14,024 research outputs found
The art of being human : a project for general philosophy of science
Throughout the medieval and modern periods, in various sacred and secular guises, the unification of all forms of knowledge under the rubric of ‘science’ has been taken as the prerogative of humanity as a species. However, as our sense of species privilege has been called increasingly into question, so too has the very salience of ‘humanity’ and ‘science’ as general categories, let alone ones that might bear some essential relationship to each other. After showing how the ascendant Stanford School in the philosophy of science has contributed to this joint demystification of ‘humanity’ and ‘science’, I proceed on a more positive note to a conceptual framework for making sense of science as the art of being human. My understanding of ‘science’ is indebted to the red thread that runs from Christian theology through the Scientific Revolution and Enlightenment to the Humboldtian revival of the university as the site for the synthesis of knowledge as the culmination of self-development. Especially salient to this idea is science‘s epistemic capacity to manage modality (i.e. to determine the conditions under which possibilities can be actualised) and its political capacity to organize humanity into projects of universal concern. However, the challenge facing such an ideal in the twentyfirst century is that the predicate ‘human’ may be projected in three quite distinct ways, governed by what I call ‘ecological’, ‘biomedical’ and ‘cybernetic’ interests. Which one of these future humanities would claim today’s humans as proper ancestors and could these futures co-habit the same world thus become two important questions that general philosophy of science will need to address in the coming years
A Connection between Submillimeter Continuum Flux and Separation in Young Binaries
We have made sensitive 800-micron continuum observations of low-mass,
pre-main sequence (PMS) binary stars with projected separations less than 25 AU
in Taurus-Auriga to study disks in the young binary environment. We did not
detect any of the observed binaries, with typical 3-sigma upper limits of about
30 mJy. Combining our observations with previous 1300-micron observations of
PMS Taurus binaries by Beckwith et al. (1990) and others, we find that the
submillimeter fluxes from binaries with projected separations between 1 AU and
50 AU are significantly lower than fluxes from binaries with projected
separations > 50 AU. The submillimeter fluxes from the wider binaries are
consistent with those of PMS single stars. This may indicate lower disk surface
densities and masses in the close binaries. Alternatively, dynamical clearing
of gaps by close binaries is marginally sufficient to lower their submillimeter
fluxes to the observed levels, even without reduction of surface densities
elsewhere in the disks.Comment: 12 pages, uuencoded compressed postscript with figures; Wisconsin
Astrophysics 526; to appear in ApJ Letter
Domestication as innovation : the entanglement of techniques, technology and chance in the domestication of cereal crops
The origins of agriculture involved pathways of domestication in which human behaviours and plant genetic adaptations were entangled. These changes resulted in consequences that were unintended at the start of the process. This paper highlights some of the key innovations in human behaviours, such as soil preparation, harvesting and threshing, and how these were coupled with genetic ‘innovations’ within plant populations. We identify a number of ‘traps’ for early cultivators, including the needs for extra labour expenditure on crop-processing and soil fertility maintenance, but also linked gains in terms of potential crop yields. Compilations of quantitative data across a few different crops for the traits of nonshattering and seed size are discussed in terms of the apparently slow process of domestication, and parallels and differences between different regional pathways are identified. We highlight the need to bridge the gap between a Neolithic archaeobotanical focus on domestication and a focus of later periods on crop-processing activities and labour organization. In addition, archaeobotanical data provide a basis for rethinking previous assumptions about how plant genetic data should be related to the origins of agriculture and we contrast two alternative hypotheses: gradual evolution with low selection pressure versus metastable equilibrium that prolonged the persistence of ‘semi-domesticated’ populations. Our revised understanding of the innovations involved in plant domestication highlight the need for new approaches to collecting, modelling and integrating genetic data and archaeobotanical evidence
Microbotanical signatures of kreb: differentiating inflorescence phytoliths from northern African wild grasses
Throughout northern Africa, evidence for an intensification of wild grass gathering is reflected in Holocene archaeological contexts. However, both the recovery of macrobotanical assemblages and the specificity of their taxonomic classification are heavily influenced by food processing and post-depositional conditions. In contrast, inflorescence phytoliths provide high levels of taxonomic specificity and preserve well in most archaeological contexts. This study analyses the in situ morphology of inflorescence phytoliths from modern specimens of nine wild C4 grass species commonly observed in ethnographic studies and recovered in seed assemblages from archaeological contexts across northern Africa. Morphological differences in Interdigitate phytoliths within the fertile florets of six Paniceae species enabled differentiation between them. The morphological parameters established in this study provide an additional resource for archaeological and palaeoecological analyses using phytoliths, which demonstrates the effectiveness of applying this method to African wild grass species.Introduction Materials and methods - Selected species - Sample preparation and analysis - Phytolith nomenclature Results Variations in phytolith occurrence between inflorescence bracts - Glumes - Lemmas - Paleas Classification of Interdigitate morphotypes Discussion Conclusion
Cascaded Photoenhancement: Implications for Photonic Chemical and Biological Sensors
Our analysis shows that coupling of gold nanoparticles to microspheres will evoke a cascading effect from the respective photoenhancement mechanisms. We refer to this amplification process as cascaded photoenhancement, and the resulting cavity amplification of surface-enhanced Raman scattering (SERS) and fluorescence as CASERS and CAF, respectively. Calculations, based on modal analysis of scattering and absorption by compound spheres, presented herein indicate that the absorption cross sections of metal nanoparticles immobilized onto dielectric microspheres can be greatly enhanced by cavity resonances in the microspheres without significant degradation of the resonators. Gain factors associated with CSP of 10(exp 3) - 10(exp 4) are predicted for realistic experimental conditions using homogenous microspheres. Cascaded surface photoenhancement thus has the potential of dramatically increasing the sensitivities of fluorescence and vibrational spectroscopies
Neutrino-Neutrino Scattering and Matter-Enhanced Neutrino Flavor Transformation in Supernovae
We examine matter-enhanced neutrino flavor transformation
() in the region above the neutrino
sphere in Type II supernovae. Our treatment explicitly includes contributions
to the neutrino-propagation Hamiltonian from neutrino-neutrino forward
scattering. A proper inclusion of these contributions shows that they have a
completely negligible effect on the range of - vacuum
mass-squared difference, , and vacuum mixing angle, , or
equivalently , required for enhanced supernova shock re-heating.
When neutrino background effects are included, we find that -process
nucleosynthesis from neutrino-heated supernova ejecta remains a sensitive probe
of the mixing between a light and a with a
cosmologically significant mass. Neutrino-neutrino scattering contributions are
found to have a generally small effect on the
parameter region probed by -process nucleosynthesis. We point out that the
nonlinear effects of the neutrino background extend the range of sensitivity of
-process nucleosynthesis to smaller values of .Comment: 38 pages, tex, DOE/ER/40561-150-INT94-00-6
The measurement of low pay in the UK labour force survey
Consideration of the National Minimum Wage requires estimates of the distribution of hourly pay. The UK Labour Force Survey (LFS) is a key source of such estimates. The approach most frequently adopted by researchers has been to measure hourly earnings from several questions on pay and hours. The Office for National Statistics is now applying a new approach, based on an alternative more direct measurement introduced in March 1999. These two measures do not produce identical values and this paper investigates sources of discrepancies and concludes that the new variable is more accurate. The difficulty with using the new variable is that it is only available on a subset of respondents. An approach is developed in which missing values of the new variable are replaced by imputed values. The assumptions underlying this imputation approach and results of applying it to LFS data are presented. The relation to weighting approaches is also discussed
An Iterative and Toolchain-Based Approach to Automate Scanning and Mapping Computer Networks
As today's organizational computer networks are ever evolving and becoming
more and more complex, finding potential vulnerabilities and conducting
security audits has become a crucial element in securing these networks. The
first step in auditing a network is reconnaissance by mapping it to get a
comprehensive overview over its structure. The growing complexity, however,
makes this task increasingly effortful, even more as mapping (instead of plain
scanning), presently, still involves a lot of manual work. Therefore, the
concept proposed in this paper automates the scanning and mapping of unknown
and non-cooperative computer networks in order to find security weaknesses or
verify access controls. It further helps to conduct audits by allowing
comparing documented with actual networks and finding unauthorized network
devices, as well as evaluating access control methods by conducting delta
scans. It uses a novel approach of augmenting data from iteratively chained
existing scanning tools with context, using genuine analytics modules to allow
assessing a network's topology instead of just generating a list of scanned
devices. It further contains a visualization model that provides a clear, lucid
topology map and a special graph for comparative analysis. The goal is to
provide maximum insight with a minimum of a priori knowledge.Comment: 7 pages, 6 figure
Simulation of primordial object formation
We have included the chemical rate network responsible for the formation of
molecular Hydrogen in the N-body hydrodynamic code, Hydra, in order to study
the formation of the first cosmological at redshifts between 10 and 50. We have
tested our implementation of the chemical and cooling processes by comparing
N-body top hat simulations with theoretical predictions from a semi-analytic
model and found them to be in good agreement. We find that post-virialization
properties are insensitive to the initial abundance of molecular hydrogen. Our
main objective was to determine the minimum mass () of perturbations
that could become self gravitating (a prerequisite for star formation), and the
redshift at which this occurred. We have developed a robust indicator for
detecting the presence of a self-gravitating cloud in our simulations and find
that we can do so with a baryonic particle mass-resolution of 40 solar masses.
We have performed cosmological simulations of primordial objects and find that
the object's mass and redshift at which they become self gravitating agree well
with the results from the top hat simulations. Once a critical
molecular hydrogen fractional abundance of about 0.0005 has formed in an
object, the cooling time drops below the dynamical time at the centre of the
cloud and the gas free falls in the dark matter potential wells, becoming self
gravitating a dynamical time later.Comment: 45 pages, 17 figures, submitted to Ap
Long-term trends in particulate matter from wood burning in the United Kingdom: Dependence on weather and social factors
Particulate matter from wood burning emissions (Cwood) was quantified at five locations in the United Kingdom (UK), comprising three rural and two urban sites between 2009 and 2021. The aethalometer method was used. Mean winter Cwood concentrations ranged from 0.26 μg m-3 (in rural Scotland) to 1.30 μg m-3 (London), which represented on average 4% (in rural environments) and 5% (urban) of PM10 concentrations; and 8% of PM2.5. Concentrations were greatest in the evenings in winter months, with larger evening concentrations in the weekends at the urban sites. Random-forest (RF) machine learning regression models were used to reconstruct Cwood concentrations using both meteorological and temporal explanatory variables at each site. The partial dependency plots indicated that temperature and wind speed were the meteorological variables explaining the greatest variability in Cwood, with larger concentrations during cold and calm conditions. Peaks of Cwood concentrations took place during and after events that are celebrated with bonfires. These were Guy Fawkes events in the urban areas and on New Year's Day at the rural sites; the later probably related to long-range transport. Time series were built using the RF. Having removed weather influences, long-term trends of Cwood were estimated using the Theil Sen method. Trends for 2015-2021 were downward at three of the locations (London, Glasgow and rural Scotland), with rates ranging from -5.5% year-1 to -2.5% year-1. The replacement of old fireplaces with lower emission wood stoves might explain the decrease in Cwood especially at the urban sites The two rural sites in England observed positive trends for the same period but this was not statistically significant
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