Three-point bounds for energy minimization

Three-point semidefinite programming bounds are one of the most powerful known tools for bounding the size of spherical codes. In this paper, we use them to prove lower bounds for the potential energy of particles interacting via a pair potential function. We show that our bounds are sharp for seven points in RP^2. Specifically, we prove that the seven lines connecting opposite vertices of a cube and of its dual octahedron are universally optimal. (In other words, among all configurations of seven lines through the origin, this one minimizes energy for all potential functions that are completely monotonic functions of squared chordal distance.) This configuration is the only known universal optimum that is not distance regular, and the last remaining universal optimum in RP^2. We also give a new derivation of semidefinite programming bounds and present several surprising conjectures about them.Comment: 30 page

The Costs of Computer-Assisted Instruction

The purpose of this paper is to estimate the costs and cost feasibility of utilizing computer-assisted instruction (CAI) for compensatory education. Cost data were collected from an experiment on the effectiveness of CA1 that had been established in Los Angeles and sponsored by the National Institute of Education. Based upon the resource ingredients approach to measuring costs, it was found that up to three daily lo-minute sessions of drill and practice could be provided for each disadvantaged child within the 1977- 1978 allocation of funds from Title I of the Elementary and Secondary Education Act of 1965. If the computer system were shared between two schools, the higher costs would permit only two daily sessions. Costs were also estimated for a more advanced CA1 system, and somewhat surprisingly the costs were in the same range. This finding reflects the very heavy costs of “software” that do not seem to decline with more advanced technologies. Also, it is possible that the latter technology will be found to be more effective at the same cost level. However, because comparative effectiveness data between the CA1 approach and other instructional strategies are not readily available, such cost-effectiveness comparisons will have to be deferred until some future date

Single-photon detection timing jitter in a visible light photon counter

Visible light photon counters (VLPCs) offer many attractive features as photon detectors, such as high quantum efficiency and photon number resolution. We report measurements of the single-photon timing jitter in a VLPC, a critical performance factor in a time-correlated single-photon counting measurement, in a fiber-coupled closed-cycle cryocooler. The measured timing jitter is 240 ps full-width-at-half-maximum at a wavelength of 550 nm, with a dark count rate of 25 000 counts per second. The timing jitter increases modestly at longer wavelengths to 300 ps at 1000 nm, and increases substantially at lower bias voltages as the quantum efficiency is reduced

Paper Session III-B - In-Space Operations Driven Mars Transfer Vehicle System

Mars transfer vehicles (MTV\u27s) using nuclear thermal propulsion (NTP) to reduce transit time introduce a new dimension in the design for in-space operations. The objective of the paper is to define practical concepts based on a set of design-for-operation strategies. An artificial-g MTV using NTP is characterized in this study. Manifests of MTV elements for the heavy lift launch vehicles (HLLV\u27s) are shown to affect in-space assembly and maintenance requirements. A main goal is to minimize EVA operations during the assembly of a MTV in Low-Earth-Orbit (LEO). Self-build, self-build/ depot hybrid, free-flyer robotic spacecrafts, build-up by lunar vehicles, and construction platform are concepts investigated. Maintainability analysis indicates that the self-build/ depot hybrid concept is optimum over the self- build and platform concept

Ability of γδ T cells to modulate the Foxp3 T cell response is dependent on adenosine.

Whether γδ T cells inhibit or enhance the Foxp3 T cell response depends upon their activation status. The critical enhancing effector in the supernatant is adenosine. Activated γδ T cells express adenosine receptors at high levels, which enables them to deprive Foxp3+ T cells of adenosine, and to inhibit their expansion. Meanwhile, cell-free supernatants of γδ T cell cultures enhance Foxp3 T cell expansion. Thus, inhibition and enhancement by γδ T cells of Foxp3 T cell response are a reflection of the balance between adenosine production and absorption by γδ T cells. Non-activated γδ T cells produce adenosine but bind little, and thus enhance the Foxp3 T cell response. Activated γδ T cells express high density of adenosine receptors and have a greatly increased ability to bind adenosine. Extracellular adenosine metabolism and expression of adenosine receptor A2ARs by γδ T cells played a major role in the outcome of γδ and Foxp3 T cell interactions. A better understanding of the functional conversion of γδ T cells could lead to γδ T cell-targeted immunotherapies for related diseases

Combined Drug Efficacy of EGFR and ASCT2 Inhibitors in Preclinical Models of Colorectal Cancer

https://openworks.mdanderson.org/sumexp22/1082/thumbnail.jp

Implications of laparoscopic inguinal hernia repair on open, laparoscopic, and robotic radical prostatectomy

PurposeThere have been anecdotal reports of surgeons having to abandon radical prostatectomy (RP) after laparoscopic inguinal hernia repair (LIHR) due to obliteration of tissue planes by mesh. Nodal dissection may also be compromised. We prospectively collected data from four experienced prostate surgeons from separate institutions. Our objective was to evaluate the success rate of performing open RP (ORP), laparoscopic RP (LRP) and robotic assisted RP (RALRP) and pelvic lymph node dissection (PLND) after LIHR, and the frequency of complications.MethodsA retrospective analysis of prospectively maintained databases of men who underwent RP after LIHR between 2004 and 2010 at four institutions was undertaken. The data recorded included age, preoperative prostate-specific antigen, preoperative Gleason score, and clinical stage. The operative approach, success or failure to perform RP, success or failure to perform PLND, pathological stage, and complications were also recorded.ResultsA total of 1,181 men underwent RP between 2004 and 2010. Fifty-seven patients (4.8%) underwent RP after LIHR. An ORP was attempted in 19 patients, LRP in 33, and RALRP in 5. All 57 cases were able to be successfully completed. Ten of the 18 open PLND were able to be completed (55.6%). Four of the 22 laparoscopic LND were able to be completed (18.2%). Robotic LND was possible in 5 of 5 cases (100%). Therefore, it was not possible to complete a LND 56.8% of patients. Complications were limited to ten patients. These complications included one LRP converted to ORP due to failure to progress, and one rectourethral fistula in a salvage procedure post failed high intensity focused ultrasound.ConclusionsLIHR is an increasingly common method of treating inguinal hernias. LIHR is not a contra-indication to RP. However PLND may not be possible in over 50% of patients who have had LIHR. Therefore, these patients may be under-staged and under treated

Versatile silicon-waveguide supercontinuum for coherent mid-infrared spectroscopy

Infrared spectroscopy is a powerful tool for basic and applied science. The molecular spectral fingerprints in the 3 um to 20 um region provide a means to uniquely identify molecular structure for fundamental spectroscopy, atmospheric chemistry, trace and hazardous gas detection, and biological microscopy. Driven by such applications, the development of low-noise, coherent laser sources with broad, tunable coverage is a topic of great interest. Laser frequency combs possess a unique combination of precisely defined spectral lines and broad bandwidth that can enable the above-mentioned applications. Here, we leverage robust fabrication and geometrical dispersion engineering of silicon nanophotonic waveguides for coherent frequency comb generation spanning 70 THz in the mid-infrared (2.5 um to 6.2 um). Precise waveguide fabrication provides significant spectral broadening and engineered spectra targeted at specific mid-infrared bands. We use this coherent light source for dual-comb spectroscopy at 5 um.Comment: 26 pages, 5 figure

NMR-based Metabolic Profiling of Pancreatic Cancer and Response to Glutamine Transport Inhibition

https://openworks.mdanderson.org/sumexp21/1227/thumbnail.jp

A Dual (Brachial and Contralateral Femoral) Approach for Subintimal Angioplasty of Long Ilio-Femoral Occlusive Disease Including the Iliac Ostium

As techniques and device technology have improved, the success rates and long patency of ilio-femoral occlusive disease have also improved. In the case of extensive iliac occlusive disease, however, wire passage and handling remain a challenge due to the relatively weak guiding catheter backup support with the contralateral femoral approach. There has been no report on methods to overcome this problem. We performed a successful percutaneous translunimal angioplasty for long ilio-femoral occlusive disease including the iliac ostium by a dual approach including simultaneous brachial and contralateral femoral arteries for subintimal angioplasty