73 research outputs found
Can New Physics hide inside the proton?
Modern global analyses of the structure of the proton include collider
measurements which probe energies well above the electroweak scale. While these
provide powerful constraints on the parton distribution functions (PDFs), they
are also sensitive to beyond the Standard Model (BSM) dynamics if these affect
the fitted distributions. Here we present a first simultaneous determination of
the PDFs and BSM effects from deep-inelastic structure function data by means
of the NNPDF framework. We consider representative four-fermion operators from
the SM Effective Field Theory (SMEFT), quantify to which extent their effects
modify the fitted PDFs, and assess how the resulting bounds on the SMEFT
degrees of freedom are modified. Our results demonstrate how BSM effects that
might otherwise be reabsorbed into the PDFs can be systematically disentangled
Organic ionic plastic crystal nanofibre composites as solid state electrolytes
This thesis studies the ion conduction within the crystalline structure of the organic compounds known as ionic plastic crystals reinforced with electrospun polymer nanofibres, with the aim of utilizing the composite materials as solid-state electrolytes in lithium battery technology.<br /
The strangest proton?
We present an improved determination of the strange quark and antiquark parton distribution functions of the proton by means of a global QCD analysis that takes into account a comprehensive set of strangeness-sensitive measurements: charm-tagged cross sections for fixed-target neutrino–nucleus deep-inelastic scattering, and cross sections for inclusive gauge-boson production and W-boson production in association with light jets or charm quarks at hadron colliders. Our analysis is accurate to next-to-next-to-leading order in perturbative QCD where available, and specifically includes charm-quark mass corrections to neutrino–nucleus structure functions. We find that a good overall description of the input dataset can be achieved and that a strangeness moderately suppressed in comparison to the rest of the light sea quarks is strongly favored by the global analysis
Using statistical methods to determine spatio-temporal distribution of aphids and aphidophagous ladybirds in alfalfa fields
This study was conducted to determine distribution pattern and related parameters of spotted alfalfa aphid, Therioaphis maculata (Buckten), pea aphid, Acyrthosiphon pisum (Harris) and two coccinellid species (Coccinella septempunctata L. and Hippodamia variegata Goeze) in six alfalfa fields during two growing seasons, 2016 and 2017. Weekly sampling was started when alfalfa plants reached 10 cm in height and continued until harvest. Each field was divided into 20m×20m plots. Two samples per plot per sampling time were randomly taken using a 1 × 1 m quadrat, to count adult coccinellids. Twenty alfalfa stems (longer than 10cm) per plot were randomly cut and shaken eight times on a white pan to record the aphids' density. The aphids that fell into the pan were counted and recorded. The ratio of variance to mean, as well as Taylor’s power law (TPL) and Iwao’s patchiness index (IPI), were used to determine the spatial distribution patterns of the insects. The variance exceeded the mean on all sampling dates, which may imply an aggregative distribution. Aggregation was also confirmed by using regression coefficient of both TPL (parameter b) and coefficient of IPI (β), which both were significantly above unity. Correlation between aphid counts and those of the coccinellids indicated that there was a positive but weak relationship between predator and prey densities in the fields, although a weak correlation may imply that factors other than prey accessibility contribute to the spatial distribution of the predators. Using different statistical methods provides useful information about the spatial distribution and dispersal pattern of aphids and natural enemies in alfalfa fields, and this information can be used in the biological control of pests
Biological parameters of Trialeurodes vaporariorum (Hem.: Aleyrodidae) in four greenhouse cucumber cultivars
Greenhouse whitefly, Trialeurodes vaporariorum (Westwood), is an important pest of greenhouse throughout the world that causes serious damage on agricultural products. In this research, some biological parameters of the pest were studied in four cucumber cultivars (Royal Sluis, Soltan, Negin and Vida) at two heights (60 and 90 cm) in a greenhouse at 19-26 °C and 80% ± 5 RH. The developmental time of all immature stages were 27.49 ± 0.34, 28.23 ± 0.3, 26.63 ± 0.24 and 27.44 ± 0.3 days, in all cultivars, respectively, but it was slightly longer at the height of 90 cm compared to 60 cm (28.65 ± 0.24 vs. 26.43 ± 0.14 days, respectively). The preimaginal mortality percent ranged from 4 to 7% in different treatments, although this difference was not significant. Female longevities were 27.9 ± 0.67, 21.35 ± 0.34, 26.71 ± 0.6 and 22 ± 0.46 days in the cultivars, respectively (P < 0.01). It was also averaged as 23.29 ± 0.4 and 26.4 ± 0.66 days at both heights. The number of eggs / female were 203.82 ± 4.89, 132.26 ± 3.57, 210.68 ± 5.31 and 162.79 ± 5.15 in different cultivars with an average of 167.66 ± 5.68 and 187.98 ± 4.75 in 90 and 60 cm (P < 0.01). The sex ratio showed no significance among the cultivars at all heights
Effects of imidacloprid, indoxacarb and endosulfan on egg, third-instar larva and pupa of green lacewing Chrysoperla carnea (Neu.: Chrysopidae)
The common green lacewing is a known biocontrol agent because of its wide geographical distribution, high compatibility with different agricultural systems, high searching ability and ease of rearing. Adults and larvae were reared on artificial diet and eggs of Anagasta kuehniella (Zell.) respectively. The toxicity of insecticides was assessed on eggs (dipping method), third-instar larvae (contact method), and pupae (topical application) of Chrysoperla carnea Stephens. In order to study the sublethal effects, the third-instar larvae were treated with recommended field rate of each insecticide. The effects of the insecticides were assessed using demographic toxicology methods. Rearing conditions were 26 ± 2ºC, 60 ± 10% relative humidity and a photoperiod of 16: 8 h (L: D). The results revealed that the insecticides did not affect eggs even at doses higher than recommended field rates. The LD50 values, of endosulfan, imidacloprid and indoxacarb for pupal stage were estimated to be 144, 33, and 21 µg ai/insect respectively. Since the insecticides did not affect the third-instar larvae at the recommended field rate, the LC50 was not estimated for this stage. The results showed that, only net reproduction rate (R0) was significantly affected by treatments. The highest and lowest amounts of rm were 0.176 and 0.152 for control and indoxacarb treatmnets respectively. Based on both acute toxicity and demographic toxicology methods, the rate of toxicity of the tested insecticides was as follows: indoxacarb > endosulfan > imidacloprid
Importance of vegetation index in codling moth Cydia pomonella distribution modeling
Codling moth, Cydia pomonella L. (Lepidoptera: Tortricidae) is the key insect pest of apple orchards in Iran. This study was conducted in the main apple-growing regions of East Azarbaijan Province to generate potential habitat suitability maps of C. pomonella using MaxEnt modeling and to determine the importance of vegetation index in improving the accuracy of these models. Field surveys for collecting the occurrence data of codling moth were conducted during three growing seasons, 2017 - 2019. The activity of codling moth adult males was monitored using delta-shaped traps baited with female sex pheromone. Fifteen environmental variables were considered as potential predictors for estimating codling moth distribution. These variables were categorized into topographic, climatic, and remote sensing variables. A MaxEnt modeling algorithm was used to predict the distribution of codling moth. Model performance was evaluated using the area under the receiver operating characteristic curve (AUC). By using the topographic, climatic, and topographic+climatic variables, the AUC values were 0.840, 0.951, and 0.938, respectively. The model including normalized difference vegetation index (NDVI) had the highest AUC value (0.99), which strongly supports model predictive power and indicates the importance of vegetation index in codling moth distribution modeling. NDVI was the most contributed variable in the model followed by precipitation of September, slope, minimum temperature of May, and mean temperature of April. The distribution map obtained in MaxEnt provides an important tool for identifying potential risk zones of codling moth. This map can assist managers in forecasting and planning control measures and therefore, effective management of current infestations of codling moth
Lethal and sublethal effects of endosulfan, imidacloprid and indoxacarb on first instar larvae of Chrysoperla carnea (Neu.: Chrysopidae) under laboratory conditions
The common green lacewing is an important natural enemy used for pest control in greenhouses. It is also very common in many agricultural systems. Hence, studying lethal and sublethal effects of insecticides on this predator would be useful. Toxicity of endosulfan, imidacloprid and indoxacarb was assessed on 1st instar larvae of Chrysoperla carnea (Stephens) in laboratory. Residual bioassays were carried out in glass Petri dishes. The LC50 values, for endosulfan, imidacloprid and indoxacarb were estimated 251, 24.6 and 133 mg ai/l, respectively. Imidacloprid was the most toxic among insecticides tested. To assess the sublethal effects, the 1st instars were treated with LC25 of each insecticide. Thereafter, these effects were studied using fertility life table experiments. The analysis of variance revealed significant difference between treatments and control with respect to developmental time of the 1st instar larvae. However, no significant difference was observed among endosulfan, imidacloprid and indoxacarb treatments considering the larval developmental time. Differences between treatments and control were not significant for the developmental time of the 2nd and 3rd instars, pupae, sex ratio, adult longevity, and adult fertility. The results showed that only net reproduction rate (R0) was significantly affected by treatments. The gross reproductive rate (GRR), intrinsic rate of increase (rm), doubling time (DT), mean generation time (T) and finite rate of increase (λ) were not affected. The highest and the lowest amounts of rm were 0.178 and 0.169 in control and indoxacarb, respectively. Imidacloprid was the most toxic of the insecticides tested on the 1st instar followed by indoxacarb and endosulfan. If results similar to laboratory findings are obtained in field conditions, these insecticides might be appropriate candidates for IPM programs
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The strangest proton?
Abstract: We present an improved determination of the strange quark and antiquark parton distribution functions of the proton by means of a global QCD analysis that takes into account a comprehensive set of strangeness-sensitive measurements: charm-tagged cross sections for fixed-target neutrino–nucleus deep-inelastic scattering, and cross sections for inclusive gauge-boson production and W-boson production in association with light jets or charm quarks at hadron colliders. Our analysis is accurate to next-to-next-to-leading order in perturbative QCD where available, and specifically includes charm-quark mass corrections to neutrino–nucleus structure functions. We find that a good overall description of the input dataset can be achieved and that a strangeness moderately suppressed in comparison to the rest of the light sea quarks is strongly favored by the global analysis
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