1,411 research outputs found
Effect of temperature and nutrient concentration on the growth of six species of sooty blotch and flyspeck fungi
We assessed the effects of temperature and nutrient concentration on the growth of commonly occurring members of the sooty blotch and flyspeck (SBFS) complex in the Midwest United States. Radial growth in vitro of two isolates of each of six SBFS species (Dissoconium aciculare, Colletogloeum sp. FG2, Peltaster sp. P2, Sybren sp. CS1, Pseudocercosporella sp. RH1, and Peltaster fructicola) was measured at 10, 15, 20, 25, 30 and 35°C for 7 weeks. Optimal growth for all six species occurred at 20 to 25°C, with slower growth at 10 and 15°C and little to no growth at 30 or 35°C. Differences in growth rate among species were evident at 10, 15, and 35°C. In a separate trial, the same isolates were incubated at 25°C in darkness on cellulose membrane (12–14 kDa) placed on Noble agar that had been amended to obtain concentrations of 0%, 0.01%, 0.05% or 0.5% apple juice. After 3 weeks, colonies were digitally photographed and colony opacity was assessed. The presence and concentration of apple juice strongly impacted colony morphology as evidenced by changes in colony tone, and some species were more sensitive to changes in apple juice concentration than others. These findings are the first published evidence of differences among newly described SBFS species in response to temperature and nutrient concentration Response of tomato rootstocks with the Mi resistance gene to Meloidogyne incognita race 2 at different soil temperature
CFRP Dimensional Stability Investigations for Use on the LISA Mission Telescope
The Laser Interferometer Space Antenna (LISA) is a mission designed to detect low frequency gravitational-waves. In order for LISA to succeed in its goal of direct measurement of gravitational waves, many subsystems must work together to measure the distance between proof masses on adjacent spacecraft. One such subsystem, the telescope, plays a critical role as it is the laser transmission and reception link between spacecraft. Not only must the material that makes up the telescope support structure be strong, stiff and light, but it must have a dimensional stability of better than 1 pm Hz(exp -1/2) at 3 mHz and the distance between the primary and the secondary mirrors must change by less than 2.5 micron over the mission lifetime. CFRP is the current baseline materiaL however, it has not been tested to the pico-meter level as required by the LISA mission. In this paper we present dimensional stability results, outgassing effects occurring in the cavity and discuss its feasibility for use as the telescope spacer for the LISA spacecraft
Dynamical Topology Change in String Theory
Exact string solutions are presented, providing backgrounds where a dynamical
change of topology is occuring. This is induced by the time variation of a
modulus field. Some lessons are drawn concerning the region of validity of
effective theories and how they can be glued together, using stringy
information in the region where the topology changes.Comment: LaTeX file, 17pp., CERN-TH.7219/94, LPTENS-94/11. (Discussions have
been clarified in several places
Reliability and validity of neurobehavioral function on the Psychology Experimental Building Language test battery in young adults
Background. The Psychology Experiment Building Language (PEBL) software consists of over one-hundred computerized tests based on classic and novel cognitive neuropsychology and behavioral neurology measures. Although the PEBL tests are becoming more widely utilized, there is currently very limited information about the psychometric properties of these measures.
Methods. Study I examined inter-relationships among nine PEBL tests including indices of motor-function (Pursuit Rotor and Dexterity), attention (Test of Attentional Vigilance and Time-Wall), working memory (Digit Span Forward), and executive-function (PEBL Trail Making Test, Berg/Wisconsin Card Sorting Test, Iowa Gambling Test, and Mental Rotation) in a normative sample (N = 189, ages 18–22). Study II evaluated test–retest reliability with a two-week interest interval between administrations in a separate sample (N = 79, ages 18–22).
Results. Moderate intra-test, but low inter-test, correlations were observed and ceiling/floor effects were uncommon. Sex differences were identified on the Pursuit Rotor (Cohen’s d = 0.89) and Mental Rotation (d = 0.31) tests. The correlation between the test and retest was high for tests of motor learning (Pursuit Rotor time on target r = .86) and attention (Test of Attentional Vigilance response time r = .79), intermediate for memory (digit span r = .63) but lower for the executive function indices (Wisconsin/Berg Card Sorting Test perseverative errors = .45, Tower of London moves = .15). Significant practice effects were identified on several indices of executive function.
Conclusions. These results are broadly supportive of the reliability and validity of individual PEBL tests in this sample. These findings indicate that the freely downloadable, open-source PEBL battery (http://pebl.sourceforge.net) is a versatile research tool to study individual differences in neurocognitive performance
Elements of String Cosmology
Aspects of string cosmology for critical and non-critical strings are
discussed emphasizing the necessity to account for the dilaton dynamics for a
proper incorporation of ``large - small" duality. This drastically modifies the
intuition one has with Einstein's gravity. For example winding modes, even
though contribute to energy density, oppose expansion and if not annihilated
will stop the expansion. Moreover we find that the radiation dominated era of
the standard cosmology emerges quite naturally in string cosmology. Our
analysis of non-critical string cosmology provides a reinterpretation of the
(universal cover of the) recently studied two dimensional black hole solution
as a conformal realization of cosmological solutions found previously by
Mueller.Comment: 34 page
On orbifolds and free fermion constructions
This work develops the correspondence between orbifolds and free fermion
models. A complete classification is obtained for orbifolds X/G with X the
product of three elliptic curves and G an abelian extension of a group (Z_2)^2
of twists acting on X. Each such quotient X/G is shown to give a geometric
interpretation to an appropriate free fermion model, including the geometric
NAHE+ model. However, the semi-realistic NAHE free fermion model is proved to
be non-geometric: its Hodge numbers are not reproduced by any orbifold X/G. In
particular cases it is shown that X/G can agree with some Borcea-Voisin
threefolds, an orbifold limit of the Schoen threefold, and several further
orbifolds thereof. This yields free fermion models with geometric
interpretations on such special threefolds.Comment: 46 pages; typos corrected and references adde
Nanostructure of cellulose microfibrils in spruce wood
The structure of cellulose microfibrils in wood is not known in detail, despite the abundance of cellulose in woody biomass and its importance for biology, energy, and engineering. The structure of the microfibrils of spruce wood cellulose was investigated using a range of spectroscopic methods coupled to small-angle neutron and wide-angle X-ray scattering. The scattering data were consistent with 24-chain microfibrils and favored a “rectangular” model with both hydrophobic and hydrophilic surfaces exposed. Disorder in chain packing and hydrogen bonding was shown to increase outwards from the microfibril center. The extent of disorder blurred the distinction between the I alpha and I beta allomorphs. Chains at the surface were distinct in conformation, with high levels of conformational disorder at C-6, less intramolecular hydrogen bonding and more outward-directed hydrogen bonding. Axial disorder could be explained in terms of twisting of the microfibrils, with implications for their biosynthesis
Understanding gendered influences on women's reproductive health in Pakistan: Moving beyond the autonomy paradigm
Recent research and policy discourse commonly view the limited autonomy of women in developing countries as a key barrier to improvements in their reproductive health. Rarely, however, is the notion of women's autonomy interrogated for its conceptual adequacy or usefulness for understanding the determinants of women's reproductive health, effective policy formulation or program design. Using ethnographic data from 2001, including social mapping exercises, observation of daily life, interviews, case studies and focus group discussions, this paper draws attention to the incongruities between the concept of women's autonomy and the gendered social, cultural, economic and political realities of women's lives in rural Punjab, Pakistan. These inadequacies include: the concept's undue emphasis on women's independent, autonomous action; a lack of attention to men and masculinities; a disregard for the multi-sited constitution of gender relations and gender inequality; an erroneous assumption that uptake of reproductive health services is an indicator of autonomy; and a failure to explore the interplay of other axes of disadvantage such as caste, class or socio-economic position. This paper calls for alternative, more nuanced, theoretical approaches for conceptualizing gender inequalities in order to enhance our understanding of women's reproductive wellbeing in Pakistan. The extent to which our arguments may be relevant to the wider South Asian context, and women's lives in other parts of the world, is also discussed
Dynamical Topology Change, Compactification and Waves in String Cosmology
Exact string solutions are presented, where moduli fields are varying with
time. They provide examples where a dynamical change of the topology of space
is occurring. Some other solutions give cosmological examples where some
dimensions are compactified dynamically or simulate pre-big bang type
scenarios. Some lessons are drawn concerning the region of validity of
effective theories and how they can be glued together, using stringy
information in the region where the geometry and topology are not well defined
from the low energy point of view. Other time dependent solutions are presented
where a hierarchy of scales is absent. Such solutions have dynamics which is
qualitatively different and resemble plane gravitational waves. (Talk given at
the Trieste Spring School and Workshop, 1994.)Comment: 29pp. LateX, no figures
Very high energy observations of the BL Lac objects 3C 66A and OJ 287
Using the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE), we
have observed the BL Lac objects 3C 66A and OJ 287. These are members of the
class of low-frequency-peaked BL Lac objects (LBLs) and are two of the three
LBLs predicted by Costamante and Ghisellini to be potential sources of very
high energy (>100 GeV) gamma-ray emission. The third candidate, BL Lacertae,
has recently been detected by the MAGIC collaboration. Our observations have
not produced detections; we calculate a 99% CL upper limit of flux from 3C 66A
of 0.15 Crab flux units and from OJ 287 our limit is 0.52 Crab. These limits
assume a Crab-like energy spectrum with an effective energy threshold of 185
GeV.Comment: 24 pages, 15 figures, Accepted for publication in Astroparticle
Physic
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