Genres of Spam

Spam is currently the dominant form of communications on the internet, accounting for most e-mail traffic. Spam is a marketing device, it is also an expensive and time-consuming nuisance for industrires as well as a major vehicle for serious internet crimes. While considerable research has focused on the technical aspects of spam, how it works and how it can be blocked, our research aims to better understand why it works. We explore how genre theory can contribute to our understanding of ‘spam’. Our study consists of two parts. The first examined the content, form and specific features and considered the manifest relationship to existing genres of communication. The second part of the study focused on a detailed analysis of 111 Nigerian letters, a particularly noxious form of spam. Genre is generally considered useful because it makes communications more recognizable and understandable to recipients, helping readers process information. Our study suggests that spam is not a single genre but adaptations of many recognizable print genres. With spam, genre operates at several levels and is often used to mask rather than reveal intent. The paper concludes that spam exploits genre by conforming to known forms while at the same time breaching those norms

Effect of water availability on changes in root amino acids and associated rhizospere on root exudation of amino acids in Pisum sativum L

Root exudation is considered to regulate the abundance of the microbial community. It may vary both qualitatively and quantitatively in response to the environment in which the plant is growing. A part of exuded N derives from amino acids (AAs). This, in turn, may help plants to cope with abiotic stresses by favouring positive interactions with the rhizosphere environment, thus playing a potential role in maintaining healthy plants. In this respect, an under-investigated area is the effect of stress due to water deficit (WD). It is proposed that the AA profile in the rhizosphere may be altered by WD, reflecting a modulation of root AA exudation linked to a physiological response of the plant to water stress. To investigate this, Pisum sativum L. plants, grown in unsterilised Rhizobium leguminosarum-enriched soil, were stem-labelled with 15N-urea for 96 h, and then subjected/not subjected to 72 h of WD. The concentrations and abundance of 15N-labelling in individual AAs were determined in both roots and the associated rhizosphere at 24, 48 and 72 h after stress application. It was found that both AAs metabolism in the pea root and AAs exudation were strongly modified in WD conditions. After 24 h of WD, the concentrations of all measured AAs increased in the roots, accompanied by a dramatic stress-related increase in the 15N-labelling of some AAs. Furthermore, after 48–72 h of WD, the concentrations of Pro, Ala and Glu increased significantly within the rhizosphere, notably with a concomitant increase in 15N-enrichment in Pro, Ser, Asn, Asp, Thr and Ile. These results support the concept that, in response to WD, substantial amounts of recently assimilated N are rapidly translocated from the shoots to the roots, a portion of which is exuded as AAs. This leads to the rhizosphere being relatively augmented by specific AAs (notably HSer, Pro and Ala) in WD conditions, with a potential impact on soil water retention

Article Are Hydrogen Bonds Unique among Weak Interactions in Their Ability to Mediate Electronic Coupling?

Superexchange effects on the electronic coupling element for electron transfer are investigated using water dimers and atomic donors and acceptors. We compare the electronic coupling elements obtained with H-bonded dimers to those obtained for other water dimer geometries at given donor−acceptor and oxygen−oxygen distances. The H-bonded orientation does not yield significantly different coupling elements from non-H-bonded orientations at a given oxygen−oxygen distance. In addition, the distance dependence of the coupling mediated by H-bonds is not significantly different from that for other dimer geometries. It is found that protonation of the intervening waters has a significant effect on coupling elements for donor/acceptor pairs with low ionization potentials. The implications of these results are discussed for condensed-phase ground- and excited-state electron transfers

Dynamics of spin-2 Bose condensate driven by external magnetic fields

Dynamic response of the F=2 spinor Bose-Einstein condensate (BEC) under the influence of external magnetic fields is studied. A general formula is given for the oscillation period to describe population transfer from the initial polar state to other spin states. We show that when the frequency and the reduced amplitude of the longitudinal magnetic field are related in a specific manner, the population of the initial spin-0 state will be dynamically localized during time evolution. The effects of external noise and nonlinear spin exchange interaction on the dynamics of the spinor BEC are studied. We show that while the external noise may eventually destroy the Rabi oscillations and dynamic spin localization, these coherent phenomena are robust against the nonlinear atomic interaction.Comment: 16 pages, 7 figures. accepted by Phys. Rev.

Microscopic Derivation of Non-Markovian Thermalization of a Brownian Particle

In this paper, the first microscopic approach to the Brownian motion is developed in the case where the mass density of the suspending bath is of the same order of magnitude as that of the Brownian (B) particle. Starting from an extended Boltzmann equation, which describes correctly the interaction with the fluid, we derive systematicaly via the multiple time-scale analysis a reduced equation controlling the thermalization of the B particle, i.e. the relaxation towards the Maxwell distribution in velocity space. In contradistinction to the Fokker-Planck equation, the derived new evolution equation is non-local both in time and in velocity space, owing to correlated recollision events between the fluid and particle B. In the long-time limit, it describes a non-markovian generalized Ornstein-Uhlenbeck process. However, in spite of this complex dynamical behaviour, the Stokes-Einstein law relating the friction and diffusion coefficients is shown to remain valid. A microscopic expression for the friction coefficient is derived, which acquires the form of the Stokes law in the limit where the mean-free in the gas is small compared to the radius of particle B.Comment: 28 pages, no figure, submitted to Journal of Statistical Physic

Amino acid fingerprint in the rhizosphere of Pisum sativum in response to water stress

In cropping systems, legumes release substantial amounts of nitrogen (N) into the soil, via rhizodeposition, and constitute a sustainable source of N, instead of synthetic N fertilisers (Fustec et al. 2010). More frequent or/and intense droughts and floodings, due to climate change and intensification of agriculture, may affect N rhizodeposition (Preece & Peñuelas 2016). However, the effects of water stress on this process are poorly documented. A part of N derived from root exudates, mainly in amino acids (AAs) form, is suspected shape and regulate rhizosphere microbial community, thus playing a potential role in maintaining plant health in case of abiotic stress (Moe 2013). We hypothesized that root AA exudation could change significantly, according to water availability, and would help to understand N metabolism changes in plant-rhizosphere interactions. Because studying exudation from plant grown in unsterilized soil is challenging (Oburger et al. 2013), we have measured the rhizosphere AA fingerprint (RAAF), as the result of interactions between AA exudation and rhizospheric environment. In addition, plants were stem-labeled (cotton-wick) with 15N-urea for 72 h to provide direct evidence of a link between root AA and exudation in the soil. The RAAF was measured in Pisum sativum rhizosphere, under either a water deficit or a water excess for 72 h. Water deficit decreases biomass accumulation in shoots but not in roots. Then, water deficit had no significant effect on total AAs released into the rhizosphere but, it significantly modified the composition of RAAF, with a preferential increase of proline, alanine and glutamate and a rise in isotopic enrichment of AAs derived from oxaloacetate in tricarboxylic acidic cycle (asparagine, aspartate, threonine and isoleucine). These results support the idea that, under the early stages of water deficit, recently assimilated N is rapidly translo-cated to the roots, and part of it is exudated in AAs. Most of the exudated AAs are known to have a specific role in increasing the water holding capacity around the root and to favour the establishment of positive interactions with plant-growth promoting bacteria (Apostel et al. 2013, Hinsinger et al. 2003). A study aimed at establishing a better understanding of the relationship between microorganisms and AA release under water deficit is now necessary

Effects of a Protein Preload on Gastric Emptying, Glycemia, and Gut Hormones After a Carbohydrate Meal in Diet-Controlled Type 2 Diabetes

OBJECTIVE: We evaluated whether a whey preload could slow gastric emptying, stimulate incretin hormones, and attenuate postprandial glycemia in type 2 diabetes. RESEARCH DESIGN AND METHODS: Eight type 2 diabetic patients ingested 350 ml beef soup 30 min before a potato meal; 55 g whey was added to either the soup (whey preload) or potato (whey in meal) or no whey was given. RESULTS: Gastric emptying was slowest after the whey preload (P < 0.0005). The incremental area under the blood glucose curve was less after the whey preload and whey in meal than after no whey (P < 0.005). Plasma glucose-dependent insulinotropic polypeptide, insulin, and cholecystokinin concentrations were higher on both whey days than after no whey, whereas glucagon-like peptide 1 was greatest after the whey preload (P < 0.05). CONCLUSIONS: Whey protein consumed before a carbohydrate meal can stimulate insulin and incretin hormone secretion and slow gastric emptying, leading to marked reduction in postprandial glycemia in type 2 diabetes.Jing Ma, Julie E. Stevens, Kimberly Cukier, Anne F. Maddox, Judith M. Wishart, Karen L. Jones, Peter M. Clifton, Michael Horowitz, and Christopher K. Rayne

Phase diffusion as a model for coherent suppression of tunneling in the presence of noise

We study the stabilization of coherent suppression of tunneling in a driven double-well system subject to random periodic $\delta-$function ``kicks''. We model dissipation due to this stochastic process as a phase diffusion process for an effective two-level system and derive a corresponding set of Bloch equations with phase damping terms that agree with the periodically kicked system at discrete times. We demonstrate that the ability of noise to localize the system on either side of the double-well potenital arises from overdamping of the phase of oscillation and not from any cooperative effect between the noise and the driving field. The model is investigated with a square wave drive, which has qualitatively similar features to the widely studied cosinusoidal drive, but has the additional advantage of allowing one to derive exact analytic expressions.Comment: 17 pages, 4 figures, submitted to Phys. Rev.

Heating and decoherence suppression using decoupling techniques

We study the application of decoupling techniques to the case of a damped vibrational mode of a chain of trapped ions, which can be used as a quantum bus in linear ion trap quantum computers. We show that vibrational heating could be efficiently suppressed using appropriate ``parity kicks''. We also show that vibrational decoherence can be suppressed by this decoupling procedure, even though this is generally more difficult because the rate at which the parity kicks have to applied increases with the effective bath temperature.Comment: 13 pages, 5 figures. Typos corrected, references adde

Photoabsorption and photoion spectroscopy of atomic uranium in the region of 6p and 5d excitations

The photoabsorption process in atomic uranium has been investigated experimentally and theoretically in the 15–150-eV region. Using the dual laser plasma technique, the 6p photoabsorption spectrum has been recorded while for the first time the 5d region has been remeasured photoelectrically using both photoabsorption and photoion spectroscopy. Interpretation of the photoabsorption spectra is supported by Hartree-Fock calculations which take into account spin-flip decay and the interaction of many discrete states with many continua. The 6p spectrum is entirely dominated by spin-orbit split 6p⃗6d transitions. The 5d-subshell photoabsorption is shown to consist predominantly of discrete 5d⃗5f excitations; here the electrostatic and spin-orbit interactions are comparable in strength