9,287 research outputs found
Hominin evolution was caused by introgression from Gorilla
The discovery of Paranthropus deyiremeda in 3.3-3.5 million year old fossil
sites in Afar, together with 30% of the gorilla genome showing lineage sorting
between humans and chimpanzees, and a NUMT ("nuclear mitochondrial DNA
segment") on chromosome 5 that is shared by both gorillas, humans and
chimpanzees, and shown to have diverged at the time of the Pan-Homo split
rather than the Gorilla/Pan-Homo split, provides conclusive evidence that
introgression from the gorilla lineage caused the Pan-Homo split, and the
speciation of both the Australopithecus lineage and the Paranthropus lineage.Comment: arXiv admin note: text overlap with arXiv:1808.0630
Sustainable Value Proposition Design in a Product-Service System
Many companies have started to add services to their tangible products in order to defend themselves from increased competition from low-cost economies. Research regarding the transition towards product-service systems (PSS) and how the PSS providers' business models are affected exists, but there is a lack of research regarding how the suppliers to the PSS providers are affected by the transition towards PSS. Therefore, this thesis studies the situation for a supplier/partner to an OEM that has changed their business model to a PSS providing one. As the first step in a development of a new business model aims this thesis to provide guidelines for how to set up value propositions suitable for a supplier/partner in this new environment. When technologically complex products, such as aircraft engines, are provided through PSS offerings it is hard to translate customer needs into quality parameters, which makes it hard to sustain the value to customer over time. Therefore, how to keep the value offering sustainable over time is also investigated in this thesis. The aim of this study was to investigate how a sustainable value proposition can be designed for a product and technology supplier/partner to an OEM that offers PSS solutions. The research has been performed through studying relevant literature and collecting empirical data from a case company through semi-structured interviews and a workshop. The case company in this research is Volvo Aero Corporation (VAC). The empirical findings show that VAC wants to offer product-service bundled solution, which fit the whole spectra of PSS value propositions, to their partners/customers. To be able to deliver these different types of product-service bundled solutions different value propositions that suit the different kinds of PSS offerings are needed. Requirements that must be fulfilled to be able to offer and deliver the different types of value propositions exist in terms of securing sufficient information access, aligning the incentives of all actors involved and achieving an internal consensus of what is delivered
Calculation of rotor impedance for use in design analysis of helicopter airframe vibrations
Excessive vibration is one of the most prevalent technical obstacles encountered in the development of new rotorcraft. The inability to predict these vibrations is primarily due to deficiencies in analysis and simulation tools. The Langley Rotorcraft Structural Dynamics Program was instituted in 1984 to meet long term industry needs in the area of rotorcraft vibration prediction. As a part of the Langley program, this research endeavors to develop an efficient means of coupling the rotor to the airframe for preliminary design analysis of helicopter airframe vibrations. The main effort was to modify the existing computer program for modeling the dynamic and aerodynamic behavior of rotorcraft called DYSCO (DYnamic System COupler) to calculate the rotor impedance. DYSCO was recently developed for the U.S. Army and has proven to be adaptable for the inclusion of new solution methods. The solution procedure developed to use DYSCO for the calculation of rotor impedance is presented. Verification of the procedure by comparison with a known solution for a simple wind turbine model is about 75 percent completed, and initial results are encouraging. After the wind turbine impedance is confirmed, the verification effort will continue by comparison to solutions of a more sophisticated rotorcraft model. Future work includes determination of the sensitivity of the rotorcraft airframe vibrations to helicopter flight conditions and rotor modeling assumptions. When completed, this research will ascertain the feasibility and efficiency of the impedance matching method of rotor-airframe coupling for use in the analysis of airframe vibrations during the preliminary rotorcraft design process
The design and development of a spacecraft appendage tie down mechanism
The design and evolution is described of a spacecraft Appendage Tie Down Mechanism (ATDM). Particular emphasis is paid to the mechanical aspects of using dry lubricants to increase the efficiency of acme threads and worm gearing. The ATDM consists of five major components. These are a dc torque motor, a worm gear speed reducer, the tension bolt (or T-bolt), nut capture and centering jaws and the capture nut. In addition, there are several minor components such as limit switch assemblies and an antibackdrive mechanism which couples the drive motor to the worm shaft. A development model of the ATDM in various configurations was under test for some time. In its latest version, it has successfully completed thermal vacuum testing, vibration testing, and extended life testing
The Jurisdictional Difficulties of Defining Charter-School Teachers Unions Under Current Labor Law
As charter schools have flourished in form, they have also evolved in variety: parents can send their children to a trilingual immersion school or a school whose classes meet entirely online. The same flexibility that charters offer as an alternative to traditional public schools also makes them difficult to classify for purposes of labor law. When charter-school teachers form a union, it is not clear why the National Labor Relations Board (NLRB), and not a state labor analogue, should have jurisdiction over a charter-school labor dispute. And yet, the NLRB has asserted jurisdiction in most charter-school cases. This Note examines the NLRB’s test for determining whether the broad protections of the National Labor Relations Act apply to a group of workers in the context of charter-school employees. It proposes a more robust test for differentiating between charter schools for purposes of the Act, and it applies the test to two charter schools
A method for modeling bias in a person's estimates of likelihoods of events
It is of practical importance in decision situations involving risk to train individuals to transform uncertainties into subjective probability estimates that are both accurate and unbiased. We have found that in decision situations involving risk, people often introduce subjective bias in their estimation of the likelihoods of events depending on whether the possible outcomes are perceived as being good or bad. Until now, however, the successful measurement of individual differences in the magnitude of such biases has not been attempted. In this paper we illustrate a modification of a procedure originally outlined by Davidson, Suppes, and Siegel (3) to allow for a quantitatively-based methodology for simultaneously estimating an individual's subjective utility and subjective probability functions. The procedure is now an interactive computer-based algorithm, DSS, that allows for the measurement of biases in probability estimation by obtaining independent measures of two subjective probability functions (S+ and S-) for winning (i.e., good outcomes) and for losing (i.e., bad outcomes) respectively for each individual, and for different experimental conditions within individuals. The algorithm and some recent empirical data are described
Titian's Christ with the Coin: Recovering the spiritual currency of numismatics in Renaissance Ferrara
Titian painted Christ with the Coin for Alfonso d'Este around 1516. The painting served as the cover piece for a collection of ancient coins and has been read as a commentary on politics and taxation. Instead, this article reveals how the painting reconfigured Alfonso's interaction with ancient coins, transforming the everyday activity of the collector into an occasion of spiritual reformation. Reading numismatic antiquarianism against the exegetical tradition that accrued around the Gospel pericope (Matthew 22:21) reveals the painting as the nexus of two regimes of virtue - one Christian, one classical - both of which turn upon coins as manifold objects
Effects of increased levels of androgens on voice and vocal folds in women with congenital adrenal hyperplasia and female-to-male transsexual persons
Voice virilization in women may occur due to increased levels of androgens. Women with
congenital adrenal hyperplasia (CAH) are at risk for voice virilization due to an enzyme
deficiency that causes increased production of androgens and lack of cortisol. Female-to-male
transsexual persons, trans men, are treated with testosterone, with virilization of the voice as a
desired outcome. The overall aim of the project was to provide new knowledge on how
female voice and vocal folds are affected by endogenous and exogenous androgen exposure,
and the consequences virilization of the voice may have in a patient’s life.
Study I: Thirty-eight women with CAH and 24 age-matched controls participated. Their
voices were recorded and acoustically and perceptually analyzed. Theyanswered questions
about subjective voice problems. Endocrine datawere obtained from medical journals. The
results showed that women with CAH spoke with significantly lower mean fundamental
frequency (F0), had darker voice quality, and rated higher on the statement “my voice is a
problem in my daily life” than the controls. Voice virilization was associated with late
diagnosis or problems with glucocorticoid medication, but not with severity of mutation.
Proper treatment with glucocorticoids is important to avoid long periods of increased
androgen levels to prevent irreversible voice virilization.
Study II: Forty-two women with CAH and 43 age-matched controls filled out the Voice
Handicap Index (VHI) and answered questions about voice function related to virilization.
Endocrine data were obtained from medical journals. Women with CAH scored significantly
higher than the controls on VHI when the results were divided into groups by voice handicap:
none/mild, moderate, and severe. A virilized voice in women with CAH correlated with less
voice satisfaction. Seven percent of the women with CAH had voice problems related to
voice virilization. Voice virilization was associatedwith long periods of under-treatment with
glucocorticoids and higher bone mineral density, confirming results and conclusions from
study I. It is recommended that women with CAH who experience voice problems are
referred for voice assessment.
Study III: Four women with CAH and virilized voices, and 5 female and 4 male controls
participated. A procedure for magnetic resonance imaging of the vocal folds was developed.
The results showed that the cross-sectional area of the thyroarytenoid (TA) muscle was larger
in women with virilized voices than in female controls, and smaller than in males. The larger
TA area correlated with lower F0 values obtained from acoustic analysisof habitual speech
range profiles. Thus, the anatomical explanation for voice virilization may be a larger crosssectional area of the TA muscle, suggesting androgen receptors in the vocal folds. These
findings need to be confirmed in a larger study.
Study IV: Fifty trans men participated in a longitudinal study. Voice assessments, performed
before testosterone treatment started and regularly up to 24 months, included audiorecordings of speech and voice range profiles and self-ratings of voice function. A significant
lowering of mean F0 was found after 3 months, after 6 months, and up to 12 months, when
group data were congruent with reference data for males. No correlations were found
between levels of testosterone, EVF, Hb, SHBG or LH, and F0 values. Lower F0 values
correlated with greater satisfaction with the voice. A quarter of the participants had received
voice therapy for problems associated with virilization, such as vocal fatigue or unstable
voice. Voice assessment during testosterone treatment is important to detect the potentially
large subgroup of trans men that needs voice therapy
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