Direct observation of growth and collapse of a Bose-Einstein condensate with attractive interactions

The dynamical behavior of Bose-Einstein condensation (BEC) in a gas with attractive interactions is striking. Quantum theory predicts that BEC of a spatially homogeneous gas with attractive interactions is precluded by a conventional phase transition into either a liquid or solid. When confined to a trap, however, such a condensate can form provided that its occupation number does not exceed a limiting value. The stability limit is determined by a balance between self-attraction and a repulsion arising from position-momentum uncertainty under conditions of spatial confinement. Near the stability limit, self-attraction can overwhelm the repulsion, causing the condensate to collapse. Growth of the condensate, therefore, is punctuated by intermittent collapses, which are triggered either by macroscopic quantum tunneling or thermal fluctuation. Previous observation of growth and collapse has been hampered by the stochastic nature of these mechanisms. Here we reduce the stochasticity by controlling the initial number of condensate atoms using a two-photon transition to a diatomic molecular state. This enables us to obtain the first direct observation of the growth of a condensate with attractive interactions and its subsequent collapse.Comment: 10 PDF pages, 5 figures (2 color), 19 references, to appear in Nature Dec. 7 200

Modeling and compensation of cutting-forces generated during the EDM process for ultra high-precision robots

This work deals with the calibration of industrial robots operating at sub-micrometric precision. We demonstrate that the cutting-forces generated by the robot manufacturing process cause a significant deformation of the robot geometry, lo- wering its absolute accuracy. Then, we propose a way of studying and modeling such deformations, in order to compen- sate them during the robot usage. We have taken the micro electro-discharge machining process on the robot Agietron micro-nano as a case study and we have used an ultra high-precision measuring system to evaluate the deformations due to cutting-forces. Finally, we have built a mathematical model of the robot physical behavior and we have implemented it in the robot controller, in order to compensate the deformations in real-time

DLC Thin Films and Carbon Nanocomposite Growth by Thermionic Vacuum Arc (TVA) Technology

The aim of this chapter is to report the results on synthesis DLC thin films and carbon nanocomposites by the versatile nanofabrication method based on plasma entitled thermionic vacuum Arc (TVA). TVA technology is based on the localized ignition of the arc plasma in vacuum conditions. Among thin film coating methods by vacuum deposition techniques with high purity, low roughness, and good adhesion on the substrates, TVA is one of the major suitable methods to become a powerful coating technology. Two or three different TVA discharges can be ignited simultaneously in the same chamber for multi-material processing using TVA and separate power supplies. These TVA discharges are localized and do not interfere with each other. Simultaneous two or three TVA discharges were already used for the production of alloy/composite of various materials. This is due to the high versatility concerning the configuration of experimental arrangements, taking into account the number of electron guns, symmetry of the electrodes, relative position of the anode versus cathode, and also the huge opportunity to combine the materials to be deposited: bi- and multi-layers, nanocomposites, or alloys in order to have specific applications. This chapter presents the comparative results concerning the surface-free energy information processing, the reflective index, the hardness, and the morphology to provide a coherent description of the diamond-like carbon films and carbon nanocomposites synthesized by thermionic vacuum arc (TVA) and related configurations where Me = Ag, Al, Cu, Ni, and Ti: binary composites (C-Me, C-Si) and ternary composites (C+Si+Me). The results include reports on the distribution in size, surface, geometry, and dispersion of the nanosized constituents, tailoring and understanding the role of interfaces between structurally or chemically dissimilar phases on bulk properties, as well as the study of physical properties of nanocomposites (structural, chemical, mechanical, tribological). The results presented here could have a great impact on the development of advanced materials and many manufacturing industries, as well as expanding the technologically important field of interface science where the control of the film-substrate interface would be critical

Evaluating the incidence of pathological complete response in current international rectal cancer practice

The mainstay of management for locally advanced rectal cancer is chemoradiotherapy followed by surgical resection. Following chemoradiotherapy, a complete response may be detected clinically and radiologically (cCR) prior to surgery or pathologically after surgery (pCR). We aim to report the overall complete pathological response (pCR) rate and the reliability of detecting a cCR by conventional pre-operative imaging.A pre-planned analysis of the European Society of Coloproctology (ESCP) 2017 audit was performed. Patients treated by elective rectal resection were included. A pCR was defined as a ypT0 N0 EMVI negative primary tumour; a partial response represented any regression from baseline staging following chemoradiotherapy. The primary endpoint was the pCR rate. The secondary endpoint was agreement between post-treatment MRI restaging (yMRI) and final pathological staging.Of 2572 patients undergoing rectal cancer surgery in 277 participating centres across 44 countries, 673 (26.2%) underwent chemoradiotherapy and surgery. The pCR rate was 10.3% (67/649), with a partial response in 35.9% (233/649) patients. Comparison of AJCC stage determined by post-treatment yMRI with final pathology showed understaging in 13% (55/429) and overstaging in 34% (148/429). Agreement between yMRI and final pathology for T-stage, N-stage, or AJCC status were each graded as 'fair' only (n = 429, Kappa 0.25, 0.26 and 0.35 respectively).The reported pCR rate of 10% highlights the potential for non-operative management in selected cases. The limited strength of agreement between basic conventional post-chemoradiotherapy imaging assessment techniques and pathology suggest alternative markers of response should be considered, in the context of controlled clinical trials

Hybrid density functional studies of bulk actinide oxides

Actinide materials are systems rich in interesting physics, while playing an important role in environmental preservation, and a good comprehension of their electronic structure is therefore of particular importance. A first-principles computational methodology is proposed in this work, affording accurate density functional theory studies in such strongly-correlated crystalline systems. The main ingredient behind the success of this approach is the use of hybrid density functionals, which provide good agreement with known experimental data for the optimum structural and electronic properties of the actinide oxides considered in this study. The predictive capabilities of the method help understand certain unusual properties and phenomena associated with these compounds, from puzzling experimental findings to the relative stability of heavy actinide oxides. Plutonium dioxide is taken as a case study in this work and detailed structural investigations are considered for this compound, such as the effects of non-stoichiometry and of various lattice distortions. The interstitial oxygen in PuO2.25 for example is found to be singly charged, consistent with experimental observations and contrary to the O2- previously proposed theoretically. A tetragonal distortion of the PuO2 lattice, with a very small orthorhombic component, is energetically favorable in our description at zero temperature. Such lattice deformation anticipates the experimentally observed orthorhombic phase, to which many actinide dioxides transform at high pressures. We also confirm that non-hydrostatic effects could be responsible for the intriguing value of the only measurement to date of the bulk modulus of PuO2. Unexpected f orbital populations are predicted in heavy actinide dioxides, and they could elucidate certain perplexing structural measurements made on these compounds. These occupancies point to an early-occurring half-filled shell effect, and can also explain the lack of experimental evidence for the heavier actinide dioxides. These findings suggest that accepted models of electronic structure for certain open-shell compounds are not always warranted, and that their theoretical descriptions should be revised accordingly

Spokeheel: Autonomous robot with high mobility and magnetic adhesion.

This paper describes the conception of a mobile robot for industrial inspection of ferromagnetic environments

Continuous Wearable-Sensor Monitoring After Colorectal Surgery: A Systematic Review of Clinical Outcomes and Predictive Analytics

Background and Objectives: Early ambulation and timely detection of postoperative complications are cornerstones of colorectal Enhanced Recovery After Surgery (ERAS) programmes, yet the traditional bedside checks performed every 4–8 h may miss clinically relevant deterioration. The consumer wearables boom has spawned a new generation of wrist- or waistband-mounted sensors that stream step count, heart-rate and temperature data continuously, creating an opportunity for data-driven early-warning strategies. No previous systematic review has focused exclusively on colorectal surgery. Methods: Three databases (PubMed, Embase, and Scopus) were searched (inception—1 May 2025) for prospective or retrospective studies that used a consumer-grade or medical-grade wearable to collect objective physical-activity or vital-sign data during the peri-operative period of elective colorectal resection. Primary outcomes were postoperative complication rates, length-of-stay (LOS) and 30-day readmission. Two reviewers screened records, extracted data and performed risk-of-bias appraisals with ROBINS-I or RoB 2. Narrative synthesis was adopted because of the heterogeneity in devices, recording windows and outcome definitions. Results: Nine studies (n = 778 patients) met eligibility: one randomised controlled trial (RCT), seven prospective cohort studies and one retrospective analysis. Five studies relied on step-count metrics alone; four combined step-count with heart-rate or skin-temperature streams. Median wear time was 6 d (range 2–30). Higher day-1 step count (≥1000 steps) was associated with shorter LOS (odds ratio 0.63; 95% CI 0.45–0.84). Smart-band–augmented ERAS pathways shortened protocol-defined LOS by 1.1 d. Pre-operative inactivity (<5000 steps·day−1) and low “return-to-baseline” activity on the day before discharge independently predicted any complication (OR 0.39) and 30-day readmission (OR 0.60 per 10% increment). A prospective 101-patient study that paired pedometer-recorded ambulation with daily lung-ultrasound scores found fewer pulmonary complications when patients walked further (Spearman r = –0.36, p < 0.05). Conclusions: Continuous, patient-worn sensors are feasible and yield clinically meaningful data after colorectal surgery. Early postoperative step-count trajectories and activity-derived recovery indices correlate with LOS, complications and readmission, supporting their incorporation into digital ERAS dashboards. Standardised outcome definitions, open algorithms for signal processing and multicentre validation are now required