Determination of the Spin-Hall-Effect-Induced and the Wedged-Structure-Induced Spin Torque Efficiencies in Heterostructures with Perpendicular Magnetic Anisotropy

We report that by measuring current-induced hysteresis loop shift versus in-plane bias magnetic field, the spin Hall effect (SHE) contribution of the current-induced effective field per current density, $\chi_{SHE}$, can be estimated for Pt and Ta-based magnetic heterostructures with perpendicular magnetic anisotropy (PMA). We apply this technique to a Pt-based sample with its ferromagnetic (FM) layer being wedged-deposited and discover an extra effective field contribution, $\chi_{Wedged}$, due to the asymmetric nature of the deposited FM layer. We confirm the correlation between $\chi_{Wedged}$ and the asymmetric depinning process in FM layer during magnetization switching by magneto-optical Kerr (MOKE) microscopy. These results indicate the possibility of engineering deterministic spin-orbit torque (SOT) switching by controlling the symmetry of domain expansion through the materials growth process

Three-terminal resistive switch based on metal/metal oxide redox reactions

A solid-state three-terminal resistive switch based on gate-voltage-tunable reversible oxidation of a thin-film metallic channel is demonstrated. The switch is composed of a cobalt wire placed under a GdOx layer and a Au top electrode. The lateral resistance of the wire changes with the transition between cobalt and cobalt oxide controlled by a voltage applied to the top electrode. The kinetics of the oxidation and reduction process are examined through time- and temperature-dependent transport measurements. It is shown that that reversible voltage induced lateral resistance switching with a ratio of 10 3 can be achieved at room temperature. The reversible non-volatile redox reaction between metal and metal oxide may provide additional degrees of freedom for post-fabrication control of properties of solid-state materials. This type of three-terminal device has potential applications in neuromorphic computing and multilevel data storage, as well as applications that require controlling a relatively large current.National Science Foundation (U.S.) (Grant DMR-1419807

Magneto-ionic control of interfacial magnetism

In metal/oxide heterostructures, rich chemical electronic magnetic and mechanical properties can emerge from interfacial chemistry and structure. The possibility to dynamically control interface characteristics with an electric field paves the way towards voltage control of these properties in solid-state devices. Here, we show that electrical switching of the interfacial oxidation state allows for voltage control of magnetic properties to an extent never before achieved through conventional magneto-electric coupling mechanisms. We directly observe in situ voltage-driven O{superscript 2−] migration in a ​Co/metal-oxide bilayer, which we use to toggle the interfacial magnetic anisotropy energy by >0.75 erg cm[superscript −2] at just 2 V. We exploit the thermally activated nature of ion migration to markedly increase the switching efficiency and to demonstrate reversible patterning of magnetic properties through local activation of ionic migration. These results suggest a path towards voltage-programmable materials based on solid-state switching of interface oxygen chemistry.National Science Foundation (U.S.) (NSF-ECCS-1128439)National Science Foundation (U.S.). Materials Research Science and Engineering Centers (Program) (DMR-0819762)Samsung (Firm) (Samsung Global MRAM Innovation program

Survival outcomes of salvage surgery in the watch-and-wait approach for rectal cancer with clinical complete response after neoadjuvant chemoradiotherapy: a systematic review and meta-analysis

Purpose This systematic review and meta-analysis compared the outcomes of the watch-and-wait (WW) approach versus radical surgery (RS) in rectal cancers with clinical complete response (cCR) after neoadjuvant chemoradiotherapy. Methods This study followed the PRISMA guidelines. Major databases were searched to identify relevant articles. WW and RS were compared through meta-analyses of pooled proportions. Primary outcomes included overall survival (OS), disease-free survival (DFS), local recurrence, and distant metastasis rates. Pooled salvage surgery rates and outcomes were also collected. The Newcastle-Ottawa scale was employed to assess the risk of bias. Results Eleven studies including 1,112 rectal cancer patients showing cCR after neoadjuvant chemoradiation were included. Of these patients, 378 were treated nonoperatively with WW, 663 underwent RS, and 71 underwent local excision. The 2-year OS (risk ratio [RR], 0.95; P=0.94), 5-year OS (RR, 2.59; P=0.25), and distant metastasis rates (RR, 1.05; P=0.80) showed no significant differences between WW and RS. Local recurrence was more frequent in the WW group (RR, 6.93; P<0.001), and 78.4% of patients later underwent salvage surgery (R0 resection rate, 97.5%). The 2-year DFS (RR, 1.58; P=0.05) and 5-year DFS (RR, 2.07; P=0.02) were higher among RS cases. However, after adjustment for R0 salvage surgery, DFS showed no significant between-group difference (RR, 0.82; P=0.41). Conclusion Local recurrence rates are higher for WW than RS, but complete salvage surgery is often possible with similar long-term outcomes. WW is a viable strategy for rectal cancer with cCR after neoadjuvant chemoradiation, but further research is required to improve patient selection

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Controversy and consensus on the management of elevated sperm DNA fragmentation in male infertility: A global survey, current guidelines, and expert recommendations

Purpose Sperm DNA fragmentation (SDF) has been associated with male infertility and poor outcomes of assisted reproductive technology (ART). The purpose of this study was to investigate global practices related to the management of elevated SDF in infertile men, summarize the relevant professional society recommendations, and provide expert recommendations for managing this condition. Materials and Methods An online global survey on clinical practices related to SDF was disseminated to reproductive clinicians, according to the CHERRIES checklist criteria. Management protocols for various conditions associated with SDF were captured and compared to the relevant recommendations in professional society guidelines and the appropriate available evidence. Expert recommendations and consensus on the management of infertile men with elevated SDF were then formulated and adapted using the Delphi method. Results A total of 436 experts from 55 different countries submitted responses. As an initial approach, 79.1% of reproductive experts recommend lifestyle modifications for infertile men with elevated SDF, and 76.9% prescribe empiric antioxidants. Regarding antioxidant duration, 39.3% recommend 4–6 months and 38.1% recommend 3 months. For men with unexplained or idiopathic infertility, and couples experiencing recurrent miscarriages associated with elevated SDF, most respondents refer to ART 6 months after failure of conservative and empiric medical management. Infertile men with clinical varicocele, normal conventional semen parameters, and elevated SDF are offered varicocele repair immediately after diagnosis by 31.4%, and after failure of antioxidants and conservative measures by 40.9%. Sperm selection techniques and testicular sperm extraction are also management options for couples undergoing ART. For most questions, heterogenous practices were demonstrated. Conclusions This paper presents the results of a large global survey on the management of infertile men with elevated SDF and reveals a lack of consensus among clinicians. Furthermore, it demonstrates the scarcity of professional society guidelines in this regard and attempts to highlight the relevant evidence. Expert recommendations are proposed to help guide clinicians

Deep Learning Image Augmentation using Inpainting with Partial Convolution and GANs

The 21st century has seen the remarkable transformation of machine vision by deep learning. This has enabled intelligent systems like autonomous vehicles and facial recognition software. However, the success of deep learning is largely predicated on the availability of sufficient data; in many instances, data may be scarce and expensive to source. In this thesis, we implemented two deep learning techniques: (1) inpainting using partial convolution and (2) generative adversarial network (GAN) to generate synthetic data to train deep learning image classifiers. We show that the addition of synthetic training images dramatically improved the accuracies of our defect classifiers. Using Gradient- Class Activation Map (Grad-CAM), we also demonstrate that the decision rules learned by the classifiers are significantly enhanced where the classifiers are accurately activating at the specific defect locations upon addition of synthetic training images. The study was performed at Amgen using real images of syringes and vials, indicating the practicality of the technique for industrial applications.M.B.A.S.M

Dynamic modulation of material properties by solid state proton gating

This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2019Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 195-215).As functionalities become more abundant in solid state devices, one key capability which remains lacking is an effective means to dynamically tune material properties. In this thesis, we establish a pathway towards this capability by utilizing the simplest ion known to mankind: the proton. We demonstrate for the first time dynamic control of magnetic properties in an all-solid-state heterostructures using solid state proton gating in a metal/oxide heterostructure. We also demonstrate dynamic modulation of magnetic anisotropy at a metal-metal interface through hydrogen insertion in a heavy metal adjacent to a ferromagnet. Besides magnetic properties, solid state proton gating also enables dynamic modulation of optical properties in a thin film oxide. We observe fast gating of optical reflectivity by ~10% at timescale down to ~20ms in a metal/oxide/metal heterostructure. Finally, we also demonstrate a room temperature reversible solid oxide fuel cell based on hydrogen storage. The cell has a small form factor which is suitable for energy storage in solid state microelectronics application. Our work hence provides a platform for complete control of material properties through solid state proton gating.by Aik Jun Tan.Ph. D.Ph.D. Massachusetts Institute of Technology, Department of Materials Science and Engineerin