Últimos itens adicionados do Acervo: Harvard University

A Universidade de Harvard (em inglês: Harvard University) é uma universidade privada membro da Ivy League, localizada em Cambridge, Massachusetts, Estados Unidos, e cuja história, influência e riqueza tornam-a uma das mais prestigiadas universidades do mundo.

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Infants' and toddlers' reasoning about others: Connections to prosocial development and language

Hobbs, Kathryn Virginia
Fonte: Harvard University Publicador: Harvard University
Tipo: Thesis or Dissertation
EN_US
Often overlooked in the study of theory of mind (ToM) development, the understanding of motivational states, such as goals and desires, is both an important capacity in its own right and also a likely precursor to more advanced social and cognitive skills. This dissertation explored infants' and toddlers' reasoning about agents' motivational states, linking those representations to the domains of language and prosocial development. Parts I and II of the dissertation asked about toddlers' abilities to use representations of others' motivational states to guide helping behaviors. Part I used a spontaneous helping paradigm with two goal objects, one previously liked and the other disliked. Three- but not 2-year-olds helped appropriately by giving an actor her desired object, reflecting prosocial concern for others' specific desires at age 3. Part II probed the understanding of goals and helping of 14- and 24-month-olds. After establishing that toddlers encode simple reaching actions as goal-directed, a series of 4 experiments using an object-giving paradigm investigated toddlers' abilities to use goal representations to guide helping. The results indicate that 24- but not 14-month-olds used representations of prior goals to inform their helping behaviors; 14-month-olds were capable of using only current goals to guide helping. Part III of the dissertation asked whether there is continuity in the developmental relationship between language and ToM by investigating links between toddlers' understanding of motivational states and their vocabulary size. Experiment 1 found no correlation between the vocabulary size of typically hearing toddlers and their performance on tasks measuring motivational state understanding. Experiment 2 compared the same motivational state understanding of typically hearing toddlers and deaf toddlers with smaller vocabularies...

Exploring Cancer's Fractured Genomic Landscape: Searching for Cancer Drivers and Vulnerabilities in Somatic Copy Number Alterations

Zack, Travis Ian
Fonte: Harvard University Publicador: Harvard University
Tipo: Thesis or Dissertation
EN_US
Somatic copy number alterations (SCNAs) are a class of alterations that lead to deviations from diploidy in developing and established tumors. A feature that distinguishes SCNAs from other alterations is their genomic footprint. The large genomic footprint of SCNAs in a typical cancer's genome presents both a challenge and an opportunity to find targetable vulnerabilities in cancer. Because a single event affects many genes, it is often challenging to identify the tumorigenic targets of SCNAs. Conversely, events that affect multiple genes may provide specific vulnerabilities through "bystander" genes, in addition to vulnerabilities directly associated with the targets. We approached the goal of understanding how the structure of SCNAs may lead to dependency in two ways. To improve our understanding of how SCNAs promote tumor progression we analyzed the SCNAs in 4934 primary tumors in 11 common cancers collected by the Cancer Genome Atlas (TCGA). The scale of this dataset provided insights into the structure and patterns of SCNA, including purity and ploidy rates across disease, mechanistic forces shaping patterns of SCNA, regions undergoing significantly recurrent SCNAs, and correlations between SCNAs in regions implicated in cancer formation. In a complementary approach...

Writing Herself: Resistance, Rebellion, and Revolution in Korean Women's Lyric Poetry, 1925--2012

Choi, Jung Ja
Fonte: Harvard University Publicador: Harvard University
Tipo: Thesis or Dissertation
EN_US
Despite a recent global surge in the reception and translation of Korean women poets, there has been surprisingly little scholarship on this topic. This dissertation aims to expand the focus of Western scholarship beyond the Korean male canon by providing the first in-depth analysis of the works of Korean women poets in the 20th and 21st centuries. The poets I chose to examine for this study played a critical role in revolutionizing traditional verse patterns and in integrating global socio-political commentary into modern Korean poetry. In particular, by experimenting widely with forms from epic narrative, memoir in verse, and shamanic narration to epistolary verse and avant-garde styles, they opened up new possibilities for Korean women's lyric poetry. In addition, they challenged the traditional notion of lyric poetry as simply confessional, emotional, passive, or feminine. Their poetry went beyond the commonplace themes of nature, love, and longing, engaging with socio-political concerns such as racial, class, and gender discrimination, human rights issues, and the ramifications of the greatest calamities of the 20th century, including the Holocaust, the Korean War, and the Kwangju Uprising. Unlike the dominant scholarship that tends to highlight the victimization of women and their role as passive observers...

Short-Term Mortality Prediction in Advanced Cancer Patients Eligible for End-of-Life (EOL) Care Processes Using Electronic Health Records

Elfiky, Aymen
Fonte: Harvard University Publicador: Harvard University
Tipo: Thesis or Dissertation; text Formato: application/pdf
EN
Purpose: For terminally ill cancer patients, accurate and consistent prediction of mortality can have far reaching implications for care delivery and resource utilization. The objective of this study was to apply machine learning and informatics methodologies to construct, test, and compare the performance of short-term mortality prediction models in patients with advanced stage, non-curative cancer using EHR and registry. Methods: EHR and registry data were collected on 22,700 and 7,300 adult, Stage IV prostate and bladder cancer patients. The patients received care between 2004-2014. The ‘traditional’ feature set included standard demographics, 20-variable co-morbidity count. The ‘cumulative impact’ feature set was compiled using a time-segmented tally of encounters in the 1-3 and 3-12 months prior to t0. Lastly, the ‘novel’ features used to augment the above data included cancer stage at initial diagnosis, cancer grade, number of standard treatment lines, durable medical equipment, non-elective hospital admissions, ER visits, inpatient consults. Classifiers tested included Naïve Bayes, support vector machine (SVM), K nearest neighbor (k-NN), artificial neural nets (ANN), random forest (RF), and logistic regression. Each disease cohort was analyzed using the same training and validation samples to compare the different classifiers. Area under receiver operating curve (AUC) was used as the performance measure for all classifiers. Results: Each of the classifiers trained using the augmented features i.e. ‘cumulative impact’ and ‘novel’ features performed better than their ‘traditional’ model counterparts. For the prostate cancer cohort...

Use of Health Information Technology to Improve Communication and Follow-Up of Critical Results

O'Connor, Stacy D.
Fonte: Harvard University Publicador: Harvard University
Tipo: Thesis or Dissertation; text Formato: application/pdf
EN

Automated System for Gathering and Reporting Clinical Outcomes to Providers

Gross, Benjamin
Fonte: Harvard University Publicador: Harvard University
Tipo: Thesis or Dissertation; text Formato: application/pdf
EN
BACKGROUND: Automated communication systems can help healthcare providers learn about their patients’ outcomes to detect patients who haven’t improved as expected. OBJECTIVE: To provide feedback to healthcare providers on patient outcomes following acute care visits. DESIGN: A cross-sectional study was conducted at two primary care clinics at Massachusetts General Hospital in which consenting patients received follow-up survey emails one and three weeks after acute care visits. In both surveys, patients were asked about the status of the problem for which they were seen and about subsequent provider contact. Patients’ responses were sent to their providers. Patients and providers were surveyed regarding satisfaction with the system. PRIMARY GOAL: To test the feasibility of implementing the system. Primary outcomes included: patient enrollment and response rate, problem resolution, and provider and patient satisfaction with the system. KEY RESULTS: Of 936 patients who had acute care visits during the study period, 326 (35%) agreed to participate in the study. One hundred forty-four patients responded to at least one of the two surveys they received (44% of participants, 15% of all patients who had urgent care visits). Twenty-two patients (15% of responders) reported lack of improvement in at least one of the surveys. The system informed providers of eight unimproved patients who had not contacted any provider since their visit. Seventy-seven percent of responding patients recommended that the clinic continue to send patients follow-up emails in the future. Ninety-seven percent of responding providers said they liked receiving the reports from our system. CONCLUSIONS: Gathering and reporting clinical outcomes to providers is feasible using an asynchronous and secure online survey system initiated via standard email. A system that requires minimal effort from clinic staff allows providers to detect and focus their attention on unimproved patients while improving overall patient satisfaction.

A Concept-Wide Association Study of Clinical Notes in Search of New Predictors of Kidney Failure

Singh, Karandeep
Fonte: Harvard University Publicador: Harvard University
Tipo: Thesis or Dissertation; text Formato: application/pdf
EN
Importance: Identifying modifiable risk factors for kidney disease progression is critical towards the development of strategies to prevent the onset of kidney failure. Existing epidemiologic approaches are unable to translate unstructured clinical information into knowledge about potential risks. Objective: The objective of this study is to use clinical notes to identify novel risk factors for kidney failure. Design: We conducted a retrospective study consisting of evaluating the end stage renal disease (ESRD) using individual concepts extracted from clinical notes in the year prior to the first outpatient general nephrology visit. We treated death as a competing risk in this analysis and used proportional subdistribution hazards regression. We determined statistical significance in univariate and multivariate models using a 5% threshold for false discovery rate (q-value < 0.05). The multivariate models included the Tangri score, an established predictive score for ESRD. Setting: A tertiary care center. Participants: Patients were included if they were seen by an adult outpatient nephrologist at a Brigham and Women’s Hospital-affiliated clinic between January 1, 2004 and June 18, 2014. Patients were excluded if they had visits only with renal transplant (and not general nephrology)...

Acute myocardial infarction activates distinct inflammation and proliferation pathways in circulating monocytes, prior to recruitment, and identified through conserved transcriptional responses in mice and humans

Ruparelia, Neil; Godec, Jernej; Lee, Regent; Chai, Joshua T.; Dall'Armellina, Erica; McAndrew, Debra; Digby, Janet E.; Forfar, J. Colin; Prendergast, Bernard D.; Kharbanda, Rajesh K.; Banning, Adrian P.; Neubauer, Stefan; Lygate, Craig A.; Channon, Keith
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
EN_US
Aims Monocytes play critical roles in tissue injury and repair following acute myocardial infarction (AMI). Specifically targeting inflammatory monocytes in experimental models leads to reduced infarct size and improved healing. However, data from humans are sparse, and it remains unclear whether monocytes play an equally important role in humans. The aim of this study was to investigate whether the monocyte response following AMI is conserved between humans and mice and interrogate patterns of gene expression to identify regulated functions. Methods and results Thirty patients (AMI) and 24 control patients (stable coronary atherosclerosis) were enrolled. Female C57BL/6J mice (n = 6/group) underwent AMI by surgical coronary ligation. Myocardial injury was quantified by magnetic resonance imaging (human) and echocardiography (mice). Peripheral monocytes were isolated at presentation and at 48 h. RNA from separated monocytes was hybridized to Illumina beadchips. Acute myocardial infarction resulted in a significant peripheral monocytosis in both species that positively correlated with the extent of myocardial injury. Analysis of the monocyte transcriptome following AMI demonstrated significant conservation and identified inflammation and mitosis as central processes to this response. These findings were validated in both species. Conclusions: Our findings show that the monocyte transcriptome is conserved between mice and humans following AMI. Patterns of gene expression associated with inflammation and proliferation appear to be switched on prior to their infiltration of injured myocardium suggesting that the specific targeting of inflammatory and proliferative processes in these immune cells in humans are possible therapeutic strategies. Importantly...

Inhibition of the βbarrel assembly machine by a peptide that binds BamD

Hagan, Christine Lepicier; Wzorek, Joseph Stanley; Kahne, Daniel
Fonte: Proceedings of the National Academy of Sciences Publicador: Proceedings of the National Academy of Sciences
Tipo: Artigo de Revista Científica
EN_US
The protein complex that assembles integral membrane β-barrel proteins in the outer membranes of Gram-negative bacteria is an attractive target in the development of new antibiotics. This complex, the β-barrel assembly machine (Bam), contains two essential proteins, BamA and BamD. We have identified a peptide that inhibits the assembly of β-barrel proteins in vitro by characterizing the interaction of BamD with an unfolded substrate protein. This peptide is a fragment of the substrate protein and contains a conserved amino acid sequence. We have demonstrated that mutations of this sequence in the full-length substrate protein impair the protein’s assembly,implying that BamD’s interaction with this sequence is an important part of the assembly mechanism. Finally, we have found that in vivo expression of a peptide containing this sequence causes growth defects and sensitizes E. coli to antibiotics to which they are normally resistant. Therefore, inhibiting the binding of substrates to BamD is a viable strategy for developing new antibiotics directed against Gram-negative bacteria.; Chemistry and Chemical Biology

Kinetic Role of Carbon in Solid-State Synthesis of Zirconium Diboride using Nanolaminates: Nanocalorimetry Experiments and First-Principles Calculations

Lee, Dongwoo; Sim, Gi-dong; Zhao, Kejie; Vlassak, Joost J.
Fonte: American Chemical Society (ACS) Publicador: American Chemical Society (ACS)
Tipo: Artigo de Revista Científica
EN_US
Reactive nanolaminates afford a promising route for the low-temperature synthesis of zirconium diboride, an ultrahigh-temperature ceramic with metallic properties. Although the addition of carbon is known to facilitate sintering of ZrB2, its effect on the kinetics of the formation reaction has not been elucidated. We have employed a combined approach of nanocalorimetry and first-principles theoretical studies to investigate the kinetic role of carbon in the synthesis of ZrB2 using B4C/Zr reactive nanolaminates. Structural characterization of the laminates by XRD and TEM reveal that the reaction proceeds via interdiffusion of the B4C and Zr layers, which produces an amorphous Zr3B4C alloy. This amorphous alloy then crystallizes to form a supersaturated ZrB2(C) compound. A kinetic analysis shows that carbon lowers the energy barriers for both interdiffusion and crystallization by more than 20%. Energetic calculations based on first-principles modeling suggest that the reduction of the diffusion barrier may be attributed to the stronger bonding between Zr and C as compared to the bonding between Zr and B.; Engineering and Applied Sciences

Feedback-Induced Phase Transitions in Active Heterogeneous Conductors

Ocko, Samuel A; Mahadevan, Lakshminarayanan
Fonte: American Physical Society (APS) Publicador: American Physical Society (APS)
Tipo: Artigo de Revista Científica
EN_US
An active conducting medium is one where the resistance (conductance) of the medium is modified by the current (flow) and in turn modifies the flow, so that the classical linear laws relating current and resistance, e.g., Ohm’s law or Darcy’s law, are modified over time as the system itself evolves. We consider a minimal model for this feedback coupling in terms of two parameters that characterize the way in which addition or removal of matter follows a simple local (or nonlocal) feedback rule corresponding to either flow-seeking or flow-avoiding behavior. Using numerical simulations and a continuum mean field theory, we show that flow avoiding feedback causes an initially uniform system to become strongly heterogeneous via a tunneling (channel-building) phase separation; flow-seeking feedback leads to an immuring (wallbuilding) phase separation. Our results provide a qualitative explanation for the patterning of active conducting media in natural systems, while suggesting ways to realize complex architectures using simple rules in engineered systems.; Mathematics

Fluid-driven fingering instability of a confined elastic meniscus

Biggins, John S.; Wei, Z; Mahadevan, Lakshminarayanan
Fonte: IOP Publishing Publicador: IOP Publishing
Tipo: Artigo de Revista Científica
EN_US
When a fluid is pumped into a cavity in a confined elastic layer, at a critical pressure, destabilizing fingers of fluid invade the elastic solid along its meniscus (Saintyves B. et al., Phys. Rev. Lett., 111 (2013) 047801). These fingers occur without fracture or loss of adhesion and are reversible, disappearing when the pressure is decreased. We develop an asymptotic theory of pressurized highly elastic layers trapped between rigid bodies in both rectilinear and circular geometries, with predictions for the critical fluid pressure for fingering, and the finger wavelength. Our results are in good agreement with recent experimental observations of this elastic interfacial instability in a radial geometry. Our theory also shows that, perhaps surprisingly, this lateral-pressure–driven instability is analogous to a transverse-displacement–driven instability of the elastic layer. We verify these predictions by using non-linear finite-element simulations on the two systems which show that in both cases the fingering transition is first order (sudden) and hence has a region of bistability.; Mathematics

Dynamics of evaporative colloidal patterning

Kaplan, Cihan Nadir; Wu, Ning; Mandre, Shreyas; Aizenberg, Joanna; Mahadevan, Lakshminarayanan
Fonte: AIP Publishing Publicador: AIP Publishing
Tipo: Artigo de Revista Científica
EN_US
Drying suspensions often leave behind complex patterns of particulates, as might be seen in the coffee stains on a table. Here, we consider the dynamics of periodic band or uniform solid film formation on a vertical plate suspended partially in a drying colloidal solution. Direct observations allow us to visualize the dynamics of band and film deposition, where both are made of multiple layers of close packed particles. We further see that there is a transition between banding and filming when the colloidal concentration is varied. A minimal theory of the liquid meniscus motion along the plate reveals the dynamics of the banding and its transition to the filming as a function of the ratio of deposition and evaporation rates. We also provide a complementary multiphase model of colloids dissolved in the liquid, which couples the inhomogeneous evaporation at the evolving meniscus to the fluid and particulate flows and the transition from a dilute suspension to a porous plug. This allows us to determine the concentration dependence of the bandwidth and the deposition rate. Together, our findings allow for the control of drying-induced patterning as a function of the colloidal concentration and evaporation rate.; Mathematics

The Influence of Contexts on Decision-Making

Gal, Ya'akov; Grosz, Barbara J.; Pfeffer, Avi; Shieber, Stuart Merrill; Allain, Alex
Fonte: Harvard University Publicador: Harvard University
Tipo: Research Paper or Report
EN_US
Many environments in which people and computer agents interact involve deploying resources to accomplish tasks and satisfy goals. This paper investigates the way that the contextual setting in which decisions are made affects the behavior of people and the performance of computer agents that interact with people in such environments. It presents experiments that measured negotiation behavior in two types of contextual settings. One provided a task context that made explicit the relationship between goals, tasks and resources, The other provided a completely abstract context in which the payoffs for all decision choices were listed. Results show that people are more helpful, less selfish, and less competitive when making decisions in task contexts than when making them in completely abstract contexts. Further, their overall performance was better in task contexts. A predictive computational model that was trained on data obtained in task contexts outperformed a model that was trained under abstract contexts. These results indicate that modeling the way people make decisions in context is essential for the design of computer agents that will interact with people.; Engineering and Applied Sciences

Neural Decoding Reveals Impaired Face Configural Processing in the Right Fusiform Face Area of Individuals with Developmental Prosopagnosia

Zhang, Jiedong; Liu, Jia; Xu, Yaoda
Fonte: Society for Neuroscience Publicador: Society for Neuroscience
Tipo: Artigo de Revista Científica
EN_US
Most of human daily social interactions rely on the ability to successfully recognize faces. Yet ∼2% of the human population suffers from face blindness without any acquired brain damage [this is also known as developmental prosopagnosia (DP) or congenital prosopagnosia]). Despite the presence of severe behavioral face recognition deficits, surprisingly, a majority of DP individuals exhibit normal face selectivity in the right fusiform face area (FFA), a key brain region involved in face configural processing. This finding, together with evidence showing impairments downstream from the right FFA in DP individuals, has led some to argue that perhaps the right FFA is largely intact in DP individuals. Using fMRI multivoxel pattern analysis, here we report the discovery of a neural impairment in the right FFA of DP individuals that may play a critical role in mediating their face-processing deficits. In seven individuals with DP, we discovered that, despite the right FFA's preference for faces and it showing decoding for the different face parts, it exhibited impaired face configural decoding and did not contain distinct neural response patterns for the intact and the scrambled face configurations. This abnormality was not present throughout the ventral visual cortex...

Device effect on panoramic video+context tasks

Pece, Fabrizio; Tompkin, James; Pfister, Hanspeter; Kautz, Jan; Theobalt, Christian
Fonte: Association for Computing Machinery Publicador: Association for Computing Machinery
Tipo: Artigo de Revista Científica
EN_US
Panoramic imagery is viewed daily by thousands of people, and panoramic video imagery is becoming more common. This imagery is viewed on many different devices with different properties, and the effect of these differences on spatio-temporal task performance is yet untested on these imagery. We adapt a novel panoramic video interface and conduct a user study to discover whether display type affects spatio-temporal reasoning task performance across desktop monitor, tablet, and head-mounted displays. We discover that, in our complex reasoning task, HMDs are as effective as desktop displays even if participants felt less capable, but tablets were less effective than desktop displays even though participants felt just as capable. Our results impact virtual tourism, telepresence, and surveillance applications, and so we state the design implications of our results for panoramic imagery systems.; Engineering and Applied Sciences

Links that speak: The global language network and its association with global fame

Ronen, Shahar; Gonçalves, Bruno; Hu, Kevin Z.; Vespignani, Alessandro; Pinker, Steven; Hidalgo, César A.
Fonte: Proceedings of the National Academy of Sciences Publicador: Proceedings of the National Academy of Sciences
Tipo: Artigo de Revista Científica
EN_US
Languages vary enormously in global importance because of historical, demographic, political, and technological forces. However, beyond simple measures of population and economic power, there has been no rigorous quantitative way to define the global influence of languages. Here we use the structure of the networks connecting multilingual speakers and translated texts, as expressed in book translations, multiple language editions of Wikipedia, and Twitter, to provide a concept of language importance that goes beyond simple economic or demographic measures. We find that the structure of these three global language networks (GLNs) is centered on English as a global hub and around a handful of intermediate hub languages, which include Spanish, German, French, Russian, Portuguese, and Chinese. We validate the measure of a language’s centrality in the three GLNs by showing that it exhibits a strong correlation with two independent measures of the number of famous people born in the countries associated with that language. These results suggest that the position of a language in the GLN contributes to the visibility of its speakers and the global popularity of the cultural content they produce.; Psychology

Adapting to Agents' Personalities in Negotiation

Gal, Ya'akov; Talman, Shavit; Hadad, Meirav; Kraus, Sarit
Fonte: Harvard University Publicador: Harvard University
Tipo: Research Paper or Report
EN_US
To establish cooperative relationships, agents must be willing to engage in helpful behavior and to keep their commitments with agents who reciprocate this behavior. However, in uncertain and dynamic environments, it is difficult to identify the degree of helpfulness of other agents. This paper approaches this problem by characterizing agents’ helpfulness in terms of cooperation and reliability. An agent chooses an action based on other agents’ helpfulness as well as the dependency relationship between the agent and others. This model was evaluated in a negotiation game in which players needed to exchange resources to reach their goals, but did not have information about each other’s resources. Results showed that the model allowed agents to identify and to adapt to others’ varying degree of helpfulness, even while they are constantly changing their strategy. Moreover, agents who vary their cooperativeness and reliability depending on those traits of others, can outperform agents who do not, as well as increase the social welfare of the group.; Engineering and Applied Sciences

Clock quantum Monte Carlo technique: An imaginary-time method for real-time quantum dynamics

McClean, Jarrod Ryan; Aspuru-Guzik, Alan
Fonte: American Physical Society (APS) Publicador: American Physical Society (APS)
Tipo: Artigo de Revista Científica
EN_US
In quantum information theory, there is an explicit mapping between general unitary dynamics and Hermitian ground-state eigenvalue problems known as the Feynman-Kitaev clock Hamiltonian. A prominent family of methods for the study of quantum ground states is quantum Monte Carlo methods, and recently the full configuration interaction quantum Monte Carlo (FCIQMC) method has demonstrated great promise for practical systems. We combine the Feynman-Kitaev clock Hamiltonian with FCIQMC to formulate a technique for the study of quantum dynamics problems. Numerical examples using quantum circuits are provided as well as a technique to further mitigate the sign problem through time-dependent basis rotations. Moreover, this method allows one to combine the parallelism of Monte Carlo techniques with the locality of time to yield an effective parallel-in-time simulation technique.; Chemistry and Chemical Biology

Bayesian network structure learning using quantum annealing

O’Gorman, B.; Babbush, Ryan Joseph; Perdomo-Ortiz, A.; Aspuru-Guzik, Alan; Smelyanskiy, V.
Fonte: Springer Science + Business Media Publicador: Springer Science + Business Media
Tipo: Artigo de Revista Científica
EN_US
We introduce a method for the problem of learning the structure of a Bayesian network using the quantum adiabatic algorithm. We do so by introducing an efficient reformulation of a standard posterior-probability scoring function on graphs as a pseudo-Boolean function, which is equivalent to a system of 2-body Ising spins, as well as suitable penalty terms for enforcing the constraints necessary for the reformulation; our proposed method requires (n2) qubits for n Bayesian network variables. Furthermore, we prove lower bounds on the necessary weighting of these penalty terms. The logical structure resulting from the mapping has the appealing property that it is instance-independent for a given number of Bayesian network variables, as well as being independent of the number of data cases.; Chemistry and Chemical Biology