Unsupervised Intuitive Physics from Visual Observations

While learning models of intuitive physics is an increasingly active area of research, current approaches still fall short of natural intelligences in one important regard: they require external supervision, such as explicit access to physical states, at training and sometimes even at test times. Some authors have relaxed such requirements by supplementing the model with an handcrafted physical simulator. Still, the resulting methods are unable to automatically learn new complex environments and to understand physical interactions within them. In this work, we demonstrated for the first time learning such predictors directly from raw visual observations and without relying on simulators. We do so in two steps: first, we learn to track mechanically-salient objects in videos using causality and equivariance, two unsupervised learning principles that do not require auto-encoding. Second, we demonstrate that the extracted positions are sufficient to successfully train visual motion predictors that can take the underlying environment into account. We validate our predictors on synthetic datasets; then, we introduce a new dataset, ROLL4REAL, consisting of real objects rolling on complex terrains (pool table, elliptical bowl, and random height-field). We show that in all such cases it is possible to learn reliable extrapolators of the object trajectories from raw videos alone, without any form of external supervision and with no more prior knowledge than the choice of a convolutional neural network architecture

Arterial Pulse Wave Velocities are Unchanged Following 12 Weeks of Circuit Weight Training

Arterial stiffness is decreased after vigorous endurance training and increased after high-intensity resistance training. The effects of a combined program of moderate endurance and resistance exercise on arterial stiffness have not been determined. PURPOSE: To determine whether12 weeks of circuit weight training will decrease both central and peripheral arterial stiffness as estimated from pulse wave velocity (PWV). METHODS: Thirteen males and eight females (age 22 ± 2, height 162 ± 8 cm, weight 78 ± 20 kg) were assigned to control (n = 10) or exercise (n = 11) groups. Aerobic capacity and muscular strength were assessed before and at the end of the 12 week period. Arterial pressures and PWV (Doppler) were recorded every four weeks. Velocities from the carotid to femoral artery and from the femoral to dorsalis pedis artery were used as estimates of central and peripheral stiffness. RESULTS: Muscular strength increased by 26% (P = .001) and VO2 max increased by 17% (P = .06) following circuit training in the exercise group, but was unchanged for controls. Circuit weight training did not affect arterial pressures, (systolic = 117 ± 3, diastolic = 74 ± 3 mmHg; pooled across groups), or central and peripheral PWV (central PWV = 6.2 ± 0.6, peripheral PWV = 9.5 ± 0.7 m ∙ s-1; pooled across groups). CONCLUSIONS: In contrast to other reports of increases in arterial stiffness following high-intensity resistance training, increases in muscular strength following moderate-intensity exercise in the current study were not associated with increased arterial stiffness. Circuit training may be an appropriate exercise prescription to increase muscular strength for patients at risk for peripheral artery disease

Phase 1b Trial of Proteasome Inhibitor Carfilzomib with Irinotecan in Lung Cancer and Other Irinotecan-Sensitive Malignancies That Have Progressed on Prior Therapy (Onyx IST Reference Number: CAR-IST-553)

Introduction Proteasome inhibition is an established therapy for many malignancies. Carfilzomib, a novel proteasome inhibitor, was combined with irinotecan to provide a synergistic approach in relapsed, irinotecan-sensitive cancers. Materials and Methods Patients with relapsed irinotecan-sensitive cancers received carfilzomib (Day 1, 2, 8, 9, 15, and 16) at three dose levels (20/27 mg/m2, 20/36 mg/m2 and 20/45 mg/m2/day) in combination with irinotecan (Days 1, 8 and 15) at 125 mg/m2/day. Key eligibility criteria included measurable disease, a Zubrod PS of 0 or 1, and acceptable organ function. Patients with stable asymptomatic brain metastases were eligible. Dose escalation utilized a standard 3 + 3 design. Results Overall, 16 patients were enrolled to three dose levels, with four patients replaced. Three patients experienced dose limiting toxicity (DLT) and the maximum tolerated dose (MTD) was exceeded in Cohort 3. The RP2 dose was carfilzomib 20/36 mg/m2 (given on Days 1, 2, 8, 9, 15, and 16) and irinotecan 125 mg/m2 (Days 1, 8 and 15). Common Grade (Gr) 3 and 4 toxicities included fatigue (19%), thrombocytopenia (19%), and diarrhea (13%). Conclusions Irinotecan and carfilzomib were well tolerated, with common toxicities of fatigue, thrombocytopenia and neutropenic fever. Objective clinical response was 19% (one confirmed partial response (PR) in small cell lung cancer (SCLC) and two unconfirmed); stable disease (SD) was 6% for a disease control rate (DCR) of 25%. The recommended phase II dose was carfilzomib 20/36 mg/m2 and irinotecan125 mg/m2. The phase II evaluation is ongoing in relapsed small cell lung cancer

Principles of meiotic chromosome assembly revealed in S. cerevisiae

During meiotic prophase, chromosomes organise into a series of chromatin loops emanating from a proteinaceous axis, but the mechanisms of assembly remain unclear. Here we use Saccharomyces cerevisiae to explore how this elaborate three-dimensional chromosome organisation is linked to genomic sequence. As cells enter meiosis, we observe that strong cohesin-dependent grid-like Hi-C interaction patterns emerge, reminiscent of mammalian interphase organisation, but with distinct regulation. Meiotic patterns agree with simulations of loop extrusion with growth limited by barriers, in which a heterogeneous population of expanding loops develop along the chromosome. Importantly, CTCF, the factor that imposes similar features in mammalian interphase, is absent in S. cerevisiae, suggesting alternative mechanisms of barrier formation. While grid-like interactions emerge independently of meiotic chromosome synapsis, synapsis itself generates additional compaction that matures differentially according to telomere proximity and chromosome size. Collectively, our results elucidate fundamental principles of chromosome assembly and demonstrate the essential role of cohesin within this evolutionarily conserved process

A comparison of shearing strengths of glued joints at various grain directions as determined by four methods of test

Information reviewed and reaffirmed March 1956

Spin- and energy relaxation of hot electrons at GaAs surfaces

The mechanisms for spin relaxation in semiconductors are reviewed, and the mechanism prevalent in p-doped semiconductors, namely spin relaxation due to the electron-hole exchange interaction, is presented in some depth. It is shown that the solution of Boltzmann-type kinetic equations allows one to obtain quantitative results for spin relaxation in semiconductors that go beyond the original Bir-Aronov-Pikus relaxation-rate approximation. Experimental results using surface sensitive two-photon photoemission techniques show that the spin relaxation-time of electrons in p-doped GaAs at a semiconductor/metal surface is several times longer than the corresponding bulk spin relaxation-times. A theoretical explanation of these results in terms of the reduced density of holes in the band-bending region at the surface is presented.Comment: 33 pages, 12 figures; earlier submission replaced by corrected and expanded version; eps figures now included in the tex