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Based on the data of volatile organic compounds (VOCs) collected from July to October, 2014 in the centre of Kunming, characteristic of their variability and source identification by principal component analysis (PCA) were analyzed. In summer, 40.60% of the total VOC concentrations were attributed to biogenic emissions and industrial process, 19.33% to vehicle emissions, 19.19% to solvent usage, 10.02% to fuel evaporation(including LPG/NG leakage and gasoline evaporation), and 8.34% to industrial production. In autumn, 39.73% of the total VOC concentrations were attributed to industrial production, 27.67% to solvent usage, 21.26% to vehicle emissions, 8.12% to fuel evaporation.

In this paper, a modeling method based on physical deformation is described. The proposed method is designed to solve the modeling of deformation products with requirements such as a local shape requirement or space assembly. It is utilized to designing products by analogy to balloon inflating, and the deformation process obeys physical laws of motion. First of all, the boundary of spatial constraint of deformable component is obtained according to design requirements and assembly environment. Secondly, component is initialized by a simplified mass-spring model, and the process of expansion is simulated by increasing the internal pressure until the deformation extent meets the needs. Finally, several examples are illustrated for verifying this method. Comparing to traditional design method, this method gets concept model under the condition of design constraint firstly, then regards the concept model as references for detail design. Therefore, the idea can avoid repeated modification of artificial design and shorten design period significantly.

TV reporters in Taiwan often encounter accidents during regular assignment runs, which may be a significant factor that increases their intentions to leave their job. Occupational hazard has always been ignored by news media organizations. Recent research has shown that a positive organizational safety climate may improve safety-related issues. To build on previous research conducted, this study investigates the moderating effect of safety climate between safety leadership and turnover intentions. This research collected 268 valid samples with an 89% response rate. Using the hierarchical linear model, results show that the transformational leadership style is negatively related to turnover intentions and the passive leadership style is positively related. Moreover, the moderation tests found a negative relationship between the interaction of passive leadership and safety and employees' turnover intentions. This implies that when reporters are working in a positive safety climate environment, their turnove...

Recently, differentiation in phenotypic traits (P(ST)) and differentiation at neutral molecular markers (F(ST)) across populations have been become an important topic in evolutionary biology. The Minjiang River is a key genetic introgression zone between the Chinese mitten crab (Eriocheir sinensis) and the Hepu mitten crab (Eriocheir hepuensis), making it an excellent area to study their genetics and evolutionary mechanisms. We compared and analyzed P(ST) in 14 phenotypic traits and F(ST) in six microsatellite markers from 133 individuals of the mitten crab, sampled in the Minjiang River in 2009 and 2010. The results indicated that 11 phenotypic traits were significantly different (P F(ST), suggesting that directional selection is occurring. This study provides valuable data to the further study and analysis of the molecular evolution of the mitten crab, and contributes a useful reference in comparing P(ST) and F(ST) in other aquatic organisms.

Inter Simple Sequence Repeats (ISSR) markers were applied to assess the genetic diversity in F 1 , F 2 , and F 3 generations of “Whole Red” pattern Cyprinus carpio.var.color as testing group, and their base population (F 0 ) as control group. Among four populations, 120, 118, 101 and 110 bands ranging from 200 to 2500 bp were amplified respectively. As analyzed, the percentage of polymorphic bands (PPB) ranged from 51.5% to 67.8%; Shannon’s information index ( H 0 ) varied from 0.2176 to 0.2745 among populations. With the increase of selected generations’ populations, it showed a reduction in genetic diversity. Analysis of molecular variance revealed that a greater proportion of total genetic variation existed within populations (70%) rather than among populations (30%). Cluster analysis divided the four populations into two groups. Genetic difference value ( G st from 0.1588 to 0.2766) indicated that the differentiation has taken place to some extent among “Whole Red” C. carpio var.color .

A high-manganese austenitic steel matrix (Mn13) composite reinforced with TiN ceramic particles was synthesized by means of Vacuum-Evaporation Pattern Casting (V-EPC). The composite microstructure and interface bonding of TiN/matrix were analyzed utilizing optical microscope (OM) and X-ray diffraction (XRD). The effects of different volume fraction of TiN on impact wear resistance were evaluated by MLD-10 impact wear test. The results showed that TiN was evenly distributed in composite layer and had a good interface bonding with matrix when the volume fractions of TiN were 27% and 36%, respectively. However, cast defects and TiN agglomeration occurred when the TiN volume fraction increased to 48%. Compared with high-manganese austenitic steel (Mn13), the impact wear resistance of the TiN-reinforced composite is better. In small impact load conditions, composite layer can effectively resist abrasives wear and TiN particles played an important role in determining impact wear resistance of composite layer. In large impact load, the synergistic roles of spalling of TiN particles and the increase of work hardening of Mn13 based material are responsible for impact wear resistance.

An ultra-high-pressure liquid chromatography/MS3 (UPLC-MS3) method has been developed and validated for the quantitative determination of four major TSNAs in mainstream cigarette smoke using MS3 scan mode on a hybrid triple quadrupole-linear ion trap mass spectrometer. The new method combining the UPLC with MS3 scan mode offers decreased sample analysis time and good selectivity. After mainstream cigarette smoke was collected on a Cambridge filter pad, the particulate matter was extracted with ammonium acetate solution and analyzed by UPLC-MS3 using isotopically labeled analogues as internal standards. Four TSNAs were completely separated on an Agilent XDB-C18 UPLC column using isocratic elution during a 6 min LC run time. Excellent linearity was obtained over the concentration range of 1.0-150.0 ng/mL for all TSNAs with values for correlation coefficient (r) between 0.9985-0.9994. Limits of detection (LOD) of each TSNA varied from 0.023 to 0.067 ng/mL, and lower limits of quantification (LLOQ) varied from 0.077 to 0.223 ng/mL, respctively. The recovery of each TSNA was from 89.2 to 106.8%. The method achieved excellent reproducibility with RSD 2.1-6.8% for intra-assay and 3.4-9.1% for inter-assay. This method can be used as an effective approach to significantly improve the detection capability for TSNAs in complex matrices.

Silver carp Hypophthalmichthys molitrix (Cyprinidae) is native to China and has been introduced to over 80 countries. The extent of genetic diversity in introduced silver carp and the genetic divergence between introduced and native populations remain largely unknown. In this study, 241 silver carp sampled from three major native rivers and two non-native rivers (Mississippi River and Danube River) were analyzed using nucleotide sequences of mitochondrial COI gene and D-loop region. A total of 73 haplotypes were observed, with no haplotype found common to all the five populations and eight haplotypes shared by two to four populations. As compared with introduced populations, all native populations possess both higher haplotype diversity and higher nucleotide diversity, presumably a result of the founder effect. Significant genetic differentiation was revealed between native and introduced populations as well as among five sampled populations, suggesting strong selection pressures might have occurred in introduced populations. Collectively, this study not only provides baseline information for sustainable use of silver carp in their native country (i.e., China), but also offers first-hand genetic data for the control of silver carp in countries (e.g., the United States) where they are considered invasive.

The determination of hydrogen cyanide in cigarette mainstream smoke has been achieved by ion chromatography (IC) with pulsed amperometric detection (PAD). The proposed method of totally trapping whole cigarette mainstream smoke by Cambridge filters, which are treated with sodium hydroxide/ethanol solution, possesses the advantage of fast analysis time over the widespread used solution absorption method. The possible co-existing interferents are evaluated under the optimized detection conditions and excellent recoveries of cyanide are obtained. The cyanide content of absorption solution can be directly determined by the optimized IC-PAD method without any pretreatments. The linear range is 0.0147-2.45 μg/mL with R² value of 0.9997. The limit of the detection is 3 μg/L for a 25 μL injection loop. The overall relative standard deviation of the method is less than 5.20% and the recovery range from 94.3% to 101.0%. The results obtained from the developed method are in good agreement with that of continuous flow analyzer (CFA) method.

The bighead carp Hypophthalmichthys nobilis is native to China but has been introduced to over 70 countries and is established in many large river systems. Genetic diversity and variation in introduced bighead carp have not previously been evaluated, and a systematic comparison among fish from different river systems was unavailable. In this study, 190 bighead carp specimens were sampled from five river systems in three countries (Yangtze, Pearl, and Amur rivers, China; Danube River, Hungary; Mississippi River basin, USA) and their mitochondrial 16S ribosomal RNA gene and D-loop region were sequenced (around 1,345 base pairs). Moderate genetic diversity was found in bighead carp, ranging from 0.0014 to 0.0043 for nucleotide diversity and from 0.6879 to 0.9333 for haplotype diversity. Haplotype analysis provided evidence that (1) multiple haplotype groups might be present among bighead carp, (2) bighead carp probably originated from the Yangtze River, and (3) bighead carp in the Mississippi River ...

The grass carp (Ctenopharyngodon idella), a freshwater species native to China, have been introduced in more than 100 countries. In this paper, inter simple sequence repeat (ISSR) markers were used to evaluate genetic variation within and among grass carp populations sampled from its native (China) and colonized habitats (USA, Hungary, and Japan). Twenty-two ISSR primers were used to generate 207 bands, of which 82 (39.61 %) were polymorphic. The highest genetic diversity was observed in the Yangtze River population, whereas the lowest diversity was found in the Tone River population (Japan). Compared with colonized populations, the native populations possess approximately twice as much genetic diversity. The AMOVA analysis showed a relatively high level of genetic variation within populations. Significant genetic differences were revealed both among the native populations and between pooled native and colonized populations.

Reciprocal differences have been observed widely for given traits in fish breeding programs, but maternal and paternal effects and heritable extranuclear genetic effects have often been omitted in the evaluation of genetic variance. In this study, we have applied a mixed genetic model to conduct a complete diallel cross using three varieties of red common carp (Cyprinus carpio L.), namely, C.carpio. var. singuonensis, C. carpio var. wuyuanensis and C.carpio var. color. Parental and direct (additive and dominance) genetic effects for growth-related traits at 8 and 20 months post-hatch were analyzed. At 8 months post-hatch, only significant additive and dominance variances were observed, while maternal and paternal variances were low and non-significant in the traits evaluated: body weight, total length, standard length, pre-dorsal height, pre-dorsal width, caudal peduncle length, and caudal peduncle height. At 20 months post-hatch, with the exception of significant additive and/or dominance variances, maternal variances were significant for the traits of body weight, pre-dorsal height, pre-dorsal width, and caudal peduncle height, and the paternal variance was significant only for total length. The maternal effects in the common carp had greater genetic influence on offspring than the paternal effects. Female C. carpio var. wuyuanensis were more suitable as brooders than males, but both female and male C. carpio var. color can be used as brooders according to breeding programs of improved traits. Cyprinus carpio var. singuonensis was the worst brooder of the three varieties of common carp evaluated.

Based upon morphological characters, Silver carp Hypophthalmichthys molitrix and bighead carp Hypophthalmichthys nobilis (or Aristichthys nobilis) have been classified into either the same genus or two distinct genera. Consequently, the taxonomic relationship of the two species at the generic level remains equivocal. This issue is addressed by sequencing complete mitochondrial genomes of H. molitrix and H. nobilis, comparing their mitogenome organization, structure and sequence similarity, and conducting a comprehensive phylogenetic analysis of cyprinid species. As with other cyprinid fishes, the mitogenomes of the two species were structurally conserved, containing 37 genes including 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNA (tRNAs) genes and a putative control region (D-loop). Sequence similarity between the two mitogenomes varied in different genes or regions, being highest in the tRNA genes (98.8%), lowest in the control region (89.4%) and intermediate in the protein-coding genes (94.2%). Analyses of the sequence comparison and phylogeny using concatenated protein sequences support the view that the two species belong to the genus Hypophthalmichthys. Further studies using nuclear markers and involving more closely related species, and the systematic combination of traditional biology and molecular biology are needed in order to confirm this conclusion.

A diallel cross was conducted with three variants of red common carp, Cyprinus carpio var. singuonensis , C. carpio var. wuyuanensis and C. carpio var. color , raised in two separate experimental stations. Additive effects, dominance effects, additive × environment (A × E) and dominance × environment (D × E) interactions of growth-related traits of 8-month-old fish were estimated by using a mixed genetic model. It was found that the traits of body weight (BW), standard length (SL) and pre-dorsal height (PDH) were mainly controlled by dominance effects, whereas they were very weakly controlled by the additive, genotype × environment (A × E and D × E) interaction effects. For the trait of pre-dorsal width (PDW), additive effects were the predominant effects, while dominance and genotype × environment interaction effects were less important. Also, significant D × E interaction effects in BW, and significant A × E interaction effects in PDH and PDW were detected. In all the studied traits, the prediction of genetic merit (breeding values) for the three variants indicated that C. carpio var. color was the best one for genetic improvement through direct selection in different environmental conditions, and the cross combination of C. carpio var. color and C. carpio var. singuonensis was the best for heterosis utilization by hybridization, while C. carpio var. wuyuanensis was the best for improving the body height in red common carp.

Mitochondrial DNA COII gene sequence analysis and RAPD analysis were carried out to assess the phylogenetic relationships of three colored strains of common carps, e.g., the ornamental (Koi) carp from Japan, and the Oujiang color common carp as well as the Long-fin common carp from China. Phylogenetic trees from two methods indicated Oujiang color common carp and Long-fin common to be non-monophyletic, and Koi carp might have originated from China and shared a common ancestor with Oujiang color common carp. Meanwhile, the comparative results showed that genetic diversity of Oujiang color common carp was higher than that of Long-fin common carp in China.

Tarim schizothoracin (Schizothorax biddulphi Günther) is an extremely endangered freshwater fish that thrives only in the Tarim River drainage in China. In this paper, we initially determined the complete mitochondrial genome of schizothoracin fishes. The mitochondrial genome of S. biddulphi was 16,585 bp long, which is similar to most vertebrates. It contains the same gene order and a similar number of gene or region including 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes, and 1 putative control region.

A theoretical model is developed to describe the interaction of a particle and an oscillating bubble at arbitrary separation between them. The derivation of the model is based on the multipole expansion of the particle and bubble velocity potentials and the use of Lagrangian mechanics. The model consists of three coupled ordinary differential equations. One of them accounts for the pulsation of the bubble and the other two describe the translation of the bubble and particle in an infinite, incompressible liquid. The model here is accurate to order 1/d 10, where d is the distance between the centers of the particle and bubble. The effects of the size and density of the particle are investigated, namely, the interaction between the particle and bubble changes from repulsion to attraction with the increment of the particle density, and the increment of the particle size makes the interaction between the particle and bubble stronger. It is demonstrated that the driving frequency and acoustic pressure amplitude can affect the interaction of the particle and bubble. It is shown that the correct modeling of the translational dynamics of the bubble and particle at small separation distances requires terms accurate up to the tenth order.

Blackchin tilapia, Sarotherodon melanotheron, is a highly salt-tolerant species in tilapias. In this paper, the complete mitochondrial genome of S. melanotheron was determined first. The mitogenome (16,627 bp) had the typical vertebrate mitochondrial gene arrangement, including 13 protein-coding, 22 tRNA, 2 rRNA genes, and 1 putative control region. It shared 95.1%, 93.2%, and 92.2% mitogenome sequence with Oreochromis aureus, Oreochromis niloticus, and Oreochromis mossambicus, respectively.

Purpose: To compare the difference between Uygur and Han patients with breast cancer in molecular subtype. Methods: 4 immunohistochemical (IHC) markers (ER, PR, HER-2 and KI-67) were used to divide Uygur and Han breast cancer patients into 4 subtypes (Luminal A, Luminal B, HER-2 over expression and Basal-like), respectively. statistical analysis were used to evaluate difference in molecular subtype characteristics by race, tumor size, age of onset, menstruation and birth status, histological grade and lymph node metastasis. Results: There is no statistical difference on the molecular subtypes between Han and Uygur. But some characteristics about four subtypes between Han and Uygur have statistical difference like age onset of the Her-2 overexpression cases, subtypes of age less than 35 years, menarche age of the Basal-like cases and tumor size of the Luminal A cases. Between Han and Uygur there is statistical difference on the menarche age, number of childbirths, and tumor size. The HER-2 overexpression and Basal-like subtypes were more likely to be grade III tumors both of Han and Uygur. Between 4 molecular subtypes of Han there have statistical difference in number of metastasis lymph nodes. Conclusions: Our result shows that there are some significant differences between Uygur and Han in the pathological features as well as molecular subtypes. Correct understanding the difference of breast cancer between Uygur and Han can provide guidance for clinical practice.

Seventeen microsatellite DNA loci from the Australian short-finned eel (Anguilla australis Richardson) were isolated and their amplification characteristics were described. The polymerase chain reaction primers were tested on 40 eel individuals. The primers amplified loci with relatively high numbers of alleles, ranging from five to 14 with an average of nine per locus. Mean observed heterozygosity (H(O) ) and expected heterozygosity (H(E) ) were 0.6779 and 0.7374, respectively, indicating that these markers would be useful for population studies. No loci deviated significantly from Hardy-Weinberg equilibrium (P = 0.05) and no evidence was found for genotypic disequilibrium among loci at a 5% significance level.

Previously, a flow cytometer was modified with a PZT transducer in order to study the radial oscillations of statistically significant numbers of microbubbles (J. Acoust. Soc. Am. 126, 2954–2962, (2009)). We reported the results of pressure calibration for transient sonication in a recent symposium (ASA, Indianapolis, 2013). Here, we report the results of pressure calibration for steady-state sonication. Because the flow channel width (

To study the role of arginase-1 (Arg-1) expression in differential diagnosis of hepatocellular carcinoma (HCC), Arg-1 staining pattern in clear cell neoplasm (HCC and non-HCC) and Arg-1 expression in non-hepatocellular tumors.Seventy-eight cases of HCC (including 8 cases of clear cell type and 70 cases of non- clear cell type) and 246 cases of non-hepatocellular neoplasms (including 29 cases of metastatic tumors such as breast cancer, nasopharyngeal carcinoma and neuroendocrine carcinoma, 77 cases of tumors with clear cell changes such as malignant melanoma, clear cell renal cell carcinoma and alveolar soft part sarcoma, and 140 cases of other types of tumors such as ovarian endometrioid adenocarcinoma, pituitary tumor and thyroid papillary carcinoma) were studied.Immunohistochemical study for Arg-1 was performed on the paraffin-embedded tumor tissue.In HCC, Arg-1 demonstrated both cytoplasmic and nuclear staining, with an overall sensitivity of 96.2% (75/78).In well, moderately and poorly differentiated HCC, the sensitivity was 15/15, 100% (41/41) and 86.4% (19/22), respectively. That was in contrast to negative staining for Arg-1 in all the 29 cases of metastatic tumors studied. The sensitivity, specificity, positive predictive value and negative predictive value of Arg-1 in distinguishing HCC from metastatic tumors was 96.2%, 100%, 100% and 90.6%, respectively. Cytoplasmic and membranous staining was observed in clear cell type of HCC. The overall sensitivity of Arg-1 expression in the 77 cases of tumors with clear cell changes was 14.3% (11/77), including 8/15 for malignant melanoma, 2/4 for ovarian clear cell carcinoma and 1/1 gall bladder adenocarcinoma with clear cell component.In malignant melanoma and ovarian clear cell carcinoma, only cytoplasmic staining was demonstrated. There was no expression of Arg-1 in the 140 cases of other tumor types studied.Arg-1 is a sensitive and specific marker for HCC.It is a potentially useful immunohistochemical marker in distinguishing HCC from metastatic tumors. Though also expressed in malignant melanoma and ovarian clear cell carcinoma, Arg-1 shows a different staining pattern as compared with that in HCC.

To study the expression of β-catenin protein and the status of loss of heterozygosity (LOH) on chromsome 10q in medulloblastoma, with clinical correlation.Immunohistochemical study for β-catenin protein was carried out in 50 cases of medulloblastoma encountered in the First Affiliated Hospital of Xinjiang Medical University during the period from 2002 to 2011, including 32 cases of classic medulloblastoma, 13 cases of desmoplastic medulloblastoma and 5 cases of medulloblastoma with extensive nodularity. The status of LOH on 10q was also detected by fluorescence in-situ hybridization. The clinicopathologic characteristics and prognostic parameters were studied by Kaplan-Meien and Cox analysis.The rates of expression of β-catenin protein in classic medulloblastoma, desmoplastic medulloblastoma and medulloblastoma with extensive nodularity were 53.1% (17/32), 4/13 and 1/5, respectively. The rate of LOH on 10q was 33.3% (8/24) in classic medulloblastoma and 2/11 in desmoplastic medulloblastoma. There was no statistically significant difference between the two tumor types. Univariate analysis showed that the expression of β-catenin protein (P = 0.022), lack of LOH on 10q (P = 0.020), extensiveness of tumor resection (P0.01), radiotherapy (P = 0.002) and chemotherapy (P0.01) represented important prognostic factors.Medulloblastoma with expression of β-catenin protein and without LOH on 10q carries a better prognosis. Assessment of these parameters is helpful in evaluating prognosis and subsequent patient management.

Seventeen microsatellite DNA loci from the Australian short-finned eel (Anguilla australis Richardson) were isolated and their amplification characteristics were described. The polymerase chain reaction primers were tested on 40 eel individuals. The primers amplified loci with relatively high numbers of alleles, ranging from five to 14 with an average of nine per locus. Mean observed heterozygosity (H(O) ) and expected heterozygosity (H(E) ) were 0.6779 and 0.7374, respectively, indicating that these markers would be useful for population studies. No loci deviated significantly from Hardy-Weinberg equilibrium (P = 0.05) and no evidence was found for genotypic disequilibrium among loci at a 5% significance level.

Taxonomic classification of three mitten crabs (Eriocheir sinensis, E. hepuensis, and E. japonica) has long been controversial. In this study, the complete mitogenomes of the three crabs were reported. The three mitogenomes were conserved in the organization of genes with 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes, and 1 control region. Nucleotide variations among the crabs were identified in both coding and non-coding regions. In addition, variable numbers of tandem repeats in control region were identified in the mitten crabs. The mitogenome sequences provide a valuable resource to elucidate taxonomic relationship and evolutionary history of the three mitten crabs.

Report generation is arguably the most important task for Web-based database applications, since dynamic Web pages consisting of database reports are essential to almost every transaction. When a report is generated, the layout of the data sources must be converted to the layout of the report. In this paper, we propose a report-structure tree to model the layout of nested reports. A series of tree nodes are used to define the structure of reports, produce nested results, and offer aggregation functions. We enhance our previous work (TPS) to support the design of report-structure trees visually. We show that sophisticated nested reports can be created easily

Nucleotide sequence of Cytochrome coxidase subunit II (CO II) of mitochondrial DNA ( mtDNA) was analyzed from four populations of the red common carp (C. c. var. singuonensis, C. c. var. wananensis, C. c. var. wuyuanensis and C. c. var. color) as well as one population of wild common carp in China to detect their genetic variability and phylogenetic relationship. Nineteen nucleotide variable positions were detected in analyzed 607 bp length sequence and 15 haplotypes were defined among five populations,but only one shared haplotype was observed in C. c. var. singuonensis and C. c. var. color, respectively. The characteristic intrapopulation single nucleotide polymorphisms (SNP) were observed in 103th, 149th, 239th, 368th, 395th nucleotide position. The highest haplotypic diversity (h) and nucleotide diversity (pi) existed in C. c. var. wuyuanensis and the lowest exited in C. c. var. wananensis. The significant fixation indices (Fst) in most comparisons between populations were observed. The neighbor-joining trees from haplotypes and populations of red common carp indicated C. c. var singuonensis and C. c. var. color might have originated from one monophyletic group, while C. c. var. wananensis and C. c. var. wuyuanenesis might have originated from an independent evolutionary branch.

We incorporated an ultrasound transducer into a flow cytometer to "activate" microbubbles passing the laser interrogation zone (J. Acoust. Soc. Am. 126, 2954–2962, (2009)). This system allows high throughput recording of the volume oscillations of microbubbles, and has led to a new bubble dynamics model that incorporates shear thinning (Phys. Med. Biol. 58, 985–998 (2013)). Important parameters in the model include the ambient microbubble size, R0, driving pressure, PA, and the shell parameters χ and κ, the shell elasticity and viscosity, respectively. R0 is obtained by calibrating the cytometer. Pressure calibration is difficult because the flow channel width (

Using an appropriate approximation, we have formulated the interacting equation of multi-bubble motion for a system of a single bubble and a spherical bubble cluster. The behavior of the bubbles is observed in coupled and uncoupled states. The oscillation of bubbles inside the cluster is in a coupled state. The numerical simulation demonstrates that the secondary Bjerknes force can be influenced by the number density, initial radius, distance, driving frequency, and amplitude of ultrasound. However, if a bubble approaches a bubble cluster of the same initial radii, coupled oscillation would be induced and a repulsive force is evoked, which may be the reason why the bubble cluster can exist steadily. With the increment of the number density of the bubble cluster, a secondary Bjerknes force acting on the bubbles inside the cluster decreases due to the strong suppression of the coupled bubbles. It is shown that there may be an optimal number density for a bubble cluster which can generate an optimal cavitation effect in liquid for a stable driving ultrasound.

This paper proposes a general proof-theoretic framework, where negative literals in a query are proved by a new mechanism of negation-as-failure. This new mechanism handles nonground negative literals and thus guarantees that queries never flounder. We show how to derive proof procedures within this framework, which are always sound, for a number of semantics formalisms, including the GCWA (generalized closed world assumption) and the stable model semantics of logic programs. We also show a new proof procedure for the well-founded semantics which is "more complete" than the previous one in that the floundered queries can be safely pursued.