Klipsun Magazine, 1977, Volume 07, Issue 04 - April

https://cedar.wwu.edu/klipsun_magazine/1036/thumbnail.jp

Klipsun Magazine, 1977, Volume 07, Issue 05 - June

https://cedar.wwu.edu/klipsun_magazine/1037/thumbnail.jp

Extremely limited synthesis of long chain polyunsaturates in adults: implications for their dietary essentiality and use as supplements

La communauté scientifique accorde beaucoup d’intérêt à plusieurs acides gras polyinsaturés (PUFA) et à leur atténuation potentielle du taux de mortalité et de morbidité causée par les maladies dégénératives du système cardiovasculaire et du cerveau. Il n’en demeure pas moins que la confusion demeure au sujet du taux de conversion chez l’humain des PUFA en amont – acide linoléique ou α-linolénique (ALA) – en des substances respectives à plus longue chaîne. On ne connaît toujours pas les bienfaits potentiels de l’ALA en amont de l’acide eicosapentaénoïque (EPA) ou de l’acide docosahexaénoïque (DHA). La confusion est en partie née du fait que les mammifères disposent des enzymes nécessaires pour synthétiser les PUFA à chaîne longue à partir des PUFA en amont alors que les études in vivo chez l’humain révèlent que ≈5 % de l’ALA est converti en EPA et moins de 0,5 % de l’ALA est converti en DHA. Du fait de la très faible capacité de cette voie de synthèse chez des humains en bonne santé non végétariens, même un grand apport alimentaire d’ALA a un effet négligeable sur la concentration plasmatique de DHA ; on observe le même phénomène chez les PUFA oméga-6 : l’apport alimentaire d’acide linoléique a peu d’effet sur la concentration plasmatique de l’acide arachidonique. Nonobstant cette conversion à faible rendement, l’ALA et l’EPA ont potentiellement un rôle à jouer au plan de la santé chez l’humain qui n’a rien à voir avec la conversion en DHA dans la voie de désaturation-élongation des acides gras.Abstract: There is considerable interest in the potential impact of several polyunsaturated fatty acids (PUFAs) in mitigating the significant morbidity and mortality caused by degenerative diseases of the cardiovascular system and brain. Despite this interest, confusion surrounds the extent of conversion in humans of the parent PUFA, linoleic acid or alpha-linolenic acid (ALA), to their respective long-chain PUFA products. As a result, there is uncertainty about the potential benefits of ALA versus eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA). Some of the confusion arises because although mammals have the necessary enzymes to make the long-chain PUFA from the parent PUFA, in vivo studies in humans show that asymptotically equal to 5% of ALA is converted to EPA and <0.5% of ALA is converted to DHA. Because the capacity of this pathway is very low in healthy, nonvegetarian humans, even large amounts of dietary ALA have a negligible effect on plasma DHA, an effect paralleled in the omega6 PUFA by a negligible effect of dietary linoleic acid on plasma arachidonic acid. Despite this inefficient conversion, there are potential roles in human health for ALA and EPA that could be independent of their metabolism to DHA through the desaturation - chain elongation pathway

Fish and human brain evolution

Carlson and Kingston ([2007]: Am J Hum Biol 19:132–141) propose that preformed dietary docosahexaenoic acid (an omega-3 fatty acid in fish) did not have a significant role in hominin encephalization. Their position hinges on claiming that humans are able to make sufficient docosahexaenoic acid from the plant-based \parent" omega-3 fatty acid—alinolenic acid. They also suggest that hominin fish consumption occurred too late to have materially influenced encephalization. The authors quantify here a summary of the published data showing that humans cannot make sufficient docosahexaenoic acid to maintain normal infant brain development. The authors also provide evidence that the fossil record shows that some of the earliest hominins were regularly consuming fish. Hence, we reject Carlson and Kingston’s position and reiterate support for the concept that access to shore-based diets containing docosahexaenoic acid was necessary for hominin encephalization beyond the level seen in the great apes. Am. J. Hum. Biol. 19:578–581, 2007

Reducing microwave loss in superconducting resonators due to trapped vortices

Microwave resonators with high quality factors have enabled many recent breakthroughs with superconducting qubits and photon detectors, typically operated in shielded environments to reduce the ambient magnetic field. Insufficient shielding or pulsed control fields can introduce vortices, leading to reduced quality factors, although increased pinning can mitigate this effect. A narrow slot etched into the resonator surface provides a straightforward method for pinning enhancement without otherwise affecting the resonator. Resonators patterned with such a slot exhibited over an order of magnitude reduction in the excess loss due to vortices compared with identical resonators from the same film with no slot

Microstrip superconducting quantum interference device amplifiers with submicron Josephson junctions: enhanced gain at gigahertz frequencies

We present measurements of an amplifier based on a dc superconducting quantum interference device (SQUID) with submicron Al-AlOx-Al Josephson junctions. The small junction size reduces their self-capacitance and allows for the use of relatively large resistive shunts while maintaining nonhysteretic operation. This leads to an enhancement of the SQUID transfer function compared to SQUIDs with micron-scale junctions. The device layout is modified from that of a conventional SQUID to allow for coupling signals into the amplifier with a substantial mutual inductance for a relatively short microstrip coil. Measurements at 310 mK exhibit gain of 32 dB at 1.55 GHz.Comment: Version with high resolution figures at: http://physics.syr.edu/~bplourde/bltp-publications.ht

Klipsun Magazine, 1977, Volume 07, Issue 03 - March

https://cedar.wwu.edu/klipsun_magazine/1035/thumbnail.jp

Picovoltmeter for probing vortex dynamics in a single weak-pinning Corbino channel

We have developed a picovoltmeter using a Nb dc Superconducting QUantum Interference Device (SQUID) for measuring the flux-flow voltage from a small number of vortices moving through a submicron weak-pinning superconducting channel. We have applied this picovoltmeter to measure the vortex response in a single channel arranged in a circle on a Corbino disk geometry. The circular channel allows the vortices to follow closed orbits without encountering any sample edges, thus eliminating the influence of entry barriers.Comment: 4 pages, 3 figures, submitted to Review of Scientific Instrument