Gain Suppression Research Articles

Clinical, Immunological and Virological Responses of Zidovudine-Lamivudine-Nevirapine versus Zidovudine-Lamivudine-Efavirenz Antiretroviral Treatment (ART) Among HIV-1 Infected Children: Asella Teaching and Referral Hospital, South-East Ethiopia.

Background:Antiretroviral Therapy(ART) remarkably reduced HIV-1 infection-related mortality in children. The efficacy and safety of different ART regimen in pediatric age groups remained issues of debates and available evidence were scarce especially among children taking the of one the two prototypes (NVP or EFV) Non-Nucleoside Reverse Transcriptase Inhibitor(NNRTI) as backbone of ART regimen.Therefore, the objective of this study was to compare clinical, immunological and virological responses of zidovudine-lamivudine-nevirapine (AZT+3TC+ NVP) versus zidovudine-lamivudine-efavirenz (AZT+3TC+EFV) ART regimen among HIV-1 infected children.Methods:A retrospective cross-sectional study was done by reviewing medical records of the patients to evaluate clinical, immunological and virological outcomes of NVP+AZT+3TC versus EFV+AZT+3TC ART regimen among HIV-1 infected children. Data were entered into Epi-info version 7.2.2 for clean up and exported to SPSS version 17 for analysis. Paired and Independent t-tests were used to compare the CD4 cell count, weight and virologic level at six months with corresponding baseline value; and the mean weight, CD4 gain and viral suppression across the two ART regimens at six months of ART respectively.Results:Medical records of 122 patients from NVP-based regimen and 61 patients from EFV group were reviewed. After six months of NVP+AZT+3TC treatment, the mean CD4 cell count difference from baseline was 215(95% CI, 175.414-245.613, p<0.001). From EFV+AZT+3TC group, the mean CD4 cell count difference from baseline was 205(95% CI 155.404-235.623, p< 0.001). The mean CD4 count difference between the two regimens was comparable (p 0.145). Similarly, optimal viral suppression was achieved in 82% (100/122) of NVP+AZT+3TC regimen and 83% (44/61) of EFV+AZT+3TC regimen which was still comparable across the two groups.Conclusion:There was no difference in clinical, immunological and virological outcomes among patients taking NVP+AZT+3TC or EFV+AZT+3TC ART regimen.

Printed Antenna Array with Flat-Top Radiation Pattern

AbstractA printed antenna array consisting of 10 wideband symmetrical pentagonal dipoles is presented. The feed network of impedance transformers is employed to provide appropriate amplitude and phase distribution necessary to obtain flat top beam pattern. The measured results demonstrate excellent radiation characteristics including 38° flat gain region with maximum ripple of 3.5 dB at the centre frequency. Furthermore, the proposed antenna that is placed in corner reflector with angle of 60° has good gain (17 dBi) and side lobe suppression (18.9 dB). Although it is designed at the centre frequencyfc=12 GHz, it was shown to be capable of shaping a good flat top radiation pattern within a fractional bandwidth at least 6 % of centre frequency. Also, proposed antenna features cheap, simple and easy fabrication that makes it suitable for mass production.

A Circularly Polarized Rectenna Array Based on Substrate Integrated Waveguide Structure With Harmonic Suppression

A compact circularly polarized rectenna with harmonic suppression for wireless power transmission at 5.8 GHz is proposed in this letter. The substrate integrated waveguide structure is adopted for enhanced gain, unidirectional patterns, and surface wave suppression. A rectifier, which consists of a matching network, a diode, and a dc-pass filter, is integrated with the antenna at the back side. The proposed rectenna is fabricated and measured. It features 6.9 dB gain, 0.67 dB axial ratio, and 30 dB return loss. The conversion efficiency is 65.87% with a 700 Ω load. A rectenna array is also built for an increased aperture. It shows 61.49% conversion efficiency with 650 Ω load in measurement. Both the rectenna and array are satisfactory choices for wireless power transfer usage.

Using deep learning to detect small targets in infrared oversampling images

According to the oversampling imaging characteristics, an infrared small target detection method based on deep learning is proposed. A 7-layer deep convolutional neural network (CNN) is designed to automatically extract small target features and suppress clutters in an end-to-end manner. The input of CNN is an original oversampling image while the output is a clutter-suppressed feature map. The CNN contains only convolution and non-linear operations, and the resolution of the output feature map is the same as that of the input image. The L1-norm loss function is used, and a mass of training data is generated to train the network effectively. Results show that compared with several baseline methods, the proposed method improves the signal clutter ratio gain and background suppression factor by 3-4 orders of magnitude, and has more powerful target detection performance.

Effect of a Dietary Supplement Containing Raspberry Ketone on CYP3A Activity in Healthy Women

Objective: Raspberry ketone (RK) is available as a supplement with effect on weight gain suppression. Recent studies have found that various herbal products can affect the activities of drug metabolizing enzymes and drug efflux proteins, and provoke clinically relevant drug-drug interactions. Capsaicin, a molecule having a similar chemical structure to RK, is another well-known cytochrome P450 (CYP) inhibitor. On the other hand, it is totally unclear whether RK has any effect on human CYP activities. In this study, we evaluated the effect of orally administered RK on CYP3A activity by measuring 6beta-hydroxycortisol/cortisol ratio in urine samples. Methods: This clinical study was conducted with approval by the Institutional Review Board at Gunma University Hospital. A total of 7 healthy women aged between 20 and 35 years were included and all of them provided written informed consent. Urine samples were collected from all subjects on the morning of day 5 (± 1 day) of menstrual cycle. In the subsequent RK phase, subjects took 3 tablets (16.7 mg/tab) of RK 3 times daily for 7 days, followed by urine sampling on the morning of day 8. In the control phase, the second morning urine sampling was performed 8 days after the first sampling. Urine 6 beta-hydroxycortisol and cortisol concentrations were measured by HPLC UV method and the 6 beta-hydroxycortisol to cortisol ratio was compared between the two phases. Results: The mean basal and assessment ratios in the RK phase were 7.49 ± 4.76 and 9.20 ± 8.05, respectively, while the corresponding ratios in the control phase were 5.36 ± 3.17 and 5.19 ± 4.61, showing no significant difference in either phase. Conclusion: RK does not affect CYP3A activity.

Small target detection using edge-preserving background estimation based on maximum patch similarity

Infrared small target detection is widely applied in lots of practical applications, but due to the complicated edges in practical scenarios, most existing detection algorithms usually lead to many false alarms and cannot detect the target accurately. Addressing this problem, a novel edge-preserving background estimation method based on maximum patch similarity was proposed in this article. At first, we will propose an improved local adaptive contrast measure to suppress the pixel-size electronic noises. Then, maximum patch similarity with minimum improved local adaptive contrast measure can be utilized to preserve the edge in the estimated background. Finally, we can obtain target image by filtering the background image from original image and use adaptive threshold segmentation to detect the small target in our target image. It is shown from experiments that our proposed method has better detection results in diverse infrared images, improving signal-to-clutter ratio gain and background suppression factor of the images significantly and efficiently.

Infrared small target detection based on directional zero-crossing measure

Infrared small target detection under complex background and low signal-to-clutter ratio (SCR) condition is of great significance to the development on precision guidance and infrared surveillance. In order to detect targets precisely and extract targets from intricate clutters effectively, a detection method based on zero-crossing saliency (ZCS) map is proposed. The original map is first decomposed into different first-order directional derivative (FODD) maps by using FODD filters. Then the ZCS map is obtained by fusing all directional zero-crossing points. At last, an adaptive threshold is adopted to segment targets from the ZCS map. Experimental results on a series of images show that our method is effective and robust for detection under complex backgrounds. Moreover, compared with other five state-of-the-art methods, our method achieves better performance in terms of detection rate, SCR gain and background suppression factor.

Abstract 5148: Liposomal gemcitabine, FF-10832, improves gemcitabine (GEM) pharmacokinetics (PK) and increases anti-tumor efficacy

Abstract Introduction: FF-10832 is a liposome suspension optimized by Fujifilm nanotechnology containing 0.5 mg/mL GEM, cholesterol, HSPC, N-MPEG-DSPE. FF-10832 is expected to improve GEM PK and have strong anti-tumor effects. The PK and anti-tumor effects of FF-10832 were studied in mice and human pancreatic cancer xenograft models. Methods: Single-dose murine plasma PK of FF-10832 1 mg/kg was compared to GEM 240mg/kg. In vivo activity of GEM 240 mg/kg and FF-10832 1-5 mg/kg IV once weekly were compared in human pancreatic cancer murine xenograft models; 2 subcutaneous (Capan-1 [GEM-sensitive] and BxPC-3 [GEM-resistant]), and 1 orthotopic (SUIT-2) model. The active form of GEM (GEM triphosphate [dFdCTP]) inhibits DNA synthesis. dFdCTP tissue concentrations following FF-10832 4mg/kg and GEM 240mg/kg were compared in these models. Results: An extended plasma t½ (10.6 vs. 2.9 hours), lower clearance, and smaller volume of distribution were observed with FF-10832 vs. GEM, which correlated with greater dose exposure achieved with FF-10832 compared to GEM (AUClast 186000 vs. 73000 hr·ng/mL). FF-10832 demonstrated increased in vivo activity in SUIT-2, Capan-1, and BxPC-3 models at significantly lower doses compared to GEM. In the Capan-1 and BxPC3 models, FF-10832 showed dose-dependent tumor growth suppression with FF-10832 4 mg/kg and 5 mg/kg superior to that of GEM (p&amp;lt;0.001), respectively. Following 11 weekly doses in the SUIT-2 model, the survival rate was 0% and 20% for vehicle and GEM 240 mg/kg vs. 13% and 60% for 2 and 4 mg/kg FF-10832, respectively. Median survival time was 60 (FF-10832 2 mg/kg) and 73 (GEM 240 mg/kg) vs. 26 days (vehicle) (p &amp;lt;0.001). Median survival was not reached at FF-10832 4 mg/kg. In all models, FF-10832 2 mg/kg (equivalent efficacy to GEM 240 mg/kg) showed no body weight gain suppression. The dFdCTP tumor/bone marrow AUC ratio was significantly higher following FF-10832 (dFdCTP AUC ratio = 7) compared with non-liposomal GEM (0.8). Conclusions: FF-10832 is a stable liposomal GEM formulation demonstrating potent anti-tumor efficacy in solid tumor models with a favorable pharmacokinetic profile compared to non-liposomal GEM. Increased exposure achieved at lower GEM doses may potentially result in superior efficacy and a more tolerable safety profile for FF-10832 compared to non-liposomal GEM. Citation Format: Takeshi Matsumoto, Tsukasa Kitahashi, Takashi Komori, Hiromu Kitahara, Kohei Ono, Naoki Yamada, Hiroyuki Iwamura, Kiyohito Takada, Shinji Hagiwara, Yasuhiro Shimada. Liposomal gemcitabine, FF-10832, improves gemcitabine (GEM) pharmacokinetics (PK) and increases anti-tumor efficacy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5148. doi:10.1158/1538-7445.AM2017-5148

Thermal modulation for suppression of parametric instability in advanced gravitational wave detectors

Three-mode parametric instability is a threat to attaining design power levels in advanced gravitational wave detectors. The first observation of three-mode parametric instability in a long optical cavity revealed that instabilities could be suppressed by time variation of the mirror radius of curvature. In this paper, we present three dimensional finite element analysis of this thermo-acousto-optics system to determine whether thermal modulation could provide sufficient instability suppression without degrading time averaged optical performance. It is shown that deformations due to the time averaged heating profile on the mirror surface can be compensated by rear surface heating of the test mass. Results show that a heating source with a modulation amplitude of 1 W at 0.01 Hz is sufficient to stabilize an acoustic mode with parametric gain up to 3. The parametric gain suppression factor is linearly proportional to the peak modulation power.

Universality of Coherent Raman Gain Suppression in Gas-Filled Broadband-Guiding Photonic Crystal Fibers

As shown in the early 1960s, the gain in stimulated Raman scattering (SRS) is drastically suppressed when the rate of creation of phonons (via pump-to-Stokes conversion) is exactly balanced by the rate of phonon annihilation (via pump-to-anti-Stokes conversion). This occurs when the phonon coherence waves synchronized vibrations of a large population of molecules have identical propagation constants for both processes, i.e., they are phase-velocity matched. As recently demonstrated, hydrogen-filled photonic crystal fiber pumped in the vicinity of its zero dispersion wavelength provides an ideal system for observing this effect. Here we report that Raman gain suppression is actually a universal feature of SRS in gas-filled hollow-core fibers, and that it can strongly impair SRS even when the dephasing rate is high, particularly at high pump powers when it is normally assumed that nonlinear processes become more (not less) efficient. This counterintuitive result means that intermodal stimulated Raman scattering (for example between LP01 and LP11 core modes) begins to dominate at high power levels. The results reported have important implications for fiber-based Raman shifters, amplifiers or frequency combs, especially for operation in the ultraviolet, where the Raman gain is much higher.

Appetite and weight gain suppression effects of alcohol depend on the route and pattern of administration in Long Evans rats

Ethanol can be a food source but its effects on energy balance and contribution to obesity remain inconclusive. In this study, we hypothesized that the effects of ethanol on energy intake and body weight would depend on the administration dose, pattern and the blood ethanol concentration (BEC) time-course. Experiment 1 examined changes in food intake, diet preference, and body weight after saline or ethanol (1 and 3g/kg) injection (IP). Experiment 2 compared the effects in rats that received either 3g/kg/day ethanol administered all at once (EtOH_S) or 2 1.5g/kg injections spaced by 3h (EtOH_D). Experiment 3 examined the effects of 7.5h/day, Mon through Fri for 8weeks, voluntary ethanol drinking (5% and 10% ethanol) on food intake and body weight. Results of Experiments 1 and 2 indicate that acute ethanol administrations dose-dependently reduced energy intake, high fat diet preference and weight gain. Acute 3g/kg ethanol injection in the EtOH_S group decreased energy intake, weight gain and visceral fat to a greater extent than in the EtOH_D group. Results of Experiment 3 show that male and female rats voluntarily drank 1.65–2.31g/kg ethanol within 3.5h with reduced chow intake but unchanged total energy intake and weight gain. Furthermore, 3g/kg ethanol injection resulted in BEC that remained at intoxicating levels e.g. >120mg/dL for several hours post-administration and was higher in the EtOH_S than in the EtOH_D group. In contrast, BEC in voluntarily drinking was ~67mg/dL and decreased to below 10mg/dL 5h after termination of ethanol access. Taken together, these data suggest that 3g/kg ethanol injection robustly suppresses appetite and weight gain due to the higher BECs attained. Furthermore, BEC attained and maintained is a determining factor for how ethanol administration affects appetite and long-term energy balance.

Very Sensitive Low-Noise Active-Reset CMOS Image Sensor With In-Pixel ADC

Low light imaging is being researched intensively. The applications of increased sensitivity sensors expand to biomedicine, security, and communications providing low-cost and effective alternatives to common imaging techniques based on microscopes, intensifiers, etc. Lowering the inherent noise floor and achieving a higher sensitivity in a complementary metal-oxide semiconductor (CMOS) sensor are found at the focus of the scientific society, and new solutions emerge quickly. Methods such as output averaging, active reset, and active column sensing lower the noise floor but fail to provide the sensitivity boost, which requires a substantial signal amplification. The already proposed solutions, combining high gain and noise suppression, still fall short of the sensitivity that would enable detecting a few electrons. This brief proposes a very sensitive pixel that is designed to capture an ultralow illumination using three stage amplifiers' configuration, which allows for an effective reset operation and in-pixel analog-to-digital conversion. The provided measurement results prove the functionality of the proposed pixel architecture, indicating a remarkable sensitivity of 355 V/lx*s and a detection limit of 3 electrons, achieved consuming only 6 $\mu\text{W}$ per pixel.

Preventive Care for Children on Chronic Glucocorticoid Therapy Lacks Standardization

Chronic glucocorticoid therapy may be complicated by osteopenia, dyslipidemia, infections, weight gain, and adrenal suppression. Recommendations for screening and preventing these complications include screening for 25-hydroxyvitamin D, pneumococcal vaccine, lipid screening, influenza vaccination, and home prescription of intramuscular hydrocortisone for prevention of adrenal insufficiency. To assess adherence to these recommendations, researchers retrospectively assessed care received by 701 …

Superposition Violations in the Compensatory Eye Movement System.

Compensatory eye movements (CEM) maintain a stable image on the retina by minimizing retinal slip. The optokinetic reflex (OKR) and vestibulo-ocular reflex (VOR) compensate for low and high velocity stimuli, respectively. The OKR system is known to be highly nonlinear. The VOR is generally modeled as a linear system and assumed to satisfy the superposition and homogeneity principles. To probe CEM violation of the superposition principle, we recorded eye movement responses in C57BL/6 mice to sum of sine (SoS) stimulation, a combination of multiple nonharmonic inputs. We tested the VOR, OKR, VVOR (visually enhanced VOR), and SVOR (suppressed VOR). We used stimuli containing 0.6 Hz, 0.8 Hz, 1.0 Hz, and 1.9 Hz. Power spectra of SoS stimuli did not yield distortion products. Gains and delays of SoS and single sine (SS) responses were compared to yield relative gains and delays. We find the superposition principle is violated primarily in the OKR, VOR, and SVOR conditions. In OKR, we observed relative gain suppression of the lower SoS stimulus frequency component irrespective of the absolute frequency. Conversely, SVOR and VOR results showed gain enhancement of the lower frequency component and overall decrease in lead. Visually enhanced VOR results showed trends for overall gain suppression and delay decrease. Compensatory eye movements arguably depend on predictive signals. These results may reflect better prediction for SS stimuli. Natural CEM system stimulation generally involves complex frequency spectra. Use of SoS stimuli is a step toward unravelling the signals that really drive CEM and the predictive algorithms they depend on.

Resolving the mystery of milliwatt-threshold opto-mechanical self-oscillation in dual-nanoweb fiber

It is interesting to pose the question: How best to design an optomechanical device, with no electronics, optical cavity, or laser gain, that will self-oscillate when pumped in a single pass with only a few mW of single-frequency laser power? One might begin with a mechanically resonant and highly compliant system offering very high optomechanical gain. Such a system, when pumped by single-frequency light, might self-oscillate at its resonant frequency. It is well-known, however, that this will occur only if the group velocity dispersion of the light is high enough so that phonons causing pump-to-Stokes conversion are sufficiently dissimilar to those causing pump-to-anti-Stokes conversion. Recently it was reported that two light-guiding membranes 20 μm wide, ∼500 nm thick and spaced by ∼500 nm, suspended inside a glass fiber capillary, oscillated spontaneously at its mechanical resonant frequency (∼6 MHz) when pumped with only a few mW of single-frequency light. This was surprising, since perfect Raman gain suppression would be expected. In detailed measurements, using an interferometric side-probing technique capable of resolving nanoweb movements as small as 10 pm, we map out the vibrations along the fiber and show that stimulated intermodal scattering to a higher-order optical mode frustrates gain suppression, permitting the structure to self-oscillate. A detailed theoretical analysis confirms this picture. This novel mechanism makes possible the design of single-pass optomechanical oscillators that require only a few mW of optical power, no electronics nor any optical resonator. The design could also be implemented in silicon or any other suitable material.

Multimode modeling of digital modulation in nearly single-mode semiconductor lasers

We present multimode modeling of the digitalmodulation characteristics of nearly single-mode semiconductor lasers. The model takes into account the mechanisms of spectral suppression of modal gain; namely, symmetric and asymmetric gain suppressions. The digital modulation performance of the laser is quantitatively examined in terms of the turn-on jitter, on-off ratio and a Q-factor. We study the effect of the modulation parameters on the modulation characteristics of the laser. We also clarify the effect of the asymmetric gain suppression on the modulated signals of the oscillating modes. In addition, we examine the validity of modeling the digital modulation of the laser via a single-mode rate equation model. We show that the modulation characteristics improve with an increase in the bias and/or modulation current or with a decrease in the bit rate due to reduction in the bit-pattern effect. The asymmetric gain suppression does not affect the characteristics of the total laser signal, however it enhances the modulation of the nearest modes on the long-wavelength side of the gain spectrum.

10 Gbps Externally Modulated XGM Based Wavelength Conversion Using SOA

This paper proposes a method for All Optical Wavelength Conversion using semiconductor optical amplifier at 10Gbps. The system is demonstrated for Cross Gain Modulation (XGM) process of SOA, which is the simplest wavelength conversion technique that takes the advantage of non linear gain suppression mechanism in SOA. The system performances are analyzed using Q factor and Extinction Ratio of the eye diagram. The input pump power is varied from 2 dBm to 5 dBm; also the extinction ratio of Mach-Zehnder modulator is varied from 30 dBm to 60 dBm. Maximum Q Factor of 11.86dB is obtained for a maximum output signal power 23.94 dBm. Minimum Q Factor obtained is 7.58dB for a minimum output signal power 23.15 dBm. The extinction ratio falls from 18.56dB to 16.63dB as the input conditions are varied.

Dramatic Raman Gain Suppression in the Vicinity of the Zero Dispersion Point in a Gas-Filled Hollow-Core Photonic Crystal Fiber.

In 1964 Bloembergen and Shen predicted that Raman gain could be suppressed if the rates of phonon creation and annihilation (by inelastic scattering) exactly balance. This is only possible if the momentum required for each process is identical, i.e., phonon coherence waves created by pump-to-Stokes scattering are identical to those annihilated in pump-to-anti-Stokes scattering. In bulk gas cells, this can only be achieved over limited interaction lengths at an oblique angle to the pump axis. Here we report a simple system that provides dramatic Raman gain suppression over long collinear path lengths in hydrogen. It consists of a gas-filled hollow-core photonic crystal fiber whose zero dispersion point is pressure adjusted to lie close to the pump laser wavelength. At a certain precise pressure, stimulated generation of Stokes light in the fundamental mode is completely suppressed, allowing other much weaker phenomena such as spontaneous Raman scattering to be explored at high pump powers.

Small and dim target detection by background estimation

An effective method for small and dim moving target detection in complicated background is proposed. The proposed approach takes advantage of the Non-local means filter, and applies a novel weight calculation model based on circular mask to the original background estimation pattern. By associating similarity of grayscale distribution of the images with temporal information, the extended method estimates the complicated background precisely and extracts point target successfully. To compare existing target detection methods and the proposed one, signal-to-clutter ratio gain (SCRG) and background suppression factor (BSF) are employed for spatial performance comparison and receiver operating characteristics (ROC) is used for detection-performance comparison of the target trajectory. Experimental results demonstrate good performance of the proposed method for infrared images in complicated scene, especially for images with low signal-to-noise ratio.

Saccadic modulation of stimulus processing in primary visual cortex

Saccadic eye movements play a central role in primate vision. Yet, relatively little is known about their effects on the neural processing of visual inputs. Here we examine this question in primary visual cortex (V1) using receptive-field-based models, combined with an experimental design that leaves the retinal stimulus unaffected by saccades. This approach allows us to analyse V1 stimulus processing during saccades with unprecedented detail, revealing robust perisaccadic modulation. In particular, saccades produce biphasic firing rate changes that are composed of divisive gain suppression followed by an additive rate increase. Microsaccades produce similar, though smaller, modulations. We furthermore demonstrate that this modulation is likely inherited from the LGN, and is driven largely by extra-retinal signals. These results establish a foundation for integrating saccades into existing models of visual cortical stimulus processing, and highlight the importance of studying visual neuron function in the context of eye movements.