A 5GHz1.8V Low Power CMOS Low-Noise Amplifier

Wireless local-area networks (WLANs) have been deployed as office and home communications infrastructures worldwide. The diversification of the standards, such as IEEE 802.11 series demands the design of RF front-ends. Low power consumption is one of the most important design concerns in the application of those technologies. To maintain competitive hardware costs, CMOS has been used since it is the best solution for low cost and high integration processing, allowing analog circuits to be mixed with digital ones. In the receiver chain, the low noise amplifier (LNA) is one of the most critical blocks in a transceiver design. The sensitivity is mainly determined by the LNA noise figure and gain. It interfaces with the pre-select filter and the mixer. Furthermore, since it is the first gain stage, care must be taken to provide accurate input match, low-noise figure, good linearity and a sufficient gain over a wide band of operation. Several CMOS LNAs have been reported during the last decade, showing that the most research has been done at 802.11/b and GSM standards (900-2400MHz spectrum) and more recently at 802.11/a (5GHz band). One of the more significant disadvantages of 802.11/b is that the frequency band is crowded and subject to interference from other technologies, as is 2.4GHz cordless phones and Bluetooth. As the demand for radio-frequency integrated circuits, operating at higher frequency bands, increases, the IEEE 802.11/a standard becomes a very attractive option to wireless communication system developers. This paper presents the design and implementation of a low power, low noise amplifier aimed at IEEE 802.11a for WLAN applications. It was designed to be integrated with an active balun and mixer, representing the first step toward a fully integrated monolithic WLAN receiver. All the required circuits are integrated at the same die and are powered by 1.8V supply source. Preliminary experimental results (S-parameters) are shown and promise excellent results. The LNA circuit design details are illustrated in Section 2. Spectre simulation results focused at gain, noise figure (NF) and input/output matching are presented in Section 3. Finally, conclusions and comparison with other recently reported LNAs are made in Section 4, followed by future work.

Design and performance of a novel low-density parity-check code for distributed video coding

Low-density parity-check (LDPC) codes are nowadays one of the hottest topics in coding theory, notably due to their advantages in terms of bit error rate performance and low complexity. In order to exploit the potential of the Wyner-Ziv coding paradigm, practical distributed video coding (DVC) schemes should use powerful error correcting codes with near-capacity performance. In this paper, new ways to design LDPC codes for the DVC paradigm are proposed and studied. The new LDPC solutions rely on merging parity-check nodes, which corresponds to reduce the number of rows in the parity-check matrix. This allows to change gracefully the compression ratio of the source (DCT coefficient bitplane) according to the correlation between the original and the side information. The proposed LDPC codes reach a good performance for a wide range of source correlations and achieve a better RD performance when compared to the popular turbo codes.

Cyclotech - contribution to solve the Technetium shortage by using low energy medical cyclotrons

This paper presents work in progress, to develop an efficient and economic way to directly produce Technetium 99metastable (99mTc) using low-energy cyclotrons. Its importance is well established and relates with the increased global trouble in delivering 99mTc to Nuclear Medicine Departments relying on this radioisotope. Since the present delivery strategy has clearly demonstrated its intrinsic limits, our group decided to follow a distinct approach that uses the broad distribution of the low energy cyclotrons and the accessibility of Molybdenum 100 (100Mo) as the Target material. This is indeed an important issue to consider, since the system here presented, named CYCLOTECH, it is not based on the use of Highly Enriched (or even Low Enriched) Uranium 235 (235U), so entirely complying with the actual international trends and directives concerning the use of this potential highly critical material. The production technique is based on the nuclear reaction 100Mo (p,2n) 99mTc whose production yields have already been documented. Until this moment two Patent requests have already been submitted (the first at the INPI, in Portugal, and the second at the USPTO, in the USA); others are being prepared for submission on a near future. The object of the CYCLOTECH system is to present 99mTc to Nuclear Medicine radiopharmacists in a routine, reliable and efficient manner that, remaining always flexible, entirely blends with established protocols. To facilitate workflow and Radiation Protection measures, it has been developed a Target Station that can be installed on most of the existing PET cyclotrons and that will tolerate up to 400 μA of beam by allowing the beam to strike the Target material at an adequately oblique angle. The Target Station permits the remote and automatic loading and discharge of the Targets from a carriage of 10 Target bodies. On other hand, several methods of Target material deposition and Target substrates are presented. The object was to create a cost effective means of depositing and intermediate the target material thickness (25 - 100μm) with a minimum of loss on a substrate that is able to easily transport the heat associated with high beam currents. Finally, the separation techniques presented are a combination of both physical and column chemistry. The object was to extract and deliver 99mTc in the identical form now in use in radiopharmacies worldwide. In addition, the Target material is recovered and can be recycled.

Interactions between physical and psychosocial demands of work associated to low back pain

OBJECTIVE: To examine the interaction between physical and psychosocial demands of work associated to low back pain. METHODS: Cross-sectional study carried out in a stratified proportional random sample of 577 plastic industry workers in the metropolitan area of the city of Salvador, Northeast Brazil in 2002. An anonymous standard questionnaire was administered in the workplace by trained interviewers. Physical demands at work were self-rated on a 6-point numeric scale, with anchors at each end of the scale. Factor analysis was carried out on 11 physical demand variables to identify underlying factors. Psychosocial work demands were measured by demand, control and social support questions. Multivariate analysis was performed using the likelihood ratio test. RESULTS: The factor analysis identified two physical work demand factors: material handling (factor 1) and repetitiveness (factor 2). The multiple logistic regression analysis showed that factor 1 was positively associated with low back pain (OR=2.35, 95% CI 1.50;3.66). No interaction was found between physical and psychosocial work demands but both were independently associated to low back pain. CONCLUSIONS: The study found independent effects of physical and psychosocial work demands on low back pain prevalence and emphasizes the importance of physical demands especially of material handling involving trunk bending forward and trunk rotation regardless of age, gender, and body fitness.

Socioeconomic inequities in the health and nutrition of children in low/middle income countries

OBJECTIVE: To describe the effects of social inequities on the health and nutrition of children in low and middle income countries. METHODS: We reviewed existing data on socioeconomic disparities within-countries relative to the use of services, nutritional status, morbidity, and mortality. A conceptual framework including five major hierarchical categories affecting inequities was adopted: socioeconomic context and position, differential exposure, differential vulnerability, differential health outcomes, and differential consequences. The search of the PubMed database since 1990 identified 244 articles related to the theme. Results were also analyzed from almost 100 recent national surveys, including Demographic Health Surveys and the UNICEF Multiple Indicator Cluster Surveys. RESULTS: Children from poor families are more likely, relative to those from better-off families, to be exposed to pathogenic agents; once they are exposed, they are more likely to become ill because of their lower resistance and lower coverage with preventive interventions. Once they become ill, they are less likely to have access to health services and the quality of these services is likely to be lower, with less access to life-saving treatments. As a consequence, children from poor family have higher mortality rates and are more likely to be undernourished. CONCLUSIONS: Except for child obesity and inadequate breastfeeding practices, all the other adverse conditions analyzed were more prevalent in children from less well-off families. Careful documentation of the multiple levels of determination of socioeconomic inequities in child health is essential for understanding the nature of this problem and for establishing interventions that can reduce these differences.

Risk factors for osteoporotic fractures and low bone density in pre and postmenopausal women

OBJECTIVE: To estimate the prevalence and analyze risk factors associated to osteoporosis and low-trauma fracture in women. METHODS: Cross-sectional study including a total of 4,332 women older than 40 attending primary care services in the Greater São Paulo, Southeastern Brazil, between 2004 and 2007. Anthropometrical and gynecological data and information about lifestyle habits, previous fracture, medical history, food intake and physical activity were obtained through individual quantitative interviews. Low-trauma fracture was defined as that resulting from a fall from standing height or less in individuals 50 years or older. Multiple logistic regression models were designed having osteoporotic fracture and bone mineral density (BMD) as the dependent variables and all other parameters as the independent ones. The significance level was set at p<0.05. RESULTS: The prevalence of osteoporosis and osteoporotic fractures was 33% and 11.5%, respectively. The main risk factors associated with low bone mass were age (OR=1.07; 95% CI: 1.06;1.08), time since menopause (OR=2.16; 95% CI: 1.49;3.14), previous fracture (OR=2.62; 95% CI: 2.08;3.29) and current smoking (OR=1.45; 95% CI: 1.13;1.85). BMI (OR=0.88; 95% CI: 0.86;0.89), regular physical activity (OR=0.78; 95% CI: 0.65;0.94) and hormone replacement therapy (OR=0.43; 95% CI: 0.33;0.56) had a protective effect on bone mass. Risk factors significantly associated with osteoporotic fractures were age (OR=1.05; 95% CI: 1.04;1.06), time since menopause (OR=4.12; 95% CI: 1.79;9.48), familial history of hip fracture (OR=3.59; 95% CI: 2.88;4.47) and low BMD (OR=2.28; 95% CI: 1.85;2.82). CONCLUSIONS: Advanced age, menopause, low-trauma fracture and current smoking are major risk factors associated with low BMD and osteoporotic fracture. The clinical use of these parameters to identify women at higher risk for fractures might be a reasonable strategy to improve the management of osteoporosis.

The epidemiologic paradox of low birth weight in Brazil

OBJECTIVE: To examine whether the low birth weight (LBW) paradox exists in Brazil. METHODS: LBW and cesarean section rates between 1995 and 2007 were estimated based on data from SINASC (Brazilian Live Births Database). Infant mortality rates (IMRs) were obtained using an indirect method that correct for underreporting. Schooling information was obtained from census data. Trends in LBW rate were assessed using joinpoint regression models. The correlations between LBW rate and other indicators were graphically assessed by lowess regression and tested using Spearman's rank correlation. RESULTS: In Brazil, LBW rate trends were non-linear and non-significant: the rate dropped from 7.9% in 1995 to 7.7% in 2000, then increased to 8.2% in 2003 and remained nearly steady thereafter at 8.2% in 2007. However, trends varied among Brazilian regions: there were significant increases in the North from 1999 to 2003 (2.7% per year), and in the South (1.0% per year) and Central-West regions (0.6% per year) from 1995 to 2007. For the entire period studied, higher LBW and lower IMRs were seen in more developed compared to less developed regions. In Brazilian States, in 2005, the higher the IMR rate, the lower the LBW rate (p=0.009); the lower the low schooling rate, the lower the LBW rate (p=0.007); the higher the number of neonatal intensive care beds per 1,000 live births, the higher the LBW rate (p=0.036). CONCLUSIONS: The low birth weight paradox was seen in Brazil. LBW rate is increasing in some Brazilian regions. Regional differences in LBW rate seem to be more associated to availability of perinatal care services than underlying social conditions.

Housing conditions as a social determinant of low birthweight and preterm low birthweight

OBJECTIVE: To assess the relationship between housing conditions and low birthweight and preterm low birthweight among low-income women. METHODS: A case-control study was conducted with post-partum women living in the city of Rio de Janeiro, Southeast Brazil, in 2003-2005. Two groups of cases, low birthweight (n=96) and preterm low birthweight infants (n=68), were compared against normal weight term controls (n=393). Housing conditions were categorized into three levels: adequate, inadequate, and highly inadequate. Covariates included sociodemographic and anthropometric characteristics, risk behaviors, violence, anxiety, satisfaction during pregnancy, obstetric history and prenatal care. RESULTS: Poor housing conditions was independently associated with low birthweight (inadequate - OR 2.3 [1.1;4.6]; highly inadequate - OR 7.6 [2.1;27.6]) and preterm low birthweight (inadequate - OR 2.2 [1.1;4.3]; highly inadequate - OR 7.6 [2.4;23.9]) and factors associated with outcomes were inadequate prenatal care and previous preterm birth. Low income and low maternal body mass index remained associated with low birthweight. CONCLUSIONS: Poor housing conditions were associated with low birthweight and preterm low birthweight.

How many low birthweight babies in low- and middle-income countries are preterm?

OBJECTIVE: To assess the prevalence of preterm birth among low birthweight babies in low and middle-income countries. METHODS: Major databases (PubMed, LILACS, Google Scholar) were searched for studies on the prevalence of term and preterm LBW babies with field work carried out after 1990 in low- and middle-income countries. Regression methods were used to model this proportion according to LBW prevalence levels. RESULTS: According to 47 studies from 27 low- and middle-income countries, approximately half of all LBW babies are preterm rather than one in three as assumed in studies previous to the 1990s. CONCLUSIONS: The estimate of a substantially higher number of LBW preterm babies has important policy implications in view of special health care needs of these infants. As for earlier projections, our findings are limited by the relative lack of population-based studies.

The predominance of M2-polarized macrophages in the stroma of low-hypoxic bladder tumors is associated with BCG immunotherapy failure

OBJECTIVE: Bacillus Calmette-Guérin (BCG) immunotherapy is the gold standard treatment for superficial bladder tumors with intermediate/high risk of recurrence or progression. However, approximately 30% of patients fail to respond to the treatment. Effective BCG therapy needs precise activation of the type 1 helper cells immune pathway. Tumor-associated macrophages (TAMs) often assume an immunoregulatory M2 phenotype and may directly interfere with the BCG-induced antitumor immune response. Thus, we aim to clarify the influence of TAMs, in particular of the M2 phenotype in stroma and tumor areas, in BCG treatment outcome. PATIENTS AND METHODS: The study included 99 patients with bladder cancer treated with BCG. Tumors resected before treatment were evaluated using immunohistochemistry for CD68 and CD163 antigens, which identify a lineage macrophage marker and a M2-polarized specific cell surface receptor, respectively. CD68+ and CD163+ macrophages were evaluated within the stroma and tumor areas, and high density of infiltrating cells spots were selected for counting. Hypoxia, an event known to modulate macrophage phenotype, was also assessed through hypoxia induced factor (HIF)-1α expression. RESULTS: Patients in whom BCG failed had high stroma-predominant CD163+ macrophage counts (high stroma but low tumor CD163+ macrophages counts) when compared with the ones with a successful treatment (71% vs. 47%, P = 0.017). Furthermore, patients presenting this phenotype showed decreased recurrence-free survival (log rank, P = 0.008) and a clear 2-fold increased risk of BCG treatment failure was observed in univariate analysis (hazard ratio = 2.343; 95% CI: 1.197-4.587; P = 0.013). Even when adjusted for potential confounders, such as age and therapeutic scheme, multivariate analysis revealed 2.6-fold increased risk of recurrence (hazard ratio = 2.627; 95% CI: 1.340-5.150; P = 0.005). High stroma-predominant CD163+ macrophage counts were also associated with low expression of HIF-1α in tumor areas, whereas high counts of CD163+ in the tumor presented high expression of HIF-1α in tumor nests. CONCLUSIONS: TAMs evaluation using CD163 is a good indicator of BCG treatment failure. Moreover, elevated infiltration of CD163+ macrophages, predominantly in stroma areas but not in the tumor, may be a useful indicator of BCG treatment outcome, possibly owing to its immunosuppressive phenotype.

Efficacy of low-level laser therapy on scar tissue

Background: Physiotherapy has a very important role in the maintenance of the integumentary system integrity. There is very few evidence in humans. Nevertheless, there are some studies about tissue regeneration using low-level laser therapy (LLLT). Aim: To analyze the effectiveness of LLLT on scar tissue. Methods: Seventeen volunteers were stratified by age of their scars, and then randomly assigned to an experimental group (EG) — n = 9 – and a placebo group (PG) – n = 8. Fifteen sessions were conducted to both the groups thrice a week. However, in the PG, the laser device was switched off. Scars’ thickness, length, width, macroscopic aspect, pain threshold, pain perception, and itching were measured. Results: After 5 weeks, there were no statistically significant differences in any variable between both the groups. However, analyzing independently each group, EG showed a significant improvement in macroscopic aspect (p = 0.003) using LLLT. Taking into account the scars’ age, LLLT showed a tendency to decrease older scars’ thickness in EG. Conclusion: The intervention with LLLT appears to have a positive effect on the macroscopic scars’ appearance, and on old scars’ thickness, in the studied sample. However, it cannot be said for sure that LLLT has influence on scar tissue.

Is adolescent pregnancy a risk factor for low birth weight?

OBJECTIVE: The objective of this study was to evaluate whether adolescent pregnancy is a risk factor for low birth weight (LBW) babies. METHODS: This was a cross-sectional study of mothers and their newborns from a birth cohort in Aracaju, Northeastern Brazil. Data were collected consecutively from March to July 2005. Information collected included socioeconomic, biological and reproductive aspects of the mothers, using a standardized questionnaire. The impact of early pregnancy on birth weight was evaluated by multiple logistic regression. RESULTS: We studied 4,746 pairs of mothers and their babies. Of these, 20.6% were adolescents (< 20 years of age). Adolescent mothers had worse socioeconomic and reproductive conditions and perinatal outcomes when compared to other age groups. Having no prenatal care and smoking during pregnancy were the risk factors associated with low birth weight. Adolescent pregnancy, when linked to marital status "without partner", was associated with an increased proportion of low birth weight babies. CONCLUSIONS: Adolescence was a risk factor for LBW only for mothers without partners. Smoking during pregnancy and lack of prenatal care were considered to be independent risk factors for LBW.