Breaking the Myth of the Audiopile

For years analog audio equipment has been deemed superior to its digital counterpart. Most musicians, casual listeners, and audiophiles agree that tube based amplifiers, PA systems, and other tube-based equipment produce better sound quality. This can also be seen in the price difference in solid-state equipment compared to valve technology. Tube amps are even more fragile that transistor based amps. At a first glance this older technology seems to be more of a hassle or trend, rather than based off a deeper understanding of physics. By exploring the innards of analog sound reproduction equipment, the science behind the difference between digital and analog audio equipment becomes much clearer. By first establishing the similarities and differences between analog and digital technologies, this project exposes why tube based audio equipment sounds better than solid-state. By building an analog effects pedal as a research tool (powered by a 12AU7 pre-amp tube) and researching older related articles, the difference in the sound quality was discovered to be explained by the amount and type of distortion caused by tubes compared to that of transistors. Tubes or valves handle voltage distortions in a way that pleases the human ear. Transistors on the other hand can produce noisy distortion that musicians and audiophiles find distasteful. The reason for this is due to the physical nature of the two different amplification processes

Sex difference in awareness of threat:A meta-analysis of sex differences in attentional orienting in the dot probe task

It has been argued that females are more important to infant survival than males and that this may lead to their increased fear. One way of increasing female survival chances would be to increase their sensitivity to threat. The dot-probe task has been used to investigate attentional bias. In this meta-analysis we combine the results of dot-probe experiments and explicitly examine sex differences in attentional orienting bias. Overall there is little evidence to support the existence of sex differences and these results are considered in terms of evolutionary impact

Response to letter regarding article, "patient-reported measures provide unique insights into motor function after stroke".

Background and PurposePatient-reported outcome measures have been found useful in many disciplines but have received limited evaluation after stroke. The current study investigated the relationship that patient-reported measures have with standard impairment and disability scales after stroke.MethodsPatients with motor deficits after stroke were scored on standard assessments including NIH Stroke Scale (NIHSS), modified Rankin Scale (mRS), and Fugl-Meyer motor scale (FM), and on two patient-reported measures, the hand function domain of the Stroke Impact Scale (SIS), which documents difficulty of hand motor usage, and the amount of use portion of the Motor Activity Log (MAL), which records amount of arm motor usage.ResultsThe 43 participants had mild disability (median mRS=2), moderate motor deficits (FM=46 ± 22), and mild cognitive/language deficits. The two patient-reported outcome measures, SIS and MAL, were sensitive to the presence of arm motor deficits. Of 21 patients classified as having minimal or no impairment or disability by the NIHSS or mRS (score of 0-1), 15 (71%) reported difficulty with hand movements by the SIS score or reduced arm use by the MAL score. Furthermore, of 14 patients with a normal exam, 10 (71%) reported difficulty with hand movements or reduction in arm use.ConclusionsPatient-reported measures were a unique source of insight into clinical status in the current population. Motor deficits were revealed in a majority of patients classified by standard scales as having minimal or no disability, and in a majority of patients classified as having no deficits

The Psychometric Evaluation of Human Life Histories:A Reply to Figueredo, Cabeza de Baca, Black, Garcia, Fernandes, Wolf, and Woodley (2015)

A recent critique of Copping, Campbell, and Muncer raised several issues concerning the validity of psychometric assessment techniques in the study of life history (LH) strategies. In this reply, some of our key concerns about relying on aggregated psy- chometric measures are explained, and we raise questions generally regarding the use of higher order factor structures. Responses to some of the statistical issues raised by Figueredo et al. are also detailed. We stand by our original conclusions and call for more careful consideration of instruments used to evaluate hypotheses derived from LH theory

Fragile boundaries of tailored surface codes

Biased noise is common in physical qubits, and tailoring a quantum code to the bias by locally modifying stabilizers or changing boundary conditions has been shown to greatly increase error correction thresholds. In this work, we explore the challenges of using a specific tailored code, the XY surface code, for fault-tolerant quantum computation. We introduce efficient and fault-tolerant decoders, belief-matching and belief-find, which exploit correlated hyperedge fault mechanisms present in circuit-level noise. Using belief-matching, we find that the XY surface code has a higher threshold and lower overhead than the square CSS surface code for moderately biased noise. However, the rectangular CSS surface code has a lower qubit overhead than the XY surface code when below threshold. We identify a contributor to the reduced performance that we call fragile boundary errors. These are string-like errors that can occur along spatial or temporal boundaries in planar architectures or during logical state preparation and measurement. While we make partial progress towards mitigating these errors by deforming the boundaries of the XY surface code, our work suggests that fragility could remain a significant obstacle, even for other tailored codes. We expect that our decoders will have other uses; belief-find has an almost-linear running time, and we show that it increases the threshold of the surface code to 0.937(2)% in the presence of circuit-level depolarising noise, compared to 0.817(5)% for the more computationally expensive minimum-weight perfect matching decoder.Comment: 16 pages, 17 figure

Developmental changes in hypoxic exposure and responses to anoxia in Drosophila melanogaster

© 2015. Published by The Company of Biologists Ltd. Holometabolous insects undergo dramatic morphological and physiological changes during ontogeny. In particular, the larvae of many holometabolous insects are specialized to feed in soil, water or dung, inside plant structures, or inside other organisms as parasites where they may commonly experience hypoxia or anoxia. In contrast, holometabolous adults usually are winged and live with access to air. Here, we show that larval Drosophila melanogaster experience severe hypoxia in their normal laboratory environments; third instar larvae feed by tunneling into a medium without usable oxygen. Larvae move strongly in anoxia for many minutes, while adults (like most other adult insects) are quickly paralyzed. Adults survive anoxia nearly an order of magnitude longer than larvae (LT50: 8.3 versus 1 h). Plausibly, the paralysis of adults is a programmed response to reduce ATP need and enhance survival. In support of that hypothesis, larvae produce lactate at 3× greater rates than adults in anoxia. However, when immobile in anoxia, larvae and adults are similarly able to decrease their metabolic rate, to about 3% of normoxic conditions. These data suggest that Drosophila larvae and adults have been differentially selected for behavioral and metabolic responses to anoxia, with larvae exhibiting vigorous escape behavior likely enabling release from viscous anoxic media to predictably normoxic air, while the paralysis behavior of adults maximizes their chances of surviving flooding events of unpredictable duration. Developmental remodeling of behavioral and metabolic strategies to hypoxia/anoxia is a previously unrecognized major attribute of holometabolism

Biomarkers of Rehabilitation Therapy Vary According To Stroke Severity

Biomarkers that capture treatment effects could improve the precision of clinical decision making for restorative therapies. We examined the performance of candidate structural, functional,and angiogenesis-related MRI biomarkers before and after a 3-week course of standardized robotic therapy in 18 patients with chronic stroke and hypothesized that results vary significantly according to stroke severity. Patients were 4.1 ± 1 months poststroke, with baseline arm Fugl-Meyer scores of 20–60. When all patients were examined together, no imaging measure changed over time in a manner that correlated with treatment-induced motor gains. However, when also considering the interaction with baseline motor status, treatment-induced motor gains were significantly related to change in three functional connectivity measures: ipsilesional motor cortex connectivity with (1) contralesional motor cortex (p = 0 003), (2) contralesional dorsal premotor cortex (p = 0 005), and (3) ipsilesional dorsal premotor cortex (p = 0 004). In more impaired patients, larger treatment gains were associated with greater increases in functional connectivity, whereas in less impaired patients larger treatment gains were associated with greater decreases in functional connectivity. Functional connectivity measures performed best as biomarkers of treatment effects after stroke. The relationship between changes in functional connectivity and treatment gains varied according to baseline stroke severity. Biomarkers of restorative therapy effects are not one-size-fits-all after stroke