Improved alternating gradient transport and focusing of neutral molecules

Polar molecules, in strong-field seeking states, can be transported and focused by an alternating sequence of electric field gradients that focus in one transverse direction while defocusing in the other. We show, by calculation and numerical simulation, how one may greatly improve the alternating gradient transport and focusing of molecules. We use a new optimized multipole lens design, a FODO-lattice beam transport line, and lenses to match the beam transport line to the beam source and to the final focus. We derive analytic expressions for the potentials, fields, and gradients that may be used to design these lenses. We describe a simple lens optimization procedure and derive the equations of motion for tracking molecules through a beam transport line. As an example, we model a straight beamline that transports a 560 m/s jet-source beam of methyl fluoride15 m from its source and focuses it to 2 mm diameter. We calculate the beam transport line acceptance and beam survival, for a beam with a velocity spread, and estimate the transmitted intensity for specified source conditions. Possible applications are discussed.Comment: 10 pages, 9 figures, one bi

Solar array thermal snap and the characteristics of its effect on UARS

The single solar array on the Upper Atmosphere Research Satellite (UARS) is subjected to a thermal distortion when the spacecraft enters and exits the Earth's shadow. The distortion results in a torque that alters the spacecraft attitude. Due to the sudden nature of the attitude discontinuity, the effect has been termed 'thermal snap'. Thermal snap has also been experienced by Landsats 4 and 5. Analyses by the spacecraft builder addressed the impact of the resultant torque on the onboard control system. This paper discusses the results of comparisons between the predicted effects of thermal snap on UARS and actual attitude solutions from UARS telemetry data. In addition, this paper describes the characteristics of the thermal snap on UARS in terms of maximum displacement, solar beta angle, and solar array drive angle. Comparisons are made between the actual times of thermal snaps and the predicted spacecraft sunrise and sunset times. The effects of the UARS thermal snap are summarized and a general comment is made relating possible effects of thermal snap on other satellites. Also, an analysis of UARS attitude solutions that span periods of thermal snap was performed to determine whether the gyro sampling time of 1/8 second is sufficient to properly model the resulting spacecraft attitude without compromising the accuracy requirements. The results of this analysis are discussed

Comparison of two on-orbit attitude sensor alignment methods

Compared here are two methods of on-orbit alignment of vector attitude sensors. The first method uses the angular difference between simultaneous measurements from two or more sensors. These angles are compared to the angular differences between the respective reference positions of the sensed objects. The alignments of the sensors are adjusted to minimize the difference between the two sets of angles. In the second method, the sensor alignment is part of a state vector that includes the attitude. The alignments are adjusted along with the attitude to minimize all observation residuals. It is shown that the latter method can result in much less alignment uncertainty when gyroscopes are used for attitude propagation during the alignment estimation. The additional information for this increased accuracy comes from knowledge of relative attitude obtained from the spacecraft gyroscopes. The theoretical calculations of this difference in accuracy are presented. Also presented are numerical estimates of the alignment uncertainties of the fixed-head star trackers on the Extreme Ultraviolet Explorer spacecraft using both methods

Letter from W.A. Lambertson to Marc T. Campbell regarding turnstiles for Forsyth Library

A letter from W.A. Lambertson to Marc T. Campbell regarding suggestions for traffic control devices at the entrance of Forsyth Library.https://scholars.fhsu.edu/library_bldg/1062/thumbnail.jp

Calculation of the LHC-kicker beam impedance

Longitudinal and transverse beam impedances are calculated for the injection kickers designed for use in the CERN Large Hadron Collider. These combine the contributions of a ceramic beam tube with conducting stripes and a traveling-wave kicker magnet. The results show peak impedances of 1300 ohm longitudinal and 8 M Omega /m transverse for four units per ring. (3 refs)

Comparing classrooms around the world: a unit plan

Often times, social studies are a forgotten subject in early childhood education. With a huge focus of the school day being on language arts and math, subjects like science and social studies have seemingly become second tier. Social studies instruction teaches essential skills that help children throughout school as well as teaching them to become responsible citizens. For these reasons, this thesis is a social studies unit plan meant for a kindergarten classroom. It explores three different countries and cultures; South Korea, El Salvador, and Germany. The unit focuses on comparing and contrasting going to school in the United States to going to school in these countries using an introductory read aloud, one full length lesson for each of the countries, and a final assessment where students will write their own book pages highlighting the comparisons they see.Honors CollegeThesis (B.?

EUVE/XTE orbit decay study

The Explorer Platform (EP) program currently comprises two missions, the Extreme Ultraviolet Explorer (EUVE) and the X-ray Timing Explorer (XTE), each of which consists of a scientific payload mounted to the EP. The EP has no orbit maintenance capability. The EP with the EUVE payload will be launched first. At the end of the EUVE mission, the spacecraft will be serviced by the Space Transportation System (STS), and the EUVE instrument will be exchanged for the XTE. The XTE mission will continue until reentry or reservicing by the STS. Because the missions will be using the EP sequentially, the orbit requirements are unusually constrained by orbit decay rates. The initial altitude must be selected so that, by the end of the EUVE mission (2.5 years), the spacecraft will have decayed to an altitude within the STS capabilities. In addition, the payload exchange must occur at an altitude that ensures meeting the minimum XTE mission lifetime (3 years) because no STS reboost will be available. Studies were performed using the Goddard Mission Analysis System to estimate the effects of mass, cross-sectional area, and solar flux on the fulfillment of mission requirements. In addition to results from these studies, conclusions are presented as to the accuracy of the Marshall Space Flight Center solar flux predictions

Reducing Readmission Rates By Improving Transitions Of Care For Stroke Patients In The Pre-Covid And Covid Eras

Introduction: Acute cerebrovascular disease ranks among the top causes of 30-day readmissions. Studies have shown that enhancing and streamlining transitions of care (TOC) for patients can improve readmission rates for many conditions. Our research explores the impact of in-person and telemedicine TOC stroke clinic on readmission rates at an urban comprehensive stroke center. Methods: Participants were identified by ICD-10 diagnoses corresponding with stroke or transient ischemic attack at Thomas Jefferson University Hospital (TJUH). Starting in January of 2019, an in-person TOC clinic visit with a vascular neurologist or nurse practitioner was automatically scheduled within 1-3 weeks for patients discharged to home. When coronavirus precautions began, these visits transitioned to telemedicine. Follow-up telephone surveys assessing self-efficacy, confidence and perceived value of TOC clinic were administered. Readmission statistics were collected from the TJUH electronic health record. Preliminary data analysis was performed in SPSS. Results: 208 individuals (113 in-person, 95 telemedicine) seen in TOC clinic were included in preliminary analysis. The 30-day all-cause readmission rate was 5.8% (12 patients). Of these readmissions, 2 were seen in the clinic (2.1%), and 10 were evaluated via telemedicine (8.8%). Chi Square revealed a between group difference (X2 = 4.318, p = 0.038). Participants in both the in-person group (u = 8.421, SD = 1.835) and telemedicine group (u = 8.100, SD = 1.875) considered TOC a valuable experience. Analysis of perceived TOC value did not differ between groups (t = 0.654, p = 0.515). Discussion: Stroke readmissions represent a significant source of morbidity, mortality and healthcare spending in the United States. Overall, there were fewer readmissions among TJUH TOC clinic patients compared to institutional and national 30-day stroke readmission rates. Understanding the relative impact of an in-person and telemedicine TOC stroke clinic will provide valuable information as healthcare systems navigate the post-COVID era