45915 research outputs found
Sort by
Decoupling of multifrequency dipole antenna arrays for microwave imaging applications
No full textThe mutual coupling between elements of a multifrequency dipole antenna array is experimentally investigated by S-parameter measurements and planar near-field scanning of the radiated field. A multifrequency array with six dipoles is analyzed. In order to reduce the coupling between dipoles, a planar metasurface is placed atop the array acting as superstrate. The mutual coupling of the antenna elements in the absence and presence of the superstrate is presented comparatively. Between 3 and 20 dB mutual coupling reduction is achieved when the superstrate is used. By scanning the field radiated by the antennas and far-field measurements of the radiation pattern, it is observed that the superstrate confines the radiated power, increases the boresight radiation, and reduces the endfire radiation
Antiviral activity of an N-allyl acridone against dengue virus
No full textBackground: Dengue virus (DENV), a member of the family Flaviviridae, is at present the most widespread causative agent of a human viral disease transmitted by mosquitoes. Despite the increasing incidence of this pathogen, there are no antiviral drugs or vaccines currently available for treatment or prevention. In a previous screening assay, we identified a group of N-allyl acridones as effective virus inhibitors. Here, the antiviral activity and mode of action targeted to viral RNA replication of one of the most active DENV-2 inhibitors was further characterized. Results: The compound 10-allyl-7-chloro-9(10H)-acridone, designated 3b, was active to inhibit the in vitro infection of Vero cells with the four DENV serotypes, with effective concentration 50% (EC50) values in the range 12.5-27.1 mu M, as determined by virus yield inhibition assays. The compound was also effective in human HeLa cells. No cytotoxicity was detected at 3b concentrations up to 1000 mu M. Mechanistic studies demonstrated that virus entry into the host cell was not affected, whereas viral RNA synthesis was strongly inhibited, as quantified by real time RT-PCR. The addition of exogenous guanosine together with 3b rescued only partially the infectivity of DENV-2. Conclusions: The acridone derivative 3b selectively inhibits the infection of Vero cells with the four DENV serotypes without a direct interaction with the host cell or the virion but interfering specifically with the intracellular virus multiplication. The mode of antiviral action for this acridone apparently involves the cellular enzyme inosine-monophospahe dehydrogenase together with another still unidentified target related to DENV RNA synthesis
Crimean-Congo hemorrhagic fever among health care workers, Turkey
No full textWe investigated 9 cases of Crimean-Congo hemorrhagic fever (1 fatal, 2 asymptomatic) among health care workers in Turkey. Needlestick injuries were reported for 4 workers. Eight received ribavirin. In addition to standard precautions, airborne infection isolation precautions are essential during aerosol-generating procedures. For postexposure prophylaxis and therapy, ribavirin should be given
The effect of additional local anesthesia on postoperative pain level applied at the end of the rhinoplasty operation
No full textObjective: We aimed to assess the effect of additional local anesthesia on postoperative pain levels which made at the end of the rhinoplasty operation. Material and Method: Sixty-six patients who had open technique rhinoplasty operation included in this study. Patients were operated under general anesthesia. Additional local anesthesia was applied at the end of the operation. Patient's pain level was evaluated with Visual Analog Scale (VAS) at preoperative intravenous catheterization, recovery room, postoperative 1st 2rsd, 4th, 6th, 12th, 18th, 24th hours and compared with the group who had no additional local anesthesia. Result: The highest pain levels were at the catheterization, 1st and 2rsd hours. There was a significant difference between 1st and 2nd hours pain level between groups. First and 2nd hour pain levels were significantly lower in the additional local anesthesia group. Conclusion: Additional local anesthesia decreases the early postoperative pain levels and this possibly increases the patient satisfaction
Evaluating fluoroquinolone use in patients admitted to the tuberculosis outpatient clinic
No full textObjective: Inelaborate use of new quinolones with strong anti-tuberculosis (TB) activity leads to difficulty in diagnosis and more importantly, quinolone-resistant Mycobacterium tuberculosis. We aimed to determine the frequency of quinolone use in patients who were referred to our hospital for suspected TB and to evaluate the association between quinolone use and different clinical laboratory parameters. Methods: Between November 15 and December 15, 2013, all patients who were admitted to the TB outpatient clinic with no previous diagnosis of TB were included in this study. Demographic and clinical laboratory findings and history of antibiotic use were recorded. Patients' quinolone use were questioned by showing fluoroquinolone antibiotic boxes' photographs available on the market. The departments of the doctors who prescribed quinolones were recorded. Results: The mean age of 179 patients included in the study was 37 +/- 16 (15-89) years. Among these, 113 patients (63.1%) were male. Seventy five patients (41.9%) were diagnosed as tuberculosis according to the clinical-radiological and/or bacteriological findings. Of 179 patients, 58.1% (n=104) had been prescribed antibiotics for current complaints before referral to our clinic. Sixteen patients (15%) had been recommended fluoroquinolones. Fluoroquinolones were prescribed by seven internal medicine specialists, five pulmonologists, three emergency medicine specialists, and one family medicine practitioner. Among 16 fluoroquinolones prescribed, nine were moxifloxacin, four were levofloxacin, and three were gemifloxacin. Quinolone use revealed a significant inverse relationship only with the presence of hemoptysis (p=0.04). Conclusion: Besides increased educational activities regarding the rational use of antibiotics in recent years, the quinolone group of antibiotics is still prescribed for suspected TB cases. To avoid quinolone-resistant M. tuberculosis strains, further education is required
Optimal reduced dimensional representation of classical molecular dynamics
No full textAn optimal reduced space method for capturing the low-frequency motion in classical molecular dynamics calculations is presented. This technique provides a systematic means for carrying out reduced-dimensional calculations in an effective set of reduced coordinates. The method prescribes an optimal reduced subspace linear transformation for the low frequency motion. The method is illustrated with a dynamics calculation for a model potential, where the original six-dimensional space is reduced to two (three) dimensions, depending on the desired frequency cutoff value
A lightning discharge producing a beam of relativistic electrons into space
No full textStrong electric fields associated with lightning generate brief (similar to 1 ms) but intense Terrestrial Gamma-ray Flashes (TGFs), detected by spacecrafts. A few events are thought to be the signature of a relativistic electron beam escaping the atmosphere, which is distinguishable from a TGF since the lightning discharge is along the geomagnetic field line from the spacecraft, rather than below. We refer to this event herein as a 'Terrestrial Energetic-electron Flash' (TEF), and present the first TEF with associated discharge. The TEF was detected by the Gamma-ray Burst Monitor aboard the Fermi satellite, and is correlated with a lightning discharge detected by three Stanford University AWESOME ELF/VLF receivers, a Duke University ULF receiver, and by the GLD360 lightning geolocation network. The discharge, nearly simultaneous with the generated electrons, was of intense peak current and of positive polarity, and with a modest total charge transfer, similar to TGF-associated discharges
Performance evaluation of super-resolution reconstruction from video
No full textSeveral algorithms have been proposed to enhance the resolution of a reference image from multiple still images or video that may be captured/stored in raw or compressed format. This paper provides a thorough study of how the performance of the projections onto convex sets (POCS) method is affected by camera parameters, quantization of the pixel-values, motion estimation errors, and quantization in the DCT-domain (when compressed data is used). Experimental results are provided to evaluate the practical applicability of super-resolution reconstruction in various scenarios. It has been observed that the quality of the resolution enhancement depends on the quantization of pixel intensity values in the RGB (uncompressed) or YUV (compressed) domains by the video capture device, as well as the accuracy of the estimated motion parameters between successive frames
Universal image steganalysis using rate-distortion curves
No full textThe goal of image steganography is to embed information in a cover image using modifications that are undetectable. In actual practice, however, most techniques produce stego images that are perceptually identical to the cover images but exhibit statistical irregularities that distinguish them from cover images. Statistical steganalysis exploits these irregularities in order to provide the best discrimination between cover and stego images. In general, the process utilizes a heuristically chosen feature set along with a classifier trained on suitable data sets. In this paper, we propose an alternative feature set for steganalysis based on rate-distortion characteristics of images. Our features are based on two key observations: i) data hiding methods typically increase the image entropy in order to encode hidden messages; ii) data hiding methods are limited to the set of small, imperceptible distortions. The proposed feature set is used as the basis of a steganalysis algorithm and its performance is investigated using different data hiding methods
Lion Gate, Hattusa
No full textThe Lion Gate in the south-west of Hattusa. At Hattuša, the capital city of Hittites (today in the Çorum Province, Turkey) from their beginning in the 17th century BC until the collapse of the empire in early 12th century BC. By the 12th century the city came to cover an area of 182 hectars, surrounded by a 3.3 km long defensive wall. The Aslanlı Kapı (Lion Gate) with two stone lions were believed to protect the city from evil spirits. The Lion Gate was one of the six defensive walls of the city. Besides natural outcrops that were turned out to the part of the walls, massive ramparts were made to create artificial fortresses.Black & white photograph