IIT@Harvard

In this paper we present a set of efficient image based rendering methods capable of rendering multiple frames per second on a PC. The first method warps Sprites with Depth representing smooth surfaces without the gaps found in other techniques. A second method for more general scenes performs warping from an intermediate representation called a Layered Depth Image (LDI). An LDI is a view of the scene from a single input camera view, but with multiple pixels along each line of sight. The size of the representation grows only linearly with the observed depth complexity in the scene. Moreover, because the LDI data are represented in a single image coordinate system, McMillan's warp ordering algorithm can be successfully adapted. As a result, pixels are drawn in the output image in back-to-front order. No z-buffer is required, so alphacompositing can be done efficiently without depth sorting. This makes splatting an efficient solution to the resampling problem. 1 Introduction Image base...

Abstract Connections between neurons can be mapped by acquiring and analysing electron microscopic brain images. In recent years, this approach has been applied to chunks of brains to reconstruct local connectivity maps that are highly informative 1–6 , but nevertheless inadequate for understanding brain function more globally. Here we present a neuronal wiring diagram of a whole brain containing 5 × 10 7 chemical synapses 7 between 139,255 neurons reconstructed from an adult female Drosophila melanogaster 8,9 . The resource also incorporates annotations of cell classes and types, nerves, hemilineages and predictions of neurotransmitter identities 10–12 . Data products are available for download, programmatic access and interactive browsing and have been made interoperable with other fly data resources. We derive a projectome—a map of projections between regions—from the connectome and report on tracing of synaptic pathways and the analysis of information flow from inputs (sensory and ascending neurons) to outputs (motor, endocrine and descending neurons) across both hemispheres and between the central brain and the optic lobes. Tracing from a subset of photoreceptors to descending motor pathways illustrates how structure can uncover putative circuit mechanisms underlying sensorimotor behaviours. The technologies and open ecosystem reported here set the stage for future large-scale connectome projects in other species.

Abstract The fruit fly Drosophila melanogaster has emerged as a key model organism in neuroscience, in large part due to the concentration of collaboratively generated molecular, genetic and digital resources available for it. Here we complement the approximately 140,000 neuron FlyWire whole-brain connectome 1 with a systematic and hierarchical annotation of neuronal classes, cell types and developmental units (hemilineages). Of 8,453 annotated cell types, 3,643 were previously proposed in the partial hemibrain connectome 2 , and 4,581 are new types, mostly from brain regions outside the hemibrain subvolume. Although nearly all hemibrain neurons could be matched morphologically in FlyWire, about one-third of cell types proposed for the hemibrain could not be reliably reidentified. We therefore propose a new definition of cell type as groups of cells that are each quantitatively more similar to cells in a different brain than to any other cell in the same brain, and we validate this definition through joint analysis of FlyWire and hemibrain connectomes. Further analysis defined simple heuristics for the reliability of connections between brains, revealed broad stereotypy and occasional variability in neuron count and connectivity, and provided evidence for functional homeostasis in the mushroom body through adjustments of the absolute amount of excitatory input while maintaining the excitation/inhibition ratio. Our work defines a consensus cell type atlas for the fly brain and provides both an intellectual framework and open-source toolchain for brain-scale comparative connectomics.

The threat of COVID-19 has increased the health risks of going to an office or factory, leading more workers to do their jobs remotely. In this paper, we provide results from firm surveys on both small and large businesses on the prevalence and productivity of remote work, and expectations about the persistence of remote work once the COVID-19 crisis ends. We present four main findings. First, while overall levels of remote work are high, there is considerable variation across industries. The Dingel and Neiman (2020) measure of suitability for remote work does a remarkably good job of predicting the industry level patterns of remote work -highlighting the challenge of moving many industries to remote work. Second, remote work is much more common in industries with better educated and better paid workers. Third, in our larger survey, employers think that there has been less productivity loss from remote working in better educated and higher paid industries. Fourth, more than one-third of firms that had employees switch to remote work believe that remote work will remain more common at their company even after the COVID-19 crisis ends.

Accurate knowledge of a patient's disease state and trajectory is critical in a clinical setting. Modern electronic healthcare records contain an increasingly large amount of data, and the ability to automatically identify the factors that influence patient outcomes stand to greatly improve the efficiency and quality of care. We examined the use of latent variable models (viz. Latent Dirichlet Allocation) to decompose free-text hospital notes into meaningful features, and the predictive power of these features for patient mortality. We considered three prediction regimes: (1) baseline prediction, (2) dynamic (time-varying) outcome prediction, and (3) retrospective outcome prediction. In each, our prediction task differs from the familiar time-varying situation whereby data accumulates; since fewer patients have long ICU stays, as we move forward in time fewer patients are available and the prediction task becomes increasingly difficult. We found that latent topic-derived features were effective in determining patient mortality under three timelines: inhospital, 30 day post-discharge, and 1 year post-discharge mortality. Our results demonstrated that the latent topic features important in predicting hospital mortality are very different from those that are important in post-discharge mortality. In general, latent topic features were more predictive than structured features, and a combination of the two performed best. The time-varying models that combined latent topic features and baseline features had AUCs that reached 0.85, 0.80, and 0.77 for in-hospital, 30 day post-discharge and 1 year post-discharge mortality respectively. Our results agreed with other work suggesting that the first 24 hours of patient information are often the most predictive of hospital mortality. Retrospective models that used a combination of latent topic features and structured features achieved AUCs of 0.96, 0.82, and 0.81 for in-hospital, 30 day, and 1-year mortality prediction. Our work focuses on the dynamic (time-varying) setting because models from this regime could facilitate an on-going severity stratification system that helps direct care-staff resources and inform treatment strategies.

PURPOSE: Defining a study population and creating an analytic dataset from longitudinal healthcare databases involves many decisions. Our objective was to catalogue scientific decisions underpinning study execution that should be reported to facilitate replication and enable assessment of validity of studies conducted in large healthcare databases. METHODS: We reviewed key investigator decisions required to operate a sample of macros and software tools designed to create and analyze analytic cohorts from longitudinal streams of healthcare data. A panel of academic, regulatory, and industry experts in healthcare database analytics discussed and added to this list. CONCLUSION: Evidence generated from large healthcare encounter and reimbursement databases is increasingly being sought by decision-makers. Varied terminology is used around the world for the same concepts. Agreeing on terminology and which parameters from a large catalogue are the most essential to report for replicable research would improve transparency and facilitate assessment of validity. At a minimum, reporting for a database study should provide clarity regarding operational definitions for key temporal anchors and their relation to each other when creating the analytic dataset, accompanied by an attrition table and a design diagram. A substantial improvement in reproducibility, rigor and confidence in real world evidence generated from healthcare databases could be achieved with greater transparency about operational study parameters used to create analytic datasets from longitudinal healthcare databases.

This paper develops a theory of the firm in which a firm's centralized asset ownership and low-powered incentives give the manager, as an equilibrium outcome, interpersonal authority over employees (in a world with open disagreement). The paper thus provides micro-foundations for the idea that bringing a project inside the firm gives the manager control over that project, while explaining concentrated asset ownership, low-powered incentives, and centralized authority as typical characteristics of firms. The paper also leads to new perspectives on the firm as a legal entity and on the relationship between the Knightian and Coasian views of the firm. (JEL D23, L20)

Metasurface absorbing material, which obtains near‐unity electromagnetic absorption through subwavelength artificial structure, plays an important role in the area of stealth and shielding technology, biological imaging, etc. However, they usually suffer from narrow bandwidth and only work on planar surfaces. Here, for the first time, this study demonstrates a soft water‐resonator‐based metasurface, which functions as an active absorbing material across an ultrabroadband range of Ku, K, and Ka bands. Distinct from conventional metallic metasurface, the water‐resonator‐based metasurface absorbs the microwave by dielectric magnetic resonance and periodic grating effect, which has a perfect absorptivity of ≈99% and an absorption bandwidth (absorptivity higher than 90%) that covers 78.9% of the central frequency. Furthermore, near‐unity absorption is maintained when the soft metasurface material is bent into different curvatures, promising high potential applications for antennas in reducing side lobe radiation, eliminating wall reflection in anechoic chambers, antiradar detection, and stealth.

Menstrual and hormonal disturbances have been reported in thin, dieting and exercising Western women, and also recently in rural African women. A study of salivary progesterone profiles was undertaken in a Nepali population to examine whether seasonal increases in workload and changes in energy balance influenced ovarian function. Women's energy expenditure levels were moderately heavy in the winter and very heavy in the monsoon, and body mass fluctuated by -2.8 to +4.8 kg. Samples were collected from 24 normally menstruating women in two seasons, each individual serving as her own control. Progesterone levels were significantly depressed in the monsoon relative to winter for women who lost weight, but not for women who gained weight, indicating that energy imbalance is associated with a loss of fecundity. No differences in body mass index were found between women who lost or gained weight. Progesterone levels were age-dependent, and the degree of hormonal disturbance between age-groups was related to weight loss. The study demonstrates seasonal changes in the fecundity of hard-working Nepali women and a direct link between ovarian function and weight loss (negative energy balance), which is independent of current nutritional status.

Prior research with preschool children has established that dialogic or active book reading is an effective method for expanding young children’s vocabulary. In this exploratory study, we asked whether similar benefits are observed when a robot engages in dialogic reading with preschoolers. Given the established effectiveness of active reading, we also asked whether this effectiveness was critically dependent on the expressive characteristics of the robot. For approximately half the children, the robot’s active reading was expressive; the robot’s voice included a wide range of intonation and emotion (Expressive). For the remaining children, the robot read and conversed with a flat voice, which sounded similar to a classic text-to-speech engine and had little dynamic range (Flat). The robot's movements were kept constant across conditions. We performed a verification study using Amazon Mechanical Turk to confirm that the Expressive robot was viewed as significantly more expressive, more emotional, and less passive than the Flat robot. We invited 45 preschoolers with an average age of 5 years who were either English Language Learners (ELL), bilingual, or native English speakers to engage in the reading task with the robot. The robot narrated a story from a picture book, using active reading techniques and including a set of target vocabulary words in the narration. Children were post-tested on the vocabulary words and were also asked to retell the story to a puppet. A subset of 34 children performed a second story retelling 4-6 weeks later. Children reported liking and learning from the robot a similar amount in the Expressive and Flat conditions. However, as compared to children in the Flat condition, children in the Expressive condition were more concentrated and engaged as indexed by their facial expressions; they emulated the robot's story more in their story retells; and they told longer stories during their delayed retelling. Furthermore, children who responded to the robot’s active reading questions were more likely to correctly identify the target vocabulary words in the Expressive condition than in the Flat condition. Taken together, these results suggest that children may benefit more from the expressive robot than from the flat robot.

The research and evaluation evidence is mounting: out-of-school-time (OST) programs can keep young people safe, support working families, and improve academic achievement and social development. Over 6 million children are enrolled in after-school programs nationwide, but an estimated 14.3 million children still care for themselves in the nonschool hours. Because of this discrepancy, OST stakeholders need information about how to maximize participation in OST programs. The Harvard Family Research Project (HRFP) has developed a conceptual model, based on scholarly theory, empirical research, and knowledge gained from providers, that describes the characteristics that predict participation in OST programs as well as the potential benefits of that participation. In the center of the model, participation is conceived as a three-part construct of enrollment, attendance, and engagement. This equation serves as the basis for framing this issue of New Directions for Youth Development. The chapter provides an overview of why participation in OST programs matters for young people, describes some of the barriers and challenges to youth participation, teases out more precise definitions of participation, and presents HFRP's conceptual model of participation. It focuses on the participation equation and concludes by highlighting some overarching themes that recur throughout the issue and that have an impact on future directions for research and evaluation.

(Uploaded by Plazi for the Bat Literature Project) No abstract provided.

A rapid heating method of hydrolysis by the use of microwave oven has been applied to amino acid analysis of proteins and peptides. This convenient method has been compared with the conventional 6 N HCl hydrolysis at 110 degrees for 24 h. The advantages of this new method are its expedition and the accurate and comparable results as compared to the tedious conventional technique. The method provides a rapid processing of multiple samples within minutes instead of days and inexpensive access to the important data of amino acid compositions of proteins by the commonly used microwave oven. The necessary change in the design of hydrolysis vials and the safety precautions accompanying this novel use of microwave acid-digestion method are also described.

BACKGROUND: Ipilimumab improves survival in metastatic melanoma patients. This population frequently develops brain metastases, which have been associated with poor survival and are often treated with radiation. Therefore, outcomes following ipilimumab and radiation are of interest, especially given case reports and animal studies suggest combined treatment may generate abscopal responses outside the radiation field. FINDINGS: We reviewed sixteen consecutive melanoma patients who received 1 to 8 courses of radiation, with a sum total of 51, systematically evaluating abscopal responses by following the largest extra-cranial lesion. We also reviewed other series of patients treated with cranial radiation and ipilimumab. Our patients received between 1 and 8 courses of cranial radiation. Four patients received radiation concurrently with ipilimumab. Median survival was 14 months, and 17 months in patients initially treated with SRS. Interestingly, after radiotherapy, there was a 2.8-fold increased likelihood that the rate of extra-cranial index lesion response improved that didn't reach statistical significance (p = 0.07); this was more pronounced when ipilimumab was administered within three months of radiation (p < 0.01). CONCLUSION: Our experience and review of recently published series suggest ipilimumab and cranial radiation is well tolerated and can result in prolonged survival. Timing of ipilimumab administration in relation to radiation may impact outcomes. Additionally, our results demonstrate a trend for favorable systemic response following radiotherapy worthy of further evaluation in studies powered to detect potential synergies between radiation and immunotherapy.

Proceedings of the National Academy of Sciences (PNAS), a peer reviewed journal of the National Academy of Sciences (NAS) - an authoritative source of high-impact, original research that broadly spans the biological, physical, and social sciences.

Abstract A catalogue of neuronal cell types has often been called a ‘parts list’ of the brain 1 , and regarded as a prerequisite for understanding brain function 2,3 . In the optic lobe of Drosophila , rules of connectivity between cell types have already proven to be essential for understanding fly vision 4,5 . Here we analyse the fly connectome to complete the list of cell types intrinsic to the optic lobe, as well as the rules governing their connectivity. Most new cell types contain 10 to 100 cells, and integrate information over medium distances in the visual field. Some existing type families (Tm, Li, and LPi) 6–10 at least double in number of types. A new serpentine medulla (Sm) interneuron family contains more types than any other. Three families of cross-neuropil types are revealed. The consistency of types is demonstrated by analysing the distances in high-dimensional feature space, and is further validated by algorithms that select small subsets of discriminative features. We use connectivity to hypothesize about the functional roles of cell types in motion, object and colour vision. Connectivity with ‘boundary types’ that straddle the optic lobe and central brain is also quantified. We showcase the advantages of connectomic cell typing: complete and unbiased sampling, a rich array of features based on connectivity and reduction of the connectome to a substantially simpler wiring diagram of cell types, with immediate relevance for brain function and development.

Abstract Mobile health applications (“apps”) have rapidly proliferated, yet their ability to improve outcomes for patients remains unclear. A validated tool that addresses apps’ potentially important dimensions has not been available to patients and clinicians. The objective of this study was to develop and preliminarily assess a usable, valid, and open-source rating tool to objectively measure the risks and benefits of health apps. We accomplished this by using a Delphi process, where we constructed an app rating tool called THESIS that could promote informed app selection. We used a systematic process to select chronic disease apps with ≥4 stars and &lt;4-stars and then rated them with THESIS to examine the tool’s interrater reliability and internal consistency. We rated 211 apps, finding they performed fair overall (3.02 out of 5 [95% CI, 2.96–3.09]), but especially poorly for privacy/security (2.21 out of 5 [95% CI, 2.11–2.32]), interoperability (1.75 [95% CI, 1.59–1.91]), and availability in multiple languages (1.43 out of 5 [95% CI, 1.30–1.56]). Ratings using THESIS had fair interrater reliability ( κ = 0.3–0.6) and excellent scale reliability ( ɑ = 0.85). Correlation with traditional star ratings was low ( r = 0.24), suggesting THESIS captures issues beyond general user acceptance. Preliminary testing of THESIS suggests apps that serve patients with chronic disease could perform much better, particularly in privacy/security and interoperability. THESIS warrants further testing and may guide software and policymakers to further improve app performance, so apps can more consistently improve patient outcomes.

Abstract. In this pilot study, we aimed to generate a reference stan-dard of clinical acronyms and abbreviations normalized to concepts from a standardized, medical vocabulary for the ShARe/CLEF eHealth 2013 challenge. In this paper, we review prior text normalization shared tasks, reference standard generation approaches, and recent clinical acronym and abbreviation normalization research. We report inter-annotator agree-ment for the reference standard and performance for participant systems.

BACKGROUND: Being a part of community is critical for survival and individuals with major depressive disorder (MDD) have a greater sensitivity to interpersonal stress that makes them vulnerable to future episodes. Social rejection is a critical risk factor for depression and it is said to increase interpersonal stress and thereby impairing social functioning. It is therefore critical to understand the neural correlates of social rejection in MDD. METHODS: To this end, we scanned 15 medicated MDD and 17 healthy individuals during a modified cyberball passing game, where participants were exposed to increasing levels of social exclusion. Neural responses to increasing social exclusion were investigated and compared between groups. RESULTS: We showed that compared to controls, MDD individuals exhibited greater amygdala, insula, and ventrolateral prefrontal cortex activation to increasing social exclusion and this correlated negatively with hedonic tone and self-esteem scores across all participants. CONCLUSIONS: These preliminary results support the hypothesis that depression is associated with hyperactive response to social rejection. These findings highlight the importance of studying social interactions in depression, as they often lead to social withdrawal and isolation.

BACKGROUND: Pulsed field ablation (PFA) is a nonthermal energy that may provide safety advantages over radiofrequency ablation (RFA). One-shot PFA catheters have been developed for pulmonary vein isolation, but they do not permit flexible lesion sets. This study investigated a novel lattice-tip catheter designed for focal RFA or PFA ablation. METHODS: The effects of PFA (biphasic, 24 amperes) were investigated in 25 swine using a lattice-tip catheter and system (Affera Inc). Step 1 (n=14) examined the feasibility to create atrial line of block and described its acute effects on the phrenic nerve and esophagus. Step 2 (n=7) examined the subacute effects of PFA on block durability, phrenic nerve, and esophagus ≥2 weeks. Step 3 compared the effects of PFA and RFA on the esophagus using a mechanical deviation model approximating the esophagus to the right atrium (n=4) and by direct ablation within its lumen (n=4). The effects of endocardial PFA and RFA on the phrenic nerve were also compared (n=10). Histological analysis was performed. RESULTS: PFA produced acute block in 100% of lines, achieved with 2.1 (1.3-3.2) applications/cm line. Histological analysis following (35 [18-37]) days showed 100% transmurality (thickness range 0.4-3.4 mm) with a lesion width of 19.4 (10.9-27.4 mm). PFA selectively affected cardiomyocytes but spared blood vessels and nervous tissue. PFA applied from the posterior atria (23 [21-25] applications) to the approximated esophagus (6 [4.5-14] mm) produced transmural lesions without esophageal injury. PFA (16.5 [15-18] applications) applied inside the esophageal lumen produced mild edema compared with RFA (13 [12-14] applications) which produced epithelial ulcerations. PFA resulted in no or transient stunning of the phrenic nerve (<5 minutes) without histological changes while RFA produced paralysis. CONCLUSIONS: PFA using a lattice-tip ablation catheter for focal ablation produced durable atrial lesions and showed lower vulnerability to esophageal or phrenic nerve damage compared with RFA.