Comment on "Probing the ultimate limit of fiber-optic strain sensing"     

Cranch GA  Foster S 《Science (New York, N.Y.)》2012,335(6066):286; author reply 286

Gagliardi et al. (Reports, 19 November 2010, p. 1081) described an ultrahigh-resolution fiber-optic strain sensor. This comment addresses an error in the calculation of the fundamental thermodynamic noise in optical fiber resonators and shows that the actual thermodynamic noise level is lower by a factor of at least 11 than that calculated.  相似文献   

IBI series winner. An inquiry-based curriculum for nonmajors     

Jackson DP  Laws PW  Franklin SV 《Science (New York, N.Y.)》2012,335(6067):418-419

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Elastic domains regulate growth and organogenesis in the plant shoot apical meristem     

Kierzkowski D  Nakayama N  Routier-Kierzkowska AL  Weber A  Bayer E  Schorderet M  Reinhardt D  Kuhlemeier C  Smith RS 《Science (New York, N.Y.)》2012,335(6072):1096-1099

Although genetic control of morphogenesis is well established, elaboration of complex shapes requires changes in the mechanical properties of cells. In plants, the first visible sign of leaf formation is a bulge on the flank of the shoot apical meristem. Bulging results from local relaxation of cell walls, which causes them to yield to internal hydrostatic pressure. By manipulation of tissue tension in combination with quantitative live imaging and finite-element modeling, we found that the slow-growing area at the shoot tip is substantially strain-stiffened compared with surrounding fast-growing tissue. We propose that strain stiffening limits growth, restricts organ bulging, and contributes to the meristem's functional zonation. Thus, mechanical signals are not just passive readouts of gene action but feed back on morphogenesis.  相似文献   

Melanesian blond hair is caused by an amino acid change in TYRP1     

Kenny EE  Timpson NJ  Sikora M  Yee MC  Moreno-Estrada A  Eng C  Huntsman S  Burchard EG  Stoneking M  Bustamante CD  Myles S 《Science (New York, N.Y.)》2012,336(6081):554

Naturally blond hair is rare in humans and found almost exclusively in Europe and Oceania. Here, we identify an arginine-to-cysteine change at a highly conserved residue in tyrosinase-related protein 1 (TYRP1) as a major determinant of blond hair in Solomon Islanders. This missense mutation is predicted to affect catalytic activity of TYRP1 and causes blond hair through a recessive mode of inheritance. The mutation is at a frequency of 26% in the Solomon Islands, is absent outside of Oceania, represents a strong common genetic effect on a complex human phenotype, and highlights the importance of examining genetic associations worldwide.  相似文献   

Continental-scale effects of nutrient pollution on stream ecosystem functioning     

Woodward G  Gessner MO  Giller PS  Gulis V  Hladyz S  Lecerf A  Malmqvist B  McKie BG  Tiegs SD  Cariss H  Dobson M  Elosegi A  Ferreira V  Graça MA  Fleituch T  Lacoursière JO  Nistorescu M  Pozo J  Risnoveanu G  Schindler M  Vadineanu A  Vought LB  Chauvet E 《Science (New York, N.Y.)》2012,336(6087):1438-1440

Excessive nutrient loading is a major threat to aquatic ecosystems worldwide that leads to profound changes in aquatic biodiversity and biogeochemical processes. Systematic quantitative assessment of functional ecosystem measures for river networks is, however, lacking, especially at continental scales. Here, we narrow this gap by means of a pan-European field experiment on a fundamental ecosystem process--leaf-litter breakdown--in 100 streams across a greater than 1000-fold nutrient gradient. Dramatically slowed breakdown at both extremes of the gradient indicated strong nutrient limitation in unaffected systems, potential for strong stimulation in moderately altered systems, and inhibition in highly polluted streams. This large-scale response pattern emphasizes the need to complement established structural approaches (such as water chemistry, hydrogeomorphology, and biological diversity metrics) with functional measures (such as litter-breakdown rate, whole-system metabolism, and nutrient spiraling) for assessing ecosystem health.  相似文献   

Heralded entanglement between widely separated atoms     

J Hofmann  M Krug  N Ortegel  L Gérard  M Weber  W Rosenfeld  H Weinfurter 《Science (New York, N.Y.)》2012,337(6090):72-75

Entanglement is the essential feature of quantum mechanics. Notably, observers of two or more entangled particles will find correlations in their measurement results that cannot be explained by classical statistics. To make it a useful resource, particularly for scalable long-distance quantum communication, the heralded generation of entanglement between distant massive quantum systems is necessary. We report on the creation and analysis of heralded entanglement between spins of two single rubidium-87 atoms trapped independently 20 meters apart. Our results illustrate the viability of an integral resource for quantum information science, as well as for fundamental tests of quantum mechanics.  相似文献   

Clovis age Western Stemmed projectile points and human coprolites at the Paisley Caves     

DL Jenkins  LG Davis  TW Stafford  PF Campos  B Hockett  GT Jones  LS Cummings  C Yost  TJ Connolly  RM Yohe  SC Gibbons  M Raghavan  M Rasmussen  JL Paijmans  M Hofreiter  BM Kemp  JL Barta  C Monroe  MT Gilbert  E Willerslev 《Science (New York, N.Y.)》2012,337(6091):223-228

The Paisley Caves in Oregon record the oldest directly dated human remains (DNA) in the Western Hemisphere. More than 100 high-precision radiocarbon dates show that deposits containing artifacts and coprolites ranging in age from 12,450 to 2295 (14)C years ago are well stratified. Western Stemmed projectile points were recovered in deposits dated to 11,070 to 11,340 (14)C years ago, a time contemporaneous with or preceding the Clovis technology. There is no evidence of diagnostic Clovis technology at the site. These two distinct technologies were parallel developments, not the product of a unilinear technological evolution. "Blind testing" analysis of coprolites by an independent laboratory confirms the presence of human DNA in specimens of pre-Clovis age. The colonization of the Americas involved multiple technologically divergent, and possibly genetically divergent, founding groups.  相似文献   

A distinct role of the temporal-parietal junction in predicting socially guided decisions     

RM Carter  DL Bowling  C Reeck  SA Huettel 《Science (New York, N.Y.)》2012,337(6090):109-111

To make adaptive decisions in a social context, humans must identify relevant agents in the environment, infer their underlying strategies and motivations, and predict their upcoming actions. We used functional magnetic resonance imaging, in conjunction with combinatorial multivariate pattern analysis, to predict human participants' subsequent decisions in an incentive-compatible poker game. We found that signals from the temporal-parietal junction provided unique information about the nature of the upcoming decision, and that information was specific to decisions against agents who were both social and relevant for future behavior.  相似文献   

Discrimination of alleles and copy numbers at the <Emphasis Type="Italic">Q</Emphasis> locus in hexaploid wheat using quantitative pyrosequencing     

Sebastian Förster  Erika Schumann  W. Eberhard Weber  Klaus Pillen 《Euphytica》2012,186(1):207-218

Speltoid spikes are characterized by pyramidal spike morphology featuring an elongated rachis and tenacious glumes. Speltoids are considered undesirable spike aberrants in wheat breeding leading to increased heterogeneity within a cultivar candidate. As a consequence, the presence of speltoids may result in rejection of a cultivar candidate during official field trials or denial of cultivar certification during seed multiplication. A reliable method is, thus, required to assess the occurrence of speltoids, early on in a wheat breeding program. The domestication gene Q located on the long arm of wheat chromosome 5A is known to suppress the speltoid phenotype in wheat. Here, a quantitative pyrosequencing assay was developed to distinguish between normal wheat plants, which possess two copies of the Q allele, and aberrants, which are either aneuploids lacking the correct number of chromosome 5A copies or plants which carry the primitive q allele. An accurate and reproducible determination of the Q gene copy number was achieved for different wheat genotypes based on homoeologous sequence quantification with two primer combinations at the Q locus. Single plants with one to four copies of the Q allele could be detected by quantitative pyrosequencing which corresponded to the occurrence of speltoid (1 Q allele), normal (2 Q alleles), and compact (more than 2 Q alleles) spikes. Q and q specific alleles could be differentiated at SNP position 2299 of the Q gene. This SNP is assumed to be related to the emergence of free-threshing wheat forms. To our knowledge this is the first report for detection of aneuploids and differentiation of Q alleles in bread wheat using pyrosequencing technology. In future, quantitative pyrosequencing assay can be applied in wheat breeding programs to carry out marker-assisted selection against the presence of speltoid spike aberrants.  相似文献   

In vitro antimicrobial activity of miconazole and polymyxin B against canine meticillin-resistant Staphylococcus aureus and meticillin-resistant Staphylococcus pseudintermedius isolates     

Boyen F  Verstappen KM  De Bock M  Duim B  Weese JS  Schwarz S  Haesebrouck F  Wagenaar JA 《Veterinary dermatology》2012,23(4):381-5, e70

Background – Meticillin‐resistant Staphylococcus aureus (MRSA) and meticillin‐resistant Staphylococcus pseudintermedius (MRSP) infections are increasingly reported in dogs, and these bacteria may be isolated from ear infections. Hypothesis/Objectives – The main aim of the present study was to investigate the in vitro antimicrobial activity of miconazole, polymyxin B and a combination of both against 24 canine MRSA and 50 canine MRSP isolates. The minimal inhibitory concentration (MIC) values of 12 other antimicrobial agents were also determined. Methods – All MIC values were determined according to a broth microdilution assay. Results – Acquired resistance was found to all tested agents, except for linezolid, miconazole and polymyxin B. The MIC values for miconazole and polymyxin B against MRSA were in the range of 4–8 and 8–64 μg/mL, respectively, while the MIC values for miconazole and polymyxin B against MRSP were in the range of 1–2 and 0.25–4 μg/mL, respectively. Using a combination of miconazole and polymyxin B, there was no evidence for enhanced in vitro activity of the combination (i.e. synergy) of both products. Nevertheless, MIC₉₀ values of the combination of these antimicrobial agents and of a commercial product containing both agents were at least 1000 times lower than the concentration present in the commercial product. Conclusions and clinical importance – These results indicate that the topical use of a combination of miconazole and polymyxin B in a 43.5:1 ratio may have potential for the treatment of MRSA‐mediated and MRSP‐associated otitis externa in dogs.  相似文献