| 651. |
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| 652. |
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| 653. |
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| 654. |
- Li, P. F., et al.
(författare)
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Dynamics of low energy electrons transmitting throughstraight glass capillary: Tilt angle dependence br
- 2022
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Ingår i: Acta Physica Sinica. - : Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences. - 1000-3290. ; 71:8
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Tidskriftsartikel (refereegranskat)abstract
- It is a hot topic that using glass capillary to focus and shape the charged particle beam, for it isinexpensive and simple. There are the cases that single glass capillaries are used to make the microbeam of thepositive ions. When it comes to electrons, their transmitting through insulating capillaries is complex and theattempt to use the glass capillary to produce electron beams in the size of micrometer needs further exploring.In this paper, the charging-up process of the 900-eV electrons transmitting through a glass capillary withthe grounded conductive-coated outer surface is reported. Two-dimensional angular distributions of thetransmitted electrons and their time evolutions are measured for the cases of various tilt angles of glass tube. Itis found that there are a considerable number of transmitted electrons at the tilt angle exceeding thegeometrical opening angle (1 degrees) of the glass tube. The intensity of transmitted electrons for large tilt angle (i.e. -1.15 degrees)can be considered as first falling to zero, then keeping zero for a long time, finally rising to a certain stablevalue. Correspondingly, the angular distribution center experiences moving towards negative-positive-negative-settled. The energy losses are measured for various tilt angles. The larger the tilt angles, the larger the energyloss of transmitted electrons is. To better understand the physics behind the observed phenomena, thesimulations of the energy loss for transmitted electrons at various tilt angles are performed by the Monte Carlomethod. The comparation between the simulated energy losses and the measured energy losses shows that theexperimental results are well explained by multiple deflections from the wall.
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| 655. |
- Li, P. F., et al.
(författare)
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Stable transmission of low energy electrons in glass tube with outer surface grounded conductively shielding
- 2022
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Ingår i: Acta Physica Sinica. - : Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences. - 1000-3290. ; 71:7
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Tidskriftsartikel (refereegranskat)abstract
- The electron microbeam is useful for modifying certain fragments of biomolecule. It is successful to applythe guiding effect to making the microbeam of positively charged particles by using single glass capillary.However, the mechanism for the electron transport through insulating capillaries is unclear. Meanwhile,previous researches show that there are oscillations of the transmission intensity of electrons with time in theglass capillaries with outer serface having no grounded conductive shielding, So, the application of glasscapillary to making the microbeam of electrons is limited. In this paper, the transmission of 1.5 and 0.9 keV electrons through the glass capillary without/with thegrounded conductive-coated outer surface are investigated, respectively. This study aims to understand themechanism for low energy electron transport in the glass capillaries, and find the conditions for the steadytransport of the electrons. Two-dimensional angular distribution of the transported electrons and its timeevolution are measured. It is found that the intensity of the transported electrons with the incident energythrough the glass capillaries for the glass capillaries without and with the grounded conductive-coated outersurface show the typical geometrical transmission characteristics. The time evolution of the 1.5- keV electrontransport presents an extremely complex variation for the glass capillary without the grounded conductive-coated outer surface. The intensity first falls, then rises and finally oscillates around a certain mean value.Correspondingly, the angular distribution center experiences moving towards positive-negative-settlement. Incomparison, the charge-up process of the 0.9 keV electron transport through the glass capillary with thegrounded conductive-coated outer surface shows a relatively simple behavior. At first, the intensity declines rapidly with time. Then, it slowly rises till a certain value and stays steady subsequently. The angulardistribution of transported electrons follows the intensity distribution in general, but with some delay. It quicklymoves to negative direction then comes back to positive direction. Finally, it regresses extremely slowly andends up around the tilt angle. To better understand the physics behind the observed phenomena, the simulationfor the interaction of the electrons with SiO2 material is performed to obtain the possible deposited chargedistribution by the CASINO code. Based on the analysis of the experimental results and the simulated chargedeposition, the conditions for stabilizing the electron transport through glass capillary arepresented.
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| 656. |
- Menkveld, Albert J., et al.
(författare)
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Nonstandard Errors
- 2024
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Ingår i: JOURNAL OF FINANCE. - : Wiley-Blackwell. - 0022-1082 .- 1540-6261. ; 79:3, s. 2339-2390
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Tidskriftsartikel (refereegranskat)abstract
- In statistics, samples are drawn from a population in a data-generating process (DGP). Standard errors measure the uncertainty in estimates of population parameters. In science, evidence is generated to test hypotheses in an evidence-generating process (EGP). We claim that EGP variation across researchers adds uncertainty-nonstandard errors (NSEs). We study NSEs by letting 164 teams test the same hypotheses on the same data. NSEs turn out to be sizable, but smaller for more reproducible or higher rated research. Adding peer-review stages reduces NSEs. We further find that this type of uncertainty is underestimated by participants.
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| 657. |
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| 658. |
- Segev, Gideon, et al.
(författare)
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The 2022 solar fuels roadmap
- 2022
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Ingår i: Journal of Physics D. - : IOP Publishing. - 0022-3727 .- 1361-6463. ; 55:32
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Tidskriftsartikel (refereegranskat)abstract
- Renewable fuel generation is essential for a low carbon footprint economy. Thus, over the last five decades, a significant effort has been dedicated towards increasing the performance of solar fuels generating devices. Specifically, the solar to hydrogen efficiency of photoelectrochemical cells has progressed steadily towards its fundamental limit, and the faradaic efficiency towards valuable products in CO2 reduction systems has increased dramatically. However, there are still numerous scientific and engineering challenges that must be overcame in order to turn solar fuels into a viable technology. At the electrode and device level, the conversion efficiency, stability and products selectivity must be increased significantly. Meanwhile, these performance metrics must be maintained when scaling up devices and systems while maintaining an acceptable cost and carbon footprint. This roadmap surveys different aspects of this endeavor: system benchmarking, device scaling, various approaches for photoelectrodes design, materials discovery, and catalysis. Each of the sections in the roadmap focuses on a single topic, discussing the state of the art, the key challenges and advancements required to meet them. The roadmap can be used as a guide for researchers and funding agencies highlighting the most pressing needs of the field.
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| 659. |
- Weeland, CJ, et al.
(författare)
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The thalamus and its subnuclei-a gateway to obsessive-compulsive disorder
- 2022
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Ingår i: Translational psychiatry. - : Springer Science and Business Media LLC. - 2158-3188. ; 12:1, s. 70-
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Tidskriftsartikel (refereegranskat)abstract
- Larger thalamic volume has been found in children with obsessive-compulsive disorder (OCD) and children with clinical-level symptoms within the general population. Particular thalamic subregions may drive these differences. The ENIGMA-OCD working group conducted mega- and meta-analyses to study thalamic subregional volume in OCD across the lifespan. Structural T1-weighted brain magnetic resonance imaging (MRI) scans from 2649 OCD patients and 2774 healthy controls across 29 sites (50 datasets) were processed using the FreeSurfer built-in ThalamicNuclei pipeline to extract five thalamic subregions. Volume measures were harmonized for site effects using ComBat before running separate multiple linear regression models for children, adolescents, and adults to estimate volumetric group differences. All analyses were pre-registered (https://osf.io/73dvy) and adjusted for age, sex and intracranial volume. Unmedicated pediatric OCD patients (<12 years) had larger lateral (d = 0.46), pulvinar (d = 0.33), ventral (d = 0.35) and whole thalamus (d = 0.40) volumes at unadjusted p-values <0.05. Adolescent patients showed no volumetric differences. Adult OCD patients compared with controls had smaller volumes across all subregions (anterior, lateral, pulvinar, medial, and ventral) and smaller whole thalamic volume (d = −0.15 to −0.07) after multiple comparisons correction, mostly driven by medicated patients and associated with symptom severity. The anterior thalamus was also significantly smaller in patients after adjusting for thalamus size. Our results suggest that OCD-related thalamic volume differences are global and not driven by particular subregions and that the direction of effects are driven by both age and medication status.
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| 660. |
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