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OALib Journal期刊

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Is decreased bone mineral density associated with development of scoliosis? A bipedal osteopenic rat model
Ozgur Dede, Ibrahim Akel, Gokhan Demirkiran, Nadir Yalcin, Ralph Marcucio, Emre Acaroglu
Scoliosis , 2011, DOI: 10.1186/1748-7161-6-24
Abstract: Fifty Sprague-Dawley rats were rendered bipedal at the 3rd postnatal week and separated into control (25 rats) and heparin (25 rats receiving 1 IU/gr body weight/day) groups. DEXA scans after 4 weeks of heparin administration showed low bone mass in the heparin group. Anteroposterior and lateral x-rays of the surviving 42 animals (19 in heparin and 23 in control groups) were taken under anesthesia at the 40th week to evaluate for spinal deformity. Additional histomorphometric analysis was done on spine specimens to confirm the low bone mass in heparin receiving animals. Results of the DEXA scans, histomorphometric analysis and radiological data were compared between the groups.Bone mineral densities of rats in the heparin group were significantly lower than the control group as evidenced by both the DEXA scans and histomorphometric analyses. However, the incidence of scoliosis (82% in heparin and 65% in control; p > 0.05) as well as the curve magnitudes (12.1 ± 3.8 in heparin versus 10.1 ± 4.3 degrees in control; p > 0.05) were not significantly different. Osteopenic rats were significantly less kyphotic compared to control specimens (p = 0.001).This study has revealed two important findings. One is that bipedality (in the absence of pinealectomy) by itself may be a cause of scoliosis in this animal model. Further studies on animal models need to consider bipedality as an independent factor. Secondly, relative hypokyphosis in osteopenic animals may have important implications. The absence of sagittal plane analyses in previous studies makes comparison impossible, but nonetheless these findings suggest that osteopenia may be important in the development of 3D deformity in adolescent idiopathic scoliosis.Adolescent idiopathic scoliosis remains to be a major area of research. Many factors, such as proprioceptive defects, genetics, asymmetric or abnormal growth, soft tissue or neuromuscular conditions, have been scrutinized as potential causes [1-5], but none have been
Enslavement of Wireless Sensor Network to an RF Energy Harvesting System  [PDF]
Alex Mouapi, Nadir Hakem
Open Journal of Antennas and Propagation (OJAPr) , 2017, DOI: 10.4236/ojapr.2017.52006
Abstract: The abundance of telecommunications systems makes it possible to have somewhat significant quantity of radiofrequency energy in the environment. This energy can be recycled to power ultra-low-power devices such as Wireless Sensor Network (WSN). In this paper, the performance of a miniature RF/DC converter is evaluated in order to enslave a WSN’s per-formance to the amount of the recovered energy. More precisely, a highly sensitive and efficient rectifier is designed to achieve optimum performance in the GSM band. The design method relies on a judicious choice of the rectifying diode which is the basis of most losses in a rectifying antenna (rectenna). Optimum performance is achieved by using the gradient method search proposed in the Advanced Design System (ADS) software. A rectifier based on Schottky diodes HSMS 2850 used in a voltage doubler topology is thus obtained. A maximum RF/DC conversion efficiency of 36% is reached for an RF input power level of 10 dBm. An energy budget of a sensor node in a WSN having an equitable distribution of network loads is then defined and used to evaluate the performance of the WSN regarding the distance at which the Base Station (BS) can be located. The Low Energy Adaptive Clustering Hierarchy (LEACH) protocol is used for this purpose. The distance separating the WSN from the BS is used as the enslavement parameter. Our analysis shows that increasing the duration of each round results in an increase in the range of the WSN. As an example, a network with 100 nodes distributed over an area of may be located at 1.3 km from the base station when each node of the WSN must perform measurements every 1 min.
Scattering from Perfectly Magnetic Conducting Surfaces: the Extended Theory of Boundary Diffraction Wave Approach
Ugur Yalcin
PIER M , 2009, DOI: 10.2528/PIERM09042210
Abstract: In this paper, the uniform scattered fields from a perfectly magnetic conducting (PMC) surface are studied with the theory of boundary diffraction wave (TBDW). The vector potential is described by considering the TBDW for the PMC surfaces. The TBDW is then applied to the problem of scattering from the PMC half plane. The total scattered fields are obtained and compared numerically with the exact solution for the same problem. The numerical results show that the solution of the TBDW is very the exact solution.
Uniform Scattered Fields of the Extended Theory of Boundary Diffraction Wave for PEC Surfaces
Ugur Yalcin
PIER M , 2009, DOI: 10.2528/PIERM09031201
Abstract: In this paper, the uniform scattered fields from a perfectly conducting (PEC) half plane are studied with the extended theory of the boundary diffraction wave. A new vector potential of the boundary diffraction wave is found by considering the Fermat principle for the PEC surfaces. This vector potential is applied to the Helmholtz-Kirchhoff integral, and the theory of the boundary diffraction wave is extended to the PEC surfaces. The extended theory of the boundary diffraction wave is then applied to the scattering problem for the PEC half plane. The total scattered fields are compared numerically with the exact solution for the same problem. The numerical comparisons given in the paper show that the solution of the extended theory of the boundary diffraction wave is very close to the exact solution.
Socioeconomic burden of nosocomial infections.
Yalcin Ata
Indian Journal of Medical Sciences , 2003,
Abstract: Nosocomial infection represents an important public health problem in developing countries as in developed ones. Economic concerns have taken on increasing importance in infection control since the mid 1970s in the USA, however there are few papers on the economics of NI in other countries. Studies on the costs of NI have used different methods, definitions and degrees of stringency when calculating indirect costs and there is therefore still uncertainty over their true economic impact on the community and on the workplace economy. Drug and especially antibiotic acquisition in addition to increased length of stay are the widely and well described parameters. Extra cost of NI include; bed, intensive care unit stay, hematological, biochemical, microbiological and radiological tests, antibiotics, other drugs, extra surgical procedures and working hours. In addition to high morbidity and mortality one of the well described parameters is the extra length of stay in the hospital. High mortality rates and economic expense which NI represents emphasizes the justification for measures of control of this entity. To estimate better the current personnel and financial resources necessary to support infection control activities and to prevent NI, it is imperative that those conducting studies of hospital epidemiology and healthcare outcomes research determine these current costs.
Refining of Polysulfide Pulps
Yalcin Copur
Journal of Applied Sciences , 2007,
Abstract: This study compares the modified kraft process, polysulfide pulping, one of the methods to obtain higher pulp yield, with conventional kraft method. More specifically, the study focuses on the refining effects of polysulfide pulp, which is an area with limited literature. Physical, mechanical and chemical properties of kraft and polysulfide pulps (4% elemental sulfur addition to cooking digester) cooked under the same conditions were studied as regards to their behavior under various PFI refining (0, 3000, 6000, 9000 revs.). Polysulfide (PS) pulping, compared to the kraft method, resulted in higher pulp yield and higher pulp kappa number. Polysulfide also gave pulp having higher tensile and burst index. However, the strength of polysulfide pulp, tear index at a constant tensile index, was found to be 15% lower as compared to the kraft pulp. Refining studies showed that moisture holding ability of chemical pulps mostly depends on the chemical nature of the pulp. Refining effects such as fibrillation and fine content did not have a significant effect on the hygroscopic behavior of chemical pulp.
Poliovirus Vaccines
Isik Yalcin
Cocuk Enfeksiyon Dergisi , 2008,
Abstract: The two types of poliovirus vaccines are inactivated vaccine, given parenterally, and live virus vaccine, given orally. Oral poliovirus is the vaccine of choice for global eradication. Either inactivated vaccine or oral vaccine may be given concurrently with other routinely recommended childhood vaccines. No serious adverse events have been associated with the vaccine. Oral poliovirus vaccine can cause vaccine associated paralytic poliomyelitis.
General Conceptual View on Resource Advantage Theory
Bilal Yalcin
Business and Economics Research Journal , 2010,
Abstract: In order to continue for an organization to exist it needs to finance itself for its own resource on the other hand service with considering consumers need and expectations by present them lowest price and highest quality also. Under these conditions these kind of organizations need to analyze the behaviour (nature) of the rival organizations and position themselves accordingly in order to get advantage on the rival organizations. In this study, a general conceptual view on resource advantage theory is developed. Theory explains having the lowest cost resources than rival organisations geting advantage with organisation resources, market position, financial performance and evironmental factors. Theory is able to achieve efficiency and effectiveness in the organisations and use to have strategic marketing decisions.
Productive elements in group cohomology
Ergun Yalcin
Mathematics , 2011,
Abstract: Let $G$ be a finite group and $k$ be a field of characteristic $p>0$. A cohomology class $\zeta \in H^n(G,k)$ is called productive if it annihilates $\Ext^*_{kG}(L_{\zeta},L_{\zeta})$. We consider the chain complex $\bPz$ of projective $kG$-modules which has the homology of an $(n-1)$-sphere and whose $k$-invariant is $\zeta$ under a certain polarization. We show that $\zeta$ is productive if and only if there is a chain map $\Delta: \bPz \to \bPz \otimes \bPz$ such that $(\id \otimes \epsilon)\Delta\simeq \id$ and $(\epsilon \otimes \id)\Delta \simeq \id$. Using the Postnikov decomposition of $\bPz \otimes \bPz$, we prove that there is a unique obstruction for constructing a chain map $\Delta$ satisfying these properties. Studying this obstruction more closely, we obtain theorems of Carlson and Langer on productive elements.
Rank Three $p$-Group Actions on Products of Spheres
Ergun Yalcin
Mathematics , 2014,
Abstract: Let $p$ be an odd prime. We prove that every rank three $p$-group acts freely and smoothly on a product of three spheres. To construct this action, we first prove a generalization of a theorem of L\" uck and Oliver on constructions of $G$-equivariant vector bundles. We also give some other applications of this generalization.
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