Abscission of grapevine fruitlets in relation to ethylene biosynthesis

The ethylene content of grapevine (Vitis vinifera, cv. Chardonnay) flowers and fruitlets was followed during flowering, i.e. from stage 18 to stage 32 (EICHHORN and LORENZ 1977). A strong rise of ethylene was observed at the beginning of abscission, corresponding to stage 23. High levels of ethylene were found in the whole period in which abscission occurred, indicating a possible role of ethylene in grapevine fruitlet abscission. The rise of ethylene was associated with a rise of 1-aminocyclopropane-1-carboxylic acid (ACC) content and ACC oxidase activity. At the end of abscission (stage 28-29), the levels of ethylene, ACC and ACC oxidase activity decreased to a level close to that at pre-bloom. The ethylene evolution in two clones with different sensitivity to berry drop revealed the relationship between ethylene and the intensity of abscission, and confirmed that the abscission promoting effect of ethylene depends on the phenological stage. Results are discussed with regard to possible hormonal interactions between ethylene, ACC, ACC oxidase and abscisic acid.

An in vitro model to study abscission in grapevine (Vitis vinifera L.)

Research Not

Collective identity and basketball: An explanation for the decreasing number of African-Americans on America\u27s baseball diamonds

A growing body of evidence shows a widening gulf between baseball and African-Americans. African-Americans comprise less than three percent of the players at the highest competitive levels of youth baseball and three percent of NCAA Division I baseball players. African-Americans constitute less than five percent of spectators at some Major League parks and the percentage of African-American players in the Major Leagues has reached a 30-year low. Basketball has become pre-eminent among sports in African-American culture. Baseball assumed that role at one time, with even small African-American enclaves sponsoring and supporting teams during the first decades of the 20th Century. But the cultural shift away from baseball to basketball has been brought about partly through the process of collective identity. Collective identity involves the absorption of cultural traits by an individual in the formation of self-identity. African-American youth are more apt to gravitate to basketball rather than baseball because of the cultural premium placed on the former and various factors that facilitate interest in the sport. A survey of literature on race theory and on leisure studies shows that four factors tied to collective identity influence African-American youths\u27 preference for basketball: encouragement by authority figures to pursue basketball, basketball\u27s portrayal as a form of expression and empowerment, the abundance of black role models in basketball, and the perception of basketball\u27s influence on social mobility. Future research should explore other cultural and social factors which predispose youth to favor certain sports

Analysis of nanopore detector measurements using Machine-Learning methods, with application to single-molecule kinetic analysis

<p>Abstract</p> <p>Background</p> <p>A nanopore detector has a nanometer-scale trans-membrane channel across which a potential difference is established, resulting in an ionic current through the channel in the pA-nA range. A distinctive channel current blockade signal is created as individually "captured" DNA molecules interact with the channel and modulate the channel's ionic current. The nanopore detector is sensitive enough that nearly identical DNA molecules can be classified with very high accuracy using machine learning techniques such as Hidden Markov Models (HMMs) and Support Vector Machines (SVMs).</p> <p>Results</p> <p>A non-standard implementation of an HMM, emission inversion, is used for improved classification. Additional features are considered for the feature vector employed by the SVM for classification as well: The addition of a single feature representing spike density is shown to notably improve classification results. Another, much larger, feature set expansion was studied (2500 additional features instead of 1), deriving from including all the HMM's transition probabilities. The expanded features can introduce redundant, noisy information (as well as diagnostic information) into the current feature set, and thus degrade classification performance. A hybrid Adaptive Boosting approach was used for feature selection to alleviate this problem.</p> <p>Conclusion</p> <p>The methods shown here, for more informed feature extraction, improve both classification and provide biologists and chemists with tools for obtaining a better understanding of the kinetic properties of molecules of interest.</p

The NTD Nanoscope: potential applications and implementations

<p>Abstract</p> <p>Background</p> <p>Nanopore transduction detection (NTD) offers prospects for a number of highly sensitive and discriminative applications, including: (i) single nucleotide polymorphism (SNP) detection; (ii) targeted DNA re-sequencing; (iii) protein isoform assaying; and (iv) biosensing via antibody or aptamer coupled molecules. Nanopore event transduction involves single-molecule biophysics, engineered information flows, and nanopore cheminformatics. The NTD Nanoscope has seen limited use in the scientific community, however, due to lack of information about potential applications, and lack of availability for the device itself. Meta Logos Inc. is developing both pre-packaged device platforms and component-level (unassembled) kit platforms (the latter described here). In both cases a lipid bi-layer workstation is first established, then augmentations and operational protocols are provided to have a nanopore transduction detector. In this paper we provide an overview of the NTD Nanoscope applications and implementations. The NTD Nanoscope Kit, in particular, is a component-level reproduction of the standard NTD device used in previous research papers.</p> <p>Results</p> <p>The NTD Nanoscope method is shown to functionalize a single nanopore with a channel current modulator that is designed to transduce events, such as binding to a specific target. To expedite set-up in new lab settings, the calibration and troubleshooting for the NTD Nanoscope kit components and signal processing software, the NTD Nanoscope Kit, is designed to include a set of test buffers and control molecules based on experiments described in previous NTD papers (the model systems briefly described in what follows). The description of the Server-interfacing for advanced signal processing support is also briefly mentioned.</p> <p>Conclusions</p> <p>SNP assaying, SNP discovery, DNA sequencing and RNA-seq methods are typically limited by the accuracy of the error rate of the enzymes involved, such as methods involving the polymerase chain reaction (PCR) enzyme. The NTD Nanoscope offers a means to obtain higher accuracy as it is a single-molecule method that does not inherently involve use of enzymes, using a functionalized nanopore instead.</p

Convection in nanofluids with a particle-concentration-dependent thermal conductivity

Thermal convection in nanofluids is investigated by means of a continuum model for binary-fluid mixtures, with a thermal conductivity depending on the local concentration of colloidal particles. The applied temperature difference between the upper and the lower boundary leads via the Soret effect to a variation of the colloid concentration and therefore to a spatially varying heat conductivity. An increasing difference between the heat conductivity of the mixture near the colder and the warmer boundary results in a shift of the onset of convection to higher values of the Rayleigh number for positive values of the separation ratio psi>0 and to smaller values in the range psi<0. Beyond some critical difference of the thermal conductivity between the two boundaries, we find an oscillatory onset of convection not only for psi<0, but also within a finite range of psi>0. This range can be extended by increasing the difference in the thermal conductivity and it is bounded by two codimension-2 bifurcations.Comment: 13 pages, 11 figures; submitted to Physical Review

Are Anti-Spit Tobacco Campaigns Striking Out? A Survey of Iowa and Nebraska College Baseball Players

This is the publisher's version, also available electronically from: http://digitalcommons.unl.edu/greatplainsresearch/842Anti-spit tobacco information is replete with fear appeals, including firsthand accounts of death and debilitation, to make users aware of the health risks and dangers. Those dangers, however, are well known by baseball players whose association with spit tobacco is historic. A survey of 217 Iowa and Nebraska college players showed that despite their awareness of spit tobacco's dangers, the players use spit tobacco to relax and focus on the field. This study supports other research showing that fear appeals may not be the most appropriate approach for anti-tobacco advertising campaigns. The study suggests that campaigns should promote relaxation and stress reduction techniques as alternatives to spit tobacco

Nebraska Immigration: Deliberative Polling and Civic Engagement on Broadcast and New Media Coverage

Data were analyzed from an October 2007 deliberative poll event in Omaha, Nebraska. The focus of pre-event survey questions was on the usefulness of media sources on the coverage of the global immigration issue. The goal of the project was to promote civic engagement of citizens on an important public issue. The focus of post-event survey questions was on attention paid to media. Additionally, a post-event focus group explored public opinion on credibility of various news sources. While the deliberative poll produced some evidence of short-term effects in terms of citizens learning about the immigration issue, attitudes about media credibility appeared to be well established before the event and based on personal experiences. These beliefs may also have influenced the course of dialogue within the deliberative poll event. The method proved valuable for exploring in-depth views about controversial issues