7,460 research outputs found

    Work and information processing in a solvable model of Maxwell's demon

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    We describe a minimal model of an autonomous Maxwell demon, a device that delivers work by rectifying thermal fluctuations while simultaneously writing information to a memory register. We solve exactly for the steady-state behavior of our model, and we construct its phase diagram. We find that our device can also act as a "Landauer eraser", using externally supplied work to remove information from the memory register. By exposing an explicit, transparent mechanism of operation, our model offers a simple paradigm for investigating the thermodynamics of information processing by small systems.Comment: Main Text (6 pages, 3 figures) + Suppl. Info. (3 pages). To appear in PNA

    Sub-Doppler laser cooling of fermionic 40K atoms in three-dimensional gray optical molasses

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    We demonstrate sub-Doppler cooling of 40K on the D_1 atomic transition. Using a gray molasses scheme, we efficiently cool a compressed cloud of 6.5x10^8 atoms from ~ 4\mK to 20uK in 8 ms. After transfer in a quadrupole magnetic trap, we measure a phase space density of ~10^-5. This technique offers a promising route for fast evaporation of fermionic 40K.Comment: 6 pages; 7 figures; submitted to EP

    Nootropics use in the workplace. Psychiatric and ethical aftermath towards the new frontier of bioengineering

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    OBJECTIVE: The authors have sought to expound upon and shed a light on the rise of nootropics, which have gradually taken on a more and more relevant role in workplaces and academic settings. MATERIALS AND METHODS: Multidisciplinary databases have been delved into by entering the following keys: "nootropics", "cognitive enhancement", "workplace", "productivity", "ethics", "bioengineering". In addition, a broad-ranging search has been undertaken on institutional websites in order to identify relevant analysis and recommendations issued by international institutions and agencies. Papers and reports have been independently pored over by each author. This search strategy has led to the identification of 988 sources but only 64 were considered appropriate for the purposes of the paper after being selected by at least 3 of the authors, independently. RESULTS: The notion of an artificially enhanced work performance - carried out by the 'superworker' - is particularly noteworthy and resonates with the conception of contemporary work on so many different levels: the rising need and demands for higher degrees of flexibility and productivity on the job, the implications of a '24/7' society, where more and more services are available at any time, the ever greater emphasis on entrepreneurial spirit, individual self-reliance and self-improvement, and last but not least, the impact of an ageing society on economic standards and performance. CONCLUSIONS: Moreover, it is worth mentioning that human enhancement technologies will predictably and increasingly go hand in hand with gene editing, bioengineering, cybernetics and nanotechnology. Applications are virtually boundless, and may ultimately affect all human traits (physical strength, endurance, vision, intelligence and even personality and mood)

    IN-SYNC. VII. Evidence for a decreasing spectroscopic binary fraction from 1 to 100 Myr within the IN-SYNC sample

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    We study the occurrence of spectroscopic binaries in young star-forming regions using the INfrared Spectroscopy of Young Nebulous Clusters(IN-SYNC) survey, carried out in SDSS-III with the APOGEE spectrograph. Multi-epoch observations of thousands of low-mass stars in Orion A, NGC 2264, NGC 1333, IC 348, and the Pleiades have been carried out, yielding H-band spectra with a nominal resolution of R=22,500 for sources with H \le 12 mag. Radial velocity precisions of \sim0.3 kms1km\:s^{-1} were achieved, which we use to identify radial velocity variations indicative of undetected companions. We use Monte Carlo simulations to assess the types of spectroscopic binaries to which we are sensitive, finding sensitivity to binaries with orbital periods <104< 10^{4} d, for stars with 2500KTeff6000K2500 {\rm K} \le T_\mathrm{eff} \le 6000 {\rm K} and vsini\it{v} \sin \it{i} \le 100 kms1km\:s^{-1}. Using Bayesian inference, we find evidence for a decline in the spectroscopic binary fraction, by a factor of 3-4 from the age of our pre-main-sequence sample to the Pleiades age . The significance of this decline is weakened if spot-induced radial-velocity jitter is strong in the sample, and is only marginally significant when comparing any one of the pre-main-sequence clusters against the Pleiades. However, the same decline in both sense and magnitude is found for each of the five pre-main-sequence clusters, and the decline reaches statistical significance of greater than 95% confidence when considering the pre-main-sequence clusters jointly. Our results suggest that dynamical processes disrupt the widest spectroscopic binaries (Porb103104P_{\rm orb} \approx 10^3 - 10^4 d) as clusters age, indicating that this occurs early in the stars' evolution, while they still reside within their nascent clusters.Comment: 21 pages, 9 Figure

    IN-SYNC. VIII. Primordial Disk Frequencies in NGC 1333, IC 348, and the Orion A Molecular Cloud

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    In this paper, we address two issues related to primordial disk evolution in three clusters (NGC 1333, IC 348, and Orion A) observed by the INfrared Spectra of Young Nebulous Clusters (IN-SYNC) project. First, in each cluster, averaged over the spread of age, we investigate how disk lifetime is dependent on stellar mass. The general relation in IC 348 and Orion A is that primordial disks around intermediate mass stars (2--5MM_{\odot}) evolve faster than those around loss mass stars (0.1--1MM_{\odot}), which is consistent with previous results. However, considering only low mass stars, we do not find a significant dependence of disk frequency on stellar mass. These results can help to better constrain theories on gas giant planet formation timescales. Secondly, in the Orion A molecular cloud, in the mass range of 0.35--0.7MM_{\odot}, we provide the most robust evidence to date for disk evolution within a single cluster exhibiting modest age spread. By using surface gravity as an age indicator and employing 4.5 μm\mu m excess as a primordial disk diagnostic, we observe a trend of decreasing disk frequency for older stars. The detection of intra-cluster disk evolution in NGC 1333 and IC 348 is tentative, since the slight decrease of disk frequency for older stars is a less than 1-σ\sigma effect.Comment: 25 pages, 26 figures; submitted for publication (ApJ

    Irish Studies in Spain: 2015-March 2016

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    In October 2015 the Irish fashion retailer chain Primark opened its second world-wide biggest premises in Madrid. Low-cost fashion, low-cost travel, low-cost food … low-cost life? What about quality? Fortunately, Irish-Spanish relationships cannot be reduced to economic endeavours or to the Kinahan mafia clan criminal forays into the Spanish “Costa del Sol” (Málaga). Even if the period covered by this review has not been particularly fruitful in terms of publications by Spanish or Spanish affiliated scholars, it has been rich in cultural events, both academic and informative, with assorted commemorations and celebrations of Irish culture, particularly music, cinema and literature. I will start here by first commenting on Spanish translations of both fictional and non-fictional works by Irish authors
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