348 research outputs found
The Effects of Pigment and Adhesive on Strength Development in Coated Paper
The application of a coating is expected to increase basepaper strength by a mechanism of adhesive penetration and enhancement of interfiber bonding similar to the strength improvements seen with size press treatments. It was felt, therefore, that the amount of strength improvement could be used as a measure of binder migration into the sheet. Pigmented and nonpigmented coatings were applied to a basepaper with a keegan coater. The pigment used was a predispersed clay, and the adhesive was a low viscosity polyvinyl alcohol. Both types of coatings produced statistically significant strength increases (up to 15% increase in tensile strength) over the levels of adhesive application. However, the amount of adhesive applied, and could not be used to measure binder migration. This study did, however, lead to a new theory to explain the strength improvement due to coating film formation and PVA-clay bridging
Hunting for sustainability : lion conservation in Selous Game Reserve, Tanzania
The Selous Game Reserve (SGR) in Tanzania, at 47,500kmÂČ is large, and is reliant on trophy hunting by tourists for revenue. The study of lions (Panthera leo) in SGR therefore offers the opportunity to investigate sustainable resource utilization as a tool in conservation. Using a combination of methods the lion population of SGR was estimated at 4300 (range 1700-6900), representing Africaâs largest lion population. The north and west of the reserve had higher densities of lions. The population of an 800kmÂČ intensively studied area in northern SGR at Matambwe has remained relatively constant since 1997, but the adult sex ratio has decreased from roughly 1 male : 1.3 female in 1997 to 1 male : 3 females in 2009.
The ecology of the Matambwe lions of northern SGR was studied from 2006-2009, and lion distribution in this area was best explained by lean or dry season prey biomass. Two different methods were used to work out the lion carrying capacity. Environmental and anthropogenic factors that best explained lion distribution in northern SGR were distance to the reserve boundary and villages and soil type of an area.
The SGR is divided into 43 hunting blocks which are leased by companies. The management of trophy hunting in SGR and Tanzania is driven by a quota system set through educated guesswork by the government for each hunting block. Based on a study of lion hunting off-take, a reduction of the lion hunting quota to one lion 1000kmâ»ÂČ for SGR is suggested. Attempts to estimate the lion population per hunting block and then suggest a quota based on a figure below ten percent of the adult male population also leads to a reduction in the hunting quota.
The impact that length of block tenure by companies has on trophy hunting of lions in SGR was investigated. The blocks in SGR with the most lions shot 1000kmâ»ÂČ annually were the blocks that experienced the steepest declines in trophy offtake from 1996 to 2008 and tended to be under short-term tenure. These short-term blocks, however, brought in the greatest amount of revenue for the government.
The important factor in the long-term survival of the lion will be human attitudes and actions. Detailed interviews with key informants and general questionnaires highlighted many different possible ways to reform lion trophy hunting in SGR. Many of the necessary reforms are not new, yet there seems to be reluctance to embrace these reforms
Creepiness Creeps In: Uncanny Valley Feelings Are Acquired in Childhood
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/150519/1/cdev12999_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150519/2/cdev12999.pd
Infants' use of social partnerships to predict behavior
The experiences of social partners are important motivators of social action. Can infants use such experiences to make predictions about how social agents will behave? Sixteenâmonthâold infants were introduced to two social pairs. Initial events established withinâpair cooperation as well as betweenâpair conflict involving an individual from each pair. Following these events, infants looked longer when betweenâpair members who had never previously interacted now cooperated â instead of conflicted â with each other. Thus, infants tracked the thirdâperson allegiances and inferred that the conflict would generalize across social partnerships. These findings demonstrate a critical feature of early social cognition and promote needed, further research on the role of social allegiances in social cognition across development.The experiences of social partners are important motivators of social action. Can infants use such experiences to make predictions about how social agents will behave? In three studies, following initial instances of conflict between individual members of different social pairs, sixteenâmonthâold infants looked longer when those individuals' social partnersâwho had never previously interactedâcooperated rather than conflicted with one other. Thus, infants tracked the agents' thirdâperson allegiances and inferred that the conflict would generalize across social partnerships.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/115912/1/desc12267.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/115912/2/desc12267_am.pd
Melanin-based coloration in juvenile kestrels (Falco tinnunculus) covaries with anti-predatory personality traits
Recent studies have shown that melanin-based coloration is associated with the ability to cope with stressful environments, potentially explaining why coloration covaries with anti-predator behaviours, boldness and docility. To investigate whether these relationships are consistent across species, we performed a study in the European kestrel (Falco tinnunculus). Similar to our results found previously in the barn owl (Tyto alba), nestling kestrels displaying a larger sub-terminal black tail band stayed on their back longer (tonic immobility test) and breathed at a lower rate than individuals with a smaller black band when handled. However, in contrast to barn owls, nestling kestrels with a larger black tail band were more aggressive and more agitated. Our results strengthen the hypothesis that melanin coloration is related to stress response and in turn to the reaction to predators, a very important personality trait (i.e. boldness)
Infants Use Statistical Sampling to Understand the Psychological World
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/133581/1/infa12131.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/133581/2/infa12131_am.pd
Tree scattering amplitudes of the spin-4/3 fractional superstring I: the untwisted sectors
Scattering amplitudes of the spin-4/3 fractional superstring are shown to
satisfy spurious state decoupling and cyclic symmetry (duality) at tree-level
in the string perturbation expansion. This fractional superstring is
characterized by the spin-4/3 fractional superconformal algebra---a
parafermionic algebra studied by Zamolodchikov and Fateev involving chiral
spin-4/3 currents on the world-sheet in addition to the stress-energy tensor.
Examples of tree scattering amplitudes are calculated in an explicit c=5
representation of this fractional superconformal algebra realized in terms of
free bosons on the string world-sheet. The target space of this model is
three-dimensional flat Minkowski space-time with a level-2 Kac-Moody so(2,1)
internal symmetry, and has bosons and fermions in its spectrum. Its closed
string version contains a graviton in its spectrum. Tree-level unitarity (i.e.,
the no-ghost theorem for space-time bosonic physical states) can be shown for
this model. Since the critical central charge of the spin-4/3 fractional
superstring theory is 10, this c=5 representation cannot be consistent at the
string loop level. The existence of a critical fractional superstring
containing a four-dimensional space-time remains an open question.Comment: 42 pages, 4 figures, latex, IASSNS-HEP-93/57, CLNS-92/117
Fractional Superstrings with Space-Time Critical Dimensions Four and Six
We propose possible new string theories based on local world-sheet symmetries
corresponding to extensions of the Virasoro algebra by fractional spin
currents. They have critical central charges and Minkowski
space-time dimensions for an integer. We present evidence
for their existence by constructing modular invariant partition functions and
the massless particle spectra. The dimension and strings have
space-time supersymmetry.Comment: 9 page
Low-Lying States of the Six-Dimensional Fractional Superstring
The fractional superstring Fock space is constructed in terms of
\bZ_4 parafermions and free bosons. The bosonization of the \bZ_4
parafermion theory and the generalized commutation relations satisfied by the
modes of various parafermion fields are reviewed. In this preliminary analysis,
we describe a Fock space which is simply a tensor product of \bZ_4
parafermion and free boson Fock spaces. It is larger than the Lorentz-covariant
Fock space indicated by the fractional superstring partition function. We
derive the form of the fractional superconformal algebra that may be used as
the constraint algebra for the physical states of the FSS. Issues concerning
the associativity, modings and braiding properties of the fractional
superconformal algebra are also discussed. The use of the constraint algebra to
obtain physical state conditions on the spectrum is illustrated by an
application to the massless fermions and bosons of the fractional
superstring. However, we fail to generalize these considerations to the massive
states. This means that the appropriate constraint algebra on the fractional
superstring Fock space remains to be found. Some possible ways of doing this
are discussed.Comment: 69 pages, LaTeX, CLNS 91/112
Augmented reality for the virtual dissection of white matter pathways
Background: The human white matter pathway network is complex and of critical importance for functionality. Thus, learning and understanding white matter tract anatomy is important for the training of neuroscientists and neurosurgeons. The study aims to test and evaluate a new method for fiber dissection using augmented reality (AR) in a group which is experienced in cadaver white matter dissection courses and in vivo tractography. Methods: Fifteen neurosurgeons, neurolinguists, and neuroscientists participated in this questionnaire-based study. We presented five cases of patients with left-sided perisylvian gliomas who underwent awake craniotomy. Diffusion tensor imaging fiber tracking (DTI FT) was performed and the language-related networks were visualized separated in different tracts by color. Participants were able to virtually dissect the prepared DTI FTs using a spatial computer and AR goggles. The application was evaluated through a questionnaire with answers from 0 (minimum) to 10 (maximum). Results: Participants rated the overall experience of AR fiber dissection with a median of 8 points (mean ± standard deviation 8.5 ± 1.4). Usefulness for fiber dissection courses and education in general was rated with 8 (8.3 ± 1.4) and 8 (8.1 ± 1.5) points, respectively. Educational value was expected to be high for several target audiences (student: median 9, 8.6 ± 1.4; resident: 9, 8.5 ± 1.8; surgeon: 9, 8.2 ± 2.4; scientist: 8.5, 8.0 ± 2.4). Even clinical application of AR fiber dissection was expected to be of value with a median of 7 points (7.0 ± 2.5). Conclusion: The present evaluation of this first application of AR for fiber dissection shows a throughout positive evaluation for educational purposes
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