Understanding the variation of lags with respect to the X-ray flux is important to explore the geometry of the inner region of the accretion disk in AGNs.We performed frequency-lag,energy–lag and spectral studies for...Understanding the variation of lags with respect to the X-ray flux is important to explore the geometry of the inner region of the accretion disk in AGNs.We performed frequency-lag,energy–lag and spectral studies for two sets of observations,in order to investigate the variations in lags with respect to X-ray flux in the AGN source Mrk 704 using the XMM-Newton observatory.We divided one of the light curves into two sections which were noticed to exhibit a flux variation.The frequency-lag spectra in different energy domains revealed that reverberation(soft)lags varied along with the flux.For the first time,we show that the blurred reflection model can consistently explain the soft excess observed in the X-ray spectra for this source.The fluxes of soft(i.e.,reflection)and hard components were noted to vary by~18%and~9%respectively,across the sections.The soft lag amplitude was found to be larger at the high flux state than the amplitude at the low flux state.Most importantly,we found that both frequency-lag and energy–lag spectra do not display significant variation between two observational data sets despite a flux variation of 43%.This phenomenon cannot be explained by the reflection model because the soft lag amplitudes must be larger in the high flux state.The probable scenario is that,in the low flux state,the obscuring cloud delays the reflected soft photons which increases the soft lag amplitude.展开更多
AIM To investigate the outcome of flexible endoscopic myotomy performed with the Hook knife in patients with symptomatic Zenker's diverticulum(ZD).METHODS All consecutive patients treated for ZD at our institution...AIM To investigate the outcome of flexible endoscopic myotomy performed with the Hook knife in patients with symptomatic Zenker's diverticulum(ZD).METHODS All consecutive patients treated for ZD at our institution between 7/2012 and 12/2016 were included.The flexible endoscopic soft diverticuloscope-assisted technique with endoclips placement and Hook knife myotomy were performed in all patients.Here we report a retrospective review of prospectively collected data.Demographics,dysphagia score(Dakkak and Bennett),associated symptoms and adverse events were collected pre-procedure,at 2 and 6 mo post-procedure,and at the end of the follow-up period.Clinical success was defined as at least 1-point improvement in dysphagia score and a residual dysphagia score≤1,with no need for reintervention.Dysphagia scores were compared before treatment and at end-of-follow-up using the Wilcoxon test.RESULTS Twenty-four patients were included.Mean size of ZD was 3.0 cm(range 2-8 cm).Mean number of sessions was 1.17/patient(range 1-3 sessions).Overall clinical success was 91.7%.Two adverse events(8.3%) occurred,and both were managed conservatively.No bleeding or perforation was reported.Mild pain was reported by 9 patients(37.5%).Median hospital stay was 1 d(range 1-6).Median follow-up was 19.5 mo(range 6-53).Mean ± SD dysphagia score was 2.25±0.89 before treatment and decreased to 0.41 ± 0.92 at end-of-follow-up(P<0.001).Regurgitation and cough dropped from 91.7% and 50% to 12.5% and 0% at the end of follow-up,respectively.Recurrence was observed in 3 patients,and all 3 were symptom-free after one more session.CONCLUSION The Hook knife,used in the soft diverticuloscope-assisted technique setting,is efficient and safe for treatment of ZD.展开更多
Piezoelectric materials with unique properties are hugely appealing for high sensitivity sensors and ultrasonic transducers.Here,Pb(Ni_(1/3)Nb_(2/3))O_(3)-Pb(Yb_(1/2)Nb_(1/2))O_(3)-PbTiO_(3)piezoelectric system was de...Piezoelectric materials with unique properties are hugely appealing for high sensitivity sensors and ultrasonic transducers.Here,Pb(Ni_(1/3)Nb_(2/3))O_(3)-Pb(Yb_(1/2)Nb_(1/2))O_(3)-PbTiO_(3)piezoelectric system was designed and investigated in detail.The optimized piezoelectric response(d_(33)=826 pC/N,d_(33)∗=1017 pm/V)together with good temperature stability and negligible performance degradation up to 10^(6) cycles was achieved in 0.58PNN-0.10PYN-0.32PT composition.Rayleigh analysis revealed the amplification of intrinsic and extrinsic contributions in MPB region due to more spontaneous polarization orientations and an increase in chemical disorder of system after the introduction of PYN.The origin of high piezoelectric response was investigated through the combination of scanning electron microscopy and piezoresponse force microscopy.The diversity of B-site cations was shown to enhance local structural heterogeneity,weaken long-range ferroelectric ordered domains,and lower free energy barrier via the formation of nanodomain configuration that promoted polarization rotation,thereby improving piezoelectric properties of the material.Therefore,it is suggested that increasing the diversity of B-site cations is an effective strategy for achieving outstanding piezoelectric performance.展开更多
During the next 10 years Brazil's agricultural area will expand to meet increased domestic and worldwide demand for food,fuel,and fiber.Present choices regarding land use will determine to what degree this expansi...During the next 10 years Brazil's agricultural area will expand to meet increased domestic and worldwide demand for food,fuel,and fiber.Present choices regarding land use will determine to what degree this expansion will have adverse effects that include soil erosion,reservoir siltation,water quality problems,loss of biodiversity and social conflict,especially around indigenous reservations.This paper presents an up-to-date inventory of soil erosion in Brazil caused by crop and livestock activities and provides estimates based on three different hypothetical land-use scenarios to accommodate the expansion of Brazilian agricultural activity by 2020:Scenario 1-expansion of cropping into areas of natural vegetation,without adoption of conservation practices;Scenario 2-expansion of cropping into areas of degraded pasture,without adoption of conservation practices;Scenario 3-expansion of cropping into areas of degraded pasture,together with conservation practices in 100%of the expanded area.The worst-case scenario involves expansion of agriculture into areas of native vegetation in the Brazilian Savannah(Cerrado)and Brazilian rainforest(Amazon)biomes,and could increase total soil erosion in Brazil(currently about 800 million metric tons a year)by as much as 20%.In the best-case scenar-io,crop expansion under a conservation agriculture model would utilize currently degraded pasture,especially in the Savannah(circa 40 million hectares),reducing soil erosion in Brazil by around 20%.For this to occur,however,a national soil and water conservation policy needs to be implemented in Brazil to support a sustainable model of agriculture in which the environment can be preserved as much as possible.展开更多
基金K.S.acknowledges the financial support from the Indian Space Research Organisation(ISRO),Government of India。
文摘Understanding the variation of lags with respect to the X-ray flux is important to explore the geometry of the inner region of the accretion disk in AGNs.We performed frequency-lag,energy–lag and spectral studies for two sets of observations,in order to investigate the variations in lags with respect to X-ray flux in the AGN source Mrk 704 using the XMM-Newton observatory.We divided one of the light curves into two sections which were noticed to exhibit a flux variation.The frequency-lag spectra in different energy domains revealed that reverberation(soft)lags varied along with the flux.For the first time,we show that the blurred reflection model can consistently explain the soft excess observed in the X-ray spectra for this source.The fluxes of soft(i.e.,reflection)and hard components were noted to vary by~18%and~9%respectively,across the sections.The soft lag amplitude was found to be larger at the high flux state than the amplitude at the low flux state.Most importantly,we found that both frequency-lag and energy–lag spectra do not display significant variation between two observational data sets despite a flux variation of 43%.This phenomenon cannot be explained by the reflection model because the soft lag amplitudes must be larger in the high flux state.The probable scenario is that,in the low flux state,the obscuring cloud delays the reflected soft photons which increases the soft lag amplitude.
文摘AIM To investigate the outcome of flexible endoscopic myotomy performed with the Hook knife in patients with symptomatic Zenker's diverticulum(ZD).METHODS All consecutive patients treated for ZD at our institution between 7/2012 and 12/2016 were included.The flexible endoscopic soft diverticuloscope-assisted technique with endoclips placement and Hook knife myotomy were performed in all patients.Here we report a retrospective review of prospectively collected data.Demographics,dysphagia score(Dakkak and Bennett),associated symptoms and adverse events were collected pre-procedure,at 2 and 6 mo post-procedure,and at the end of the follow-up period.Clinical success was defined as at least 1-point improvement in dysphagia score and a residual dysphagia score≤1,with no need for reintervention.Dysphagia scores were compared before treatment and at end-of-follow-up using the Wilcoxon test.RESULTS Twenty-four patients were included.Mean size of ZD was 3.0 cm(range 2-8 cm).Mean number of sessions was 1.17/patient(range 1-3 sessions).Overall clinical success was 91.7%.Two adverse events(8.3%) occurred,and both were managed conservatively.No bleeding or perforation was reported.Mild pain was reported by 9 patients(37.5%).Median hospital stay was 1 d(range 1-6).Median follow-up was 19.5 mo(range 6-53).Mean ± SD dysphagia score was 2.25±0.89 before treatment and decreased to 0.41 ± 0.92 at end-of-follow-up(P<0.001).Regurgitation and cough dropped from 91.7% and 50% to 12.5% and 0% at the end of follow-up,respectively.Recurrence was observed in 3 patients,and all 3 were symptom-free after one more session.CONCLUSION The Hook knife,used in the soft diverticuloscope-assisted technique setting,is efficient and safe for treatment of ZD.
基金supported by the National Natural Science Foundation of China(No.52173227)the Key Research and Development Program of Shaanxi(No.2022GY-184)the Innovation Fund of Xidian University,and the Fundamental Research Funds for the Central Universities(No.ZYTS23083).
文摘Piezoelectric materials with unique properties are hugely appealing for high sensitivity sensors and ultrasonic transducers.Here,Pb(Ni_(1/3)Nb_(2/3))O_(3)-Pb(Yb_(1/2)Nb_(1/2))O_(3)-PbTiO_(3)piezoelectric system was designed and investigated in detail.The optimized piezoelectric response(d_(33)=826 pC/N,d_(33)∗=1017 pm/V)together with good temperature stability and negligible performance degradation up to 10^(6) cycles was achieved in 0.58PNN-0.10PYN-0.32PT composition.Rayleigh analysis revealed the amplification of intrinsic and extrinsic contributions in MPB region due to more spontaneous polarization orientations and an increase in chemical disorder of system after the introduction of PYN.The origin of high piezoelectric response was investigated through the combination of scanning electron microscopy and piezoresponse force microscopy.The diversity of B-site cations was shown to enhance local structural heterogeneity,weaken long-range ferroelectric ordered domains,and lower free energy barrier via the formation of nanodomain configuration that promoted polarization rotation,thereby improving piezoelectric properties of the material.Therefore,it is suggested that increasing the diversity of B-site cations is an effective strategy for achieving outstanding piezoelectric performance.
文摘During the next 10 years Brazil's agricultural area will expand to meet increased domestic and worldwide demand for food,fuel,and fiber.Present choices regarding land use will determine to what degree this expansion will have adverse effects that include soil erosion,reservoir siltation,water quality problems,loss of biodiversity and social conflict,especially around indigenous reservations.This paper presents an up-to-date inventory of soil erosion in Brazil caused by crop and livestock activities and provides estimates based on three different hypothetical land-use scenarios to accommodate the expansion of Brazilian agricultural activity by 2020:Scenario 1-expansion of cropping into areas of natural vegetation,without adoption of conservation practices;Scenario 2-expansion of cropping into areas of degraded pasture,without adoption of conservation practices;Scenario 3-expansion of cropping into areas of degraded pasture,together with conservation practices in 100%of the expanded area.The worst-case scenario involves expansion of agriculture into areas of native vegetation in the Brazilian Savannah(Cerrado)and Brazilian rainforest(Amazon)biomes,and could increase total soil erosion in Brazil(currently about 800 million metric tons a year)by as much as 20%.In the best-case scenar-io,crop expansion under a conservation agriculture model would utilize currently degraded pasture,especially in the Savannah(circa 40 million hectares),reducing soil erosion in Brazil by around 20%.For this to occur,however,a national soil and water conservation policy needs to be implemented in Brazil to support a sustainable model of agriculture in which the environment can be preserved as much as possible.
