366 research outputs found
Iranian-oil-free zone and international oil prices
One of the main elements of economic sanctions against Iran due to its nuclear and military programs is crude oil exportation restrictions in addition to investment in Iranian energy related projects. Senders of such sanction are interested in understanding the impacts of such embargos on international oil prices. We apply unrestricted Vector Autoregressive (VAR) model, using impulse response (IRF) and variance decomposition (VDA) tools with annual data from 1965 to 2012 to analyze the dynamic response of international oil prices to Iranian oil export sanction. Controlling for the supply of non-Iranian oil and the world GDP per capita, we show that international oil prices respond positively to negative changes of the Iranian oil exports, our proxy of Iran oil sanctions. However, the increasing response of oil prices to the Iranian oil sanction is only significant in the first year after negative shock in Iran oil exports. Beyond the first year following shock, we do not observe a statistically significant response of oil prices
Improvement of Seismic Performance of Beam-column Connection With Replaceable Drilled Attachment Parts
Since beam-column connection plays a prominent role in steel structures, by designing and constructing it properly, the structure will behave better and safer. Numerous researches are carried out on steel connections, like Reduced Beam Section (RBS) and Drilled Flange Connection (DFC). Each connection has advantages and disadvantages. This study evaluates the effect of different connections on behavior of steel moment frames. The connections evaluated in this study are as follows: Connection with drilled attachment part, drilled connection with identical and variable diameter, beam connection with reduced flange. This connection contains one or two replaceable drilled parts that are mounted in connection place. The connection is modeled using the ABAQUS software. Finally, Finite Elements Modeling (FEM) is utilized to calculate the stiffness of each connection. According to the results of the newly introduced connection in terms of energy absorption and ductility is the best example and among the drilled models investigated in this study, drilled connection with variable diameter (proportional to diamond shape) which performed better in terms of behavior and performance than the other perforated models. Also, reduced flange connection ranks third in performance. In proposed connection the plastic hinge is formed at the attachment part of the connection that is replaceable, also there is little damage to the beams and columns, which is one of the main benefits of this connection
Inteligentno upravljanje paralelnim robotom sa Ŕest stupnjeva slobode koriŔtenim za rehabilitaciju donjih udova
The process of empowering muscles in order to make them to a normal and common value is an expensive and prolonged work, in common available methods. There are some commercial exercise machines used for this purpose called rehabilitation systems. However, due to their insufficient motion freedom and prospect of being expensive, these machines have limited usage. Hence, it is clearly necessary that Mechatronic technologies should be used in this area. In this paper, an algorithm and an improved rule are presented for controlling a rehabilitation system of lower limbs which is implemented on a 6-Degree Of Freedom (DOF) Stewart parallel robot. Impedance control and adaptive control are used for this purpose. Estimation and optimization of control parameters will be done by artificial neural networks and genetic algorithms, respectively (intelligent strategy). Safety is guaranteed since some of controller parameters can be adapted under the stability conditions given by using Routh stability theory. Thereafter, the results of simulations are presented by defining a physiotherapy standard mode on a desired trajectory. MATLAB/SIMULINK is used for simulations. Finally, a comparative discussion between this strategy and common methods is devised.Proces osposobljavanja miÅ”iÄa za normalne funkcije je skup i dugotrajan uz koriÅ”tenje dostupnih metoda. Postoje komercijalni strojevi za tu svrhu koji se nazivaju sustavi za rehabilitaciju. Zbog njihove nedostatne slobode pokreta i visoke cijene takvi strojevi imaju ograniÄenu upotrebu. Stoga je jasno da je u podruÄju rehabilitiacije potrebno koristiti mehatroniÄke sustave. U ovom radu prikazan je algoritam i poboljÅ”ano pravilo za upravljanje rehabilitacijskog sustava za donje udove koji je implementiran na Stewart paralelnom robotu sa Å”est stupnjeva slobode. Pritom je koriÅ”teno upravljanje impedancijom i adaptivno upravljanje. Za estimaciju i optimiranje parametara upravljanja koriste se neuronske mreže i genetiÄki algoritmi. Sigurnost je garantirana jer se neki parametri regulatora adaptiraju prema uvjetima stabilnosti koji su dobiveni koriÅ”tenjem Ruthove teorije stabilnosti. Nakon toga, rezultati simulacija prikazani su definiranjem standardnog fizioterapijskog rada na željenoj trajektoriji. Za simulacije se koristi MATLAB/SIMULINK. KonaÄno, u radu je dana i usporedba predložene strategije s uobiÄajenim metodama
Design and Characterization of Curved and Spherical Flexure Hinges for Planar and Spatial Compliant Mechanisms
A flexure hinge is a flexible connector that can provide a limited rotational motion between two rigid parts by means of material deformation. These connectors can be used to substitute traditional kinematic pairs (like bearing couplings) in rigid-body mechanisms. When compared to their rigid-body counterpart, flexure hinges are characterized by reduced weight, absence of backlash and friction, part-count reduction, but restricted range of motion. There are several types of flexure hinges in the literature that have been studied and characterized for different applications. In our
study, we have introduced new types of flexures with curved structures i.e. circularly curved-beam flexures and spherical flexures. These flexures have been utilized for both planar applications (e.g. articulated robotic fingers) and spatial applications (e.g. spherical compliant mechanisms). We have derived closed-form compliance equations for both circularly curved-beam flexures and
spherical flexures. Each element of the spatial compliance matrix is analytically computed as a function of hinge dimensions and employed material. The theoretical model is then validated by comparing analytical data with the results obtained through Finite Element Analysis. A case study
is also presented for each class of flexures, concerning the potential applications in the optimal design of planar and spatial compliant mechanisms. Each case study is followed by comparing the performance of these novel flexures with the performance of commonly used geometries in terms of principle compliance factors, parasitic motions and maximum stress demands. Furthermore, we have extended our study to the design and analysis of serial and parallel compliant mechanisms, where the proposed flexures have been employed to achieve spatial motions e.g. compliant spherical joints
Human Calmodulin Methyltransferase: Expression, Activity on Calmodulin, and Hsp90 Dependence
Deletion of the first exon of calmodulin-lysine N-methyltransferase (CaM KMT, previously C2orf34) has been reported in two multigene deletion syndromes, but additional studies on the gene have not been reported. Here we show that in the cells from 2p21 deletion patients the loss of CaM KMT expression results in accumulation of hypomethylated calmodulin compared to normal controls, suggesting that CaM KMT is essential for calmodulin methylation and there are no compensatory mechanisms for CaM methylation in humans. We have further studied the expression of this gene at the transcript and protein levels. We have identified 2 additional transcripts in cells of the 2p21 deletion syndrome patients that start from alternative exons positioned outside the deletion region. One of them starts in the 2nd known exon, the other in a novel exon. The transcript starting from the novel exon was also identified in a variety of tissues from normal individuals. These new transcripts are not expected to produce proteins. Immunofluorescent localization of tagged CaM KMT in HeLa cells indicates that it is present in both the cytoplasm and nucleus of cells whereas the short isoform is localized to the Golgi apparatus. Using Western blot analysis we show that the CaM KMT protein is broadly expressed in mouse tissues. Finally we demonstrate that the CaM KMT interacts with the middle portion of the Hsp90 molecular chaperon and is probably a client protein since it is degraded upon treatment of cells with the Hsp90 inhibitor geldanamycin. These findings suggest that the CaM KMT is the major, possibly the single, methyltransferase of calmodulin in human cells with a wide tissue distribution and is a novel Hsp90 client protein. Thus our data provides basic information for a gene potentially contributing to the patient phenotype of two contiguous gene deletion syndromes
Isolation and localization of cells expressing Sca-1 in the Adult Mouse Ovary: An evidence for presence of Mesenchymal Stem cells
Objective: Recently growing evident declared that āneo-oogenesisā continues in mature female life span and simultaneously another studies confirmed the presence of spermatogonial stem cells (SSCs). Even though there is agreement between scientist about SSCs population in male gender but on the other side ovarian stem cells have received raising challenges regarding the existence in the surface epithelium of ovary. Mesenchymal stem cells (MSCs) are the most applicable source of stem cells and the common marker of MSCs is Sca-1 so the purpose of this study was to clarify the incidence of stem cells in the surface epithelium of ovary
Methods: forty C57BL6 mice were sacrificed and the ovary carefully excised from its surrounding fat tissue, after mechanical and enzymatic digestion cells were stained with Sca1 to estimate the incidence of positive stem cells (SCs) population fluorescence activated cell sorting (FACS). Part of digested cells used for RT-PCR, also histological section prepared for immunohistochemical (IHC) staining of Sca-1 in ovarian surface epithelium (OSE) FACS.
Results: The gene expression of Sca-1 was confirmed in the ovarian tissue. As well, localization of Sca-1 positive cells was detected in the germinal layer of ovary and epithelial granular layer of primordial follicles. Moreover, we successfully could isolated the Sca-1positive cells through
Conclusion: The present work findings confirmed an inclusive stem cell population in the ovary which can be a strong evident for regeneration of ovarian tissue in either purpose of ovulation scar and neo-oogenesis
Congenital Insensitivity to Pain: Novel SCN9A Missense and In-Frame Deletion Mutations
SCN9A encodes the voltage-gated sodium channel Nav1.7, a protein highly expressed in pain-sensing neurons. Mutations in SCN9A cause three human pain disorders: bi-allelic loss of function mutations result in Channelopathy-associated Insensitivity to Pain (CIP), whereas activating mutations cause severe episodic pain in Paroxysmal Extreme Pain Disorder (PEPD) and Primary Erythermalgia (PE). To date, all mutations in SCN9A that cause a complete inability to experience pain are protein truncating and presumably lead to no protein being produced. Here, we describe the identification and functional characterization of two novel non-truncating mutations in families with CIP: a homozygously-inherited missense mutation found in a consanguineous Israeli Bedouin family (Nav1.7-R896Q) and a five amino acid in-frame deletion found in a sporadic compound heterozygote (Nav1.7-ĪR1370-L1374). Both of these mutations map to the pore region of the Nav1.7 sodium channel. Using transient transfection of PC12 cells we found a significant reduction in membrane localization of the mutant protein compared to the wild type. Furthermore, voltage clamp experiments of mutant-transfected HEK293 cells show a complete loss of function of the sodium channel, consistent with the absence of pain phenotype. In summary, this study has identified critical amino acids needed for the normal subcellular localization and function of Nav1.7. Ā© 2010 Wiley-Liss, Inc
Non-Type I Cystinuria Associated with Mental retardation and Ataxia in a Korean Boy with a New Missence Mutation(G173R) in the SLC7A9 Gene
Cystinuria is an inherited renal and intestinal disease characterized by defective amino acids reabsorption and cystine urolithiasis. It is unusually associated with neurologic symptoms. Mutations in two genes, SLC3A1 and SLC7A9, have been identified in cystinuric patients. This report presents a 13-yr-old boy with cystinuria who manifested difficulty in walking, ataxia, and mental retardation. Somatosensory evoked potential of posterior tibial nerve stimulation showed the central conduction dysfunction through the posterior column of spinal cord. He was diagnosed non-type I cystinuria by urinary amino acid analysis and oral cystine loading test. We screened him and his family for gene mutation by direct sequencing of SLC3A1 and SLC7A9 genes. In this patient, we identified new missence mutation G173R in SLC7A9 gene
A sensitive non-radioactive in situ hybridization method for the detection of chicken IgG Ī³-chain mRNA: a technique suitable for detecting of variety of mRNAs in tissue sections
We established a sensitive non-radioactive in situ hybridization (ISH) method for the detection of chicken IgG Ī³-chain mRNA in paraffin sections. RNA probes were transcribed in vitro from cloned chicken IgG CH1 nucleotide sequences with SP6/T7 RNA polymerases in the presence of DIG-UTP. These probes were used for hybridization and were immunodetected using anti-DIG antibodies conjugated to horseradish peroxidase. The immunoreactive products were visualized with DAB-H(2)O(2). IgG Ī³-chain mRNA-expressing cells were localized in both the spleen and oviductal tissues. This method demonstrated an excellent sensitivity since the ISH signal was clear and the background was negligible. We found that in the spleen IgG Ī³-chain mRNA-expressing cells were present mainly in the red pulp, whereas in the oviduct they appeared mainly in the mucosal stroma and not in the mucosal epithelium
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