lasers featuring very unique properties. The present review has been restricted to the systems based on the edge emitting diode lasers set-up in a hybrid configuration. The aim was to make the paper as concise as possible without sacrificing, however, most important details. We start with short description of the fundamentals essential for operation of the external cavity lasers to set the stage for explanation of their properties and some typical designs. Then, semiconductor optical amplifiers used in the external cavity lasers are highlighted more in detail as well as diffraction gratings and other types of wavelength-selective reflectors used to provide optical feedback in these lasers. This is followed by a survey of designs and properties of various external cavity lasers both with mobile bulk gratings and with fixed wavelength selective mirrors. The paper closes with description of some recent developments in the field to show prospects for further progress directed towards miniaturization and integration of the external cavity laser components used so far to set-up hybrid systems.
New material systems for third generation infrared photodetectors
Authors: Rogalski A. 
Published: September 2008

AbstractThird-generation infrared (IR) systems are being developed nowadays. In the common understanding, these systems provide enhanced capabilities-like larger numbers of pixels, higher frame rates, and better thermal resolution as well as multicolour functionality and other on-chip functions. In this class of detectors, two main competitors, HgCdTe photodiodes and quantum-well photoconductors, have being developed.Recently, two new material systems have been emerged as the candidates for third generation IR detectors, type II InAs/GaInSb strain layer superlattices (SLSs) and quantum dot IR photodetectors (QDIPs).In the paper, issue associated with the development and exploitation of multispectral photodetectors from these new materials is discussed. Discussions is focused on most recently on-going detector technology efforts in fabrication both photodetectors and focal plane arrays (FPAs). The challenges facing multicolour devices concerning complicated device structures, multilayer material growth, and device fabrication are described.
Corrugated SNOM probe with enhanced energy throughput
Authors: Antosiewicz T. , Szoplik T. 
Published: September 2008

AbstractIn a previous paper we proposed a modification of metal-coated tapered-fibre aperture probes for scanning near-field optical microscopes (SNOMs). The modification consists in radial corrugations of the metal-dielectric interface oriented inward the core. Their purpose is to facilitate the excitation of surface plasmons, which increase the transport of energy beyond the cut-off diameter and radiate a quasi-dipolar field from the probe output rim. An increase in energy output allows for reduction of the apex diameter, which is the main factor determining the resolution of the microscope. In two-dimensional finite-difference time-domain (FDTD) simulations we analyse the performance of the new type of SNOM probe. We admit, however, that the two-dimensional approximation gives better results than expected from exact three-dimensional ones. Nevertheless, optimisation of enhanced energy throughput in corrugated probes should lead to at least twice better resolution with the same sensitivity of detectors available nowadays.
Electronic Warfare
Authors: Inkol Robert 
Published: September 2008

AbstractElectronic warfare (EW) concerns the concepts, doctrine, and technology for maximizing the military value of the electromagnetic spectrum. This value is achieved in several ways: exploiting signals emitted by an opponent's systems, degrading the ability of an opponent to use his systems, and the application of techniques and procedures for preserving the ability of friendly forces to use their own systems effectively. This article gives a general overview of the concepts and technologies associated with EW.
VLSICircuit Layout
Authors: Zhang Lihong 
Published: September 2008

AbstractVLSI circuits have experienced significant growth in the past half a century. As an important design phase, VLSI physical design is an extremely tedious and error‐prone process. In this article, the fundamental characteristics of physical design are described. Then the general physical design methodology mainly for VLSI digital systems is discussed. In particular, three major physical design subproblems, including partitioning, floorplan and placement, and routing, are explained in more detail. The formulation of each subproblem and the related algorithms are presented. The state‐of‐the‐art teachniques are summarized. To exhibit a more general overview, the features of physical design for analog integrated circuits are also outlined. The article concludes with some emerging topics regarding the modern VLSI layout.
Posets and Lattices
Authors: Ciucci Davide , Cattaneo Gianpiero 
Published: September 2008

Abstract
The basic notions of posets and lattices are introduced with a wide presentation of examples. In particular, distributive and modular lattices are treated. With respect to the distributive behavior, we discuss Boolean algebras with the associated orthocomplementation mapping. General orthoalgebras are also investigated with application to the quantum logic of subspaces of a finite dimensional Hilbert space.
Requirements Specification and Analysis
Authors: Subramanian Naryanan 
Published: September 2008

AbstractRequirements specification and analysis identify, analyze, and model the functionality or “what's” of a prospective software system. The requirements specification and analysis phase of a software project is the most important phase of software development and should not be omitted under any condition. More than half of all software projects have failed because of errors in requirements specification and analysis. The result of this phase is the software requirements specifications document or the SRS that serves as the starting point for the next phase of software development, namely, software design. It is important to note that the requirements specification and analysis phase focuses only on what the software system should do and not on how it should be done; that is, implementation details are not allowed to affect this phase. Software requirements can be classified into two types: functional requirements and nonfunctional requirements, and the SRS includes both types of requirements, analysis artifacts, and models. The source for software requirements is very often the end user of the prospective software system, and the requirements elicited from the end users may be captured in the form of tabular lists, use‐cases, user stories, or decision tables. Once requirements have been captured, they are analyzed for determining priorities, dependencies, versions, schedule formation, staff size determination, project cost estimation, formulating acceptance tests, and analyzing nonfunctional requirements. After analysis, the requirements are modeled using unified modeling language diagrams, entity‐relationship diagrams, data flow diagrams, or formal methods. This article also discusses requirements management, tool support for requirements specification and analysis, and important research issues in this field.