Numerical Analysis and Measurement of Electric field Strength inside GTEM Cell at GSM Frequencies

A miniaturised gigahertz transverse electromagnetic (GTEM) cell is designed and fabricated to generate uniform electric (E-) field, essential for studying the radio frequency exposure effect on tissue equivalent liquids at global system for mobile (GSM) communication frequencies (914 MHz and 2.10 GHz). The simulation procedure is discussed and its results are compared with measurement data. The E-field strength inside the GTEM cell is scanned using a microstrip based E-field probe and complete uncertainty evaluation procedure is discussed. Theoretically, simulated and measured E-field strength is reported with expanded uncertainty

Total Radiated Power Measurement in an Uncalibrated Reverberation Chamber

With the increased use of wireless communication in recent years, the use of reverberation chamber (RC) has increased to a great extent. Reverberation chambers have been eminently used for EMC testing and shielding effectiveness. The environment it provides is very similar to the reverberant surroundings that antenna undergoes in real life use. An experiment to measure total radiated power of antenna, antenna efficiency and quality factor of chamber in indoor environment is proposed. This will make the measurement very simple and inexpensive as designing and calibration of chamber will not be needed. In this paper, we have used three different techniques to compare total radiated power, quality factor, Rician K factor and efficiency of a patch antenna measured in indoor environment with RC data. The three method used include plate stirring method and two time domain methods. The time domain methods use modulated pulse and Gaussian pulse respectively for the measurement. The antenna and chamber parameters are measured in the real time and the data matched well with the RC data for different techniques

Spectroscopic study of binding of a cationic Pheophorbide-a to an antiparallel quadruplex Tel22

Aim. To study the binding of a water-soluble cationic Pheophorbide-a derivative (CatPheo-a) ta a Na+–stabilized antiparallel quadruplex formed by 22-mer oligonucleotide d[AG3(T2AG3)3] of the human DNA telomeric sequence (Tel22, PDB ID: 143D). Methods. Absorption and polarized fluorescence spectroscopy were used to determine the properties of DNA–ligand complexes. Fluorescence titration was applied to evaluate the Tel22 dye binding affinity. Absorption melting was used to estimate the effect of CatPheo-a on thermodynamic parameters of the Tel22 quadruplex folding. IR spectroscopy was used to detect singlet oxygen generation . Results. CatPheo-a was found to bind effectively to the Tel22 quadruplex via two competitive binding modes, which are characterized by opposite changes in the dye fluorescence. The spectroscopic properties of CatPheo-a + Tel22 complexes were determined. Thermodynamic parameters of the Tel22 quadruplex folding with/without CatPheo-a were calculated. Conclusions. CatPheo-a destabilizes the quadruplex structure of Tel22 with a two-fold decrease in the equilibrium quadruplex folding constant at 37°C. The efficiency of singlet oxygen generation by CatPheo-a is higher than that by the anionic Pheo-a.Мета. Дослідити зв’язування водорозчинної катіонної похідної Феофорбіду-a (CatPheo-a) з Na+–стабілізованим антипаралельним квадруплексом, утвореним 22-мерним олігонуклеотидом d[AG3(T2AG3)3] теломерної послідовності ДНК людини (Tel22, PDB ID: 143D). Методи. Абсорбційна та поляризована флуоресцентна спектроскопія були застосовані для визначення властивостей комплексів ДНК–ліганд. Флуоресцентне титрування використовували для оцінки аффінності зв’язування барвника з Tel22. Абсорбційне плавлення було застосоване для оцінки впливу CatPheo-a на термодинамічні параметри формування квадруплексу Tel22. ІЧ-спектроскопію використовували для виявлення генерації синглетного кисню. Результати. Встановлено, що CatPheo-a ефективно зв’язується з квадруплексом Tel22 шляхом двох конкуруючих типів зв’язування, які характеризуються протилежними змінами флуоресценції барвника. Визначені спектроскопічні властивості комплексів CatPheo-a + Tel22. Розраховані термодинамічні параметри формування Tel22 квадруплексу з/без CatPheo-a. Висновки. Виявлено, що CatPheo-a дестабілізує структуру квадруплекса Tel22, знижуючи в 2 рази рівноважну константу його утворення при 37°C. Ефективність генерації синглетного кисню CatPheo-a вища, ніж у аніонного Pheo-a.Цель. Изучить связывание водорастворимого катионного производного Феофорбида-a (CatPheo-a) с Na+–стабилизированным антипараллельным квадруплексом, образованным 22-мерным олигонуклеотидом d[AG3(T2AG3)3] теломерной последовательности ДНК человека (Tel22, PDB ID: 143D). Методы. Абсорбционная и поляризованная флуоресцентная спектроскопия были применены для установления свойств комплексов ДНК–лиганд. Флуоресцентное титрование применяли для оценки аффинности связывания красителя с Tel22. Абсорбционное плавление было использовано для оценки влияния CatPheo-a на термодинамические параметры формирования квадруплекса Tel22. ИК-спектроскопию применяли для обнаружения генерации синглетного кислорода. Результаты. Установлено, что CatPheo-a эффективно связывается с квадруплексом Tel22 посредством двух конкурирующих типов связывания, которые характеризуются противоположными изменениями флуоресценции красителя. Определены спектроскопические свойства комплексов CatPheo-a + Tel22. Рассчитаны термодинамические параметры формирования Tel22 квадруплекса с/без CatPheo-a. Выводы. Установлено, что CatPheo-a дестабилизирует структуру квадруплекса Tel22, снижая в 2 раза равновесную константу его образования при 37°C. Эффективность генерации синглетного кислорода CatPheo-a выше, чем у анионного Pheo-a

Search for Higgs bosons decaying to tautau pairs in ppbar collisions at sqrt(s) = 1.96 TeV

We present a search for the production of neutral Higgs bosons decaying into tautau pairs in ppbar collisions at a center-of-mass energy of 1.96 TeV. The data, corresponding to an integrated luminosity of 5.4 fb-1, were collected by the D0 experiment at the Fermilab Tevatron Collider. We set upper limits at the 95% C.L. on the product of production cross section and branching ratio for a scalar resonance decaying into tautau pairs, and we then interpret these limits as limits on the production of Higgs bosons in the minimal supersymmetric standard model (MSSM) and as constraints in the MSSM parameter space.Comment: 7 pages, 5 figures, submitted to PL

Measurement of the photon+b+b-jet production differential cross section in ppˉp\bar{p} collisions at \sqrt{s}=1.96~\TeV

We present measurements of the differential cross section dsigma/dpT_gamma for the inclusive production of a photon in association with a b-quark jet for photons with rapidities |y_gamma|< 1.0 and 30<pT_gamma <300 GeV, as well as for photons with 1.5<|y_gamma|< 2.5 and 30< pT_gamma <200 GeV, where pT_gamma is the photon transverse momentum. The b-quark jets are required to have pT>15 GeV and rapidity |y_jet| < 1.5. The results are based on data corresponding to an integrated luminosity of 8.7 fb^-1, recorded with the D0 detector at the Fermilab Tevatron $p\bar{p}$ Collider at sqrt(s)=1.96 TeV. The measured cross sections are compared with next-to-leading order perturbative QCD calculations using different sets of parton distribution functions as well as to predictions based on the kT-factorization QCD approach, and those from the Sherpa and Pythia Monte Carlo event generators.Comment: 10 pages, 9 figures, submitted to Phys. Lett.

Limits on anomalous trilinear gauge boson couplings from WW, WZ and Wgamma production in pp-bar collisions at sqrt{s}=1.96 TeV

We present final searches of the anomalous gammaWW and ZWW trilinear gauge boson couplings from WW and WZ production using lepton plus dijet final states and a combination with results from Wgamma, WW, and WZ production with leptonic final states. The analyzed data correspond to up to 8.6/fb of integrated luminosity collected by the D0 detector in pp-bar collisions at sqrt{s}=1.96 TeV. We set the most stringent limits at a hadron collider to date assuming two different relations between the anomalous coupling parameters Delta\kappa_\gamma, lambda, and Delta g_1^Z for a cutoff energy scale Lambda=2 TeV. The combined 68% C.L. limits are -0.057<Delta\kappa_\gamma<0.154, -0.015<lambda<0.028, and -0.008<Delta g_1^Z<0.054 for the LEP parameterization, and -0.007<Delta\kappa<0.081 and -0.017<lambda<0.028 for the equal couplings parameterization. We also present the most stringent limits of the W boson magnetic dipole and electric quadrupole moments.Comment: 10 pages, 5 figures, submitted to PL

Measurement of three-jet differential cross sections d sigma-3jet / d M-3jet in p anti-p collisions at sqrt(s)=1.96 TeV

We present the first measurement of the inclusive three-jet differential cross section as a function of the invariant mass of the three jets with the largest transverse momenta in an event in p anti-p collisions at sqrt(s) = 1.96 TeV. The measurement is made in different rapidity regions and for different jet transverse momentum requirements and is based on a data set corresponding to an integrated luminosity of 0.7 fb^{-1} collected with the D0 detector at the Fermilab Tevatron Collider. The results are used to test the three-jet matrix elements in perturbative QCD calculations at next-to-leading order in the strong coupling constant. The data allow discrimination between parametrizations of the parton distribution functions of the proton.Comment: 10 pages, 4 figures, 2 tables, submitted to Phys. Lett. B, corrected chi2 values for NNPD

Search for pair production of the scalar top quark in muon+tau final states

We present a search for the pair production of scalar top quarks ($\tilde{t}_{1}$), the lightest supersymmetric partners of the top quarks, in $p\bar{p}$ collisions at a center-of-mass energy of 1.96 TeV, using data corresponding to an integrated luminosity of {7.3 $fb^{-1}$} collected with the \dzero experiment at the Fermilab Tevatron Collider. Each scalar top quark is assumed to decay into a $b$ quark, a charged lepton, and a scalar neutrino ($\tilde{\nu}$). We investigate final states arising from $\tilde{t}_{1} \bar{\tilde{t}_{1}} \rightarrow b\bar{b}\mu\tau \tilde{\nu} \tilde{\nu}$ and $\tilde{t}_{1} \bar{\tilde{t}_{1}} \rightarrow b\bar{b}\tau\tau \tilde{\nu} \tilde{\nu}$. With no significant excess of events observed above the background expected from the standard model, we set exclusion limits on this production process in the ($m_{\tilde{t}_{1}}$,$m_{\tilde{\nu}}$) plane.Comment: Submitted to Phys. Lett.

Measurements of inclusive W+jets production rates as a function of jet transverse momentum in ppbar collisions at sqrt{s}=1.96 TeV

This Letter describes measurements of inclusive W (--> e nu) + n jet cross sections (n = 1-4), presented as total inclusive cross sections and differentially in the nth jet transverse momentum. The measurements are made using data corresponding to an integrated luminosity of 4.2 fb-1 collected by the D0 detector at the Fermilab Tevatron Collider, and achieve considerably smaller uncertainties on W +jets production cross sections than previous measurements. The measurements are compared to next-to-leading order perturbative QCD (pQCD) calculations in the n =1-3 jet multiplicity bins and to leading order pQCD calculations in the 4-jet bin. The measurements are generally in agreement with pQCD predictions, although certain regions of phase space are identified where the calculations could be improved

Measurement of spin correlation in ttbar production using dilepton final states

We measure the correlation between the spin of the top quark and the spin of the anti-top quark in (ttbar -> W+ W- b bbar -> l+ nu b l- nubar bbar) final states produced in ppbar collisions at a center of mass energy sqrt(s)=1.96 TeV, where l is an electron or muon. The data correspond to an integrated luminosity of 5.4 fb-1 and were collected with the D0 detector at the Fermilab Tevatron collider. The correlation is extracted from the angles of the two leptons in the t and tbar rest frames, yielding a correlation strength C= 0.10^{+0.45}_{-0.45}, in agreement with the NLO QCD prediction within two standard deviations, but also in agreement with the no correlation hypothesis.Comment: 10 pages, 3 figures, submitted to PL