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Biomedical subjects

Yifeng Shen

Publications and source records attributed to Yifeng Shen.

7 recordsLinked to original sources
PubMed2006

Omnidirectional total reflection for liquid surface waves propagating over a bottom with one-dimensional periodic undulations.

We study theoretically the propagation of liquid surface waves over a bottom with one-dimensional (1D) periodic undulations. We find a general criterion for omnidirectional total reflection in such a system. Numerical simulations based on a transfer matrix method demonstrate unambiguously the existence of omnidirectional total reflection for liquid surface waves propagating over a bottom with 1D periodic undulations.

Journal Article↗
PubMed2005

Self-collimation in liquid surface waves propagating over a bottom with periodically drilled holes.

Liquid surface waves propagating over a bottom with periodically drilled holes are studied experimentally and theoretically. Point source waves are generated in the center of the array of the periodically drilled holes in order to observe the evolvements of these waves. We successfully observe the self-collimation phenomenon in liquid surface waves. Band structures and constant-frequency surfaces are calculated, which can give a satisfactory interpretation of the experimental observations.

Journal Article↗
PubMed2004

Relationship between suicidal behavior of psychotic inpatients and serotonin transporter gene in Han Chinese.

Strong evidence indicates that central serotoninergic system dysfunction is associated with suicidal behavior. The relationship between the serotonin transporter protein (5-HTT) gene of psychotic patients in Han Chinese with suicidal behavior was studied since the 5-HTT plays an important role in serotoninergic transmission. Two hundred and seventy-two psychotic inpatients with suicidal behavior (suicide group) and 275 psychotic inpatients without suicidal behavior (patient control group) were recruited from six mental health facilities in Shanghai, China. Another 628 healthy adults (healthy control group) without suicidal behavior and mental disorder history were enrolled from Shanghai, China. All subjects were Han Chinese. The genotypes and the alleles of 5-HTT genes of the three groups were examined by PCR amplification. Neither the intron 2 variable number tandem repeat (VNTR) polymorphism and 5-HTTLPR (5-HTT gene-linked polymorphic region), nor the haplotype frequencies of this gene have significant differences between the suicide group and the two control groups. However, there was a significant difference in 5-HTTLPR polymorphism between inpatients with a first episode of suicidal behavior and those with recurrent suicidal behavior. Except for the possible heterogeneity between inpatients with a first episode of suicidal behavior and those with more than one, the 5-HTT gene was unlikely to be associated with suicidal behavior of psychotic patient in Han Chinese.

Adult↗
PubMed2004

Association of G72/G30 with schizophrenia in the Chinese population.

Recently, the G72 gene was reported to be associated with schizophrenia in the French Canadian and Russian populations. Here, we report the results obtained from the study of six single-nucleotide polymorphisms (SNPs: rs3916965, rs3916967, rs2391191, rs1935062, rs778293, and rs3918342), which span an 82-kb region covering the complementary DNA sequences of G72 and G30, in 537 schizophrenia cases and 538 controls of the Han Chinese. In this work, we have identified statistically significant differences in allele distributions of two markers rs3916965 (P = 0.019) and rs2391191 (P = 0.0010), and a highly significant association between haplotype AGAC of the G72/G30 locus (P = 1.7 x 10(-4)) and schizophrenia. Our data provide further evidence that markers of the G72/G30 genes are associated with schizophrenia in a non-Caucasian population.

Adult↗
PubMed2004

Superlensing effect in liquid surface waves.

We present experimental observations and numerical simulations of superlensing effect in liquid surface waves. We use rigid cylinders to create a two-dimensional periodic lattice, in which liquid surface waves propagate. Through the observation of a superlensing effect, we demonstrate the existence of negative refraction in surface waves. In addition, a complete band gap is found.

Journal Article↗
PubMed2003

Complete band gaps for liquid surface waves propagating over a periodically drilled bottom.

A plane-wave expansion approach is developed to solve the mild-slope equation for liquid surface waves propagating over a bottom with periodic structures. Band structures are calculated for the bottom periodically drilled with the square or triangular lattice of holes. Complete band gaps are found for both lattices. Parameters that influence the formation of band gaps are discussed.

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