Variational Approach for the Effects of Periodic Modulations on the Spectrum of Massless Dirac Fermion

In the variational framework, we study the electronic energy spectrum of massless Dirac fermions of graphene subjected to one-dimensional oscillating magnetic and electrostatic fields centered around a constant uniform static magnetic field. We analyze the influence of the lateral periodic modulations in one direction, created by these oscillating electric and magnetic fields, on Dirac like Landau levels depending on amplitudes and periods of the field modulations. We compare our theoretical results with those found within the framework of non-degenerate perturbation theory. We found that the technique presented here yields energies lower than that obtained by the perturbation calculation, and thus gives more stable solutions for the electronic spectrum of massless Dirac fermion subjected to a magnetic field perpendicular to graphene layer under the influence of additional periodic potentials.Comment: 8 pages, 7 figure

Boundaries of Subcritical Coulomb Impurity Region in Gapped Graphene

The electronic energy spectrum of graphene electron subjected to a homogeneous magnetic field in the presence of a charged Coulomb impurity is studied analytically within two-dimensional Dirac-Weyl picture by using variational approach. The variational scheme we used is just based on utilizing the exact eigenstates of two-dimensional Dirac fermion in the presence of a uniform magnetic field as a basis for determining analytical energy eigenvalues in the presence of an attractive/repulsive charged Coulomb impurity. This approach allows us to determine under which conditions bound state solutions can or can not exist in gapped graphene in the presence of magnetic field. In addition, the effects of uniform magnetic field on the boundaries of subcritical Coulomb impurity region in the massless limit are also analyzed. Our analytical results show that the critical impurity strength decreases with increasing gap/mass parameter, and also that it increases with increasing magnetic field strength. In the massless limit, we investigate that the critical Coulomb coupling strength is independent of magnetic field, and its upper value for the ground-state energy is 0.752.Comment: 9 pages,10 figure

Evaluation of metabolic profiles of Saanen goats in the transition period

ΔΕΝ ΔΙΑΤΙΘΕΤΑΙ ΠΕΡΙΛΗΨΗHealthy Saanen goats (n=30) in periparturient period were used in the present study. Blood samples were collected 21, 14 and 7 days before parturition, at the time of birth and postpartum days 7, 14 and 21. Non-esterifiedfatty acids (NEFA), betahydroxy butyric acid (BHBA), Total protein (TP), albumin (ALB), blood urea nitrogen (BUN), creatinine (CREA) aspartate amino transferase (AST), gamma glutamyl transferase (GGT), sorbitol dehydrogenase (SDH), glucose (GLU), cholesterol (CHOL), triglyceride (TG), calcium (Ca), phosphorus (P), and magnesium (Mg) levels were evaluated. During the study period, NEFA, SDH, CREA levels increased and CHOL and TG levels decreased at time of parturition. When the changes of parameters in prepartum and postpartum period were compared, the concentrations of NEFA, CHOL, GLU, TG, Ca were higher (p <0.001) in prepartum period;however BHBA, Mg, ALB, GGT, AST, TP, P, BUN, SDH and CREA concentrations were detected to be higher (p <0.001) in postpartum period. Metabolic Profile Test based on biochemical parameters evaluated in our study would be beneficial for diagnosis, prevention and control of diseases such as pregnancy toxemia, hypocalcemia, infertility in goats

Resolving genetic relationships in manna group of lichens from genus Aspicilia

As in many lichen-forming fungi, species of Aspicilia genus are widely distributed all over the world, but no reports exist about their phylogenetic relations based on molecular biological methods. In thecurrent study the phylogenetic relations of some Aspicilia species mainly manna group of lichens were investigated. The ITS rDNA sequence information of 12 samples from six species were generated. The samples examined were collected from different provinces of Anatolia and all the sequences were aligned with the other allied groups; Pertusaria sp., Thamnolia sp., Dibaeis sp., Diploschistes sp.,Ochrolechia sp. and Lecanora sp. sequence data obtained from GenBank. The phylogenetic tree obtained by minimum evolution analysis displayed two major branches. One of the branches with itssix members (Aspicilia contorta subsp. contorta, A. contorta subsp. hoffmanniana, Aspicilia hispida, Aspicilia fruticulosa, Aspicilia desertorum Aspicilia calcarea) composed solely of Aspicilia samplesfrom Anatolia. Three of the manna groups of lichens were placed in this branch of the tree. The other related taxa from Ostropomycetidae and Lecanoromycetidae took place in the other branch of the treewith Aspicilia samples from Anatolia. Results displayed that manna group of lichens, although do not represent taxonomical unit tend to form a group especially apperent by the Neigbour Joining analysiswith Anatolian samples. Also the sequence information from Anatolian samples displayed that Aspicilia genus is phylogenetically closer to the orders and families from Ostropomycetidae subclass rather than Lecanoromycetidae which support the placement of Hymeneliaceae within Ostropomycetidae

Structural, electronic and phononic properties of PtSe2: From monolayer to bulk

The layer dependent structural, electronic and vibrational properties of the 1T phase of two dimensional (2D) platinum diselenide are investigated by means of state-of-the-art first-principles calculations. The main findings of the study are: (i) monolayer platinum diselenide has a dynamically stable 2D octahedral structure with 1.66 eV indirect band gap, (ii) the semiconducting nature of 1T-PtSe2 monolayers remains unaffected even at high biaxial strains, (iii) top-to-top (AA) arrangement is found to be energetically the most favorable stacking of 1T-PtSe2 layers, (iv) the lattice constant (layer-layer distance) increases (decreases) with increasing number of layers, (v) while monolayer and bilayer 1T-PtSe2 are indirect semiconductors, bulk and few-layered 1T-PtSe2 are metals, (vi) Raman intensity and peak positions of the A1g and Eg modes are found to be highly dependent on the layer thickness of the material, hence; the number of layers of the material can be determined via Raman measurements.TUBITAK under the project number 117F09

Human System Engineering Applications from Distracted Driving Simulations

Most of the studies to explore the impact of distracted driving have been descriptive in nature; i.e. the research is conducted in naturalistic settings to evaluate the performance of the driver with and without distracters. However simulation models can also be used that predict the workload for driving tasks. Using concepts from process modeling, baseline models of driving tasks can be created for different driving sequences that include the associated fine motor, visual and cognitive human resources. These models can then be used to evaluate incidents of workload overload caused by different distracters, from both the internal and external vehicle environment. Identifying specific overloaded resources can lead to mitigation strategies to reduce workload and minimize distracted driving. Lessons learned from distracted driving research can then be applied to evaluation other types of manual, visual, and cognitive intensive tasks. Identifying combinations of tasks that contribute to peak workload of operators, and then simulating the impact of multi-tasking using personal devices (i.e. cell phones) can lead to management insights for other types of work environments. Additionally, iterative modeling can also include the impact of sensors and alerts, as well as enhanced workstation displays. Individual component overload can help understand causes for performance detriments during different task sequences, and the impact of additional types of technologies and activities. Using the simulation analysis, the impact on overall workload, identification of peak workload occurrences, and specific overloaded resources can lead to mitigation strategies to reduce workload and improve operator performance