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Search Results: 1 - 10 of 138699 matches for " K. Tkacz-?miech "
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Amorphous carbon layers on polymeric substrates
R.M. Nowak,S. Jonas,S. Zimowski,K. Tkacz-?miech
Journal of Achievements in Materials and Manufacturing Engineering , 2007,
Abstract: urpose: This paper is aimed to study an effect of nitrogen incorporation on the structure and tribological properties of amorphous a C:N:H layers grown on polycarbonate substrates.Design/methodology/approach: Series of the layers were deposited from CH4 + N2 gas mixture with application of Plasma Enhanced Chemical Vapour Deposition technique assisted by radio waves (RF PE CVD). An analysis of atomic-level structure of the layers was made using FT IR technique. The samples were subjected to investigations of friction coefficient and wear resistance. The respective measurements were performed using Micro-Combi-Tester and a tribometer in ball-on-disc configuration.Findings: The IR spectra of the obtained layers have demonstrated a presence of nitrogen bonded both to carbon and to hydrogen. A formation of the following bonds has been confirmed: -C≡N, -NH2, -C-NH2, >C=NH. All they are typical for a-C:N:H layers. The tribological tests have shown that the layers reduce the friction coefficient of the polycarbonate (up to 50 %) and considerably improve abrasion resistance.Research limitations/implications: Further studies in order to find relations between growing conditions and the properties of the layers should be performed. A role of the chemical composition and structure should be carefully analyzed.Practical implications: An application of carbon overcoats on polycarbonates may improve the usable properties of plastic components (hardness, scratch resistance, UV radiation resistance). This will make polycarbonates attractive materials of wide spectrum of possible applications.Originality/value: It has been shown in this research that application of RF PE CVD technique allows obtaining the a-C:N:H layers improving usable properties of plastics. The layers well adhesive to the substrate may be obtained at the temperatures below 80oC.
Immunopharmacology of ulipristal as an emergency contraceptive
Miech RP
International Journal of Women's Health , 2011, DOI: http://dx.doi.org/10.2147/IJWH.S25887
Abstract: nopharmacology of ulipristal as an emergency contraceptive Commentary (2528) Total Article Views Authors: Miech RP Published Date November 2011 Volume 2011:3 Pages 391 - 397 DOI: http://dx.doi.org/10.2147/IJWH.S25887 Ralph P Miech Department of Molecular Pharmacology, Physiology and Biotechnology, Warren Alpert School of Medicine, Brown University, Providence, RI, USA Abstract: A new progesterone antagonist, ulipristal has been made available as an emergency contraceptive. Ulipristal's major mechanism of action as an emergency contraceptive has been ascribed to its ability to delay ovulation beyond the life span of the sperm. This paper analyzes the potential action of ulipristal (1) when unprotected intercourse and administration of ulipristal occur outside the fertility window and (2) when unprotected intercourse and administration of ulipristal occur at or within 24 hours of ovulation. When unprotected intercourse and the use of a single low dose of ulipristal occur outside of the fertility window, ulipristal behaves like a placebo. When unprotected intercourse and the use of a single low dose of ulipristal occur within the fertility window but before ovulation, ulipristal behaves like an emergency contraceptive by delaying ovulation and thereby preventing fertilization. When unprotected intercourse and the administration of ulipristal occur at or within 24 hours of ovulation, then ulipristal has an abortifacient action. It is proposed that the abortifacient mechanism of a low dose of ulipristal taken after fertilization but before implantation is due to the ability of ulipristal to block the maternal innate immune system to become immunotolerant to the paternal allogenic embryo. Progesterone's critical immunotolerant actions involving early pregnancy factor, progesterone-induced blocking factor, and uterine natural killer cells are compromised by ulipristal.
Immunopharmacology of ulipristal as an emergency contraceptive
Miech RP
International Journal of Women's Health , 2011,
Abstract: Ralph P MiechDepartment of Molecular Pharmacology, Physiology and Biotechnology, Warren Alpert School of Medicine, Brown University, Providence, RI, USAAbstract: A new progesterone antagonist, ulipristal has been made available as an emergency contraceptive. Ulipristal's major mechanism of action as an emergency contraceptive has been ascribed to its ability to delay ovulation beyond the life span of the sperm. This paper analyzes the potential action of ulipristal (1) when unprotected intercourse and administration of ulipristal occur outside the fertility window and (2) when unprotected intercourse and administration of ulipristal occur at or within 24 hours of ovulation. When unprotected intercourse and the use of a single low dose of ulipristal occur outside of the fertility window, ulipristal behaves like a placebo. When unprotected intercourse and the use of a single low dose of ulipristal occur within the fertility window but before ovulation, ulipristal behaves like an emergency contraceptive by delaying ovulation and thereby preventing fertilization. When unprotected intercourse and the administration of ulipristal occur at or within 24 hours of ovulation, then ulipristal has an abortifacient action. It is proposed that the abortifacient mechanism of a low dose of ulipristal taken after fertilization but before implantation is due to the ability of ulipristal to block the maternal innate immune system to become immunotolerant to the paternal allogenic embryo. Progesterone's critical immunotolerant actions involving early pregnancy factor, progesterone-induced blocking factor, and uterine natural killer cells are compromised by ulipristal.Keywords: innate immune system, early pregnancy factor, progesterone-induced blocking factor, uterine natural killer cells, selective progesterone receptor modulator
WIKIPEDIA AND THE POLITICS OF MASS COLLABORATION
Nathaniel Tkacz
PLATFORM : Journal of Media and Communication , 2010,
Abstract: Working together to produce socio-technological objects, based on emergent platforms of economic production, is of great importance in the task of political transformation and the creation of new subjectivities. Increasingly, “collaboration” has become a veritable buzzword used to describe the human associations that create such new media objects. In the language of “Web 2.0”, “participatory culture”, “user-generated content”, “peer production” and the “produser”, first and foremost we are all collaborators. In this paper I investigate recent literature that stresses the collaborative nature of Web 2.0, and in particular, works that address the nascent processes of peer production. I contend that this material positions such projects as what Chantal Mouffe has described as the “post-political”; a fictitious space far divorced from the clamour of the everyday. I analyse one Wikipedia entry to demonstrate the distance between this post-political discourse of collaboration and the realities it describes, and finish by arguing for a more politicised notion of collaboration.
The GABA Antagonist Picrotoxin Attenuates an Ethanol-Induced Taste Aversion in Taste Aversion-Prone Rats  [PDF]
Joseph Tkacz, Stephen Hobbs, Ralph Elkins
Neuroscience & Medicine (NM) , 2011, DOI: 10.4236/nm.2011.24048
Abstract: The aversive properties of alcohol can be examined by using ethanol as a conditioning agent in a taste aversion (TA) paradigm. However, there is often variability in how organisms respond to the aversive properties of alcohol. Using a selectively bred line of TA-prone (TAP) rats, the present study sought to determine if antagonizing the GABA receptor complex with picrotoxin could block the acquisition of an ethanol-based conditioned aversion to a normally preferred fluid. Fifty TAP rats were randomly divided into 5 groups. In the two experimental groups, rats were pretreated with i.p. injections of low or high doses of the GABA Aantagonist picrotoxin prior to undergoing taste aversion conditioning —wherein consumption of a novel saccharin solution (0.1%) was followed by an i.p. injection of ethanol (1.5 mg/kg). In the primary control group, rats were treated identically, except that isotonic saline was substituted for picrotoxin. In the non-conditioning and pseudo-conditioning control groups, rats did not receive an ethanol-saccharin pairing but did receive a picrotoxin injection. Repeated measures ANOVA revealed that animals in the picrotoxin groups displayed significantly weaker TAs than the primary control group (p < 0.01), but were not different from the non-conditioning and pseudo-conditioning groups (p > 0.05) as measured by post-conditioning, two-bottle saccharin preference scores. Picrotoxin hinders the acquisition of an ethanol-induced TA, thereby supporting the hypothesis that the GABA system plays a central role in ethanol’s motivational effects. Possible mechanisms include 1) picrotoxin attenuates negative effects of ethanol, 2) picrotoxin interferes with the central associative processes that promote TA conditioning or 3) some combination of 1 and 2.
The Bolzano-Poincaré Type Theorems
Przemys?aw Tkacz,Marian Turzański
International Journal of Mathematics and Mathematical Sciences , 2011, DOI: 10.1155/2011/793848
Abstract: In 1883–1884, Henri Poincaré announced the result about the structure of the set of zeros of function , or alternatively the existence of solutions of the equation . In the case the Poincaré Theorem is well known Bolzano Theorem. In 1940 Miranda rediscovered the Poincaré Theorem. Except for few isolated results it is essentially a non-algorithmic theory. The aim of this article is to introduce an algorithmical proof of the Theorem “On the existence of a chain” and for an algorithmical proof of the Bolzano-Poincaré Theorem and to show the equivalence of Poincaré, Brouwer and “On the existence of a chain” theorems. 1. Introduction It is well known how influential topology was for the development of many other branches of mathematics and economics. Among many others, let us recall significant place of fixed point theorems of Brouwer and Banach which served as a main tool in solving problems in differential equations, theory of fractals and problems of market equilibrium. Some of these applications raised a question of computability of the fixed points. In [1, 2] Steinhaus presented following conjecture: Let some segments of the chessboard be mined. Assume that the king cannot go across the chessboard from the left edge to the right one without meeting a mined square. Then the rook can go from upper edge to the lower one moving exclusively on mined segments. According to Surówka [3] several proofs of the Steinhaus Chessboard Theorem seem to be incomplete or use induction on the size of the chessboard [4]. The simple proof of the Steinhaus Chessboard Theorem was presented in [5]. In [6] the following generalization of the Steinhaus Chessboard Theorem was published: Theorem [On the existence of a chain] For an arbitrary decomposition of n-dimensional cube onto cubes and an arbitrary coloring function for some natural number there exists an th colored chain such that and . This theorem was the main tool in the proof (see [6]) of the Bolzano-Poincaré theorem (see [7, 8]). In the first part of our paper an algorithm of finding the chain will be presented and will be shown that the theorem “on the existence of a chain”, the Bolzano-Poincaré theorem, and the Brouwer fixed point theorem are equivalent (for more informations see [9, 10]). 2. Theorems Let be the n-dimensional cube in . Its th opposite faces are defined as follows: Let be the boundary of the cube . Let be an arbitrary natural number. We call the family the decomposition of into cubes. The map is said to be a coloring function of the decomposition . The sequence where for is said to be an th colored
Performance characteristics of variously detuned VCSELs
Krzysztof Tkacz,Robert P. Sarzala,Wlodzimierz Nakwaski
Optica Applicata , 2009,
Abstract: A comprehensive model of an operation of vertical-cavity surface-emitting diode lasers (VCSELs) is used to simulate the operation of modern GaAs-based oxide-confined double intra-cavity contacted GaInNAs/GaAs quantum-well VCSELs emitting the 1.3-μm radiation. An impact of various detuning of the cavity mode with respect to a maximal active-region optical gain on VCSEL performance characteristics is examined. In particular, high-temperature VCSEL operation is investigated. Properly detuned VCSELs have been found to exhibit nearly constant lasing threshold within quite a wide range of ambient temperatures. In such temperature-insensitive VCSELs with relatively small 4 μm active regions, threshold currents change from 0.84 mA to 1.10 mA, i.e., only by 22%, within quite a wide range of ambient temperatures between 300 K and 360 K.
Forest Health Status in North America
Borys Tkacz,Ben Moody,Jaime Villa Castillo
The Scientific World Journal , 2007, DOI: 10.1100/tsw.2007.85
Abstract:
Distribution and habitats of Chamorchis alpina (L.) Rich. (Orchidaceae) in Poland
Halina Pi?ko?-Mirkowa,Zbigniew Mirek,Anna Miechówka
Acta Societatis Botanicorum Poloniae , 2001, DOI: 10.5586/asbp.2001.015
Abstract: Chamtorchis alpina (L.) Rich. is a rare high mountain species occurring in Poland exclusively in the Tatra Mts. Its distribution presented on the map and altitudinal range are based on the authors' own material collected in the field as well as on literature data supplemented by herbarium records. The orographic and edaphic factors as well as phytocoenoses in which the species occurs are characterised. Moreover, information on size of the Tatra populations is given and the threat category for Ch. alpina in Poland is discussed.
A multidisciplinary stroke clinic for outpatient care of veterans with cerebrovascular disease
Schmid AA,Kapoor JR,Miech EJ,Kuehn D
Journal of Multidisciplinary Healthcare , 2011,
Abstract: Arlene A Schmid1,2,3,4, John R Kapoor5, Edward J Miech1, Deborah Kuehn6, Mary I Dallas7, Robert D Kerns8, Albert C Lo9,10, John Concato11,12, Michael S Phipps13,14,15, Cody D Couch13, Eileen Moran13, Linda S Williams1,2,3,16, Layne A Goble17,18, Dawn M Bravata1,2,3,191Department of Veteran Affairs (VA) Health Services Research & Development (HSR&D) Center of Excellence on Implementing Evidence-Based Practice (CIEBP), 2VA HSR&D Stroke Quality Enhancement Research Initiative (QUERI) Program, Richard L Roudebush VA Medical Center, Indianapolis, IN, USA; 3Regenstrief Institute, Indianapolis, IN, USA; 4Department of Occupational Therapy, Indiana University, IN, USA; 5Department of Medicine, University of Chicago Pritzker School of Medicine, Chicago, IL, USA; 6Nursing Service, 7Physical Medicine and Rehabilitation Service, 8Psychology Service, Veterans Affairs Connecticut Healthcare System, West Haven, CT, USA; 9Departments of Neurology, Community Health, and Engineering at Brown University, Providence, RI, USA; 10Providence Veterans Administration Medical Center, Providence, RI, USA; 11Clinical Epidemiology Research Center (CERC), Veterans Affairs Connecticut Healthcare System, West Haven, CT, USA; 12Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USA; 13Department of Veterans Affairs Connecticut Healthcare System, West Haven, CT, USA; 14Robert Wood Johnson Clinical Scholars Program, 15Department of Neurology, Yale University School of Medicine, New Haven, CT, USA; 16Department of Neurology, Indiana University School of Medicine, Indianapolis, IN, USA; 17Department of Anesthesia and Perioperative Medicine, Medical University of South Carolina, Charleston, SC, USA; 18Veterans Administration Medical Center, Charleston, SC, USA; 19Department of Internal Medicine, Indiana University School of Medicine, Indianapolis, IN, USABackground: Managing cerebrovascular risk factors is complex and difficult. The objective of this program evaluation was to assess the effectiveness of an outpatient Multidisciplinary Stroke Clinic model for the clinical management of veterans with cerebrovascular disease or cerebrovascular risk factors.Methods: The Multidisciplinary Stroke Clinic provided care to veterans with cerebrovascular disease during a one-half day clinic visit with interdisciplinary evaluations and feedback from nursing, health psychology, rehabilitation medicine, internal medicine, and neurology. We conducted a program evaluation of the clinic by assessing clinical care outcomes, patient satisfaction, provider satisfaction, and cost
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