In this study,we conducted a search for dark matter using a part of the data recorded by the CMS experiment during run-I of the LHC in 2012 with a center of mass energy of 8 TeV and an integrated luminosity of 11.6 fb...In this study,we conducted a search for dark matter using a part of the data recorded by the CMS experiment during run-I of the LHC in 2012 with a center of mass energy of 8 TeV and an integrated luminosity of 11.6 fb−1.These data were gathered from the CMS open data.Dark matter,in the framework of the simplified model(mono-Z′),can be produced from proton-proton collisions in association with a new hypothetical gauge boson,Z′.Thus,the search was conducted in the dimuon plus large missing transverse momentum channel.One benchmark scenario of mono-Z′,which is known as light vector,was used for interpreting the CMS open data.No evidence of dark matter was observed,and exclusion limits were set on the masses of dark matter and Z′at 95%confidence level.展开更多
Background:Coumarins are secondary metabolites from the phenylpropanoid-type biosynthesis in higher plants.A plethora of potential phytopharmacological activities have been described for derivatives of the coumarin sc...Background:Coumarins are secondary metabolites from the phenylpropanoid-type biosynthesis in higher plants.A plethora of potential phytopharmacological activities have been described for derivatives of the coumarin scaffold:hepatoprotective,antineoplastic,antimicrobial,antituberculosis,antiviral,anti-inflammatory anticoagulant,or antithrombotic effects.Objective:A computer-based quantitative structure–activity relationships(QSAR)study for a series of 4‑chloro-3-formylcoumarins was carried out.Methods:To this end we generated the 3D models of 17 published coumarin structures,calculated their physicochemical properties(descriptors)to correlate them to their experimentally known biological activities measured as inhibition concentrations to block the target enzyme activity.Our proposed approach used free molecular modeling software and applies our scripts written in the programming language R.Results:The final multiple regression models achieved satisfactory results with a small number of descriptors–all of which were statistically significant and meaningful in the field of pharmacodynamics to develop new 3-formylcoumarins with enhanced activities targeting the human thymidine phosphorylase enzyme.Conclusion:On theoretical grounds,our in silico research contributes in a crucial step in the field of complementary phyto-medicine.This step is located between in vivo pharmacological observations of plant extracts on ethnopharmacological,preclinical or controlled clinical levels and the need to identify–at an atomic scale–all those plant ingredients responsible for the biological actions under scrutiny.Our simulations shed light on the modification of phyto-medicine’s physicochemical properties to enhance the interaction with their biomolecular target in the patient’s body.展开更多
We test different X-ray spectrum models to find the one that best represents the observed Rossi X-ray Timing Explore/Proportional Counter Array (RXTE /PCA) spectra of Her X-1 during Main High state (MH). We then apply...We test different X-ray spectrum models to find the one that best represents the observed Rossi X-ray Timing Explore/Proportional Counter Array (RXTE /PCA) spectra of Her X-1 during Main High state (MH). We then apply this model to MH observations taken over the lifetime of RXTE. From the results, we obtain patterns in the spectral parameters vs. 35-day phase during MH. The precessing-disc occultation model explains the 35-day cycle by changes in observer view of the emission regions by the accretion disc 35-day precession. Qualitatively, we find that this model can describe the main spectral changes. However, several spectral parameters show detailed changes that the models have not addressed yet. These changes will likely require modifications to the basic precessing-disc model for the 35-day cycle.展开更多
基金the Center for Theoretical Physics (CTP) at the British University in Egypt (BUE) for its continuous support,both financially and scientifically,for this work。
文摘In this study,we conducted a search for dark matter using a part of the data recorded by the CMS experiment during run-I of the LHC in 2012 with a center of mass energy of 8 TeV and an integrated luminosity of 11.6 fb−1.These data were gathered from the CMS open data.Dark matter,in the framework of the simplified model(mono-Z′),can be produced from proton-proton collisions in association with a new hypothetical gauge boson,Z′.Thus,the search was conducted in the dimuon plus large missing transverse momentum channel.One benchmark scenario of mono-Z′,which is known as light vector,was used for interpreting the CMS open data.No evidence of dark matter was observed,and exclusion limits were set on the masses of dark matter and Z′at 95%confidence level.
文摘Background:Coumarins are secondary metabolites from the phenylpropanoid-type biosynthesis in higher plants.A plethora of potential phytopharmacological activities have been described for derivatives of the coumarin scaffold:hepatoprotective,antineoplastic,antimicrobial,antituberculosis,antiviral,anti-inflammatory anticoagulant,or antithrombotic effects.Objective:A computer-based quantitative structure–activity relationships(QSAR)study for a series of 4‑chloro-3-formylcoumarins was carried out.Methods:To this end we generated the 3D models of 17 published coumarin structures,calculated their physicochemical properties(descriptors)to correlate them to their experimentally known biological activities measured as inhibition concentrations to block the target enzyme activity.Our proposed approach used free molecular modeling software and applies our scripts written in the programming language R.Results:The final multiple regression models achieved satisfactory results with a small number of descriptors–all of which were statistically significant and meaningful in the field of pharmacodynamics to develop new 3-formylcoumarins with enhanced activities targeting the human thymidine phosphorylase enzyme.Conclusion:On theoretical grounds,our in silico research contributes in a crucial step in the field of complementary phyto-medicine.This step is located between in vivo pharmacological observations of plant extracts on ethnopharmacological,preclinical or controlled clinical levels and the need to identify–at an atomic scale–all those plant ingredients responsible for the biological actions under scrutiny.Our simulations shed light on the modification of phyto-medicine’s physicochemical properties to enhance the interaction with their biomolecular target in the patient’s body.
文摘We test different X-ray spectrum models to find the one that best represents the observed Rossi X-ray Timing Explore/Proportional Counter Array (RXTE /PCA) spectra of Her X-1 during Main High state (MH). We then apply this model to MH observations taken over the lifetime of RXTE. From the results, we obtain patterns in the spectral parameters vs. 35-day phase during MH. The precessing-disc occultation model explains the 35-day cycle by changes in observer view of the emission regions by the accretion disc 35-day precession. Qualitatively, we find that this model can describe the main spectral changes. However, several spectral parameters show detailed changes that the models have not addressed yet. These changes will likely require modifications to the basic precessing-disc model for the 35-day cycle.
