The Aerodynamics of Hummingbird Flight

Hummingbirds fly with their wings almost fully extended during their entire wingbeat. This pattern, associated with having proportionally short humeral bones, long distal wing elements, and assumed to be an adaptation for extended hovering flight, has lead to predictions that the aerodynamic mechanisms exploited by hummingbirds during hovering should be similar to those observed in insects. To test these predictions, we flew rufous hummingbirds (Selasphorus rufus, 3.3 g, n = 6) in a variable–speed wind tunnel (0-12 ms-1) and measured wake structure and dynamics using digital particle image velocimetry (DPIV). Unlike hovering insects, hummingbirds produced 75% of their weight support during downstroke and only 25% during upstroke, an asymmetry due to the inversion of their cambered wings during upstroke. Further, we have found no evidence of sustained, attached leading edge vorticity (LEV) during up or downstroke, as has been seen in similarly-sized insects - although a transient LEV is produced during the rapid change in angle of attack at the end of the downstroke. Finally, although an extended-wing upstroke during forward flight has long been thought to produce lift and negative thrust, we found circulation during downstroke alone to be sufficient to support body weight, and that some positive thrust was produced during upstroke, as evidenced by a vortex pair shed into the wake of all upstrokes at speeds of 4 – 12 m s-1

Mapping a 50-spin-qubit network through correlated sensing

Spins associated to optically accessible solid-state defects have emerged as a versatile platform for exploring quantum simulation, quantum sensing and quantum communication. Pioneering experiments have shown the sensing, imaging, and control of multiple nuclear spins surrounding a single electron-spin defect. However, the accessible size and complexity of these spin networks has been constrained by the spectral resolution of current methods. Here, we map a network of 50 coupled spins through high-resolution correlated sensing schemes, using a single nitrogen-vacancy center in diamond. We develop concatenated double-resonance sequences that identify spin-chains through the network. These chains reveal the characteristic spin frequencies and their interconnections with high spectral resolution, and can be fused together to map out the network. Our results provide new opportunities for quantum simulations by increasing the number of available spin qubits. Additionally, our methods might find applications in nano-scale imaging of complex spin systems external to the host crystal.Comment: 7 pages, 5 figure

A Regularized Discrete Laminate Parametrization Technique with Applications to Wing-Box Design Optimization

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97055/1/AIAA2012-1519.pd

Scalability, test–retest reliability and validity of the Brief INSPIRE-O measure of personal recovery in psychiatric services

Introduction: Mental health services have transitioned from treating symptoms to emphasizing personal recovery. Despite its importance, integrating personal recovery into clinical practice remains work in progress. This study evaluates the psychometric qualities of the Brief INSPIRE-O, a five-item patient-reported outcome measure assessing personal recovery.Method: The study collected data from 2018 to 2020 at the Mental Health Services, Capital Region of Denmark, using an internet-based system examining 8,192 non-psychotic patients – receiving outpatient treatment.Materials: This study evaluated the Brief INSPIRE-O and used measures of symptomatology (SCL-10), well-being (WHO-5), and social functioning (modified SDS).Results: The study population comprised 76.8% females with a mean age of 32.9 years, and diagnoses included anxiety (28%), depression (34%), and personality disorder (19%). The mean Brief INSPIRE-O score (39.9) was lower than the general population norm (71.1). The Brief INSPIRE-O showed acceptable test–retest reliability (0.75), scalability (0.39), and internal consistency (0.73). Correlations with other mental health criteria were in the expected direction for symptomatology (−0.46), well-being (0.60), and social functioning (−0.43) and remained consistent across diagnoses.Discussion: The Brief INSPIRE-O demonstrated strong psychometric qualities and could be recommended as a measure of personal recovery for use in both research and clinical practice. Its strong theoretical basis and short completion time make it suitable for use for research. Incorporating Brief INSPIRE-O into clinical assessment will further support the process of mental health systems re-orientating towards personal recovery

Polarization of photospheric lines from turbulent dynamo simulations

We employ the magnetic and velocity fields from turbulent dynamo simulations to synthesize the polarization of a typical photospheric line. The synthetic Stokes profiles have properties in common with those observed in the quiet Sun. The simulated magnetograms present a level of signal similar to that of the Inter-Network regions. Asymmetric Stokes V profiles with two, three and more lobes appear in a natural way. The intensity profiles are broadened by the magnetic fields in fair agreement with observational limits. Furthermore, the Hanle depolarization signals of the Sr I 4607 A line turn out to be within the solar values. Differences between synthetic and observed polarized spectra can also be found. There is a shortage of Stokes V asymmetries, that we attribute to a deficit of structuring in the magnetic and velocity fields from the simulations as compared to the Sun This deficit may reflect the fact that the Reynolds numbers of the numerical data are still far from solar values. We consider the possibility that intense and tangled magnetic fields, like those in the simulations, exist in the Sun. This scenario has several important consequences. For example, less than 10% of the existing unsigned magnetic flux would be detected in present magnetograms. The existing flux would exceed by far that carried by active regions during the maximum of the solar cycle. Detecting these magnetic fields would involve improving the angular resolution, the techniques to interpret the polarization signals, and to a less extent, the polarimetric sensitivity.Comment: Accepted for publication in ApJ. 20 pag. 11 fig

Aerodynamics of the Hovering Hummingbird

Despite profound musculoskeletal differences, hummingbirds (Trochilidae) are widely thought to employ aerodynamic mechanisms similar to those used by insects. The kinematic symmetry of the hummingbird upstroke and downstroke has led to the assumption that these halves of the wingbeat cycle contribute equally to weight support during hovering, as exhibited by insects of similar size. This assumption has been applied, either explicitly or implicitly, in widely used aerodynamic models, and in a variety of empirical tests. Here we provide measurements of the wake of hovering rufous hummingbirds (Selasphorus rufus) obtained with digital particle image velocimetry that show force asymmetry: hummingbirds produce 75% of their weight support during the downstroke and only 25% during the upstroke. Some of this asymmetry is probably due to inversion of their cambered wings during upstroke. The wake of hummingbird wings also reveals evidence of leading-edge vortices created during the downstroke, indicating that they may operate at Reynolds numbers sufficiently low to exploit a key mechanism typical of insect hovering. Hummingbird hovering approaches that of insects, yet remains distinct because of effects resulting from an inherently dissimilar—avian—body plan

Fibrinogen beta variants confer protection against coronary artery disease in a Greek case-control study

<p>Abstract</p> <p>Background</p> <p>Although plasma fibrinogen levels are related to cardiovascular risk, data regarding the role of fibrinogen genetic variation in myocardial infarction (MI) or coronary artery disease (CAD) etiology remain inconsistent. The purpose of the present study was to investigate the effect of <it>fibrinogen A (FGA)</it>, <it>fibrinogen B (FGB) </it>and <it>fibrinogen G (FGG) </it>gene SNPs and haplotypes on susceptibility to CAD in a homogeneous Greek population.</p> <p>Methods</p> <p>We genotyped for rs2070022, rs2070016, rs2070006 in <it>FGA </it>gene, the rs7673587, rs1800789, rs1800790, rs1800788, rs1800787, rs4681 and rs4220 in <it>FGB </it>gene and for the rs1118823, rs1800792 and rs2066865 SNPs in <it>FGG </it>gene applying an arrayed primer extension-based genotyping method (APEX-2) in a sample of CAD patients (n = 305) and controls (n = 305). Logistic regression analysis was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs), before and after adjustment for potential confounders.</p> <p>Results</p> <p>None of the <it>FGA </it>and <it>FGG </it>SNPs and <it>FGA, FGB, FGG </it>and <it>FGA-FGG </it>haplotypes was associated with disease occurrence after adjustment. Nevertheless, rs1800787 and rs1800789 SNPs in <it>FGB </it>gene seem to decrease the risk of CAD, even after adjustment for potential confounders (OR = 0.42, 95%CI: 0.19-0.90, p = 0.026 and OR = 0.44, 95%CI:0.21-0.94, p = 0.039, respectively).</p> <p>Conclusions</p> <p><it>FGA </it>and <it>FGG </it>SNPs as well as <it>FGA, FGB, FGG </it>and <it>FGA-FGG </it>haplotypes do not seem to be important contributors to CAD occurrence in our sample. On the contrary, <it>FGB </it>rs1800787 and rs1800789 SNPs seem to confer protection to disease onset lowering the risk by about 50% in homozygotes for the minor alleles.</p

APC/C-Mediated Degradation of dsRNA-Binding Protein 4 (DRB4) Involved in RNA Silencing

Background: Selective protein degradation via the ubiquitin-26S proteasome is a major mechanism underlying DNA replication and cell division in all Eukaryotes. In particular, the APC/C (Anaphase Promoting Complex or Cyclosome) is a master ubiquitin protein ligase (E3) that targets regulatory proteins for degradation allowing sister chromatid separation and exit from mitosis. Interestingly, recent work also indicates that the APC/C remains active in differentiated animal and plant cells. However, its role in post-mitotic cells remains elusive and only a few substrates have been characterized. Methodology/Principal Findings: In order to identify novel APC/C substrates, we performed a yeast two-hybrid screen using as the bait Arabidopsis APC10/DOC1, one core subunit of the APC/C, which is required for substrate recruitment. This screen identified DRB4, a double-stranded RNA binding protein involved in the biogenesis of different classes of small RNA (sRNA). This protein interaction was further confirmed in vitro and in plant cells. Moreover, APC10 interacts with DRB4 through the second dsRNA binding motif (dsRBD2) of DRB4, which is also required for its homodimerization and binding to its Dicer partner DCL4. We further showed that DRB4 protein accumulates when the proteasome is inactivated and, most importantly, we found that DRB4 stability depends on APC/C activity. Hence, depletion of Arabidopsis APC/C activity by RNAi leads to a strong accumulation of endogenous DRB4, far beyond its normal level of accumulation. However, we could not detect any defects in sRNA production in lines where DRB4 was overexpressed