1,094 research outputs found

    Effect of fiber orientation on shape and stability of air-water interface on submerged superhydrophobic electrospun thin coatings

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    To better understand the role of fiber orientation on the stability of superhydrophobicelectrospun coatings under hydrostaticpressures, an integro-differential equation is developed from the balance of forces across the air–water interface between the fibers. This equation is solved numerically for a series of superhydrophobicelectrospun coatings comprised of random and orthogonal fiber orientations to obtain the exact 3D shape of the air–water interface as a function of hydrostaticpressure. More important, this information is used to predict the pressure at which the coatings start to transition from the Cassie state to the Wenzel state, i.e., the so-called critical transition pressure. Our results indicate that coatings composed of orthogonal fibers can withstand higher elevated hydrostaticpressures than those made up of randomly orientated fibers. Our results also prove that thin superhydrophobic coatings can better resist the elevated pressures. The modeling methodology presented here can be used to design nanofibrous superhydrophobic coatings for underwater applications

    Analytic Representation of The Dirac Equation

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    In this paper we construct an analytical separation (diagonalization) of the full (minimal coupling) Dirac equation into particle and antiparticle components. The diagonalization is analytic in that it is achieved without transforming the wave functions, as is done by the Foldy-Wouthuysen method, and reveals the nonlocal time behavior of the particle-antiparticle relationship. We interpret the zitterbewegung and the result that a velocity measurement (of a Dirac particle) at any instant in time is, as reflections of the fact that the Dirac equation makes a spatially extended particle appear as a point in the present by forcing it to oscillate between the past and future at speed c. From this we infer that, although the form of the Dirac equation serves to make space and time appear on an equal footing mathematically, it is clear that they are still not on an equal footing from a physical point of view. On the other hand, the Foldy-Wouthuysen transformation, which connects the Dirac and square root operator, is unitary. Reflection on these results suggests that a more refined notion (than that of unitary equivalence) may be required for physical systems

    Motor learning outcomes of handrim wheelchair propulsion during active spinal cord injury rehabilitation in comparison with experienced wheelchair users

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    Purpose: To investigate changes in wheelchair propulsion technique and mechanical efficiency across first five weeks of active inpatient spinal cord injury rehabilitation and to compare the outcomes at discharge with experienced wheelchair users with spinal cord injury. Methods: Eight individuals with recent spinal cord injury performed six weekly submaximal exercise tests. The first and last measurement additionally contained a wheelchair circuit and peak graded exercise test. Fifteen experienced individuals performed all above-mentioned tests on one occasion. Results: Mechanical efficiency and propulsion technique did not change during the five weeks of inpatient rehabilitation. Peak power output during peak graded test and performance time on the wheelchair circuit improved between the first and the last week. No difference in propulsion technique, peak power output, and performance time was found between the persons with a recent injury and the experienced group. Mechanical efficiency was higher after the correction for the difference in relative power output in the experienced group. Conclusion: The group with a recent injury did not improve mechanical efficiency and propulsion technique over the period of active rehabilitation, despite significant improvements on the wheelchair circuit and in work capacity. The only significant difference between the groups was found in mechanical efficiency. Implications for rehabilitation The lack of time-dependent changes in mechanical efficiency and propulsion technique in the group with a recent spinal cord injury, combined with the lack of differences in technique, work capacity and on the wheelchair circuit between the groups, suggest that important adaptations of motor learning may happen even earlier in rehabilitation and emphasize that the group in active rehabilitation was relatively skilled. Standardized observational analyses of handrim wheelchair propulsion abilities during early spinal cord injury rehabilitation provide detailed understanding of wheelchair technique, skill as well as wheelchair propulsion capacity. Measurement of external power output is critical to interpretation of gross efficiency, propulsion technique, and capacity. Wheelchair quality and body weight - next to wheelchair fitness and skill - require careful consideration both in early rehabilitation as well as in the chronic phase of spinal cord injury

    A close association of freedom from pain, migraine-related functional disability, and other outcomes: results of a post hoc analysis of randomized lasmiditan studies SAMURAI and SPARTAN

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    Background: While pain freedom at 2 h is a key primary outcome for current trials for acute treatment of migraine, the relationship between the degree of head pain and other efficacy measures at 2 h has rarely been explored. Following lasmiditan treatment of a migraine attack with moderate or severe head pain, we contrast those who achieve pain freedom with those who achieve mild pain but not pain freedom 2 h post dosing. Methods: Patient-level data were pooled across studies and treatment arms from two Phase 3 trials comparing lasmiditan and placebo, SAMURAI and SPARTAN. This post hoc analysis assessed freedom from the most bothersome symptom (MBS), freedom from migraine-related functional disability (disability), and improved patient global impression of change (PGIC) in patients who achieved 2 h pain freedom compared to those who experienced 2 h mild pain. Mild pain differs from pain relief which is defined as either mild pain or pain freedom. Results: Patients who achieved 2 h pain freedom (N = 913), in comparison with those with 2 h mild pain (N = 864), were significantly more likely to experience MBS freedom (91.9% vs. 44.9%), disability freedom (87.1% and 13.4%), and improved PGIC (86.5% and 31.5%) (p \u3c 0.001 for all combinations). In addition, more patients who were pain free experienced both 2 h MBS freedom and 2 h functional disability freedom (83.6%) compared to those with mild pain (10.8%; p \u3c 0.001). The proportion of patients with pain freedom who did not achieve either MBS or disability freedom (4.6%) was lower than in patients with mild pain (52.4%). Lastly, 55.2% of patients experienced mild pain before disability freedom compared to 72.1% who experienced pain freedom and disability freedom at the same time. Conclusions: This study demonstrated that, at 2 h post treatment, patients who were pain free were more likely to achieve other outcomes including freedom from their MBS, freedom from migraine-related functional disability, and improved PGIC compared to those with mild pain, confirming that 2 h pain freedom is more robustly associated with other clinical outcomes than the 2 h mild pain endpoint. Trial Registration: SAMURAI (NCT02439320); SPARTAN (NCT02605174)

    Restriction of AID activity and somatic hypermutation by PARP-1

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    Affinity maturation of the humoral immune response depends on somatic hypermutation (SHM) of immunoglobulin (Ig) genes, which is initiated by targeted lesion introduction by activation-induced deaminase (AID), followed by error-prone DNA repair. Stringent regulation of this process is essential to prevent genetic instability, but no negative feedback control has been identified to date. Here we show that poly(ADP-ribose) polymerase-1 (PARP-1) is a key factor restricting AID activity during somatic hypermutation. Poly(ADP-ribose) (PAR) chains formed at DNA breaks trigger AID-PAR association, thus preventing excessive DNA damage induction at sites of AID action. Accordingly, AID activity and somatic hypermutation at the Ig variable region is decreased by PARP-1 activity. In addition, PARP-1 regulates DNA lesion processing by affecting strand biased A:T mutagenesis. Our study establishes a novel function of the ancestral genome maintenance factor PARP-1 as a critical local feedback regulator of both AID activity and DNA repair during Ig gene diversification

    On reminder effects, drop-outs and dominance: evidence from an online experiment on charitable giving

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    We present the results of an experiment that (a) shows the usefulness of screening out drop-outs and (b) tests whether different methods of payment and reminder intervals affect charitable giving. Following a lab session, participants could make online donations to charity for a total duration of three months. Our procedure justifying the exclusion of drop-outs consists in requiring participants to collect payments in person flexibly and as known in advance and as highlighted to them later. Our interpretation is that participants who failed to collect their positive payments under these circumstances are likely not to satisfy dominance. If we restrict the sample to subjects who did not drop out, but not otherwise, reminders significantly increase the overall amount of charitable giving. We also find that weekly reminders are no more effective than monthly reminders in increasing charitable giving, and that, in our three months duration experiment, standing orders do not increase giving relative to one-off donations

    Relational considerations in the use of influence tactics.

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    It is proposed that the existing relationship between the influencing agent and the target of influence plays a central role in the choice of using hard and soft influence tactics. In a field study, 3 key aspects of the relation between agent and target were examined. and the results generally supported our hypotheses. First, the more unfairly people felt they were treated, the more often they wielded influence, especially using harder influence tactics. Second. the better the influencing agent liked the target. the relatively less often he or she used hard tactics. Finally, the more the influencing agent felt dependent upon the target, the fewer influence tactics, both hard and soft, were used. The discussion focuses on both the practical and theoretical implications of these findings

    Geriatric Assessment as a Predictor of Tolerance, Quality of Life, and Outcomes in Older Patients With Head and Neck Cancers and Lung Cancers Receiving Radiation Therapy

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    Purpose To evaluate the association between functional status based on a geriatric assessment (GA) and outcomes of tolerance to treatment in patients with lung or head and neck cancer receiving radiation therapy (RT) or chemoradiation (CRT). Methods and Materials A prospective cohort study was conducted in patients aged ≥65 years with head and neck cancer or lung cancer undergoing curative intent RT or CRT. Pretreatment GA, health-related quality of life (HRQoL), and patient-reported outcomes (PRO) were obtained. Questionnaires were repeated biweekly during RT and at 6 weeks after treatment. Dysfunction was defined as scores 3-day treatment delay, change in RT or CRT regimen, or death. Associations of dysfunction with tolerance to radiation therapy, HRQoL changes, and PRO ratings were evaluated. Results Of the 50 patients accrued, 46 had evaluable data. Mean age was 72.5 years (range, 65-92 years). At baseline, 37% had dysfunction. Poor tolerance to RT or CRT occurred in 39%. There was no association between dysfunction and tolerance. Patients with dysfunction had lower baseline HRQoL scores. From baseline to end of RT, those with baseline dysfunction had less of a decline in Role Functioning (P=.01) and Global Health Score (P=.04) domains. However, from end of RT to 6-week follow-up, those with dysfunction were more likely to continue to drop in the Physical, Role Functioning, and Social domains (all P<.01). Dysfunction at baseline was also associated with higher severity of certain PROs. Conclusions Pretreatment dysfunction was associated with continued decline and lack of recovery of HRQoL in this patient population. Larger studies could further elucidate the GA's predictive value

    Abusive Supervision, Upward Maintenance Communication, and Subordinates\u27 Psychological Distress

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    This study reanalyzes data from Tepper\u27s (2000) two-wave study regarding the effects of subordinates\u27 perceptions of supervisory abuse to assess previously unexamined relationships. As predicted, we found that subordinates who more rather than less strongly perceived that they had been abused by supervisors tended to use regulative maintenance tactics with higher frequency. Further, the positive relationship between abusive supervision and subordinates\u27 psychological distress was exacerbated by subordinates\u27 use of regulative maintenance communications, and that relationship was reduced by subordinates\u27 use of direct maintenance communication. Theoretical and practical implications are discussed

    Microtubules gate tau condensation to spatially regulate microtubule functions.

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    Tau is an abundant microtubule-associated protein in neurons. Tau aggregation into insoluble fibrils is a hallmark of Alzheimer's disease and other types of dementia1, yet the physiological state of tau molecules within cells remains unclear. Using single-molecule imaging, we directly observe that the microtubule lattice regulates reversible tau self-association, leading to localized, dynamic condensation of tau molecules on the microtubule surface. Tau condensates form selectively permissible barriers, spatially regulating the activity of microtubule-severing enzymes and the movement of molecular motors through their boundaries. We propose that reversible self-association of tau molecules, gated by the microtubule lattice, is an important mechanism of the biological functions of tau, and that oligomerization of tau is a common property shared between the physiological and disease-associated forms of the molecule
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