228 research outputs found
Routing Diverse Crowds in Emergency with Dynamic Grouping
Evacuee routing algorithms in emergency typically adopt one single criterion
to compute desired paths and ignore the specific requirements of users caused
by different physical strength, mobility and level of resistance to hazard. In
this paper, we present a quality of service (QoS) driven multi-path routing
algorithm to provide diverse paths for different categories of evacuees. This
algorithm borrows the concept of Cognitive Packet Network (CPN), which is a
flexible protocol that can rapidly solve optimal solution for any user-defined
goal function. Spatial information regarding the location and spread of hazards
is taken into consideration to avoid that evacuees be directed towards
hazardous zones. Furthermore, since previous emergency navigation algorithms
are normally insensitive to sudden changes in the hazard environment such as
abrupt congestion or injury of civilians, evacuees are dynamically assigned to
several groups to adapt their course of action with regard to their on-going
physical condition and environments. Simulation results indicate that the
proposed algorithm which is sensitive to the needs of evacuees produces better
results than the use of a single metric. Simulations also show that the use of
dynamic grouping to adjust the evacuees' category and routing algorithms with
regard for their on-going health conditions and mobility, can achieve higher
survival rates.Comment: Contains 6 pages, 5 pages. Accepted by PerNEM' 201
Temperature Dependence Of The Electrical Resistivity Of LaxLu1-xAs
We investigate the temperature-dependent resistivity of single-crystalline films of LaxLu1-xAs over the 5-300 K range. The resistivity was separated into lattice, carrier and impurity scattering regions. The effect of impurity scattering is significant below 20 K, while carrier scattering dominates at 20-80 K and lattice scattering dominates above 80 K. All scattering regions show strong dependence on the La content of the films. While the resistivity of 600 nm LuAs films agree well with the reported bulk resistivity values, 3 nm films possessed significantly higher resistivity, suggesting that interfacial roughness significantly impacts the scattering of carriers at the nanoscale limit. (C) 2013 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.Microelectronics Research Cente
Understanding prompt engineering may not require rethinking generalization
Zero-shot learning in prompted vision-language models, the practice of
crafting prompts to build classifiers without an explicit training process, has
achieved impressive performance in many settings. This success presents a
seemingly surprising observation: these methods suffer relatively little from
overfitting, i.e., when a prompt is manually engineered to achieve low error on
a given training set (thus rendering the method no longer actually zero-shot),
the approach still performs well on held-out test data. In this paper, we show
that we can explain such performance well via recourse to classical PAC-Bayes
bounds. Specifically, we show that the discrete nature of prompts, combined
with a PAC-Bayes prior given by a language model, results in generalization
bounds that are remarkably tight by the standards of the literature: for
instance, the generalization bound of an ImageNet classifier is often within a
few percentage points of the true test error. We demonstrate empirically that
this holds for existing handcrafted prompts and prompts generated through
simple greedy search. Furthermore, the resulting bound is well-suited for model
selection: the models with the best bound typically also have the best test
performance. This work thus provides a possible justification for the
widespread practice of prompt engineering, even if it seems that such methods
could potentially overfit the training data
A Discrete – Time Mathematical Model for Homogeneous Population Density Dynamics of Single Weed Species
In this paper, the biological process is utilized to formulate a discrete-time homogeneous model for the dynamics of weed population density. Steady state solutions were obtained and analyzed them for local and global stabilities. The results revealed that our model is locally asymptotically stable but globally unstable. This result is contrary to the interesting property of the most standard biological one-dimensional discrete models, which display global stability if they are locally stable. Although, our model equation falls within the category of population models that exhibit local stability but globally not stable. It is concluded that, the weed population may exhibit unexpected behaviours. Keywords: Biological process, Discrete-time model, Local stability, Global stability, Population densit
Production and Storage of Cassava Chips for Reconversion into Gari
Cassava chips (7% moisture level) produced from cassava root (IITA 94/0561) was stored for 6 months in high density polyethylene bag. Stored chips were coarse milled, rehydrated to 62.51% and seeded with fresh cassava mash (FCM) at levels of 5%, 10% and 20%. The resulting mash was fermented for 72 hr, with pH monitored every 24 hr, and processed to gari. Yield and swelling capacity of gari were determined. Sensory evaluation was carried out on water soaked gari and gari paste (‘eba’). While least values for pH was obtained in FCM throughout the fermentation period, there was reduction in values in all samples with increase in fermentation time from 30.01 to 33.40%. Yield of gari from the seeded chips ranged from 64.4-72.3%, while that of FCM was 18.7%. Swelling capacity of gari ranged from 2.0 - 3.0 in FCM and that seeded with 20% FCM, respectively. Sensory evaluation result revealed that gari produced from cassava chips seeded at 10% level is adequate for making ‘eba’ while that seeded at 5% level is adequate for consumption as soaked gari (p<0.05). Use of stored cassava chips with 10% FCM for gari production could be encouraged to reduce postharvest problem of cassava roots and the drudgery of gari processing. Keywords: Cassava chips, cassava mash, gari, ‘eba’, postharvest losses, storag
A Mathematical Model for Population Density Dynamics of Annual Weeds and its Application to Bush Mint Weed (Hyptis suaveolens)
In this paper, a discrete-time stage-structured mathematical model was formulated for the population density dynamics of annual weeds. Biological process was employed to develop the model equations and incorporates density-dependent effects at germination and established seedling stages within the weed life-cycle. Besides, the developed model framework was applied to investigate the population density dynamics of Bush Mint weed (Hyptis suaveolens). The analysis revealed that the steady state solution is locally asymptotically stable and conclude that, whenever the steady state population is disturbed through management effort the weeds will always proliferate. Also, the steady state density of H. suaveolens is globally asymptotically stable and concludes that its population density may be control or eradicated. Keywords Discrete-time, density-dependent, stage –structured, steady-state, annual weeds, biological-process, Hyptis suaveolen
Pneumococcal Tricuspid Valve Endocarditis in a Young African American: A Case for Inclusion of African Americans in Pneumococcal Vaccine Criteria
Following the development of penicillin, complications from streptococcus pneumonia such as endocarditis have become rare. However, certain independent risk factors such as cigarette smoking and being of African-American (AA) decent have been associated with a higher incidence of invasive pneumococcal disease, but only cigarette smoking has been targeted by current recommendations from the Advisory Committee on Immunological Practices (ACIPs). We report a case of a young AA smoker, who developed an isolated tricuspid valve pneumococcal endocarditis. This case will illustrate the high susceptibility for invasive pneumococcus sequelae in AA, thereby raising the argument for the consideration of AA in the Pneumococcal Conjugate Vaccine (PCV) criteria, regardless of smoking history
A Review on Mechanics and Mechanical Properties of 2D Materials - Graphene and Beyond
Since the first successful synthesis of graphene just over a decade ago, a
variety of two-dimensional (2D) materials (e.g., transition
metal-dichalcogenides, hexagonal boron-nitride, etc.) have been discovered.
Among the many unique and attractive properties of 2D materials, mechanical
properties play important roles in manufacturing, integration and performance
for their potential applications. Mechanics is indispensable in the study of
mechanical properties, both experimentally and theoretically. The coupling
between the mechanical and other physical properties (thermal, electronic,
optical) is also of great interest in exploring novel applications, where
mechanics has to be combined with condensed matter physics to establish a
scalable theoretical framework. Moreover, mechanical interactions between 2D
materials and various substrate materials are essential for integrated device
applications of 2D materials, for which the mechanics of interfaces (adhesion
and friction) has to be developed for the 2D materials. Here we review recent
theoretical and experimental works related to mechanics and mechanical
properties of 2D materials. While graphene is the most studied 2D material to
date, we expect continual growth of interest in the mechanics of other 2D
materials beyond graphene
Atomic electrostatic maps of point defects in MoS2
In this study, we use differential phase contrast images obtained by scanning transmission electron microscopy combined with computer simulations to map the atomic electrostatic fields of MoS2 monolayers and investigate the effect of sulphur monovacancies and divancancies on the atomic electric field and total charge distribution. A significant redistribution of the electric field in the regions containing defects is observed, with a progressive decrease in the strength of the projected electric field for each sulphur atom removed from its position. The electric field strength at the sulphur monovacancy sites is reduced by approximately 50% and nearly vanishes at the divacancy sites, where it drops to around 15% of the original value, demonstrating the tendency of these defects to attract positively charged ions or particles. In addition, the absence of the sulphur atoms leads to an inversion in the polarity of the total charge distribution in these regions.The authors would like to acknowledge that this project has received funding from the EU Framework Program for Research and Innovation H2020, Scheme COFUND-Cofunding of Regional, National and International Programs, under grant agreement no. 713640. This work was supported by FCT, through IDMEC, under LAETA, project no. UIDB/50022/2020. R.M.R. acknowledges the FCT grant UIDB/FIS/04650/2020-2023. D.A. acknowledges the Presidential Early Career Award for Scientists and Engineers (PECASE) through the Army Research Office (W911NF-16-1-0277) and a National Science Foundation grant (ECCS-1809017). R.M.R. acknowledges support by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UIDB/04650/2020
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