The UT 19-channel DC SQUID based neuromagnetometer

A l9-channel DC SQUID based neuromagnetometer is under construction at the University of Twente (UT). Except for the cryostat all elements of the system are developed at the UT. It comprises 19 wire-wound first-order gradiometers in a hexagonal configuration. The gradiometers are connected to planar DC SQUIDS fabricated with a Nb/Al, AlOx/Nb technology. For this connection we developed a method to bond a Nb wire to a Nb thin-film. The SQUIDs are placed in compartmentalised Nb modules. Further, external feedback is incorporated in order to eliminate cross talk between the gradiometers. The electronics basically consist of a phase-locked loop operating with a modulation frequency of 100 kHz. Between SQUID and preamplifier a small transformer is used to limit the noise contribution of the preamplifier. In the paper the overall system is described, and special attention is paid to the SQUID module (bonding, compartments, external-feedback setup, output transformer)

Mechanics of cooling liquids by forced evaporation in bubbles

Injecting a non-dissolvable gas into a saturated liquid results in sub-cooling of the liquid due to forced evaporation into the bubble. Previous studies assumed the rate of evaporation of liquid into the bubble to be independent of the degree of sub-cooling. In our study we quantify the bubble growth by direct observation using high speed imaging and prove that this hypothesis is not true. A phenomenological model of the bubble growth as a function of the degree of sub-cooling is developed and we find excellent agreement between the measurements and theory. This bubble cooling process is employed in cooling a liquid. By identification of all heat flows, we can well describe the cool down curve using bubble cooling. Bubble cooling provides an alternative cooling method for liquids without the use of complicated cooling techniques

Interferometric speckle visibility spectroscopy (ISVS) for human cerebral blood flow monitoring

Infrared light scattering methods have been developed and employed to non-invasively monitor human cerebral blood flow (CBF). However, the number of reflected photons that interact with the brain is low when detecting blood flow in deep tissue. To tackle this photon-starved problem, we present and demonstrate the idea of interferometric speckle visibility spectroscopy (ISVS). In ISVS, an interferometric detection scheme is used to boost the weak signal light. The blood flow dynamics are inferred from the speckle statistics of a single frame speckle pattern. We experimentally demonstrated the improvement of measurement fidelity by introducing interferometric detection when the signal photon number is insufficient. We apply the ISVS system to monitor the human CBF in situations where the light intensity is $\sim$100-fold less than that in common diffuse correlation spectroscopy (DCS) implementations. Due to the large number of pixels ($\sim 2\times 10^5$) used to capture light in the ISVS system, we are able to collect a similar number of photons within one exposure time as in normal DCS implementations. Our system operates at a sampling rate of 100 Hz. At the exposure time of 2 ms, the average signal photon electron number is $\sim$0.95 count/pixel, yielding a single pixel interferometric measurement signal-to-noise ratio (SNR) of $\sim$0.97. The total $\sim 2\times 10^5$ pixels provide an expected overall SNR of 436. We successfully demonstrate that the ISVS system is able to monitor the human brain pulsatile blood flow, as well as the blood flow change when a human subject is doing a breath holding task

Conceptual design of a sorption-based cryochain for the ETpathfinder

Next-generation gravitational wave detectors, including the Einstein Telescope [1] [2], aim to achieve amplitude-spectral-density strain sensitivities on the order 10−24m/Hz [3]. In the low-frequency band such sensitivities can only be obtained when thermal noise, mainly stemming from the mirror coating, is reduced by employing cryogenic cooling techniques for the mirrors. The optical surface of the mirror should not vibrate with strain noise amplitude spectral densities above 10−20m/Hz for the cryogenic mirrors in the Einstein Telescope [3]. The ETpathfinder research facility [4] [5], aims to facilitate the development and testing of critical new technologies required for the design and operation of future gravitational wave detectors. A key enabling technology for the design and operation of such advanced interferometers is the cryogenic system that cools the main optics to a temperature of approximately 10 K. Given the stringent requirements on vibrational noise for these optics, the cryogenic cooling under continuous operation should be essentially vibration free. Joule-Thomson cryocoolers using sorption compressors are known to generate an absolute minimum of vibrational noise during operation. We propose a modular cryochain design comprised of a system of sorption compressors and Joule-Thomson cold stages fitting the ETpathfinder project requirements. In this paper, we present the conceptual design of the cooler chain that is based on a parallel cascade arrangement of a 40 K neon stage, a 15 K hydrogen stage and a 8 K helium stage. The operating parameters of the sorption-based cooler chain are selected via a hybrid modeling workflow, aiming to optimize performance and other design considerations within an envelope of acceptable design parameters.</p

Personalities in female domesticated pigs: behavioural and physiological indications

The inconclusive evidence so far on the existence of distinct personality types in domesticated pigs, led us to perform the present experiment. A total of 128 gilts from 31 sows were systematically studied from birth to slaughter in two identical trials. Intra-test consistency in individual behavioural andror physiological reactions was studied in three different tests. We were not able to show consistencies in reactions of gilts over time to a backtest (at 2–4 days and 4 weeks of age) and to a novel environment test (at 10 and 24 weeks of age). Individual aggression, however, as measured in a group-feeding competition test in stable groups (at 10 and 24 weeks of age), proved to be highly consistent. Explanations for these discrepancies in intra-test consistencies are critically discussed. Inter-test consistencies were determined by relating the individual reactions of gilts to the backtest to various characteristics and responses to tests at a later age. The highest correlations were found when resistance in the first backtest was involved. No evidence was found for the existence of specific isolated categories of animals with respect to this resistance. For further analysis, extreme responding gilts in the first backtest (roughly the top and bottom 25% of the distribution) were classified as low resistant (LR; <3 escape attempts; n=31) or high resistant (HR; >4 escape attempts; n=45). By comparisons of mean responses of LR and HR gilts within groups, we have established a relationship between the backtest and several other variables. Behaviourally, the HR gilts showed more aggression in the group-feeding competition tests. Also, in the competition for the most productive teats at the anterior, a predominant position of HR piglets at this site was observed during the suckling period. The latter piglets also gained more weight during this period than LR ones. Compared to HR pigs, in the first novel environment test LR pigs hesitated longer to leave their home pens and to contact a human, but no difference in their locomotory behaviour was observed. Contrasts between LR and HR pigs in the second novel environment test were reduced or absent. Physiologically, when compared to HR gilts, LR ones had a higher reactivity of the hypothalamic–pituitary–adrenocortical (HPA) system. This was shown by higher cortisol responses to the first novel environment test, to routine weighing at 25 weeks of age, and to administration of a high dose of ACTH. It is discussed that these findings for LR and HR gilts, may provide support for the existence of behavioural and physiological responses in pigs, resembling those of proactive and reactive rodents.

Міфологізм у символістській прозі Клима Поліщука

The particularities of mythology in symbolist prose by Klym Polishchuk are explained in the article. There are two time planes of plot evolvement in fantastic stories by Klym PolishchukG past and present. Fantastic events in the past have continuation in

Effects of Feeding Brassica Mixture Cover Crops During Backgrounding on Carcass Traits and Fresh Meat Quality

Objective: Determine effects of feeding brassica-based cover crops to cattle during backgrounding on carcass characteristics and tenderness, flavor, and juiciness of longissimus dorsi steaks