Spin-resolved Quantum Interference in Graphene

The unusual electronic properties of single-layer graphene make it a promising material system for fundamental advances in physics, and an attractive platform for new device technologies. Graphene's spin transport properties are expected to be particularly interesting, with predictions for extremely long coherence times and intrinsic spin-polarized states at zero field. In order to test such predictions, it is necessary to measure the spin polarization of electrical currents in graphene. Here, we resolve spin transport directly from conductance features that are caused by quantum interference. These features split visibly in an in-plane magnetic field, similar to Zeeman splitting in atomic and quantum dot systems. The spin-polarized conductance features that are the subject of this work may, in the future, lead to the development of graphene devices incorporating interference-based spin filters.Comment: 12 pages, 4 figures, plus supplementary (11 pages, 9 figures

Inducible and constitutive heat shock gene expression responds to modification of Hsp70 copy number in Drosophila melanogaster but does not compensate for loss of thermotolerance in Hsp70 null flies

<p>Abstract</p> <p>Background</p> <p>The heat shock protein Hsp70 promotes inducible thermotolerance in nearly every organism examined to date. Hsp70 interacts with a network of other stress-response proteins, and dissecting the relative roles of these interactions in causing thermotolerance remains difficult. Here we examine the effect of <it>Hsp70 </it>gene copy number modification on thermotolerance and the expression of multiple stress-response genes in <it>Drosophila melanogaster</it>, to determine which genes may represent mechanisms of stress tolerance independent of Hsp70.</p> <p>Results</p> <p><it>Hsp70 </it>copy number in four strains is positively associated with <it>Hsp70 </it>expression and inducible thermotolerance of severe heat shock. When assayed at carefully chosen temperatures, <it>Hsp70 </it>null flies are almost entirely deficient in thermotolerance. In contrast to expectations, increasing <it>Hsp70 </it>expression levels induced by thermal pretreatment are associated with increasing levels of seven other inducible <it>Hsps </it>across strains. In addition, complete <it>Hsp70 </it>loss causes upregulation of the inducible <it>Hsps </it>and six constitutive stress-response genes following severe heat shocks.</p> <p>Conclusion</p> <p>Modification of <it>Hsp70 </it>copy number quantitatively and qualitatively affects the expression of multiple other stress-response genes. A positive association between absolute expression levels of <it>Hsp70 </it>and other <it>Hsps </it>after thermal pretreatment suggests novel regulatory mechanisms. Severe heat shocks induce both novel gene expression patterns and almost total mortality in the <it>Hsp70 </it>null strain: alteration of gene expression in this strain does not compensate for <it>Hsp70 </it>loss but suggests candidates for overexpression studies.</p

Reduced Distractibility in a Remote Culture

Background In visual processing, there are marked cultural differences in the tendency to adopt either a global or local processing style. A remote culture (the Himba) has recently been reported to have a greater local bias in visual processing than Westerners. Here we give the first evidence that a greater, and remarkable, attentional selectivity provides the basis for this local bias. Methodology/Principal Findings In Experiment 1, Eriksen-type flanker interference was measured in the Himba and in Western controls. In both groups, responses to the direction of a task-relevant target arrow were affected by the compatibility of task-irrelevant distractor arrows. However, the Himba showed a marked reduction in overall flanker interference compared to Westerners. The smaller interference effect in the Himba occurred despite their overall slower performance than Westerners, and was evident even at a low level of perceptual load of the displays. In Experiment 2, the attentional selectivity of the Himba was further demonstrated by showing that their attention was not even captured by a moving singleton distractor. Conclusions/Significance We argue that the reduced distractibility in the Himba is clearly consistent with their tendency to prioritize the analysis of local details in visual processing

Inner Speech during Silent Reading Reflects the Reader's Regional Accent

While reading silently, we often have the subjective experience of inner speech. However, there is currently little evidence regarding whether this inner voice resembles our own voice while we are speaking out loud. To investigate this issue, we compared reading behaviour of Northern and Southern English participants who have differing pronunciations for words like ‘glass’, in which the vowel duration is short in a Northern accent and long in a Southern accent. Participants' eye movements were monitored while they silently read limericks in which the end words of the first two lines (e.g., glass/class) would be pronounced differently by Northern and Southern participants. The final word of the limerick (e.g., mass/sparse) then either did or did not rhyme, depending on the reader's accent. Results showed disruption to eye movement behaviour when the final word did not rhyme, determined by the reader's accent, suggesting that inner speech resembles our own voice

Temporal dynamics of selective attention and conflict resolution during cross-dimensional go-nogo decisions

<p>Abstract</p> <p>Background</p> <p>Decision-making is a fundamental capacity which is crucial to many higher-order psychological functions. We recorded event-related potentials (ERPs) during a visual target-identification task that required go-nogo choices. Targets were identified on the basis of cross-dimensional conjunctions of particular colors and forms. Color discriminability was manipulated in three conditions to determine the effects of color distinctiveness on component processes of decision-making.</p> <p>Results</p> <p>Target identification was accompanied by the emergence of prefrontal P2a and P3b. Selection negativity (SN) revealed that target-compatible features captured attention more than target-incompatible features, suggesting that intra-dimensional attentional capture was goal-contingent. No changes of cross-dimensional selection priorities were measurable when color discriminability was altered. Peak latencies of the color-related SN provided a chronometric measure of the duration of attention-related neural processing. ERPs recorded over the frontocentral scalp (N2c, P3a) revealed that color-overlap distractors, more than form-overlap distractors, required additional late selection. The need for additional response selection induced by color-overlap distractors was severely reduced when color discriminability decreased.</p> <p>Conclusion</p> <p>We propose a simple model of cross-dimensional perceptual decision-making. The temporal synchrony of separate color-related and form-related choices determines whether or not distractor processing includes post-perceptual stages. ERP measures contribute to a comprehensive explanation of the temporal dynamics of component processes of perceptual decision-making.</p

CNTF Mediates Neurotrophic Factor Secretion and Fluid Absorption in Human Retinal Pigment Epithelium

Ciliary neurotrophic factor (CNTF) protects photoreceptors and regulates their phototransduction machinery, but little is known about CNTF's effects on retinal pigment epithelial (RPE) physiology. Therefore, we determined the expression and localization of CNTF receptors and the physiological consequence of their activation in primary cultures of human fetal RPE (hfRPE). Cultured hfRPE express CNTF, CT1, and OsM and their receptors, including CNTFRα, LIFRβ, gp130, and OsMRβ, all localized mainly at the apical membrane. Exogenous CNTF, CT1, or OsM induces STAT3 phosphorylation, and OsM also induces the phosphorylation of ERK1/2 (p44/42 MAP kinase). CNTF increases RPE survivability, but not rates of phagocytosis. CNTF increases secretion of NT3 to the apical bath and decreases that of VEGF, IL8, and TGFβ2. It also significantly increases fluid absorption (JV) across intact monolayers of hfRPE by activating CFTR chloride channels at the basolateral membrane. CNTF induces profound changes in RPE cell biology, biochemistry, and physiology, including the increase in cell survival, polarized secretion of cytokines/neurotrophic factors, and the increase in steady-state fluid absorption mediated by JAK/STAT3 signaling. In vivo, these changes, taken together, could serve to regulate the microenvironment around the distal retinal/RPE/Bruch's membrane complex and provide protection against neurodegenerative disease

Putative Nanobacteria Represent Physiological Remnants and Culture By-Products of Normal Calcium Homeostasis

Putative living entities called nanobacteria (NB) are unusual for their small sizes (50–500 nm), pleomorphic nature, and accumulation of hydroxyapatite (HAP), and have been implicated in numerous diseases involving extraskeletal calcification. By adding precipitating ions to cell culture medium containing serum, mineral nanoparticles are generated that are morphologically and chemically identical to the so-called NB. These nanoparticles are shown here to be formed of amorphous mineral complexes containing calcium as well as other ions like carbonate, which then rapidly acquire phosphate, forming HAP. The main constituent proteins of serum-derived NB are albumin, fetuin-A, and apolipoprotein A1, but their involvement appears circumstantial since so-called NB from different body fluids harbor other proteins. Accordingly, by passage through various culture media, the protein composition of these particles can be modulated. Immunoblotting experiments reveal that antibodies deemed specific for NB react in fact with either albumin, fetuin-A, or both, indicating that previous studies using these reagents may have detected these serum proteins from the same as well as different species, with human tissue nanoparticles presumably absorbing bovine serum antigens from the culture medium. Both fetal bovine serum and human serum, used earlier by other investigators as sources of NB, paradoxically inhibit the formation of these entities, and this inhibition is trypsin-sensitive, indicating a role for proteins in this inhibitory process. Fetuin-A, and to a lesser degree albumin, inhibit nanoparticle formation, an inhibition that is overcome with time, ending with formation of the so-called NB. Together, these data demonstrate that NB are most likely formed by calcium or apatite crystallization inhibitors that are somehow overwhelmed by excess calcium or calcium phosphate found in culture medium or in body fluids, thereby becoming seeds for calcification. The structures described earlier as NB may thus represent remnants and by-products of physiological mechanisms used for calcium homeostasis, a concept which explains the vast body of NB literature as well as explains the true origin of NB as lifeless protein-mineralo entities with questionable role in pathogenesis

Vitalism in contemporary chiropractic: a help or a hinderance?

Background: Chiropractic emerged in 1895 and was promoted as a viable health care substitute in direct competition with the medical profession. This was an era when there was a belief that one cause and one cure for all disease would be discovered. The chiropractic version was a theory that most diseases were caused by subluxated (slightly displaced) vertebrae interfering with “nerve vibrations” (a supernatural, vital force) and could be cured by adjusting (repositioning) vertebrae, thereby removing the interference with the body’s inherent capacity to heal. DD Palmer, the originator of chiropractic, established chiropractic based on vitalistic principles. Anecdotally, the authors have observed that many chiropractors who overtly claim to be “vitalists” cannot define the term. Therefore, we sought the origins of vitalism and to examine its effects on chiropractic today. Discussion: Vitalism arose out of human curiosity around the biggest questions: Where do we come from? What is life? For some, life was derived from an unknown and unknowable vital force. For others, a vital force was a placeholder, a piece of knowledge not yet grasped but attainable. Developments in science have demonstrated there is no longer a need to invoke vitalistic entities as either explanations or hypotheses for biological phenomena. Nevertheless, vitalism remains within chiropractic. In this examination of vitalism within chiropractic we explore the history of vitalism, vitalism within chiropractic and whether a vitalistic ideology is compatible with the legal and ethical requirements for registered health care professionals such as chiropractors. Conclusion: Vitalism has had many meanings throughout the centuries of recorded history. Though only vaguely defined by chiropractors, vitalism, as a representation of supernatural force and therefore an untestable hypothesis, sits at the heart of the divisions within chiropractic and acts as an impediment to chiropractic legitimacy, cultural authority and integration into mainstream health care

Characterization of Granulations of Calcium and Apatite in Serum as Pleomorphic Mineralo-Protein Complexes and as Precursors of Putative Nanobacteria

Calcium and apatite granulations are demonstrated here to form in both human and fetal bovine serum in response to the simple addition of either calcium or phosphate, or a combination of both. These granulations are shown to represent precipitating complexes of protein and hydroxyapatite (HAP) that display marked pleomorphism, appearing as round, laminated particles, spindles, and films. These same complexes can be found in normal untreated serum, albeit at much lower amounts, and appear to result from the progressive binding of serum proteins with apatite until reaching saturation, upon which the mineralo-protein complexes precipitate. Chemically and morphologically, these complexes are virtually identical to the so-called nanobacteria (NB) implicated in numerous diseases and considered unusual for their small size, pleomorphism, and the presence of HAP. Like NB, serum granulations can seed particles upon transfer to serum-free medium, and their main protein constituents include albumin, complement components 3 and 4A, fetuin-A, and apolipoproteins A1 and B100, as well as other calcium and apatite binding proteins found in the serum. However, these serum mineralo-protein complexes are formed from the direct chemical binding of inorganic and organic phases, bypassing the need for any biological processes, including the long cultivation in cell culture conditions deemed necessary for the demonstration of NB. Thus, these serum granulations may result from physiologically inherent processes that become amplified with calcium phosphate loading or when subjected to culturing in medium. They may be viewed as simple mineralo-protein complexes formed from the deployment of calcification-inhibitory pathways used by the body to cope with excess calcium phosphate so as to prevent unwarranted calcification. Rather than representing novel pathophysiological mechanisms or exotic lifeforms, these results indicate that the entities described earlier as NB most likely originate from calcium and apatite binding factors in the serum, presumably calcification inhibitors, that upon saturation, form seeds for HAP deposition and growth. These calcium granulations are similar to those found in organisms throughout nature and may represent the products of more general calcium regulation pathways involved in the control of calcium storage, retrieval, tissue deposition, and disposal