The role of abscisic acid and water relations in drought responses of subterranean clover

The role of water relations and abscisic acid (ABA) in the responses to drought were studied in a mediterranean forage crop, Trifolium subterraneum L. under field conditions. soil and plant water status, leaf gas exchange parameters, and xylem sap ABA content were determined at different times during a long-term soil drying episode in irrigated and droughted plants. The diurnal time-courses of these parameters were also measured at the end of a drought period. In response to soil drying stomatal conductance (g) was reduced early to 50% that of irrigated plants before any substantial change in water potential was detected. A close logarithmic regression between photosynthesis rate (A) and g was present. For the first weeks of drought the decline in A was less pronounced than in g, thus increasing water use efficiency. Stomatal conductance during diurnal time-courses showed no consistent relationships with respect to either ABA or leaf water potential. throughout the experimental period dependence of g on leaf water status was evident from the tight correlation (r(2) = 0.88, P < 0.01) achieved between stomatal conductance and midday water potential, but the correlation was also high when comparing g with respect to ABA content in xylem sap (r(2) = 0.83, P < 0.001). However, the stomata from drought acclimated plants were apparently more sensitive to xylem ABA content. For similar xylem ABA concentrations stomatal conductance was significantly higher in irrigated than in water-stressed plants.info:eu-repo/semantics/publishedVersio

Aegithus clavicornis (Linnaeus) (Coleoptera: Erotylidae) in the Dominican Republic

Establishment of fungus beetles (Coleoptera: Erotylidae) in new isolated countries is rare. We report Aegithus clavicornis (Linnaeus) for the first time from the Dominican Republic, representing the first true record for this genus from the Greater Antilles

The Two-Dimensional Stringy Black-Hole: A New Approach and a Pathology

The string propagation in the two-dimensional stringy black-hole is investigated from a new approach. We completely solve the classical and quantum string dynamics in the lorentzian and euclidean regimes. In the lorentzian case all the physics reduces to a massless scalar particle described by a Klein-Gordon type equation with a singular effective potential. The scattering matrix is found and it reproduces the results obtained by coset CFT techniques. It factorizes into two pieces : an elastic coulombian amplitude and an absorption part. In both parts, an infinite sequence of imaginary poles in the energy appear. The generic features of string propagation in curved D-dimensional backgrounds (string stretching, fall into spacetime singularities) are analyzed in the present case. A new physical phenomenon specific to the present black-hole is found : the quantum renormalization of the speed of light. We find c_{quantum} = \sqrt{{k\o{k-2}}}~c_{classical}, where $k$ is the integer in front of the WZW action. This feature is, however, a pathology. Only for $k \to \infty$ the pathology disappears (although the conformal anomaly is present). We analyze all the classical euclidean string solutions and exactly compute the quantum partition function. No critical Hagedorn temperature appears here.Comment: 32 pages, uses phyzz

Semiclassical (QFT) and Quantum (String) Rotating Black Holes and their Evaporation: New Results

Combination of both quantum field theory (QFT) and string theory in curved backgrounds in a consistent framework, the string analogue model, allows us to provide a full picture of the Kerr-Newman black hole and its evaporation going beyond the current picture. We compute the quantum emission cross section of strings by a Kerr-Newmann black hole (KNbh). It shows the black hole emission at the Hawking temperature T_{sem} in the early evaporation and the new string emission featuring a Hagedorn transition into a string state of temperature T_ s at the last stages. New bounds on the angular momentum J and charge Q emerge in the quantum string regime. The last state of evaporation of a semiclassical KNbh is a string state of temperature T_s, mass M_s, J = 0 = Q, decaying as a quantum string into all kinds of particles.(There is naturally, no loss of information, (no paradox at all)). We compute the microscopic string entropy S_s(m, j) of mass m and spin mode j. (Besides the usual transition at T_s), we find for high j, (extremal string states) a new phase transition at a temperature T_{sj} higher than T_s. We find a new formula for the Kerr black hole entropy S_{sem}, as a function of the usual Bekenstein-Hawking entropy . For high angular momentum, (extremal J = GM^2/c), a gravitational phase transition operates and the whole entropy S_{sem} is drastically different from the Bekenstein-Hawking entropy. This new extremal black hole transition occurs at a temperature T_{sem J} higher than the Hawking temperature T_{sem}.Comment: New articl

Drought effects on water flow, photosynthesis and growth of potted grapevines

In two consecutive years and under different environmental conditions, leaf gas exchange, sap flow and trunk diameter were measured to estimate transpiration of grapevine. Daily maxima of sap flow were lower than estimations obtained by gas exchange measurements. Sap flow was delayed with regard to variation of irradiance. For irrigated plants the correlation between transpiration rates of single leaves as determined by gas exchange and instantaneous sap flow was high (r2=0.84). However, the correlation of sap flow with the total daily water consumption was even higher (r2=0.98) and close to 1:1. At various water states, leaf photosynthetic rate was also correlated with sap flow (r2=0.78); the correlation coefficient increased to r2=0.91 when the daily balance was compared. Plant growth, estimated from linear variable displacement transducers was closely related to the daily sap flow.

Equatorial ozone characteristics as measured at Natal (5.9 deg S, 35.2 deg W)

Ozone density profiles obtained through electrochemical concentration cell (ECC) sonde measurements at Natal were analyzed. Time variations, as expected, are small. Outstanding features of the data are tropospheric densities substantially higher than those measured at other stations, and also a total ozone content that is higher than the averages given by satellite measurements

Wearable sensors for measuring movement in short sessions of mindfulness sitting meditation: A pilot study

Mindfulness techniques are useful tools in health and well-being. To improve and facilitate formal training, beginners need to know if they are in a stable sitting posture and if they can hold it. Previous monitoring studies did not consider stability during sitting meditation or were specific for longer traditional practices. In this paper, we have extended and adapted previous studies to modern mindfulness practices and posed two questions: (a) Which is the best meditation seat for short sessions? In this way, the applications of stability measures are expanded to meditation activities, in which the sitting posture favors stability, and (b) Which is the most sensitive location of an accelerometer to measure body motion during short meditation sessions? A pilot study involving 31 volunteers was conducted using inertial sensors. The results suggest that thumb, head, or infraclavicular locations can be chosen to measure stability despite the habitual lumbar or sacral region found in the literature. Another important finding of this study is that zafus, chairs, and meditation benches are suitable for short meditation sessions in a sitting posture, although the zafu seems to allow for fewer postural changes. This finding opens new opportunities to design very simple and comfortable measuring systems

Distribution of leaf photosynthesis and transpiration within grapevine canopies under different drought conditions

The effects of seasonal drought on the distribution of leaf area, photosynthesis and transpiration within the canopy were evaluated for two Spanish grapevine cultivars. Both varieties were cultivated according to their typical training system.At early stages of drought, reduction of photosynthesis and transpiration was only observed in sun-exposed leaves. As drought intensified, even less sun-exposed leaves were affected. Severe drought reduced photosynthesis and transpiration in all locations of the canopy except for most shaded leaves in the inner part. However, those leaves were almost unproductive, and seemed to be insensitive to variation of both light intensity and drought. Leaf area was also reduced by drought, but the distribution of these reductions within the canopy differed between cultivars, possibly reflecting differences in the training system.Leaves from all locations of the canopy except those in the central part showed a similar radiation use efficiency, suggesting that the observed variation in photosynthesis within the canopy was mostly related to different light interception, while other factors such as different leaf age should play only a minor role. Photosynthetic radiation use efficiency strongly depended on both, pre-dawn leaf water potential and light-saturated stomatal conductance. The interest of these results for modeling purposes is discussed.

Deducing signaling pathways from parallel actions of arsenite and antimonite in human epidermal keratinocytes.

Inorganic arsenic oxides have been identified as carcinogens in several human tissues, including epidermis. Due to the chemical similarity between trivalent inorganic arsenic (arsenite) and antimony (antimonite), we hypothesized that common intracellular targets lead to similarities in cellular responses. Indeed, transcriptional and proteomic profiling revealed remarkable similarities in differentially expressed genes and proteins resulting from exposure of cultured human epidermal keratinocytes to arsenite and antimonite in contrast to comparisons of arsenite with other metal compounds. These data were analyzed to predict upstream regulators and affected signaling pathways following arsenite and antimonite treatments. A majority of the top findings in each category were identical after treatment with either compound. Inspection of the predicted upstream regulators led to previously unsuspected roles for oncostatin M, corticosteroids and ephrins in mediating cellular response. The influence of these predicted mediators was then experimentally verified. Together with predictions of transcription factor effects more generally, the analysis has led to model signaling networks largely accounting for arsenite and antimonite action. The striking parallels between responses to arsenite and antimonite indicate the skin carcinogenic risk of exposure to antimonite merits close scrutiny

Effect of Host Plant on the Level of Virulence of \u3ci\u3eNilaparvata lugens\u3c/i\u3e (Homoptera: Delphacidae) on Rice Cultivars

The virulence of a planthopper, Nilaparvata lugens (Stål) biotype 3, reared on rice cultivar ASD7and of N. lugens colonies collected on Mindanao Island in the southern Philippines and reared on the widely grown commercial cultivars IR36 and IR42 was compared. Based on plant damage, insect weight, population growth, and feeding activity, the Mindanao N. lugens colonies reared on IR36 and IR42 were more virulent than biotype 3, although ASD7, IR36, and IR42 have the bph2 gene for N. lugens resistance. These results clearly indicate that in the screening of breeding lines for resistance to N. lugens, it is important to use insect populations reared on cultivars similar to those grown in farmers’ fields. Failure to do so may result in the release of a cultivar that is susceptible to the N. lugens field population