400 research outputs found

    Design of High Performance Microstrip Dual-Band Bandpass Filter

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    This paper presents a new design of dual-band bandpass filters using coupled stepped-impedance resonators for wireless systems. This architecture uses multiple couple stubs to tune the passband frequencies and the filter characteristics are improved using defected ground structure (DGS) technique. Measurement results show insertion losses of 0.93 dB and 1.13 dB for the central frequencies of 2.35 GHz and 3.61 GHz, respectively. This filter is designed, fabricated and measured and the results of the simulation and measurement are in good agreement

    Self-similar structure of a hot magnetized flow with thermal conduction

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    We have explored the structure of hot magnetized accretion flow with thermal conduction. The importance of thermal conduction in hot accretion flows has been confirmed by observations of the hot gas surrounding Sgr AA^* and a few other nearby galactic nuclei. For a steady state structure of such accretion flows a set of self similar solutions are presented. In this paper, we have actually tried to re-check the solution presented by Abbassi et al. (2008) using a physical constrain. In this study we find that Eq 29 places a new constrain that limits answers presented by Abbassi et al. 2008. In that paper the parameter space in which it is established in the new constrain was plotted. However, the new requirement makes up only a small parameter space with physically acceptable solutions. And now in this manuscript we have followed the idea with more effort, and tried to find out how thermal conduction influences the structur of the disks in a physical parameter space. We have found out that the existence of thermal conduction will lead to reduction of accretion and radial and azimuthal velocities as well as the vertical thickness of the disk, which is slightly reduced. Moreover, the surface density of the disk will increase when the thermal conduction becomes important in the hot magnetized flow.Comment: Accepted for publication, AP

    L-Carnitine Reduces in Human Conjunctival Epithelial Cells Hypertonic- Induced Shrinkage through Interacting with TRPV1 Channels

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    Background/Aims: Ocular surface health depends on conjunctival epithelial (HCjE) layer integrity since it protects against pathogenic infiltration and contributes to tissue hydration maintenance. As the same increases in tear film hyperosmolarity described in dry eye disease can increase corneal epithelial transient receptor potential vanilloid type-1 (TRPV1) channel activity, we evaluated its involvement in mediating an osmoprotective effect by L-carnitine against such stress. Methods: Using siRNA gene silencing, Ca2+imaging, planar patch- clamping and relative cell volume measurements, we determined if the protective effects of this osmolyte stem from its interaction with TRPV1. Results: TRPV1 activation by capsaicin (CAP) and an increase in osmolarity to≈450 mOsM both induced increases in Ca2+levels. In contrast, blocking TRPV1 activation with capsazepine (CPZ) fully reversed this response. Similarly, L-carnitine (1 mM) also reduced underlying whole-cell currents. In calcein-AM loaded cells, hypertonic-induced relative cell volume shrinkage was fully blocked during exposure to L-carnitine. On the other hand, in TRPV1 gene-silenced cells, this protective effect by L-carnitine was obviated. Conclusion: The described L-carnitine osmoprotective effect is elicited through suppression of hypertonic-induced TRPV1 activation leading to increases in L-carnitine uptake through a described Na+-dependent L-carnitine transporter

    3-Iodothyronamine Activates a Set of Membrane Proteins in Murine Hypothalamic Cell Lines

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    3-Iodothyronamine (3-T1AM) is an endogenous thyroid hormone metabolite. The profound pharmacological effects of 3-T1AM on energy metabolism and thermal homeostasis have raised interest to elucidate its signaling properties in tissues that pertain to metabolic regulation and thermogenesis. Previous studies identified G protein-coupled receptors (GPCRs) and transient receptor potential channels (TRPs) as targets of 3-T1AM in different cell types. These two superfamilies of membrane proteins are largely expressed in tissue which influences energy balance and metabolism. As the first indication that 3-T1AM virtually modulates the function of the neurons in hypothalamus, we observed that intraperitoneal administration of 50 mg/kg bodyweight of 3-T1AM significantly increased the c-FOS activation in the paraventricular nucleus (PVN) of C57BL/6 mice. To elucidate the underlying mechanism behind this 3-T1AM-induced signalosome, we used three different murine hypothalamic cell lines, which are all known to express PVN markers, GT1-7, mHypoE-N39 (N39) and mHypoE-N41 (N41). Various aminergic GPCRs, which are the known targets of 3-T1AM, as well as numerous members of TRP channel superfamily, are expressed in these cell lines. Effects of 3-T1AM on activation of GPCRs were tested for the two major signaling pathways, the action of Gαs/adenylyl cyclase and Gi/o. Here, we demonstrated that this thyroid hormone metabolite has no significant effect on Gi/o signaling and only a minor effect on the Gαs/adenylyl cyclase pathway, despite the expression of known GPCR targets of 3-T1AM. Next, to test for other potential mechanisms involved in 3-T1AM-induced c-FOS activation in PVN, we evaluated the effect of 3-T1AM on the intracellular Ca2+ concentration and whole-cell currents. The fluorescence-optic measurements showed a significant increase of intracellular Ca2+ concentration in the three cell lines in the presence of 10 μM 3-T1AM. Furthermore, this thyroid hormone metabolite led to an increase of whole-cell currents in N41 cells. Interestingly, the TRPM8 selective inhibitor (10 μM AMTB) reduced the 3-T1AM stimulatory effects on cytosolic Ca2+ and whole-cell currents. Our results suggest that the profound pharmacological effects of 3-T1AM on selected brain nuclei of murine hypothalamus, which are known to be involved in energy metabolism and thermoregulation, might be partially attributable to TRP channel activation in hypothalamic cells

    Vascular endothelial growth factor (VEGF) induced downstream responses to transient receptor potential vanilloid 1 (TRPV1) and 3-lodothyronamine (3-T1AM) in human corneal keratocytes

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    This study was undertaken to determine if crosstalk among the transient receptor potential (TRP) melastatin 8 (TRPM8), TRP vanilloid 1 (TRPV1), and vascular endothelial growth factor (VEGF) receptor triad modulates VEGF-induced Ca2+ signaling in human corneal keratocytes. Using RT-PCR, qPCR and immunohistochemistry, we determined TRPV1 and TRPM8 gene and protein coexpression in a human corneal keratocyte cell line (HCK) and human corneal cross sections. Fluorescence Ca2+ imaging using both a photomultiplier and a single cell digital imaging system as well as planar patch-clamping measured relative intracellular Ca2+ levels and underlying whole-cell currents. The TRPV1 agonist capsaicin increased both intracellular Ca2+ levels and whole-cell currents, while the antagonist capsazepine (CPZ) inhibited them. VEGF-induced Ca2+ transients and rises in whole-cell currents were suppressed by CPZ, whereas a selective TRPM8 antagonist, AMTB, increased VEGF signaling. In contrast, an endogenous thyroid hormone-derived metabolite 3-lodothyronamine (3-T(1)AM) suppressed increases in the VEGF-induced current. The TRPM8 agonist menthol increased the currents, while AMTB suppressed this response. The VEGF-induced increases in Ca2+ influx and their underlying ionic currents stem from crosstalk between VEGFR and TRPV1, which can be impeded by 3-T(1)AM-induced TRPM8 activation. Such suppression in turn blocks VEGF-induced TRPV1 activation. Therefore, crosstalk between TRPM8 and TRPV1 inhibits VEGFR-induced activation of TRPV1

    THE EFFECT OF ALTITUDE ON BREAKING SEED DORMANCY AND STIMULATION OF SEED GERMINATION OF PERSIAN HOGWEED (HERACLEUM PERSICUM)

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    Persian hogweed is a odorous perennial herb which has pharmaceutical and fodder values. seed is the main propagation method of this species. A seed analysis test was designed to survey the effects of high altitude on breaking dormancy and germination stimulates of Persian hogweed seeds. For this purpose seeds were collected from three different elevations (1700, 2200, 2700 masl) in Kojoor area. After primary cleanings, germination percent(GP) and germination speed (GS) of each elevation were determined by cold stratification compared to control. According to results control seeds were not germinate then seeds of this species need to treat. Statistical analysis of results showed that there are sensible differences between GP and GS of each elevation. As seeds of higher elevation germinate slower and less than higher elevation but in a longer periods. So changes of elevation is an effective factor on germination characteristics of Persian hogweed seeds which have to be considered for every seed collection and rehabilitation program of this species

    An economic insight into additive manufacturing system implementation

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    With an ever growing diffusion of Additive Manufacturing (AM) system in industrial and commercial level, as well as the direct and indirect dynamics which are being introduced resulting from its inclusion as a possible production technology on companies’ portfolio, the need to reconfigure production system and adapt the production strategy becomes even more relevant than before. There are several studies which have emphasized on the importance of a paradigm shift in order to exploit advantages of AM, not only considering changes within design and functionality of the product, but also concerning AM’s impact on the entire value chain (re)configuration. Thus, it is of crucial importance to take into consideration that for this shift to be feasible and manageable, there is a need to include both technical and managerial aspects of manufacturing. This work proposes an economic insight in order to provide a guideline for the proper evaluation of AM system implementation. © IFIP International Federation for Information Processing 2015

    Conscious sedation and analgesia in colonoscopy: Ketamine/propofol combination has superior patient satisfaction versus fentanyl/propofol

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    Background: Colonoscopy is performed without preparing sedation in many countries. However, according to the current literature patients are more satisfied when appropriate sedation is prepared for them. Objectives: We hypothesize that propofol-ketamine may prepare more patient satisfaction compared to propofol-fentanyl combination. Patients and Methods: Sixty adult patients older than 18 with ASA physical status of I, II or III were enrolled in the present study after providing the informed consent. They were prospectively randomized into two equal groups: 1- Group PF: was scheduled to receive IV bolus dose of fentanyl 1μg/kg and propofol 0.5mg/kg. 2- Group PK: was scheduled to receive IV bolus dose of ketamine 0.5mg/kg and propofol 0.5mg/kg. As a primary goal, patient's satisfaction was assessed by the use a Likert five-item scoring system in the recovery. Comparisons of hemodynamic parameters (mean heart rate, mean systolic blood pressure, mean diastolic blood pressure), mean Spo2 values during the procedure and side effects such as nausea, vomiting, and psychological reactions during the recovery period were our secondary goals. Level of sedation during the colonoscopy was assessed with the Observer's Assessment of Alertness/Sedation score (OAA/S). Results: Mean satisfaction scores in the group PK were significantly higher than the group PF (P = 0.005) while the level of sedation during the procedure was similar (P = 0.17). Hemodynamic parameters and SpO2 values were not significantly different (P > 0.05). Incidence of nausea and vomiting was the same in both groups. Conclusions: IV bolus injection of propofol-ketamine can lead to more patients' satisfaction than the other protocols during colonoscopy. © 2013 Iranian Society of Regional Anesthesia and Pain Medicine
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