Ultra Compact Inline E-Plane Waveguide Bandpass Filters Using Cross Coupling

This paper presents novel ultra-compact waveguide bandpass filters that exhibit pseudo elliptic responses with ability to place transmission zeros on both sides of the passband to form sharp roll offs. The filters contain E plane extracted pole sections cascaded with cross-coupled filtering blocks. Compactness is achieved by the use of evanescent mode sections and closer arranged resonators modified to shrink in size. The filters containing non-resonating nodes are designed by means of the generalized coupling coefficients (GCC) extraction procedure for the cross-coupled filtering blocks and extracted pole sections. We illustrate the performance of the proposed structures through the design examples of a third and a fourth order filters with center frequencies of 9.2 GHz and 10 GHz respectively. The sizes of the proposed structures suitable for fabricating using the low cost E plane waveguide technology are 38% smaller than ones of the E plane extracted pole filter of the same order.

Highly linear reconfigurable UWB filters with independently controlled dual bandnotch

This letter proposes a high-linearity reconfigurable lower ultra-wideband (3.1–5.25 GHz) filter with independently controlled dual bandnotch at WiMAX 3.5 GHz band and satellite communication systems 4.2 GHz band. Reconfigurability has been achieved by the implementation of Graphene based switches (simulation only) and PIN diodes (measurements). The simulation and measurement results in OFF state show an entire bandpass response from 3.1 GHz to 5.25 GHz and with a very low insertion loss. In ON state, the results show that sharp rejections at 3.5 GHz and 4.2 GHz are achieved, with a low passband insertion loss. The two bandnotch operate independently of each other; thus allowing to control the behaviour of the required bandnotch. The third order intermodulation products were also measured in OFF and ON states and the linearity results have been presented. The filter is able to achieve a high performance with good linearity and no significant loss.

Design, analysis and evaluation of sigma-delta based beamformers for medical ultrasound imaging applications

The inherent analogue nature of medical ultrasound signals in conjunction with the abundant merits provided by digital image acquisition, together with the increasing use of relatively simple front-end circuitries, have created considerable demand for single-bit  beamformers in digital ultrasound imaging systems. Furthermore, the increasing need to design lightweight ultrasound systems with low power consumption and low noise, provide ample justification for development and innovation in the use of single-bit  beamformers in ultrasound imaging systems. The overall aim of this research program is to investigate, establish, develop and confirm through a combination of theoretical analysis and detailed simulations, that utilize raw phantom data sets, suitable techniques for the design of simple-to-implement hardware efficient  digital ultrasound beamformers to address the requirements for 3D scanners with large channel counts, as well as portable and lightweight ultrasound scanners for point-of-care applications and intravascular imaging systems. In addition, the stability boundaries of higher-order High-Pass (HP) and Band-Pass (BP) Σ−Δ modulators for single- and dual- sinusoidal inputs are determined using quasi-linear modeling together with the describing-function method, to more accurately model the  modulator quantizer. The theoretical results are shown to be in good agreement with the simulation results for a variety of input amplitudes, bandwidths, and modulator orders. The proposed mathematical models of the quantizer will immensely help speed up the design of higher order HP and BP Σ−Δ modulators to be applicable for digital ultrasound beamformers. Finally, a user friendly design and performance evaluation tool for LP, BP and HP  modulators is developed. This toolbox, which uses various design methodologies and covers an assortment of  modulators topologies, is intended to accelerate the design process and evaluation of  modulators. This design tool is further developed to enable the design, analysis and evaluation of  beamformer structures including the noise analyses of the final B-scan images. Thus, this tool will allow researchers and practitioners to design and verify different reconstruction filters and analyze the results directly on the B-scan ultrasound images thereby saving considerable time and effort.

Fabrication and Characterization of Efficient Optical Filter Arrays Implemented by 3D Nanoimprint

In dieser Arbeit werden optische Filterarrays für hochqualitative spektroskopische Anwendungen im sichtbaren (VIS) Wellenlängenbereich untersucht. Die optischen Filter, bestehend aus Fabry-Pérot (FP)-Filtern für hochauflösende miniaturisierte optische Nanospektrometer, basieren auf zwei hochreflektierenden dielektrischen Spiegeln und einer zwischenliegenden Resonanzkavität aus Polymer. Jeder Filter erlaubt einem schmalbandigem spektralen Band (in dieser Arbeit Filterlinie genannt) ,abhängig von der Höhe der Resonanzkavität, zu passieren. Die Effizienz eines solchen optischen Filters hängt von der präzisen Herstellung der hochselektiven multispektralen Filterfelder von FP-Filtern mittels kostengünstigen und hochdurchsatz Methoden ab. Die Herstellung der multiplen Spektralfilter über den gesamten sichtbaren Bereich wird durch einen einzelnen Prägeschritt durch die 3D Nanoimprint-Technologie mit sehr hoher vertikaler Auflösung auf einem Substrat erreicht. Der Schlüssel für diese Prozessintegration ist die Herstellung von 3D Nanoimprint-Stempeln mit den gewünschten Feldern von Filterkavitäten. Die spektrale Sensitivität von diesen effizienten optischen Filtern hängt von der Genauigkeit der vertikalen variierenden Kavitäten ab, die durch eine großflächige ‚weiche„ Nanoimprint-Technologie, UV oberflächenkonforme Imprint Lithographie (UV-SCIL), ab. Die Hauptprobleme von UV-basierten SCIL-Prozessen, wie eine nichtuniforme Restschichtdicke und Schrumpfung des Polymers ergeben Grenzen in der potenziellen Anwendung dieser Technologie. Es ist sehr wichtig, dass die Restschichtdicke gering und uniform ist, damit die kritischen Dimensionen des funktionellen 3D Musters während des Plasmaätzens zur Entfernung der Restschichtdicke kontrolliert werden kann. Im Fall des Nanospektrometers variieren die Kavitäten zwischen den benachbarten FP-Filtern vertikal sodass sich das Volumen von jedem einzelnen Filter verändert , was zu einer Höhenänderung der Restschichtdicke unter jedem Filter führt. Das volumetrische Schrumpfen, das durch den Polymerisationsprozess hervorgerufen wird, beeinträchtigt die Größe und Dimension der gestempelten Polymerkavitäten. Das Verhalten des großflächigen UV-SCIL Prozesses wird durch die Verwendung von einem Design mit ausgeglichenen Volumen verbessert und die Prozessbedingungen werden optimiert. Das Stempeldesign mit ausgeglichen Volumen verteilt 64 vertikal variierenden Filterkavitäten in Einheiten von 4 Kavitäten, die ein gemeinsames Durchschnittsvolumen haben. Durch die Benutzung der ausgeglichenen Volumen werden einheitliche Restschichtdicken (110 nm) über alle Filterhöhen erhalten. Die quantitative Analyse der Polymerschrumpfung wird in iii lateraler und vertikaler Richtung der FP-Filter untersucht. Das Schrumpfen in vertikaler Richtung hat den größten Einfluss auf die spektrale Antwort der Filter und wird durch die Änderung der Belichtungszeit von 12% auf 4% reduziert. FP Filter die mittels des Volumengemittelten Stempels und des optimierten Imprintprozesses hergestellt wurden, zeigen eine hohe Qualität der spektralen Antwort mit linearer Abhängigkeit zwischen den Kavitätshöhen und der spektralen Position der zugehörigen Filterlinien.

Specific Filters Applied in Nuclear Medicine Services

In Nuclear Medicine, radioiodine, in various chemical forms, is a key tracer used in diagnostic practices and/or therapy. Due to its high volatility, medical professionals may incorporate radioactive iodine during the preparation of the dose to be administered to the patient. In radioactive iodine therapy doses ranging from 3.7 to 7.4GBq per patient are employed. Thus, aiming at reducing the risk of occupational contamination, we developed a low cost filter to be installed at the exit of the exhaust system where doses of radioactive iodine are fractionated, using domestic technology. The effectiveness of radioactive iodine retention by silver impregnated silica [10%] crystals and natural activated carbon was verified using radiotracer techniques. The results showed that natural activated carbon is effective for I2 capture for a large or small amount of substrate but its use is restricted due to its low flash point (150º C). Besides, when poisoned by organic solvents, this flash point may become lower, causing explosions if absorbing large amounts of nitrates. To hold the CH3I gas, it was necessary to increase the volume of natural activated carbon since it was not absorbed by SiO2 + Ag crystals. We concluded that, for an exhaust flow range of (306 4) m3/h, a double stage filter using SiO2 + Ag in the first stage and natural activated carbon in the second is sufficient to meet radiological safety requirements.

Employment of the Technique of Radiotracers for Analysis of Industrial Filters

The main aim of this work is to develop a methodology to evaluate the characteristics of porous media in filter using the radio-tracing technique. To do this, an experimental prototype filter made up of an acrylic cylinder, vertically mounted and supported on the lower side by a controlled leaking valve was developed. Two filters (spheres of acrylic and silica crystals) were used to check the movement of the water through the porous media using 123I in its MIBG (iodine-123-meta-iodo benzyl-guanidine) form. Further up the filter an instantaneous injection of the substance makes it possible to see the passage of radioactive clouds through the two scintillatory detectors NaI (2x2)” positioned before and immediately after the cylinder with the filtering element (porous media). The are caused by the detectors on the passage of the radioactive cloud are analyzed through statistical functions using the weighted moment method which makes it possible to calculate the Residence-Time (the amount of time the tracer takes to thoroughly pass through the filter) per the equation of dispersion in tubular flow and the one-directional flow of the radiotracer in the porous media.

Intermittent Fasting Induces Hypothalamic Modifications Resulting In Low Feeding Efficiency, Low Body Mass And Overeating.

Intermittent fasting (IF) is an often-used intervention to decrease body mass. In male Sprague-Dawley rats, 24 hour cycles of IF result in light caloric restriction, reduced body mass gain, and significant decreases in the efficiency of energy conversion. Here, we study the metabolic effects of IF in order to uncover mechanisms involved in this lower energy conversion efficiency. After 3 weeks, IF animals displayed overeating during fed periods and lower body mass, accompanied by alterations in energy-related tissue mass. The lower efficiency of energy use was not due to uncoupling of muscle mitochondria. Enhanced lipid oxidation was observed during fasting days, whereas fed days were accompanied by higher metabolic rates. Furthermore, an increased expression of orexigenic neurotransmitters AGRP and NPY in the hypothalamus of IF animals was found, even on feeding days, which could explain the overeating pattern. Together, these effects provide a mechanistic explanation for the lower efficiency of energy conversion observed. Overall, we find that IF promotes changes in hypothalamic function that explain differences in body mass and caloric intake.

Low-density Lipoprotein Cholesterol And Radiotherapy-induced Carotid Atherosclerosis In Subjects With Head And Neck Cancer.

Radiotherapy (RT) is a risk factor for accelerated carotid artery atherosclerotic disease in subjects with head and neck cancer. However, the risk factors of RT-induced carotid artery remodeling are not established. This study aimed to investigate the effects of RT on carotid and popliteal arteries in subjects with head and neck cancer and to evaluate the relationship between baseline clinical and laboratory features and the progression of RT-induced atherosclerosis. Eleven men (age = 57.9 ± 6.2years) with head and neck cancer who underwent cervical bilateral irradiation were prospectively examined by clinical and laboratory analysis and by carotid and popliteal ultrasound before and after treatment (mean interval between the end of RT and the post-RT assessment = 181 ± 47 days). No studied subject used hypocholesterolemic medications. Significant increases in carotid intima-media thickness (IMT) (0.95 ± 0.08 vs. 0.87 ± 0.05 mm; p < 0.0001) and carotid IMT/diameter ratio (0.138 ± 0.013 vs. 0.129 ± 0.014; p = 0.001) were observed after RT, while no changes in popliteal structural features were detected. In addition, baseline low-density lipoprotein cholesterol levels showed a direct correlation with RT-induced carotid IMT change (r = 0.66; p = 0.027), while no other studied variable exhibited a significant relationship with carotid IMT change. These results indicate that RT-induced atherosclerosis is limited to the irradiated area and also suggest that it may be predicted by low-density lipoprotein cholesterol levels in subjects with head and neck cancer.

Effects Of Therapeutic Approach On The Neonatal Evolution Of Very Low Birth Weight Infants With Patent Ductus Arteriosus.

To analyze the effects of treatment approach on the outcomes of newborns (birth weight [BW] < 1,000 g) with patent ductus arteriosus (PDA), from the Brazilian Neonatal Research Network (BNRN) on: death, bronchopulmonary dysplasia (BPD), severe intraventricular hemorrhage (IVH III/IV), retinopathy of prematurity requiring surgical (ROPsur), necrotizing enterocolitis requiring surgery (NECsur), and death/BPD. This was a multicentric, cohort study, retrospective data collection, including newborns (BW < 1000 g) with gestational age (GA) < 33 weeks and echocardiographic diagnosis of PDA, from 16 neonatal units of the BNRN from January 1, 2010 to Dec 31, 2011. Newborns who died or were transferred until the third day of life, and those with presence of congenital malformation or infection were excluded. Groups: G1 - conservative approach (without treatment), G2 - pharmacologic (indomethacin or ibuprofen), G3 - surgical ligation (independent of previous treatment). Factors analyzed: antenatal corticosteroid, cesarean section, BW, GA, 5 min. Apgar score < 4, male gender, Score for Neonatal Acute Physiology Perinatal Extension (SNAPPE II), respiratory distress syndrome (RDS), late sepsis (LS), mechanical ventilation (MV), surfactant (< 2 h of life), and time of MV. death, O2 dependence at 36 weeks (BPD36wks), IVH III/IV, ROPsur, NECsur, and death/BPD36wks. Student's t-test, chi-squared test, or Fisher's exact test; Odds ratio (95% CI); logistic binary regression and backward stepwise multiple regression. Software: MedCalc (Medical Calculator) software, version 12.1.4.0. p-values < 0.05 were considered statistically significant. 1,097 newborns were selected and 494 newborns were included: G1 - 187 (37.8%), G2 - 205 (41.5%), and G3 - 102 (20.6%). The highest mortality was observed in G1 (51.3%) and the lowest in G3 (14.7%). The highest frequencies of BPD36wks (70.6%) and ROPsur were observed in G3 (23.5%). The lowest occurrence of death/BPD36wks occurred in G2 (58.0%). Pharmacological (OR 0.29; 95% CI: 0.14-0.62) and conservative (OR 0.34; 95% CI: 0.14-0.79) treatments were protective for the outcome death/BPD36wks. The conservative approach of PDA was associated to high mortality, the surgical approach to the occurrence of BPD36wks and ROPsur, and the pharmacological treatment was protective for the outcome death/BPD36wks.

Low-density Three-dimensional Foam Using Self-reinforced Hybrid Two-dimensional Atomic Layers.

Low-density nanostructured foams are often limited in applications due to their low mechanical and thermal stabilities. Here we report an approach of building the structural units of three-dimensional (3D) foams using hybrid two-dimensional (2D) atomic layers made of stacked graphene oxide layers reinforced with conformal hexagonal boron nitride (h-BN) platelets. The ultra-low density (1/400 times density of graphite) 3D porous structures are scalably synthesized using solution processing method. A layered 3D foam structure forms due to presence of h-BN and significant improvements in the mechanical properties are observed for the hybrid foam structures, over a range of temperatures, compared with pristine graphene oxide or reduced graphene oxide foams. It is found that domains of h-BN layers on the graphene oxide framework help to reinforce the 2D structural units, providing the observed improvement in mechanical integrity of the 3D foam structure.

Optical And Nonoptical Aids For Reading And Writing In Individuals With Acquired Low Vision.

To evaluate the use of optical and nonoptical aids during reading and writing activities in individuals with acquired low vision. This study was performed using descriptive and cross-sectional surveys. The data collection instrument was created with structured questions that were developed from an exploratory study and a previous test based on interviews, and it evaluated the following variables: personal characteristics, use of optical and nonoptical aids, and activities that required the use of optical and nonoptical aids. The study population included 30 subjects with acquired low vision and visual acuities of 20/200-20/400. Most subjects reported the use of some optical aids (60.0%). Of these 60.0%, the majority (83.3%) cited spectacles as the most widely used optical aid. The majority (63.3%) of subjects also reported the use of nonoptical aids, the most frequent ones being letter magnification (68.4%), followed by bringing the objects closer to the eyes (57.8%). Subjects often used more than one nonoptical aid. The majority of participants reported the use of optical and nonoptical aids during reading activities, highlighting the use of spectacles, magnifying glasses, and letter magnification; however, even after the use of these aids, we found that the subjects often needed to read the text more than once to understand it. During writing activities, all subjects reported the use of optical aids, while most stated that they did not use nonoptical aids for such activities.

The Effect Of Soy Dietary Supplement And Low Dose Of Hormone Therapy On Main Cardiovascular Health Biomarkers: A Randomized Controlled Trial.

To assess the effects of a soy dietary supplement on the main biomarkers of cardiovascular health in postmenopausal women compared with the effects of low-dose hormone therapy (HT) and placebo. Double-blind, randomized and controlled intention-to-treat trial. Sixty healthy postmenopausal women, aged 40-60 years, 4.1 years mean time since menopause were recruited and randomly assigned to 3 groups: a soy dietary supplement group (isoflavone 90mg), a low-dose HT group (estradiol 1 mg plus noretisterone 0.5 mg) and a placebo group. Lipid profile, glucose level, body mass index, blood pressure and abdominal/hip ratio were evaluated in all the participants at baseline and after 16 weeks. Statistical analyses were performed using the χ2 test, Fisher's exact test, Kruskal-Wallis non-parametric test, analysis of variance (ANOVA), paired Student's t-test and Wilcoxon test. After a 16-week intervention period, total cholesterol decreased 11.3% and LDL-cholesterol decreased 18.6% in the HT group, but both did not change in the soy dietary supplement and placebo groups. Values for triglycerides, HDL-cholesterol, glucose level, body mass index, blood pressure and abdominal/hip ratio did not change over time in any of the three groups. The use of dietary soy supplement did not show any significant favorable effect on cardiovascular health biomarkers compared with HT. The trial is registered at the Brazilian Clinical Trials Registry (Registro Brasileiro de Ensaios Clínicos - ReBEC), number RBR-76mm75.

Low Hdl Cholesterol But Not High Ldl Cholesterol Is Independently Associated With Subclinical Coronary Atherosclerosis In Healthy Octogenarians.

Although low-density lipoprotein cholesterol (LDL-C) has been consistently demonstrated a predictor of atherosclerotic disease in a large spectrum of clinical settings, among individuals aged of 80 years or older this concept is uncertain. This study was evaluated in a carefully selected population if the association between LDL-C and coronary atherosclerotic burden remains significant in the very elderly. Individuals aged of 80 years or older (n = 208) who spontaneously sought primary prevention care and have never manifested cardiovascular disease, malnutrition, neoplastic or consumptive disease were enrolled for a cross-sectional analysis. Medical evaluation, anthropometric measurements, blood tests and cardiac computed tomography were obtained. In analyses adjusted for age, gender, diabetes, systolic and diastolic blood pressure, smoking and statin therapy, no association was found between coronary calcium score (CCS) and LDL-C [1.79 (0.75-4.29)]. There was no association between triglycerides and CCS. The association between high-density lipoprotein cholesterol (HDL-C) and CCS was significant and robust in unadjusted [0.32 (0.15-0.67)] as well as in the fully adjusted analysis [0.34 (0.15-0.75)]. The present study confirms in a healthy cohort of individuals aged of 80 years or more that while the association between LDL-C and coronary atherosclerosis weakens with aging, the opposite occurs with the levels of HDL-C.

Low Bone Mass In Human Immunodeficiency Virus-infected Climacteric Women Receiving Antiretroviral Therapy: Prevalence And Associated Factors.

Low bone mineral density (BMD) has been found in human immunodeficiency virus (HIV)-infected patients; however, data on associated factors remain unclear, specifically in middle-aged women. This study aims to evaluate factors associated with low BMD in HIV-positive women. In this cross-sectional study, a questionnaire was administered to 206 HIV-positive women aged 40 to 60 years who were receiving outpatient care. Clinical features, laboratory test results, and BMD were assessed. Yates and Pearson χ(2) tests and Poisson multiple regression analysis were performed. The median age of women was 47.7 years; 75% had nadir CD4 T-cell counts higher than 200, and 77.8% had viral loads below the detection limit. There was no association between low BMD at the proximal femur and lumbar spine (L1-L4) and risk factors associated with HIV infection and highly active antiretroviral therapy. Poisson multiple regression analysis showed that the only factor associated with low BMD at the proximal femur and lumbar spine was postmenopause status. Low BMD is present in more than one third of this population sample, in which most women are using highly active antiretroviral therapy and have a well-controlled disease. The main associated factor is related to estrogen deprivation. The present data support periodic BMD assessments in HIV-infected patients and highlight the need to implement comprehensive menopausal care for these women to prevent bone loss.

Effect Of Low-level Laser Therapy (lllt) On Peripheral Nerve Regeneration Using Fibrin Glue Derived From Snake Venom.

The purpose of this study was to assess whether the adhesive permits the collateral repair of axons originating from a vagus nerve to the interior of a sural nerve graft, and whether low-level laser therapy (LLLT) assists in the regeneration process. Study sample consisted of 32 rats randomly separated into three groups: Control Group (CG; n=8), from which the intact sural nerve was collected; Experimental Group (EG; n=12), in which one of the ends of the sural nerve graft was coapted to the vagus nerve using the fibrin glue; and Experimental Group Laser (EGL; n=12), in which the animals underwent the same procedures as those in EG with the addition of LLLT. Ten weeks after surgery, the animals were euthanized. Morphological analysis by means of optical and electron microscopy, and morphometry of the regenerated fibers were employed to evaluate the results. Collateral regeneration of axons was observed from the vagus nerve to the interior of the autologous graft in EG and EGL, and in CG all dimensions measured were greater and presented a significant difference in relation to EG and EGL, except for the area and thickness of the myelin sheath, that showed significant difference only in relation to the EG. The present study demonstrated that the fibrin glue makes axonal regeneration feasible and is an efficient method to recover injured peripheral nerves, and the use of low-level laser therapy enhances nerve regeneration.