Importance of second-order piezoelectric effects in zincblende semiconductors

We show that the piezoelectric effect that describes the emergence of an electric field in response to a crystal deformation in III-V semiconductors such as GaAs and InAs has strong contributions from second-order effects that have been neglected so far. We calculate the second-order piezoelectric tensors using density functional theory and obtain the piezoelectric field for [111]-oriented In$_x$Ga$_{1-x}$As quantum wells of realistic dimensions and concentration $x$. We find that the linear and the quadratic piezoelectric coefficients have the opposite effect on the field, and for large strains the quadratic terms even dominate. Thus, the piezoelectric field turns out to be a rare example of a physical quantity for which the first- and second-order contributions are of comparable magnitude.Comment: 4 pages, 3 figures, Submitted to Phys. Rev. Let

Web-based physiotherapy for people affected by multiple sclerosis: a single blind, randomized controlled feasibility study

Objective: To examine the feasibility of a trial to evaluate web-based physiotherapy compared to a standard home exercise programme in people with multiple sclerosis. Design: Multi-centre, randomized controlled, feasibility study. Setting: Three multiple sclerosis out-patient centres. Participants: A total of 90 people with multiple sclerosis (Expanded Disability Status Scale 4–6.5). Interventions: Participants were randomized to a six-month individualized, home exercise programme delivered via web-based physiotherapy (n = 45; intervention) or a sheet of exercises (n = 45; active comparator). Outcome measures: Outcome measures (0, three, six and nine months) included adherence, two-minute walk test, 25 foot walk, Berg Balance Scale, physical activity and healthcare resource use. Interviews were undertaken with 24 participants and 3 physiotherapists. Results: Almost 25% of people approached agreed to take part. No intervention-related adverse events were recorded. Adherence was 40%–63% and 53%–71% in the intervention and comparator groups. There was no difference in the two-minute walk test between groups at baseline (Intervention-80.4(33.91)m, Comparator-70.6(31.20)m) and no change over time (at six-month Intervention-81.6(32.75)m, Comparator-74.8(36.16)m. There were no significant changes over time in other outcome measures except the EuroQol-5 Dimension at six months which decreased in the active comparator group. For a difference of 8(17.4)m in two-minute walk test between groups, 76 participants/group would be required (80% power, P > 0.05) for a future randomized controlled trial. Conclusion: No changes were found in the majority of outcome measures over time. This study was acceptable and feasible by participants and physiotherapists. An adequately powered study needs 160 participants

Expression of HES and HEY genes in infantile hemangiomas

Background: Infantile hemangiomas (IHs) are the most common benign tumor of infancy, yet their pathogenesis is poorly understood. IHs are believed to originate from a progenitor cell, the hemangioma stem cell (HemSC). Recent studies by our group showed that NOTCH proteins and NOTCH ligands are expressed in hemangiomas, indicating Notch signaling may be active in IHs. We sought to investigate downstream activation of Notch signaling in hemangioma cells by evaluating the expression of the basic HLH family proteins, HES/HEY, in IHs. Materials and Methods: HemSCs and hemangioma endothelial cells (HemECs) are isolated from freshly resected hemangioma specimens. Quantitative RT-PCR was performed to probe for relative gene transcript levels (normalized to beta-actin). Immunofluorescence was performed to evaluate protein expression. Co-localization studies were performed with CD31 (endothelial cells) and NOTCH3 (peri-vascular, non-endothelial cells). HemSCs were treated with the gamma secretase inhibitor (GSI) Compound E, and gene transcript levels were quantified with real-time PCR. Results: HEY1, HEYL, and HES1 are highly expressed in HemSCs, while HEY2 is highly expressed in HemECs. Protein expression evaluation by immunofluorescence confirms that HEY2 is expressed by HemECs (CD31+ cells), while HEY1, HEYL, and HES1 are more widely expressed and mostly expressed by perivascular cells of hemangiomas. Inhibition of Notch signaling by addition of GSI resulted in down-regulation of HES/HEY genes. Conclusions: HES/HEY genes are expressed in IHs in cell type specific patterns; HEY2 is expressed in HemECs and HEY1, HEYL, HES1 are expressed in HemSCs. This pattern suggests that HEY/HES genes act downstream of Notch receptors that function in distinct cell types of IHs. HES/HEY gene transcripts are decreased with the addition of a gamma-secretase inhibitor, Compound E, demonstrating that Notch signaling is active in infantile hemangioma cells

Chaotic flow and efficient mixing in a micro-channel with a polymer solution

Microscopic flows are almost universally linear, laminar and stationary because Reynolds number, $Re$, is usually very small. That impedes mixing in micro-fluidic devices, which sometimes limits their performance. Here we show that truly chaotic flow can be generated in a smooth micro-channel of a uniform width at arbitrarily low $Re$, if a small amount of flexible polymers is added to the working liquid. The chaotic flow regime is characterized by randomly fluctuating three-dimensional velocity field and significant growth of the flow resistance. Although the size of the polymer molecules extended in the flow may become comparable with the micro-channel width, the flow behavior is fully compatible with that in a table-top channel in the regime of elastic turbulence. The chaotic flow leads to quite efficient mixing, which is almost diffusion independent. For macromolecules, mixing time in this microscopic flow can be three to four orders of magnitude shorter than due to molecular diffusion.Comment: 8 pages,7 figure

Protein structure generation via folding diffusion

The ability to computationally generate novel yet physically foldable protein structures could lead to new biological discoveries and new treatments targeting yet incurable diseases. Despite recent advances in protein structure prediction, directly generating diverse, novel protein structures from neural networks remains difficult. In this work, we present a new diffusion-based generative model that designs protein backbone structures via a procedure that mirrors the native folding process. We describe protein backbone structure as a series of consecutive angles capturing the relative orientation of the constituent amino acid residues, and generate new structures by denoising from a random, unfolded state towards a stable folded structure. Not only does this mirror how proteins biologically twist into energetically favorable conformations, the inherent shift and rotational invariance of this representation crucially alleviates the need for complex equivariant networks. We train a denoising diffusion probabilistic model with a simple transformer backbone and demonstrate that our resulting model unconditionally generates highly realistic protein structures with complexity and structural patterns akin to those of naturally-occurring proteins. As a useful resource, we release the first open-source codebase and trained models for protein structure diffusion

A Multi-Institutional Study on the Safety and Efficacy of Specimen Morcellation After Laparoscopic Radical Nephrectomy for Clinical Stage T1 or T2 Renal Cell Carcinoma

Abstract Introduction and Objective: Specimen morcellation during laparoscopic radical nephrectomy (LRN) for renal cell carcinoma (RCC) is controversial. We seek to evaluate the safety and efficacy of specimen morcellation and LRN for treatment of presumed malignant renal lesions. Methods: We retrospectively reviewed all patients who underwent LRN at three academic institutions from 1996 to 2007. One hundred eighty-eight patients underwent specimen morcellation after LRN for enhancing solid or cystic renal masses. Results: LRN was successfully performed on all the patients. Patient age ranged from 36 to 94. One hundred sixty-seven patients were in clinical stage T1, 19 patients T2, and unknown in two. The specimen was manually morcellated within a Cook Lap Sac or Endocatch II bag under laparoscopic or direct observation. On histological review of morcellated specimens, 165 patients were confirmed to have RCC, 17 had an oncocytoma, and 2 had benign cysts. At least 13 patients with RCC were pathologically upgraded to stage T3. Mean operative time was 225 minutes (range 94-650). Mean hospital stay was 2.5 days (range 1-8). In patients with RCC, 11 developed recurrent disease with mean follow-up of 21 months (range 0.3-111). In one patient, a port site recurrence occurred in concert with renal fossa and lymph node metastases. Conclusions: Intracorporeal mechanical morcellation after LRN appears to be safe and effective in clinical stage T1 and T2 RCC. This supports the use of morcellation as an alternative for intact specimen removal in properly selected patients.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78157/1/end.2009.0387.pd

Dual-stage structural response to quenching charge order in magnetite

The Verwey transition in magnetite (Fe_{3}O_{4} ) is the prototypical metal-insulator transition and has eluded a comprehensive explanation for decades. A major element of the challenge is the complex interplay between charge order and lattice distortions. Here we use ultrafast electron diffraction (UED) to disentangle the roles of charge order and lattice distortions by tracking the transient structural evolution after charge order is melted via ultrafast photoexcitation. A dual-stage response is observed in which X_{3}, X_{1}, and Delta5-type structural distortions occur on markedly different timescales of 0.7–3.2 ps and longer than 3.2 ps. We propose that these distinct timescales arise because X_{3}-type distortions strongly couple to the trimeron charge order, whereas the Delta5- distortions are more strongly associated with monoclinic to cubic distortions of the overall lattice. Our work aids in clarifying the charge-lattice interplay using UED method and illustrates the disentanglement of the complex phases in magnetite

A mobile health app for the collection of functional outcomes after inpatient stroke rehabilitation: Pilot randomized controlled trial

BACKGROUND: Monitoring the functional status of poststroke patients after they transition home is significant for rehabilitation. Mobile health (mHealth) technologies may provide an opportunity to reach and follow patients post discharge. However, the feasibility and validity of functional assessments administered by mHealth technologies are unknown. OBJECTIVE: This study aimed to evaluate the feasibility, validity, and reliability of functional assessments administered through the videoconference function of a mobile phone-based app compared with administration through the telephone function in poststroke patients after rehabilitation hospitalization. METHODS: A randomized controlled trial was conducted in a rehabilitation hospital in Southeast China. Participants were randomly assigned to either a videoconference follow-up (n=60) or a telephone follow-up (n=60) group. We measured the functional status of participants in each group at 2-week and 3-month follow-up periods. Half the participants in each group were followed by face-to-face home visit assessments as the gold standard. Validity was assessed by comparing any score differences between videoconference follow-up and home visit assessments, as well as telephone follow-up and home visit assessments. Reliability was assessed by computing agreements between videoconference follow-up and home visit assessments, as well as telephone follow-up and home visit assessments. Feasibility was evaluated by the levels of completion, satisfaction, comfort, and confidence in the 2 groups. RESULTS: Scores obtained from the videoconference follow-up were similar to those of the home visit assessment. However, most scores collected from telephone administration were higher than those of the home visit assessment. The agreement between videoconference follow-up and home visit assessments was higher than that between telephone follow-up and home visit assessments at all follow-up periods. In the telephone follow-up group, completion rates were 95% and 82% at 2-week and 3-month follow-up points, respectively. In the videoconference follow-up group, completion rates were 95% and 80% at 2-week and 3-month follow-up points, respectively. There were no differences in the completion rates between the 2 groups at all follow-up periods (X CONCLUSIONS: The videoconference follow-up assessment of functional status demonstrates higher validity and reliability, as well as higher confidence and satisfaction perceived by patients, than the telephone assessment. The videoconference assessment provides an efficient means of assessing functional outcomes of patients after hospital discharge. This method provides a novel solution for clinical trials requiring longitudinal assessments. TRIAL REGISTRATION: chictr.org.cn: ChiCTR1900027626; http://www.chictr.org.cn/edit.aspx?pid=44831&htm=4

Dual-stage structural response to quenching charge order in magnetite

The Verwey transition in magnetite (Fe3O4 ) is the prototypical metal-insulator transition and has eluded a comprehensive explanation for decades. A major element of the challenge is the complex interplay between charge order and lattice distortions. Here we use ultrafast electron diffraction (UED) to disentangle the roles of charge order and lattice distortions by tracking the transient structural evolution after charge order is melted via ultrafast photoexcitation. A dual stage response is observed in which X3, X1, and Delta5 type structural distortions occur on markedly different timescales of 0.7 to 3.2 ps and longer than 3.2 ps. We propose that these distinct timescales arise because X3 type distortions strongly couple to the trimeron charge order, whereas the Delta5-distortions are more strongly associated with monoclinic to cubic distortions of the overall lattice. Our work aids in clarifying the charge lattice interplay using UED method and illustrates the disentanglement of the complex phases in magnetite.Comment: 7 figures and 7 table