Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99


Any time

2019 ( 7 )

2018 ( 15 )

2017 ( 11 )

2016 ( 13 )

Custom range...

Search Results: 1 - 10 of 2664 matches for " Margaret Markiewicz "
All listed articles are free for downloading (OA Articles)
Page 1 /2664
Display every page Item
Impact of Endothelial Microparticles on Coagulation, Inflammation, and Angiogenesis in Age-Related Vascular Diseases
Margaret Markiewicz,Erin Richard,Natalia Marks,Anna Ludwicka-Bradley
Journal of Aging Research , 2013, DOI: 10.1155/2013/734509
Abstract: Endothelial microparticles (EMPs) are complex vesicular structures that originate from plasma membranes of activated or apoptotic endothelial cells. EMPs play a significant role in vascular function by altering the processes of inflammation, coagulation, and angiogenesis, and they are key players in the pathogenesis of several vascular diseases. Circulating EMPs are increased in many age-related vascular diseases such as coronary artery disease, peripheral vascular disease, cerebral ischemia, and congestive heart failure. Their elevation in plasma has been considered as both a biomarker and bioactive effector of vascular damage and a target for vascular diseases. This review focuses on the pleiotropic roles of EMPs and the mechanisms that trigger their formation, particularly the involvement of decreased estrogen levels, thrombin, and PAI-1 as major factors that induce EMPs in age-related vascular diseases. 1. Introduction Vascular diseases are among the most common causes of morbidity and mortality, and both number and severity of morbid vascular conditions increase with age. Regulations of angiogenesis, coagulation, and inflammation are very important issues in vascular biology, both in normal physiology and pathology [1]. It is now well established that disruption of endothelial integrity represents a crucial event in the initiation and development of cardiovascular (CV) diseases. Numerous studies have reported that microparticles (MPs) play an important role in endothelial dysfunction. Endothelial dysfunction occurs when a perturbed homeostatic endothelium disrupts vascular competency resulting in reduced vasodilatation and increased proinflammatory and prothrombotic properties of the vascular network [2]. Recently, MPs originating from various cells have been found to be associated with several vascular related diseases. Moreover, exposed procoagulant phospholipids and specific receptors at the surface of MPs act as biomessengers linking inflammation, coagulation, and angiogenesis [3–5]. Although MPs were first described as “cellular debris” that are believed to have no biological significance, recent studies documented that MPs of endothelial and other origins are biological effectors in inflammation, vascular injury, angiogenesis, and thrombosis [6–8]. MPs isolated from granulation tissue are derived from endothelial cells, monocytes, platelets, erythrocytes [9–13], and myofibroblasts [8]. They exchange biological signals and information intercellularly and each kind of MP carries the antigens and receptors of the cells they originated. MPs may
Workplace mistreatment: Health, working environment and social and economic factors  [PDF]
Margaret Hodgins
Health (Health) , 2014, DOI: 10.4236/health.2014.65057

Objective: To explore patterns of workplace mistreatment, relationships with health and with selected workplace, economic and social factors in 34 countries. Methods: Secondary data analysis of the European Working Conditions Survey. Results: Patterns of ill treatment (across occupational groups, and sectors) were broadly consistent with smaller, less representative studies. Prevalence was lower than many studies but corresponds with estimates of serious mistreatment. Mistreatment increases the risk of both physical and mental ill health and is associated with a range of work environment factors. Mistreatment is more prevalent in countries with smaller gender gaps, better performance on the GINI index for income inequality and for countries with specific anti-bullying legislation. Conclusions: Mistreatment in work is complex, and interventions are required at the level of the organization. Implementation issues need to be addressed, as specific anti-bullying legislation does not appear to provide sufficient protection.

Finding Traps in Non-linear Spin Arrays
Marcin Wiesniak,Marcin Markiewicz
Physics , 2009, DOI: 10.1103/PhysRevA.81.032340
Abstract: Precise knowledge of the Hamiltonian of a system is a key to many of its applications. Tasks such state transfer or quantum computation have been well studied with a linear chain, but hardly with systems, which do not possess a linear structure. While this difference does not disturb the end-to-end dynamics of a single excitation, the evolution is significantly changed in other subspaces. Here we quantify the difference between a linear chain and a pseudo-chain, which have more than one spin at some site (block). We show how to estimate a number of all spins in the system and the intra-block coupling constants. We also suggest how it is possible to eliminate excitations trapped in such blocks, which may disturb the state transfer. Importantly, one uses only at-ends data and needs to be able to put the system to either the maximally magnetized or the maximally mixed state. This can obtained by controlling a global decoherence parameter, such as temperature.
Stripes, Pseudogaps, and Van Hove Nesting in the Three-band tJ Model
R. S. Markiewicz
Physics , 1997, DOI: 10.1103/PhysRevB.56.9091
Abstract: Slave boson calculations have been carried out in the three-band tJ model for the high-T_c cuprates, with the inclusion of coupling to oxygen breathing mode phonons. Phonon-induced Van Hove nesting leads to a phase separation between a hole-doped domain and a (magnetic) domain near half filling, with long-range Coulomb forces limiting the separation to a nanoscopic scale. Strong correlation effects pin the Fermi level close to, but not precisely at the Van Hove singularity (VHS), which can enhance the tendency to phase separation. The resulting dispersions have been calculated, both in the uniform phases and in the phase separated regime. In the latter case, distinctly different dispersions are found for large, random domains and for regular (static) striped arrays, and a hypothetical form is presented for dynamic striped arrays. The doping dependence of the latter is found to provide an excellent description of photoemission and thermodynamic experiments on pseudogap formation in underdoped cuprates. In particular, the multiplicity of observed gaps is explained as a combination of flux phase plus charge density wave (CDW) gaps along with a superconducting gap. The largest gap is associated with VHS nesting. The apparent smooth evolution of this gap with doping masks a crossover from CDW-like effects near optimal doping to magnetic effects (flux phase) near half filling. A crossover from large Fermi surface to hole pockets with increased underdoping is found. In the weakly overdoped regime, the CDW undergoes a quantum phase transition ($T_{CDW}\to 0$), which could be obscured by phase separation.
Perfect State Transfer without State Initialization and Remote Collaboration
Marcin Markiewicz,Marcin Wiesniak
Physics , 2009, DOI: 10.1103/PhysRevA.79.054304
Abstract: We present a perfect state transfer protocol via a qubit chain with the evolution governed by the $xx$ Hamiltonian. In contrast to the recent protocol announced in [Phys. Rev. Lett. {\bf 101}, 230502 (2008)], our method does not demand any remote-cooperated initialization and sending classical information about measurement outcomes. We achieve the perfect state transfer only with the assumption of access to two spins at each end of the chain, while the initial state of the whole chain is irrelevant.
Stripes Have Hair
R. S. Markiewicz
Physics , 1998,
Abstract: It is suggested that recent experiments provide evidence for modulations along the charged stripes in the striped phase of the cuprates. Furthermore, 1/8 doping is special because it is associated with a crossover: for lower doping the magnetic stripe width changes; for higher, the hole-doped stripes grow. The crossover is reflected in the doping dependence of the spin gap.
Contrasting Pathways to Mott Gap Collapse in Electron and Hole Doped Cuprates
R. S. Markiewicz
Physics , 2003,
Abstract: Recent ARPES measurements on the electron-doped cuprate Nd_{2-x}Ce_xCuO_4 can be interpreted in a mean field model of uniform doping of an antiferromagnet, with the Mott gap closing near optimal doping. Mode coupling calculations confirm the mean field results, while clarifying the relation between the Mott gap and short-range magnetic order. The same calculations find that hole doped cuprates should follow a strikingly different doping dependence, involving instability toward spiral phases or stripes. Nevertheless, the magnetic order (now associated with stripes) again collapses near optimal doping.
Self-Consistent Renormalization Model of Mott Gap Collapse in the Cuprates
R. S. Markiewicz
Physics , 2003,
Abstract: A generalized antiferromagnetic approach to the Mott transition is analyzed with special emphasis on electron doped cuprates, where evidence for electronic phase separation is weak or absent. Fluctuations are incorporated via a self-consistent renormalization, thereby deriving a `nearly-antiferromagnetic Fermi liquid' susceptibility. The calculation is sensitive to hot-spot effects. Near optimal doping, an approximately electron-hole symmetrical Mott gap collapse is found (quantum critical points). The calculation satisfies the Mermin-Wagner theorem (Neel transition at T=0 only -- unless interlayer coupling effects are included), and the mean-field gap and transition temperature are replaced by pseudogap and onset temperature. The resulting susceptibility is used to calculate the doping dependence of the photoemission dispersion, in excellent agreement with experiment. Discussions of interlayer coupling, doping dependence of $U$, and extension to a three-band model are included.
A Survey of the Van Hove Scenario for High-T_c Superconductivity With Special Emphasis on Pseudogaps and Striped Phases
R. S. Markiewicz
Physics , 1996, DOI: 10.1016/S0022-3697(97)00025-5
Abstract: The Van Hove singularity (VHS) provides a paradigm for the study of the role of peaks in the density of states (dos) on electronic properties. More importantly, it appears to play a major role in the physics of the high-T_c superconductors, particularly since recent photoemission studies have found that the VHS is close to the Fermi level in most of the high-T_c cuprates near the composition of optimum T_c. This paper offers a comprehensive survey of the VHS model, describing both theoretical properties and experimental evidence for the picture. Special topics discussed include a survey of the Fermi surfaces of the cuprates and related compounds, and an analysis of the reliability of the slave boson approach to correlation effects. While many properties of the cuprates can be qualitatively understood by a simple rigid-band-filling model, this is inadequate for more quantitative results, since correlation effects tend to pin the Fermi level near the VHS over an extended doping range, and can lead to a nanoscale phase separation. Furthermore, the peaks in the dos lead to competition from other instabilities, both magnetic and structural (related to charge density waves). A novel form of dynamic structural instability, involving dynamic VHS-Jahn-Teller effects has been predicted. Scattered through the literature, there is considerable experimental evidence for both nanoscale phase separation of holes, and for local, possibly dynamic, structural disorder. This review attempts to gather these results into a comprehensive database, to sort the results, and to see how they fit into the Van Hove scenario. Recent experiments on underdoped cuprates are found to provide a strong confirmation that the pseudogap is driven by a splitting of the VHS degeneracy.
Van Hove Excitons and High-T$_c$ Superconductivity: VIIIC Dynamic Jahn-Teller Effects vs Spin-Orbit Coupling in the LTO Phase of La$_{2-x}$Sr$_x$CuO$_4$
R. S. Markiewicz
Physics , 1993, DOI: 10.1016/0921-4534(93)90029-P
Abstract: The possible role of the van Hove singularity (vHs) in stabilizing the low-temperature orthorhombic (LTO) phase transition in La$_{2-x}$\-Sr$_x$\-CuO$_ 4$ (LSCO) is discussed. It is found that the vHs can drive a structural distortion in two different ways, either due to spin-orbit coupling or to dynamic Jahn-Teller (JT) effects. This paper discusses the latter effect in some detail. It is shown that a model Hamiltonian introduced earlier to describe the coupled electron -- octahedral tilt motions (`cageons') has a series of phase transitions, from a high-temperature disordered JT phase (similar to the high-temperature tetragonal phase of LSCO) to an intermediate temperature dynamic JT phase, of average orthorhombic symmetry (the LTO phase) to a low temperature static JT phase (the low temperature tetragonal phase). For some parameter values, the static JT phase is absent.
Page 1 /2664
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.