Seed Discharge in Arceuthobium: A Photographic Study

Photographs, made at a speed of 5 microseconds, of the ejection of the Arceuthobium seed from its fruit, show that tumbling in the vertical plane begins soon after discharge and that most seeds have turned 90 degrees when they have traveled about 6 centimeters. As the seeds leave the fruit they have a viscous sheath around the trailing end that disintegrates after the seeds have traveled about 2 to 3 centimeters. This viscous material does not act as a rudder as has been postulated.     

Genetic Diversity Based on AIIozyme Alleles of Chinese Cultivated Rice

Genetic diversity was analyzed with 6 632 core rice cultivars selected from 60 282 Chinese rice accessions on the basis of 12 allozyme loci, Pgil, Pgi2, Amp1, Amp2, Amp3, Amp4, Sdhl, Adhl, Estl, Est2, Est5 and Est9, by starch gel electrophoresis. Among the materials examined, 52 alleles at 12 polymorphic loci were identified, which occupied 96.3% of 54 alleles found in cultivated germplasm of O. sativa L. The number of alleles per locus ranged from 2 to 7 with an average of 4.33. The gene diversity （He） each locus varied considerably from 0.017 for Amp4 to 0.583 for Est2 with an average gene diversity （Ht） 0.271, mid Shannon-Wiener index from 0.055 to 0.946 with an average of 0.468. The degree of polymorphism （DP） was in a range from 0.9 to 46.9% with an average of 21.4%. It was found that the genetic diversity in japonica （Keng） subspecies was lower in terms of allele＇s number, Ht and S-W index, being 91.8, 66.2 and 75.7% of indica （Hsien） one, respectively. Significant genetic differentiation between indica and japonica rice has been appeared in the loci Pgil, Amp2, Pgi2, and Est2, with higher average coefficient of genetic differentiation （Gst） 0.635, 0.626, 0.322 and 0.282, respectively. Except less allele number per locus （3.33） for modern cultivars, being 76.9% of landraces, the Ht and S-W index showed in similar between the modem cultivars and the landraces detected. In terms of allozyme, the rice cultivars in the Southwest Plateau and Central China have richer genetic diversity. The present study reveals again that Chinese cultivated rice germplasm has rich genetic diversity, showed by the allozyme allele variation.     

Observation of Interference Between Two Bose Condensates

Interference between two freely expanding Bose-Einstein condensates has been observed. Two condensates separated by approximately 40 micrometers were created by evaporatively cooling sodium atoms in a double-well potential formed by magnetic and optical forces. High-contrast matter-wave interference fringes with a period of approximately 15 micrometers were observed after switching off the potential and letting the condensates expand for 40 milliseconds and overlap. This demonstrates that Bose condensed atoms are "laser-like"; that is, they are coherent and show long-range correlations. These results have direct implications for the atom laser and the Josephson effect for atoms.     

Common sequence polymorphisms shaping genetic diversity in Arabidopsis thaliana

The genomes of individuals from the same species vary in sequence as a result of different evolutionary processes. To examine the patterns of, and the forces shaping, sequence variation in Arabidopsis thaliana, we performed high-density array resequencing of 20 diverse strains (accessions). More than 1 million nonredundant single-nucleotide polymorphisms (SNPs) were identified at moderate false discovery rates (FDRs), and approximately 4% of the genome was identified as being highly dissimilar or deleted relative to the reference genome sequence. Patterns of polymorphism are highly nonrandom among gene families, with genes mediating interaction with the biotic environment having exceptional polymorphism levels. At the chromosomal scale, regional variation in polymorphism was readily apparent. A scan for recent selective sweeps revealed several candidate regions, including a notable example in which almost all variation was removed in a 500-kilobase window. Analyzing the polymorphisms we describe in larger sets of accessions will enable a detailed understanding of forces shaping population-wide sequence variation in A. thaliana.     

Whole-genome patterns of common DNA variation in three human populations

Individual differences in DNA sequence are the genetic basis of human variability. We have characterized whole-genome patterns of common human DNA variation by genotyping 1,586,383 single-nucleotide polymorphisms (SNPs) in 71 Americans of European, African, and Asian ancestry. Our results indicate that these SNPs capture most common genetic variation as a result of linkage disequilibrium, the correlation among common SNP alleles. We observe a strong correlation between extended regions of linkage disequilibrium and functional genomic elements. Our data provide a tool for exploring many questions that remain regarding the causal role of common human DNA variation in complex human traits and for investigating the nature of genetic variation within and between human populations.     

Aligned multiwalled carbon nanotube membranes

An array of aligned carbon nanotubes (CNTs) was incorporated across a polymer film to form a well-ordered nanoporous membrane structure. This membrane structure was confirmed by electron microscopy, anisotropic electrical conductivity, gas flow, and ionic transport studies. The measured nitrogen permeance was consistent with the flux calculated by Knudsen diffusion through nanometer-scale tubes of the observed microstructure. Data on Ru(NH3)6(3+) transport across the membrane in aqueous solution also indicated transport through aligned CNT cores of the observed microstructure. The lengths of the nanotubes within the polymer film were reduced by selective electrochemical oxidation, allowing for tunable pore lengths. Oxidative trimming processes resulted in carboxylate end groups that were readily functionalized at the entrance to each CNT inner core. Membranes with CNT tips that were functionalized with biotin showed a reduction in Ru(NH3)6(3+) flux by a factor of 15 when bound with streptavidin, thereby demonstrating the ability to gate molecular transport through CNT cores for potential applications in chemical separations and sensing.     

Comparison of sevoflurane and isoflurane anesthetic index in unpremedicated dogs

Anesthetic respiratory effects of sevoflurane (SEVO) were compared with isoflurane (ISO) in unpremedicated dogs. Minimum alveolar concentration (MAC), apneic concentration (AC), and anesthetic index (AI) of SEVO and ISO were determined in eight 1‐year‐old healthy dogs, weighing 19 ± 3 kg (mean ± SEM) in a randomized complete block multiple cross‐over design. Dogs were mask‐induced with either SEVO or ISO in 100% oxygen. Following endotracheal intubation, dogs were instrumented, mechanically ventilated, and MAC was determined using a tail‐clamp method. Next, spontaneous ventilation was re‐established, and anesthetic concentration was increased to determine the AC. Throughout the anesthetic event, heart rate (HR), systolic blood pressure (SAP), mean blood pressure (MAP), diastolic blood pressure (DAP), respiratory rate (RR), end‐tidal carbon dioxide (Pe ′CO₂), and oxyhemoglobin saturation (SpO₂) were recorded at 3‐minute intervals. Following AC determination, AI was calculated as AC/MAC, and dogs were allowed to recover. Each dog was anesthetized four times (twice with ISO and SEVO each) at 1‐week intervals. All data were analyzed using the two‐way anova . Multiple comparisons were performed between ISO and SEVO treatments. Statistical significance was set at p < 0.05. Significant differences were noted between agents for MAC (SEVO, 2.13 ± 0.10%; ISO, 1.38 ± 0.14%; p < 0.0001), AC (SEVO, 7.34 ± 0.13%; ISO, 3.60 ± 0.13%; p < 0.0001), and AI (SEVO, 3.46 ± 0.22; ISO, 2.63 ± 0.14; p = 0.0002). Physiologic parameters were compared between SEVO and ISO at 1MAC, 2MAC, 3MAC, and AC. No differences were noted between SEVO and ISO treatments for cardiovascular parameters (HR, SAP, MAP, DAP). Significant differences were noted, favoring SEVO, for all respiratory parameters (RR, Pe ′CO₂, SpO₂) at increasing MAC multiples. Additionally, regression analysis was conducted for physiologic variable data points. Analysis of Pe ′CO₂ data points demonstrated a significant slope difference of ?6.47 ± 1.02 (B_SEVO ? B_ISO; p < 0.0001; r² = 0.6042) favoring SEVO. While expected dose‐related ventilatory depression was noted for both agents, all the respiratory parameters for SEVO demonstrated less respiratory depression than ISO at equipotent doses. These results indicated that SEVO caused less dose‐dependent ventilatory depression than ISO, having a significantly higher AI and causing less detrimental change in pulmonary parameters at increasing levels of MAC.