In large Solar Energetic Particle （SEP） events, ions can be accelerated at coronal mass ejection （CME）-driven shocks to very high energies. The spectra of heavy ions in many large SEP events show features such as ...In large Solar Energetic Particle （SEP） events, ions can be accelerated at coronal mass ejection （CME）-driven shocks to very high energies. The spectra of heavy ions in many large SEP events show features such as roll-overs or spectral breaks. In some events when the spectra are plotted in terms of energy/nucleon, they can be shifted relative to each other to make the spectral breaks align. The amount of shift is charge to mass ratio （Q/A） dependent and varies from event to event. This can be understood if the spectra of heavy ions are organized by the diffusion coefficients （Cohen et al. 2005）. In the work of Li et al. （2009）, the Q/A dependence of the scaling is related to shock geometry when the CME-driven shock is close to the Sun. For events where multiple in-situ spacecraft observations exist, one may expect that different spacecraft are connected to different portions of the CME-driven shock that have different shock geometries, therefore yielding different Q/A dependence. In this work, we examine one SEP event which occurred on 2013 November 4. We study the Q/A dependence of the energy scaling for heavy ion spectra using helium, oxygen and iron ions. Observations from STEREO-A, STEREO-B and ACE are examined. We find that the scalings are different for different spacecraft. We suggest that this is because ACE, STEREO- A and STEREO-B are connected to different parts of the shock that have different shock geometries. Our analysis indicates that studying the Q/A scaling of in-situ particle spectra can serve as a powerful tool to remotely examine the shock geometry for large SEP events.展开更多
Deposition of aggregated protein is associated with many human diseases. The mechanism by which protein aggregate species cause cellular death remains unclear. A profile revealing protein aggregation products under a ...Deposition of aggregated protein is associated with many human diseases. The mechanism by which protein aggregate species cause cellular death remains unclear. A profile revealing protein aggregation products under a diverse set of conditions allows the search of novel aggregate products and potential pathogens. To achieve this end, an isothermal transformation diagram (ITD) of lysozyme aggregation was constructed. AFM, TEM, and Thioflavin T binding assays were used to analyze the aggregate species synthesized under a broad range of pH values, protein concentrations, and incubation times. Four states were found: 1) soluble protein species;2) insoluble amyloid fibers;3) insoluble amorphous aggregates;and 4) protein hydrogels. The hydrogel-a rises from aggregated amyloid fibers. This work is part of an effort to construct an array of ITDs reporting aggregation properties of many disease relevant proteins, including amyloid beta, tau, α-synuclein, and others involved in protein aggregation diseases. In addition, we propose hydrogel cyto toxicity as a potential novel mechanism in the pathogenesis of amyloid diseases.展开更多
The CanX-7 Automatic Dependent Surveillance-Broadcast (ADS-B) nanosatellite mission collected more than four million ADS-B messages between October 2016 and April 2017. An analysis of data collected over the north Atl...The CanX-7 Automatic Dependent Surveillance-Broadcast (ADS-B) nanosatellite mission collected more than four million ADS-B messages between October 2016 and April 2017. An analysis of data collected over the north Atlantic Ocean from 05 to 28 Oct included 20,707 position messages in which the angle from satellite nadir to aircraft was determined. The proximity of the received signal strength to the noise floor of the sensor allowed for an analysis of optimal aircraft-satellite orientation for ADS-B transmission detection. The results showed a significant disparity between descending and ascending passes of the satellite. For descending passes, the average nadir angle was 50.1°?with 90% of the contacts greater than 40°. The ascending passes had an average nadir angle of 31.6°?with only 24.8% of the contacts exceeding 40°. The evidence suggests that the satellite magnetic torquer may not have been fully aligned with the north magnetic pole as the satellite moved northward, resulting in ascending pass nadir angles that were not reflective of the full range of values. Further analysis of the descending passes showed agreement with an ADS-B signal propagation model with peak reception at nadir angles of 51°?± 8°. For space-based ADS-B operations, the results support the replacement of the current aircraft upper quarter-wave monopole to an antenna that will transmit more energy directly above the airframe.展开更多
This paper presents data from a 21 cm H I emission drift scan observation of a field partially covering the NGC 4636 galaxy group with the Five-hundred meter Aperture Radio Telescope(FAST). We construct a pipeline to ...This paper presents data from a 21 cm H I emission drift scan observation of a field partially covering the NGC 4636 galaxy group with the Five-hundred meter Aperture Radio Telescope(FAST). We construct a pipeline to reduce the data, and use So Fi A for source finding. When not contaminated by Radio Frequency Interference(RFI), the FAST observations are capable of detecting all of the galaxies previously detected by the Arecibo Legacy Fast ALFA(ALFALFA) survey in the same region. Comparing to ALFALFA for the detections in common, the FAST data show consistent integrated spectra when the H I disks are spatially unresolved, and capture more flux when the H I disks are resolved. The FAST data further reveal 10 new detections in the region mutually covered with ALFALFA, and 18 new detections beyond the footprint of ALFALFA. All of the new detections have the matching optical counterparts. For the member galaxies of the NGC 4636 group, the detection limit of FAST is deeper by 0.4 dex in H I mass than that of the ALFALFA data. After correcting for the incompleteness caused by RFI contamination, we show that the H I detection rate of galaxies rises steeply with radius out to the virial radius of the group, and flattens beyond that. We also examine four spatially resolved galaxy systems with potential tidal interaction features in detail. Considering that the data have been taken during the“shared-risk” period before a major source of local RFI was eliminated, the results highlight the power of FAST in detecting extragalactic H I.展开更多
In the present paper,tides in the port of Vancouver Harbour have been investigated with a high-resolution three-dimensional hydrodynamic model based on FVCOM(Finite Volume Community Ocean Model).The model was evaluate...In the present paper,tides in the port of Vancouver Harbour have been investigated with a high-resolution three-dimensional hydrodynamic model based on FVCOM(Finite Volume Community Ocean Model).The model was evaluated against field observations including tidal elevations and tidal currents,and the evaluation showed that the model was in good agreement with the observational data.Using the model,we first investigated the horizontal distributions of tides,tidal currents,and tidally induced residual circulation,and then investigated the tidal asymmetry and dynamic mechanisms of tidal flows in the harbour.The tidal residual circulation shows a strong spatial pattern,which is associated with the local coastlines and variation of topography.The tidal asymmetry in the harbour is caused by different mechanisms,not only including the traditional factors,such as residual flows,the interaction between M_(2)and its overtide M_(4),but also the interaction of principal astronomical tides of O_(1),K_(1),and M_(2).The momentum balance is dominated by terms of the advection and the pressure gradient in First Narrows and Second Narrows,whereas terms of the local acceleration and the Coriolis are also important in the central harbour.The spatial variations of the momentum terms are strongly associated with the local changes in coastline and topography.展开更多
基金supported at UAH by NSF grants AGS-1135432 and AGS-1622391NASA grant NNX15AJ93G+5 种基金at APL by NASA grant NNX13AR20G/115828 (ACE/ULEIS and STEREO/SIT)NASA subcontract SA4889-26309 from the University of California Berkeleyat Caltech by NNX13A66G, NNX11A075Gsubcontract 00008864 of NNX15AG09Gby NSF grant AGS-1156004at SwRI partially by NSF grant AGS-1460118
文摘In large Solar Energetic Particle （SEP） events, ions can be accelerated at coronal mass ejection （CME）-driven shocks to very high energies. The spectra of heavy ions in many large SEP events show features such as roll-overs or spectral breaks. In some events when the spectra are plotted in terms of energy/nucleon, they can be shifted relative to each other to make the spectral breaks align. The amount of shift is charge to mass ratio （Q/A） dependent and varies from event to event. This can be understood if the spectra of heavy ions are organized by the diffusion coefficients （Cohen et al. 2005）. In the work of Li et al. （2009）, the Q/A dependence of the scaling is related to shock geometry when the CME-driven shock is close to the Sun. For events where multiple in-situ spacecraft observations exist, one may expect that different spacecraft are connected to different portions of the CME-driven shock that have different shock geometries, therefore yielding different Q/A dependence. In this work, we examine one SEP event which occurred on 2013 November 4. We study the Q/A dependence of the energy scaling for heavy ion spectra using helium, oxygen and iron ions. Observations from STEREO-A, STEREO-B and ACE are examined. We find that the scalings are different for different spacecraft. We suggest that this is because ACE, STEREO- A and STEREO-B are connected to different parts of the shock that have different shock geometries. Our analysis indicates that studying the Q/A scaling of in-situ particle spectra can serve as a powerful tool to remotely examine the shock geometry for large SEP events.
文摘Deposition of aggregated protein is associated with many human diseases. The mechanism by which protein aggregate species cause cellular death remains unclear. A profile revealing protein aggregation products under a diverse set of conditions allows the search of novel aggregate products and potential pathogens. To achieve this end, an isothermal transformation diagram (ITD) of lysozyme aggregation was constructed. AFM, TEM, and Thioflavin T binding assays were used to analyze the aggregate species synthesized under a broad range of pH values, protein concentrations, and incubation times. Four states were found: 1) soluble protein species;2) insoluble amyloid fibers;3) insoluble amorphous aggregates;and 4) protein hydrogels. The hydrogel-a rises from aggregated amyloid fibers. This work is part of an effort to construct an array of ITDs reporting aggregation properties of many disease relevant proteins, including amyloid beta, tau, α-synuclein, and others involved in protein aggregation diseases. In addition, we propose hydrogel cyto toxicity as a potential novel mechanism in the pathogenesis of amyloid diseases.
文摘The CanX-7 Automatic Dependent Surveillance-Broadcast (ADS-B) nanosatellite mission collected more than four million ADS-B messages between October 2016 and April 2017. An analysis of data collected over the north Atlantic Ocean from 05 to 28 Oct included 20,707 position messages in which the angle from satellite nadir to aircraft was determined. The proximity of the received signal strength to the noise floor of the sensor allowed for an analysis of optimal aircraft-satellite orientation for ADS-B transmission detection. The results showed a significant disparity between descending and ascending passes of the satellite. For descending passes, the average nadir angle was 50.1°?with 90% of the contacts greater than 40°. The ascending passes had an average nadir angle of 31.6°?with only 24.8% of the contacts exceeding 40°. The evidence suggests that the satellite magnetic torquer may not have been fully aligned with the north magnetic pole as the satellite moved northward, resulting in ascending pass nadir angles that were not reflective of the full range of values. Further analysis of the descending passes showed agreement with an ADS-B signal propagation model with peak reception at nadir angles of 51°?± 8°. For space-based ADS-B operations, the results support the replacement of the current aircraft upper quarter-wave monopole to an antenna that will transmit more energy directly above the airframe.
基金supported by the National Natural Science Foundation of China (11988101,11721303,11991052,12011540375,12073002,11903003)the China Manned Space Project (CMS-CSST-2021-A04+3 种基金CMS-CSST-2021-A06)support from the science research grants from the China Manned Space Project with No.CMS-CS ST-2021-B02the Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D),through project No.CE170100013support from the Natural Sciences and Engineering Research Council of Canada (NSERC)。
文摘This paper presents data from a 21 cm H I emission drift scan observation of a field partially covering the NGC 4636 galaxy group with the Five-hundred meter Aperture Radio Telescope(FAST). We construct a pipeline to reduce the data, and use So Fi A for source finding. When not contaminated by Radio Frequency Interference(RFI), the FAST observations are capable of detecting all of the galaxies previously detected by the Arecibo Legacy Fast ALFA(ALFALFA) survey in the same region. Comparing to ALFALFA for the detections in common, the FAST data show consistent integrated spectra when the H I disks are spatially unresolved, and capture more flux when the H I disks are resolved. The FAST data further reveal 10 new detections in the region mutually covered with ALFALFA, and 18 new detections beyond the footprint of ALFALFA. All of the new detections have the matching optical counterparts. For the member galaxies of the NGC 4636 group, the detection limit of FAST is deeper by 0.4 dex in H I mass than that of the ALFALFA data. After correcting for the incompleteness caused by RFI contamination, we show that the H I detection rate of galaxies rises steeply with radius out to the virial radius of the group, and flattens beyond that. We also examine four spatially resolved galaxy systems with potential tidal interaction features in detail. Considering that the data have been taken during the“shared-risk” period before a major source of local RFI was eliminated, the results highlight the power of FAST in detecting extragalactic H I.
基金supported by the Department of Fisheries and Oceans Canada(DFO).
文摘In the present paper,tides in the port of Vancouver Harbour have been investigated with a high-resolution three-dimensional hydrodynamic model based on FVCOM(Finite Volume Community Ocean Model).The model was evaluated against field observations including tidal elevations and tidal currents,and the evaluation showed that the model was in good agreement with the observational data.Using the model,we first investigated the horizontal distributions of tides,tidal currents,and tidally induced residual circulation,and then investigated the tidal asymmetry and dynamic mechanisms of tidal flows in the harbour.The tidal residual circulation shows a strong spatial pattern,which is associated with the local coastlines and variation of topography.The tidal asymmetry in the harbour is caused by different mechanisms,not only including the traditional factors,such as residual flows,the interaction between M_(2)and its overtide M_(4),but also the interaction of principal astronomical tides of O_(1),K_(1),and M_(2).The momentum balance is dominated by terms of the advection and the pressure gradient in First Narrows and Second Narrows,whereas terms of the local acceleration and the Coriolis are also important in the central harbour.The spatial variations of the momentum terms are strongly associated with the local changes in coastline and topography.
