bluuebunny/crossref_metadata_2025_split huggingface dataset:
A CFD-Based Robust Design of Operating Conditions for an HVAC System
Authors: Arias Luis F. , Bula Silvera Antonio J. , Sanjuan Marco E. 
Published: April 2014

HVAC systems are directly related to comfort (human health, productivity, etc.) and energy consumption. Depending on the application and geographical area, they may become a key disruptive and energy starving system. The research discussed in this paper describes a CFD-based approach for robust HVAC system design aimed at reducing variability in the conditioned area by adjusting operating parameters. Since robust design techniques aim at minimum variance (via S/N ratio), the solutions obtained allow the selection of operating parameters leading to more uniform distribution. Three variables were used: air velocity (to control energy transfer from people to the surrounding air), Unit usage (a ratio to consider the air conditioning system inertia compared to air conditioning requirements), and room temperature set point (representing the relation between the machine and the conditions room).
Embedded codes with field functions in the CFD software allow the simulation of a very basic operation strategy, and demonstrate a quasi-dynamic operation for different cooling capacities and air velocity. Results allow allocating operating parameters that lead to a more uniform temperature and relative humidity distributions, therefore, this approach can be adequately combined with statistical design of experiments for better conditions.
High Performance Isolation and Excitation of Vibration for Enhanced Identification of Inertial Sensors
Authors: Spiewak Swavik , Karpachevskyy Taras , Zaiss Curtis 
Published: April 2014

Microsystems Technology based inertial sensors offer important advantages in low-invasive measurement of spatial motion with sub-micron accuracy. However, their successful implementation hinges upon achieving very low distortion and noise at the low end of the frequency spectrum. Therefore the investigations that lead to the enhancement of inertial sensors require environments free of the ambient vibrations to the maximum possible extent.
This research focuses on developing a hybrid vibration isolation system. It comprises a custom built pre-isolation stage supporting a small size, high performance commercial vibration isolation platform. Our objective is to reduce the ambient vibrations present in typical research laboratories, usually strongly affected by the “cultural noise”, down to a level of the super quiet sites, i.e., close to the level defined by New Low Noise Model (NLNM). Performance of the developed system is illustrated with experimental results.
Prediction of Elastic Modulus of Glass Short Fiber/Wood Powder/Polypropylene Hybrid Composites
Authors: Yu Ying , Nomura Manabu , Hamada Hiroyuki 
Published: April 2014

Recent years, thermoplastics incorporated with particulate fillers have been gained high interests. To improve the mechanical properties of the natural particle reinforced polymer plastics, hybrid structure has been applied on the composite combining natural particle with stronger synthetic fibers. However, the reinforcing mechanism of the hybrid composite is quite complicated. Experiments on it may become time consuming and cost prohibitive. Therefore, researchers are interested in studying variable models to predict the elastic properties of the composites.
In this study, glass short fiber/wood particle/pp hybrid composites were prepared by injection molding process at a fixed reinforcement to matrix ratio of 51:49. 4 kinds of hybrid specimens with glass fiber/wood particle ratios of 41:10, 31:20, 21:30 and 11:40 were fabricated. The effect of hybridization content on the mechanical properties of the composites was evaluated based on tensile test. Theoretically, the elastic modulus of hybrid composites was predicted by using the rule of hybrid mixtures (RoHM) equation and classical lamination theory (CLT) and the accuracy of the two estimation models has been discussed.
Results showed that it can be considered the hybridization of wood powder into glass/PP composite could contribute to a similar high elastic modulus with high green degree. On the other hand, the fiber orientation factor, fiber length distribution factor, powder dispersion factor were very important factors and need to be considered in the prediction model.
Switching Criteria of Three Stage Air Valves
Authors: Warda H. A. , Adam I. G. , Rashad A. B. 
Published: April 2014

The performance of 3 stage air valve has been investigated experimentally. Throughout this work, more understanding of the dynamic behavior of air valves during transient is achieved. A wide range of tests were conducted, the aim of which were to obtain a graphical representation of the differential pressure versus water discharge rate characteristics for different valve float configurations and to determine the exact point at which dynamic closure occurs, whenever it occurs, and to determine the peak pressure induced when a flow of water column reaches and closes the valve.
The test rig for water discharge tests was constructed from a transparent pipe, and also transparent valve was used to allow visual interpretation of the valve behavior during transients using high speed camera. The rig was interfaced with a high pressure air/water supply in order to obtain the necessary pressure difference to vary the water column velocity. The pressure was monitored and recorded at different locations along the pipe and at the valve. Water column velocity was also recorded via an ultrasonic clamp on flow meter. The outputs of the various sensors were monitored by means of a data acquisition device.
Human Fall Evaluation Using Motion Capture and Human Modeling
Authors: Wiechel John , Metzler Sandra , Freyder Dawn , Kloppenborg Nick 
Published: April 2014

Reconstructing the mechanics and determining the cause of a person falling from a height in the absence of witness observations or a statement from the victim can be quite challenging. Often there is little information available beyond the final resting position of the victim and the injuries they sustained. The mechanics of a fall must follow the physics of falling bodies and this physics provides an additional source of information about how the fall occurred. Computational, physics-based simulations can be utilized to model the free-fall portion of the fall kinematics and to analyze biomechanical injury mechanisms. However, an accurate determination of the overall fall kinematics, including the initial conditions and any specific contributions of the person(s) involved, must include the correct position and posture of the individual prior to the fall. Frequently this phase of the analysis includes voluntary movement on the part of the fall victim, which cannot be modeled with simulations using anthropomorphic test devices (ATDs). One approach that has been utilized in the past to overcome this limitation is to run the simulations utilizing a number of different initial conditions for the fall victim. While fall simulations allow the initial conditions of the fall to be varied, they are unable to include the active movement of the subject, and the resulting interaction with other objects in the environment immediately prior to or during the fall. Furthermore, accurate contact interactions between the fall victim and multiple objects in their environment can be difficult to model within the simulation, as they are dependent on the knowledge of material properties of these objects and the environment such as elasticity and damping. Motion capture technology, however, allows active subject movement and behaviors to be captured in a quantitative, three-dimensional manner. This information can then be utilized within the fall simulation to more accurately model the initial fall conditions.
This paper presents a methodology for reconstructing fall mechanics using a combination of motion capture, human body simulation, and injury biomechanics. This methodology uses as an example a fall situation where interaction between the fall victim and specific objects in the environment, as well as voluntary movements by the fall victim immediately prior to the accident, provided information that could not be otherwise obtained. Motion capture was first used to record the possible motions of a person in the early stages of the fall. The initial position of the fall victim within the physics based simulation of the body in free fall was determined utilizing the individual body segment and joint angles from the motion capture analysis. The methodology is applied to a real world case example and compared with the actual outcome.
Modeling of Solidification and Microstructure Evolution in the Scanning Laser Epitaxy (SLE) Process for Additive Manufacturing With Nickel-Base Superalloy Powders
Authors: Acharya Ranadip , Bansal Rohan , Gambone Justin J. , Das Suman 
Published: April 2014

This paper investigates effects of natural and Marangoni convection on the resultant solidification microstructure in the scanning laser epitaxy (SLE) process. SLE is a laser-based additive manufacturing process that is being developed at the Georgia Institute of Technology for the additive manufacturing of nickel-base superalloys components with equiaxed, directionally-solidified or single-crystal microstructures through the laser melting of alloy powders onto superalloy substrates. A combined thermal and fluid flow model of the system simulates a heat source moving over a powder bed and dynamically adjusts the thermophysical property values. The geometrical and thermal parameters of the simulated laser melt pool are used to predict the solidification behavior of the alloy. The effects of natural and Marangoni convection on the resultant microstructure are evaluated through comparison with a pure conduction model. Inclusion of Marangoni effect produces shallower melt pools compared to a pure conduction model. A detailed flow analysis provides insights into the flow characteristics of the powder, the structure of rotational vortices created in the melt pool, and the solidification phenomena in the melt pool. The modeling results are compared with measurements and observation through real-time thermal imaging and video microscopy to understand the flow phenomenon.
In contrast to the single weld-bead approach, the raster scan in SLE allows every position in melt pool to be visited twice by the solid-liquid interface as the scan source progresses. To properly address this situation, time tracking is incorporated into the model to correctly couple the microstructure prediction model. An optimization study is carried out to evaluate the critical values of the transition parameters that govern the columnar-to-equiaxed transition (CET) and the oriented-to-misoriented (OMT) transition. This work is sponsored by the Office of Naval Research through grant N00014-11-1-0670.
Symbiotic Adaptation Drives Genome Streamlining of the Cyanobacterial Sponge Symbiont “
Candidatus
Synechococcus spongiarum”
Authors: Gao Zhao-Ming , Wang Yong , Tian Ren-Mao , Wong Yue Him , Batang Zenon B. , Al-Suwailem Abdulaz M. , Bajic Vladimir B. , Qian Pei-Yuan 
Published: April 2014

ABSTRACT

“
Candidatus
Synechococcus spongiarum” is a cyanobacterial symbiont widely distributed in sponges, but its functions at the genome level remain unknown. Here, we obtained the draft genome (1.66 Mbp, 90% estimated genome recovery) of “
Ca.
Synechococcus spongiarum” strain SH4 inhabiting the Red Sea sponge
Carteriospongia foliascens
. Phylogenomic analysis revealed a high dissimilarity between SH4 and free-living cyanobacterial strains. Essential functions, such as photosynthesis, the citric acid cycle, and DNA replication, were detected in SH4. Eukaryoticlike domains that play important roles in sponge-symbiont interactions were identified exclusively in the symbiont. However, SH4 could not biosynthesize methionine and polyamines and had lost partial genes encoding low-molecular-weight peptides of the photosynthesis complex, antioxidant enzymes, DNA repair enzymes, and proteins involved in resistance to environmental toxins and in biosynthesis of capsular and extracellular polysaccharides. These genetic modifications imply that “
Ca.
Synechococcus spongiarum” SH4 represents a low-light-adapted cyanobacterial symbiont and has undergone genome streamlining to adapt to the sponge’s mild intercellular environment.

IMPORTANCE
Although the diversity of sponge-associated microbes has been widely studied, genome-level research on sponge symbionts and their symbiotic mechanisms is rare because they are unculturable. “
Candidatus
Synechococcus spongiarum” is a widely distributed uncultivated cyanobacterial sponge symbiont. The genome of this symbiont will help to characterize its evolutionary relationship and functional dissimilarity to closely related free-living cyanobacterial strains. Knowledge of its adaptive mechanism to the sponge host also depends on the genome-level research. The data presented here provided an alternative strategy to obtain the draft genome of “
Ca.
Synechococcus spongiarum” strain SH4 and provide insight into its evolutionary and functional features.
Metatranscriptomics of the Human Oral Microbiome during Health and Disease
Authors: Jorth Peter , Turner Keith H. , Gumus Pinar , Nizam Nejat , Buduneli Nurcan , Whiteley Marvin 
Published: April 2014

ABSTRACT
The human microbiome plays important roles in health, but when disrupted, these same indigenous microbes can cause disease. The composition of the microbiome changes during the transition from health to disease; however, these changes are often not conserved among patients. Since microbiome-associated diseases like periodontitis cause similar patient symptoms despite interpatient variability in microbial community composition, we hypothesized that human-associated microbial communities undergo conserved changes in metabolism during disease. Here, we used patient-matched healthy and diseased samples to compare gene expression of 160,000 genes in healthy and diseased periodontal communities. We show that health- and disease-associated communities exhibit defined differences in metabolism that are conserved between patients. In contrast, the metabolic gene expression of individual species was highly variable between patients. These results demonstrate that despite high interpatient variability in microbial composition, disease-associated communities display conserved metabolic profiles that are generally accomplished by a patient-specific cohort of microbes.

IMPORTANCE
The human microbiome project has shown that shifts in our microbiota are associated with many diseases, including obesity, Crohn’s disease, diabetes, and periodontitis. While changes in microbial populations are apparent during these diseases, the species associated with each disease can vary from patient to patient. Taking into account this interpatient variability, we hypothesized that specific microbiota-associated diseases would be marked by conserved microbial community behaviors. Here, we use gene expression analyses of patient-matched healthy and diseased human periodontal plaque to show that microbial communities have highly conserved metabolic gene expression profiles, whereas individual species within the community do not. Furthermore, disease-associated communities exhibit conserved changes in metabolic and virulence gene expression.
Regulatory Protein BBD18 of the Lyme Disease Spirochete: Essential Role During Tick Acquisition?
Authors: Hayes Beth M. , Dulebohn Daniel P. , Sarkar Amit , Tilly Kit , Bestor Aaron , Ambroggio Xavier , Rosa Patricia A. 
Published: April 2014

ABSTRACT

The Lyme disease spirochete
Borrelia burgdorferi
senses and responds to environmental cues as it transits between the tick vector and vertebrate host. Failure to properly adapt can block transmission of the spirochete and persistence in either vector or host. We previously identified BBD18, a novel plasmid-encoded protein of
B. burgdorferi
, as a putative repressor of the host-essential factor OspC. In this study, we investigate the
in vivo
role of BBD18 as a regulatory protein, using an experimental mouse-tick model system that closely resembles the natural infectious cycle of
B. burgdorferi
. We show that spirochetes that have been engineered to constitutively produce BBD18 can colonize and persist in ticks but do not infect mice when introduced by either tick bite or needle inoculation. Conversely, spirochetes lacking BBD18 can persistently infect mice but are not acquired by feeding ticks. Through site-directed mutagenesis, we have demonstrated that abrogation of spirochete infection in mice by overexpression of BBD18 occurs only with
bbd18
alleles that can suppress OspC synthesis. Finally, we demonstrate that BBD18-mediated regulation does not utilize a previously described
ospC
operator sequence required by
B. burgdorferi
for persistence in immunocompetent mice. These data lead us to conclude that BBD18 does not represent the putative repressor utilized by
B. burgdorferi
for the specific downregulation of OspC in the mammalian host. Rather, we suggest that BBD18 exhibits features more consistent with those of a global regulatory protein whose critical role occurs during spirochete acquisition by feeding ticks.

IMPORTANCE
Lyme disease, caused by
Borrelia burgdorferi
, is the most common arthropod-borne disease in North America.
B. burgdorferi
is transmitted to humans and other vertebrate hosts by ticks as they take a blood meal. Transmission between vectors and hosts requires the bacterium to sense changes in the environment and adapt. However, the mechanisms involved in this process are not well understood. By determining how
B. burgdorferi
cycles between two very different environments, we can potentially establish novel ways to interfere with transmission and limit infection of this vector-borne pathogen. We are studying a regulatory protein called BBD18 that we recently described. We found that too much BBD18 interferes with the spirochete’s ability to establish infection in mice, whereas too little BBD18 appears to prevent colonization in ticks. Our study provides new insight into key elements of the infectious cycle of the Lyme disease spirochete.
Competitive Fitness in Coronaviruses Is Not Correlated with Size or Number of Double-Membrane Vesicles under Reduced-Temperature Growth Conditions
Authors: Al-Mulla Hawaa M. N. , Turrell Lauren , Smith Nicola M. , Payne Luke , Baliji Surendranath , Züst Roland , Thiel Volker , Baker Susan C. , Siddell Stuart G. , Neuman Benjamin W. 
Published: April 2014

ABSTRACT
Positive-stranded viruses synthesize their RNA in membrane-bound organelles, but it is not clear how this benefits the virus or the host. For coronaviruses, these organelles take the form of double-membrane vesicles (DMVs) interconnected by a convoluted membrane network. We used electron microscopy to identify murine coronaviruses with mutations in nsp3 and nsp14 that replicated normally while producing only half the normal amount of DMVs under low-temperature growth conditions. Viruses with mutations in nsp5 and nsp16 produced small DMVs but also replicated normally. Quantitative reverse transcriptase PCR (RT-PCR) confirmed that the most strongly affected of these, the nsp3 mutant, produced more viral RNA than wild-type virus. Competitive growth assays were carried out in both continuous and primary cells to better understand the contribution of DMVs to viral fitness. Surprisingly, several viruses that produced fewer or smaller DMVs showed a higher fitness than wild-type virus at the reduced temperature, suggesting that larger and more numerous DMVs do not necessarily confer a competitive advantage in primary or continuous cell culture. For the first time, this directly demonstrates that replication and organelle formation may be, at least in part, studied separately during infection with positive-stranded RNA virus.

IMPORTANCE
The viruses that cause severe acute respiratory syndrome (SARS), poliomyelitis, and hepatitis C all replicate in double-membrane vesicles (DMVs). The big question about DMVs is why they exist in the first place. In this study, we looked at thousands of infected cells and identified two coronavirus mutants that made half as many organelles as normal and two others that made typical numbers but smaller organelles. Despite differences in DMV size and number, all four mutants replicated as efficiently as wild-type virus. To better understand the relative importance of replicative organelles, we carried out competitive fitness experiments. None of these viruses was found to be significantly less fit than wild-type, and two were actually fitter in tests in two kinds of cells. This suggests that viruses have evolved to have tremendous plasticity in the ability to form membrane-associated replication complexes and that large and numerous DMVs are not exclusively associated with efficient coronavirus replication.
Spatial, temporal and relational patterns in respondent-driven sampling: evidence from a social network study of rural drug users
Authors: Young April M , Rudolph Abby E , Quillen Deane , Havens Jennifer R 
Published: April 2014

BackgroundRespondent-driven sampling (RDS) has become a common tool for recruiting high-risk populations for HIV research. However, few studies have explored the influence of geospatial proximity and relationship-level characteristics on RDS recruitment, particularly among high-risk individuals residing in rural areas of the US.MethodsIn a social network study of 503 drug users in rural Central Appalachia, interviewer-administered questionnaires were used to collect relationship-level data (eg, duration of relationship, frequency of communication, kinship, social/financial support, trust, drug use and sex) and residential location. Demographic and drug-use similarity were also evaluated. Residential data were geocoded and road distance (km) between participants and (1) their network members and (2) the study site were computed. Seasonal patterns were assessed using node-level analysis, and dyadic analyses were conducted using generalised linear mixed models. Adjusted ORs (AORs) and 95% CIs are reported.ResultsDifferences in distance to the study office by season and order of study entry were not observed (F=1.49, p=0.209 and β=0.074, p=0.050, respectively). Participants with transportation lived significantly further from the interview site than their counterparts (p<0.001). Dyadic analyses revealed no association between RDS recruitment likelihood and geographic proximity. However, kinship (AOR 1.62; CI 1.02 to 2.58) and frequency of communication (AOR 1.63; CI 1.25 to 2.13) were significantly associated with RDS recruitment.ConclusionsIn this sample, recruitment from one's network was likely non-random, contradicting a core RDS assumption. These data underscore the importance of formative research to elucidate potential recruitment preferences and of quantifying recruitment preferences for use in analysis.