225 research outputs found

    Surrounding the Founder: Examining the Hidden Figures of Entrepreneurship

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    Founders, as the initial architects of their organizations, receive a great deal of interest and attention in entrepreneurship research. Yet, there is still much we do not know regarding the constellation of other people surrounding the founder and supporting them throughout the entrepreneurial process. This dissertation includes three essays focused on addressing this neglected area of research, and examines various “hidden figures” which are rarely observed in entrepreneurial data and who seldom receive the same recognition as founders, but who still play a fundamental role in venture success. In the first essay, I uncover and introduce the concept of co-creators, or individuals and entities who hold no ownership stake in the business but still make a distinctive contribution in the earliest stages of founding a new business. The second essay examines the role of a second-in-command, or an individual who the founder hires later in the firm’s life cycle to help manage the increasingly complex business. The third and final essay explores coworking communities, an increasingly popular phenomenon in which communities of founders interact with, learn from, and help one another. As a whole, these essays contribute by highlighting how the immediate context around founders can play a major role in determining venture success.Doctor of Philosoph

    Leaf: Modularity for Temporary Sharing in Separation Logic (Extended Version)

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    In concurrent verification, separation logic provides a strong story for handling both resources that are owned exclusively and resources that are shared persistently (i.e., forever). However, the situation is more complicated for temporarily shared state, where state might be shared and then later reclaimed as exclusive. We believe that a framework for temporarily-shared state should meet two key goals not adequately met by existing techniques. One, it should allow and encourage users to verify new sharing strategies. Two, it should provide an abstraction where users manipulate shared state in a way agnostic to the means with which it is shared. We present Leaf, a library in the Iris separation logic which accomplishes both of these goals by introducing a novel operator, which we call guarding, that allows one proposition to represent a shared version of another. We demonstrate that Leaf meets these two goals through a modular case study: we verify a reader-writer lock that supports shared state, and a hash table built on top of it that uses shared state

    Effect of using an exercise and nutrition secure email message on the implementation of health promotion in a large health care system

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    Background and Program: Secure email messaging is used to provide timely communication between healthcare providers and patients with medical information and education. There have been increasing rates of overweight and obesity among military healthcare patients. To address this issue, we utilized a secure email messaging system that is primarily used for medication refills. This commentary demonstrates the extent to which the message was viewed and how much the message was liked. Preliminary Results: Of the 16,020 individuals emailed, 7,011 participants (43.8%) opened the email, and 1,023 patients (14.6% of those who opened it) completed the survey. Satisfaction rate for the health promotion message was 77.2%. Participants reported an intent to eat more fruit and vegetables (49.6%), decrease portion sizes (38.8%), and increase physical activity (51.1%), while 33.6% reported having no intent to change. Conclusion: The majority were satisfied with the health promotion message. This email method enables a single provider to have increased contact with patients. It is unknown if this message reached higher risk or harder to reach participants, a patient subset that could benefit most from this type of communication. This study is unique in that to our knowledge it is the first one to use secure email messaging in the military healthcare system for health promotion

    Verus: Verifying Rust Programs using Linear Ghost Types (extended version)

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    The Rust programming language provides a powerful type system that checks linearity and borrowing, allowing code to safely manipulate memory without garbage collection and making Rust ideal for developing low-level, high-assurance systems. For such systems, formal verification can be useful to prove functional correctness properties beyond type safety. This paper presents Verus, an SMT-based tool for formally verifying Rust programs. With Verus, programmers express proofs and specifications using the Rust language, allowing proofs to take advantage of Rust's linear types and borrow checking. We show how this allows proofs to manipulate linearly typed permissions that let Rust code safely manipulate memory, pointers, and concurrent resources. Verus organizes proofs and specifications using a novel mode system that distinguishes specifications, which are not checked for linearity and borrowing, from executable code and proofs, which are checked for linearity and borrowing. We formalize Verus' linearity, borrowing, and modes in a small lambda calculus, for which we prove type safety and termination of specifications and proofs. We demonstrate Verus on a series of examples, including pointer-manipulating code (an xor-based doubly linked list), code with interior mutability, and concurrent code

    Ungrading General Education: Preliminary Results from a Pilot Study

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    A group of faculty members representing more than 20 courses listed in the Eastern Kentucky University General Education curriculum participated in a pilot program to test and measure the effectiveness of “ungraded” pedagogy. “Ungrading,” as defined by the group, can be any conscious effort to move student emphasis away from grades and onto learning. Given this definition, ungrading took many forms in the pilot: gradeless classrooms, grading contracts, and greater choice of assignments by students, to name a few. At the end of the semester, quantitative and qualitative data was gathered from student course evaluations; DFW and retention rates were considered; and focus groups comprised of students in ungraded classes were convened. This piece provides preliminary results from the pilot and in an effort to begin a larger conversation about the widespread adoption of ungraded pedagogies

    A minimal binding footprint on CD1d-glycolipid is a basis for selection of the unique human NKT TCR

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    Although it has been established how CD1 binds a variety of lipid antigens (Ag), data are only now emerging that show how αÎČ T cell receptors (TCRs) interact with CD1-Ag. Using the structure of the human semiinvariant NKT TCR–CD1d–α-galactosylceramide (α-GalCer) complex as a guide, we undertook an alanine scanning mutagenesis approach to define the energetic basis of this interaction between the NKT TCR and CD1d. Moreover, we explored how analogues of α-GalCer affected this interaction. The data revealed that an identical energetic footprint underpinned the human and mouse NKT TCR–CD1d–α-GalCer cross-reactivity. Some, but not all, of the contact residues within the Jα18-encoded invariant CDR3α loop and VÎČ11-encoded CDR2ÎČ loop were critical for recognizing CD1d. The residues within the Vα24-encoded CDR1α and CDR3α loops that contacted the glycolipid Ag played a smaller energetic role compared with the NKT TCR residues that contacted CD1d. Collectively, our data reveal that the region distant to the protruding Ag and directly above the Fâ€Č pocket of CD1d was the principal factor in the interaction with the NKT TCR. Accordingly, although the structural footprint at the NKT TCR–CD1d–α-GalCer is small, the energetic footprint is smaller still, and reveals the minimal requirements for CD1d restriction

    Kepler-68: Three Planets, One With a Density Between That of Earth and Ice Giants

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    NASA's Kepler Mission has revealed two transiting planets orbiting Kepler-68. Follow-up Doppler measurements have established the mass of the innermost planet and revealed a third jovian-mass planet orbiting beyond the two transiting planets. Kepler-68b, in a 5.4 day orbit has mass 8.3 +/- 2.3 Earth, radius 2.31 +/- 0.07 Earth radii, and a density of 3.32 +/- 0.92 (cgs), giving Kepler-68b a density intermediate between that of the ice giants and Earth. Kepler-68c is Earth-sized with a radius of 0.953 Earth and transits on a 9.6 day orbit; validation of Kepler-68c posed unique challenges. Kepler-68d has an orbital period of 580 +/- 15 days and minimum mass of Msin(i) = 0.947 Jupiter. Power spectra of the Kepler photometry at 1-minute cadence exhibit a rich and strong set of asteroseismic pulsation modes enabling detailed analysis of the stellar interior. Spectroscopy of the star coupled with asteroseismic modeling of the multiple pulsation modes yield precise measurements of stellar properties, notably Teff = 5793 +/- 74 K, M = 1.079 +/- 0.051 Msun, R = 1.243 +/- 0.019 Rsun, and density 0.7903 +/- 0.0054 (cgs), all measured with fractional uncertainties of only a few percent. Models of Kepler-68b suggest it is likely composed of rock and water, or has a H and He envelope to yield its density of about 3 (cgs).Comment: 32 pages, 13 figures, Accepted to Ap

    Enhancing face validity of mouse models of Alzheimer\u27s disease with natural genetic variation.

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    Classical laboratory strains show limited genetic diversity and do not harness natural genetic variation. Mouse models relevant to Alzheimer\u27s disease (AD) have largely been developed using these classical laboratory strains, such as C57BL/6J (B6), and this has likely contributed to the failure of translation of findings from mice to the clinic. Therefore, here we test the potential for natural genetic variation to enhance the translatability of AD mouse models. Two widely used AD-relevant transgenes, APPswe and PS1de9 (APP/PS1), were backcrossed from B6 to three wild-derived strains CAST/EiJ, WSB/EiJ, PWK/PhJ, representative of three Mus musculus subspecies. These new AD strains were characterized using metabolic, functional, neuropathological and transcriptional assays. Strain-, sex- and genotype-specific differences were observed in cognitive ability, neurodegeneration, plaque load, cerebrovascular health and cerebral amyloid angiopathy. Analyses of brain transcriptional data showed strain was the greatest driver of variation. We identified significant variation in myeloid cell numbers in wild type mice of different strains as well as significant differences in plaque-associated myeloid responses in APP/PS1 mice between the strains. Collectively, these data support the use of wild-derived strains to better model the complexity of human AD
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