Robust Low-Sidelobe Transmit Beamforming under Peak-to-Average-Power Ratio Constraint.

Transmit beamforming (TBF) provides the capability of focusing illuminating power in the desired directions while reducing the emitting power in undesired directions. It is significantly important in low-altitude and slow-speed small (LSS) radar, which usually suffers from heavy clutter and rapidly changing interference on the near-ground side. Due to nonideal factors such as an inaccurate target direction and array gain-phase error, the robustness of TBF is also necessary to consider in practical applications. In this paper, we provide a robust TBF method that enables sidelobe control in preset regions and possesses high transmit efficiency in virtue of the peak-to-average-power ratio (PAPR) constraint on transmit weights. To achieve robustness, a norm upper bound is introduced to limit the fluctuation of transmit weights, and the steering vector mismatch is also considered by using a spherical uncertainty set surrounding the nominal steering vector. As the proposed robust TBF is nonconvex because of the nonconvexity of both the objective function and constraints, we translate it into a series of convex subproblems via several kinds of convex relaxation schemes. In particular, based on the special structure of the objective function and constraints, the translation of the nonconvex problem into a tractable SOCP problem is realized by using the combination of the triangle inequality and Cauchy-Schwartz inequality. Numerical results demonstrate the improvement in the efficiency and robustness of the proposed TBF method in comparison with traditional TBF methods.

Microbiome characteristics and Bifidobacterium longum in colorectal cancer patients pre- and post-chemotherapy.

BACKGROUND: With the development of next generation sequencing technology, a lot of research has focused on the role of human microbiome in regulating immunity. The present study evaluated microbiome changes of colorectal cancer patients who received XELOX regimen (capecitabine plus oxaliplatin) without requiring antimicrobials. METHODS: Stool samples from 7 patients (3 females/4 males) after screening of 11 patients before and after XELOX chemotherapy were subjected to 16S ribosomal RNA (rRNA) sequencing and flora dynamics compared at baseline and after 8 weeks of chemotherapy. Enrolled patients were newly diagnosed with stage IV colorectal cancer and had not received antimicrobial therapy or surgery. XELOX was administered for 2 cycles or 2-weekly treatments for 3 cycles. RESULTS: The patterns of relative abundance of all bacteria isolated from stool samples before or after chemotherapy treatment appeared to be different, but there were no significant differences in the Kyoto Encyclopedia of Genes and Genomes (KEGG) metabolism pathway between the two groups. The top five pathways in patients were the two-component system, phenylalanine metabolism, degradation of aromatic compounds, beta-lactam resistance and folate biosynthesis. More than 99.6% intestinal flora isolates were bacteria, <0.4% were viruses and Archaea. The relative abundances of the 5 most common bacterial phyla in fecal samples before chemotherapy were Bacteroides, Firmicutes, Proteobacteria, Actinobacteria and Verrucomicrobia. The abundance of Actinomycetes in stools after chemotherapy was increased to 2.5 fold higher than before chemotherapy. Bifidobacterium longum species were significantly elevated in stools after chemotherapy (P<0.05), and changes of relative abundance of Bifidobacterium longum species after chemotherapy from baseline in favorable outcome population (stable disease) was significant higher than them in unfavorable outcome population (progressive disease, PD) (P=0.023). CONCLUSIONS: The results indicated that Actinomyces in the gut might have a positive clinical outcome for colorectal cancer patients. This idea needs further studies to examine the actions of Actinomyces on inhibition of tumor growth.

Elevated Serum Brain-Derived Neurotrophic Factor (BDNF) but not BDNF Gene Val66Met Polymorphism Is Associated with Autism Spectrum Disorders.

The aim of our study was to illuminate the potential role of brain-derived neurotrophic factor (BDNF) in autism spectrum disorder (ASD). We measured the circulating levels of BDNF in serum and BDNF gene (Val66Met) polymorphisms, in which two indicators were then compared between ASD and normal controls. A total of 82 drug-naïve ASD children and 82 age- and gender-matched normal controls were enrolled in the study. Their serum BDNF levels were detected by the ELISA. BDNF Val66Met polymorphism genotyping was conducted as according to the laboratory's standard protocol in laboratory. The ASD severity assessment was mainly determined by the score of the Childhood Autism Rating Scale (CARS). ELISA assay showed that the mean serum BDNF level of children with ASD was significantly (P < 0.0001) higher than that of the control cases (17.75 ± 5.43 vs. 11.49 ± 2.85 ng/ml; t = 9.236). Besides, the serum BDNF levels and CARS scores (P < 0.0001) were positively related. And, the BDNF genotyping results showed that there was no difference between the ASD cases and the control. Among the children with ASD, the mean serum BDNF level of Met/Met group was lower than other groups. According to the ROC curve generated from our clinical data, the optimal cutoff value of serum BDNF levels, an indicator for diagnosis of ASD, was projected to be 12.50 ng/ml. Thus, it yielded a corresponding sensitivity of 81.7 % and the specificity of 66.9 %. Accordingly, area value under the curve was 0.836 (95 % CI, 0.774-0.897); the positive predictive value (PPV) and the negative predictive value (NPV) were 70.1 and 79.1 %, respectively. These results suggested that rather than Val66Met polymorphism, BDNF was more possible to impact the pathogenesis of ASD.

Vitamin A intake and risk of melanoma: a meta-analysis.

BACKGROUND: Mounting evidence from experimental and animal studies suggests that vitamin A may have a protective effect on melanoma, but the findings on the association of vitamin A intake with risk of melanoma have been inconsistently reported in epidemiologic studies. We attempted to elucidate the association by performing a meta-analysis. METHODS: Eligible studies were identified by searching PubMed and EMBASE databases, as well as by reviewing the references of retrieved publications. Summary odds ratios (OR) with corresponding 95% confidence interval (CI) were computed with a random-effects model. Study-specific ORs and 95% CIs for the highest vs. lowest categories of vitamin A intake were pooled. RESULTS: A total of 8 case-control studies and 2 prospective studies comprising 3,328 melanoma cases and 233,295 non-case subjects were included. The summary OR for the highest compared with the lowest intake of total vitamin A, retinol and beta-carotene was 0.86 (95% CI = 0.59-1.25), 0.80 (95% CI = 0.69-0.92) and 0.87 (95%CI = 0.62-1.20), respectively. Significant heterogeneity was observed among studies on vitamin A and beta-carotene intake, but not among studies on retinol intake. Subgroup and sensitivity analyses confirmed these findings. There was no indication of publication bias. CONCLUSION: Findings from this meta-analysis suggest that intake of retinol, rather than of total vitamin A or beta-carotene, is significantly associated with reduced risk of melanoma.

Minimally invasive botulinum toxin type A injection from the ocular surface to extraocular muscles.

AIM: To investigate a new, safe and effective injection method for strabismus patients. Botulinum toxin type A (BTXA) was injected by pulling the extraocular muscles with a minimally-invasive technique into the ocular surface, and it was ensured that the extraocular muscles was maintained in the suspended state. METHODS: A total of 32 patients with different types of strabismus were treated at our institution from February to October 2010. A small conjunctival incision (≤2mm) was made under a microscope. The extraocular muscles were pulled out with a hook to ensure an elevated position compared with the wall of eyeball. The muscle fiber was clearly seen through the conjunctiva and BTXA was injected at a small angle under the microscope. The deviation angles before and after the injection were recorded. All patients were followed up at 5 and 30 days after the operation. Recovery was defined as abolition of diplopia in straight-ahead gaze and anteroinferior gaze and the symptoms of giddiness disappeared thoroughly. Eyeball position was essentially normal. Improvement was defined as basic disappearance of diplopia in straight-ahead gaze and anteroinferior gaze; restriction of action of paralytic muscle improved. If most of the symptoms and signs still existed and disturbed normal work and life, the treatment was determined to be invalid. The injection dose for patients of 5 to 10 prism diopter (PD), 11 to 20PD, and ≥21PD was 1u, 3u and 4u to 5u, respectively. RESULTS: Of the 32 treated patients, 11(34.4%) were cured, and 18(56.3%) were improved at 5 days after the operation; 12(40%) were cured, and 15(46.9%) were improved at 30 days. Five patients (15.6%) who had unsatisfactory response after BTXA injection at 30 days received repeated injections or underwent strabismus surgery. Ptosis was present in 2.5% of the injected eyes. No retrobulbar hemorrhage or ocular perforation was found in any eye. CONCLUSION: It is safe and efficient to inject BTXA by pulling extraocular muscles with a minimally-invasive technique under the microscope to make the muscles separated from the wall of eyeball.