Initial Contact Period Research Articles

Valorization of sponge iron industrial waste into iron-modified zeolite X for ciprofloxacin removal: a multi-parameter optimization study.

Ciprofloxacin (CIP), a commonly used antibiotic, is frequently detected in water bodies and the natural environment. The profound health consequences of CIP have led to growing attention focusing on environmental concerns. Adsorption is highly preferred because of its adaptability and remarkable efficiency in removing CIP. Therefore, the current work focuses on synthesizing an eco-friendly and economical adsorbent for removing CIP. The work aims to remove CIP using zeolite X (ZX), synthesized from dolochar, and subsequently modified ZX into iron-modified zeolite X (FeZX) via ion exchange. The synthesized FeZX had a crystallinity of 82.701%, an average pore size of 5.917 nm, a micropore volume of 0.298 cc/g, a micropore area of 451.807 m2/g, and a total surface area of 478.521 m2/g. The effect of parameters such as initial CIPconcentration, pH, contact period, adsorbent dosage, and iron dosage was analyzed in the batch adsorption studies of CIP using ZX and FeZX. CIP removal of 37.786% was achieved using ZX; hence, the adsorption parameters were optimized to maximize the CIP removal using response surface methodology (RSM), specifically Box-Behnken Design (BBD) using FeZX. Maximum removal of 97.974% was achieved under optimum conditions of 8.06 pH, contact period of 59.422 min, CIP concentration of 17.117 mg/L, and adsorbent dosage of 0.478 g/L. Freundlich isotherm and pseudo-second-order kinetic models werethe most accurate representations of the experimental data. The findings indicatethe significance of using this iron-modified mesoporous zeolite as an adsorbent for efficiently treating CIP wastewater.

Adsorptive removal of malachite green dye from aqueous solution using Rumex abyssinicus derived activated carbon

The potential for malachite green dye saturated effluent to severely affect the environment and human health has prompted the search for effective treatment technologies. Thus, this study was conducted with the goal of developing activated carbon from Rumex abyssinicus for the adsorptive removal of malachite green dye from an aqueous solution. Unit operations such as drying, size reduction, impregnation with H3PO4, and thermal activation were used during the preparation of the activated carbon. An experiment was designed considering four main variables at their respective three levels: initial dye concentration (50, 100, and 150 mg/L), pH (3, 6, and 9), contact period (20, 40, and 60 min), and adsorbent dosage (0.05, 0.01, and 0.15 g/100 mL). Optimization of the batch adsorption process was carried out using the Response Surface methodology's Box Behnken approach. The characterization of the activated carbon was described by SEM for surface morphology with cracks and highly porous morphology, FTIR for multi-functional groups O–H at 3506.74 cm−1 and 3290.70 cm−1, carbonyl group stretching from aldehyde and ketone (1900–1700 cm−1), stretching motion of aromatic ring C=C (1543.12 cm−1), stretching motion of –C–H (1500–1200 cm−1), vibrational and stretching motion of –OH (1250.79 cm−1), and vibrational motion of C–O–C (1049.32 cm−1), pHpzc of 5.1, BET for the specific surface area of 962.3 m2/g, and XRD for the presence of amorphous structure. The maximum and minimum dye removal efficiencies of 99.9% and 62.4% were observed at their respective experimental conditions of (100 mg/L, 0.10 mg/100 mL, pH 6, and 40 min) and (100 mg/L, 0.15 mg/100 mL, pH 3, and 20 min), respectively. Langmuir, Freundlich, Toth, and Koble-Corrigan models were used to evaluate the experimental data, in which Koble-Corrigan model was found to be the best fit with the highest value of R2 0.998. In addition to this, the kinetic studies were undertaken using pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Boyd models, and as a result, the pseudo-second-order model proved to have a better fit among the kinetic models. The kinetics and isotherm analysis revealed that the nature of the adsorption to be homogenous and monolayer surfaces driven by chemosorption. Furthermore, the thermodynamics study revealed the nature of adsorption to be feasible, spontaneous, and endothermic. On the other hand, the reusability study depicted the fact that the adsorbent can be utilized for five cycles with a negligible drop in the removal efficiencies from 99.9 to 95.2%. Finally, the low-cost, environmentally benign, and high adsorption capacity of the adsorbent material derived from Rumex abyssinicus stem could be used to treat industrial effluents.

Boosting anionic dyes removal performance of polyacrylonitrile nanofibers by incorporating nitrogen-rich conjugated polymer

In this study, poly(1,5-diaminonaphthalene) (PDAN) as nitrogen-rich conjugated polymer was successfully synthesized and incorporated into polyacrylonitrile nanofibers (PAN NFs) by one-step-electrospinning technique. The fabricated poly(1,5-diaminonaphthalene)/polyacrylonitrile nanofiber composite (PDAN/PAN NFs) was characterized using various techniques. The modification of PAN NFs caused their surface to become rich in nitrogen-containing functional groups and conjugated CC bonds. Morphological characterization confirmed that the incorporation of PDAN into PAN NFs made their surface rougher and increased their average diameters from 197 ± 46–214 ± 46 nm. The incorporation of PDAN into PAN NFs boosted the adsorption capacity for the removal of anionic Amido Black 10B dye (AB10B) by 140 times (from 1 mg/g to 140 mg/g). The uptake of the AB10B dye from aqueous solutions by the PDAN/PAN NFs was investigated as a function of the pH value, the initial dye solution, temperature and contact period. The Dubbin-Radushkevich isotherm model was found to fit well with the equilibrium adsorption isotherm data, and the maximum adsorption capacity was determined to be 240.53 mg/g at pH 3 and 35 °C. The pseudo-second-order was a reliable kinetic model for predicting the adsorption of AB10B dye onto the PDAN/PAN NFs composite. The efficient and selective adsorption of the designed adsorbent is due to the nitrogen-rich functional groups and the π-conjugated system of PDAN. This study will pave the way for the boosting adsorption capacity and selectivity of membrane-type nanoadsorbent for the treatment of more toxic organic dyes.

The ‘spiritual borderlands’ of the far Canadian north: the ministries of William Carpenter Bompas and Robert McDonald in comparative context

Anglican Bishop William Carpenter Bompas and Archdeacon Robert McDonald spent nearly forty years in the far American north ‘spreading the word’ to Indigenous peoples living along the Yukon River in the second half of the nineteenth century. This article investigates their work primarily among the Gwichyà Gwich’in from their arrival in the 1860s to the mid-1870s when the 141st meridian west was established, creating an international border between Alaska and the Yukon, the United States and British America. The border’s creation had enormous implications for the Hudson Bay Company at Fort Yukon (Gwichyaa Zheh) because it was discovered to be west of the international boundary in Alaska and was moved further east into today’s Yukon Territories. The border forced Indigenous people to pick a side, American or British, and tested loyalties to their minister. The ‘spiritual borderland’ thus offers a window into the lives and ministries of two important northern missionaries during the initial contact period, as well as assessing their successes and failures among northern peoples.

WITHDRAWN: Heavy metal ions and dyes removal from aqueous solution using Aloevera-based biosorbent: A systematic review

This article has been withdrawn: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been withdrawn at the request of the authors, editor and publisher. The publisher regrets that an error occurred which led to the premature publication of this paper. The publisher apologizes to the readers for this unfortunate erro

Human major infections: Tuberculosis, treponematoses, leprosy-A paleopathological perspective of their evolution.

The key to evolution is reproduction. Pathogens can either kill the human host or can invade the host without causing death, thus ensuring their own survival, reproduction and spread. Tuberculosis, treponematoses and leprosy are widespread chronic infectious diseases whereby the host is not immediately killed. These diseases are examples of the co-evolution of host and pathogen. They can be well studied as the paleopathological record is extensive, spanning over 200 human generations. The paleopathology of each disease has been well documented in the form of published synthetic analyses recording each known case and case frequencies in the samples they were derived from. Here the data from these synthetic analyses were re-analysed to show changes in the prevalence of each disease over time. A total of 69,379 skeletons are included in this study. There was ultimately a decline in the prevalence of each disease over time, this decline was statistically significant (Chi-squared, p<0.001). A trend may start with the increase in the disease's prevalence before the prevalence declines, in tuberculosis the decline is monotonic. Increase in skeletal changes resulting from the respective diseases appears in the initial period of host-disease contact, followed by a decline resulting from co-adaptation that is mutually beneficial for the disease (spread and maintenance of pathogen) and host (less pathological reactions to the infection). Eventually either the host may become immune or tolerant, or the pathogen tends to be commensalic rather than parasitic.

Analysis of gait and effectiveness after unicompartmental knee arthroplasty

To explore the gait trajectory characteristics and effectiveness after unicompartmental knee arthroplasty (UKA). Thirty patients (30 knees) with anterior medial compartment osteoarthritis who were treated with UKA between January 2017 and December 2018 were selected as subjects (UKA group). According to age, gender, and side, 30 patients (30 knees) with knee osteoarthritis treated with total knee arthroplasty (TKA) were selected as control (TKA group). In addition to the range of motion (ROM) before operation showing significant difference between the two groups ( t=4.25, P=0.00), there was no significant difference in gender, age, disease duration, sides, body mass index, and preoperative hip-knee-ankle angle (HKA), Western Ontario and McMaster University Osteoarthritis Index (WOMAC) score between the two groups ( P>0.05). The incision length, drainage volume within 24 hours after operation, and the changes of hemoglobin and albumin were recorded. The WOMAC score, ROM, and HKA before and after operation were compared between the two groups. At 1 year after operation, the gait trajectory characteristics of two groups were analyzed by Vicon three-dimensional gait capture system, and the absolute symmetry index (ASI) of the lower limbs of the two groups was calculated. The incisions of the two groups healed by first intention, with no complications. The incision length, drainage volume within 24 hours, and the changes of hemoglobin and albumin after operation in the UKA group were significantly smaller than those in the control group ( P<0.05). All patients were followed up completely, the follow-up time ranged from 13 to 20 months of UKA group (mean, 18 months) and 16 to 24 months of control group (mean, 20 months). The imaging review showed that the lower limb alignment of the two groups were restored to a neutral position, and the position of prosthesis was good. At 1 year after operation, the WOMAC score, HKA, and ROM of two groups were significantly improved when compared with those before operation ( P<0.05); the postoperative WOMAC score and ROM of the UKA group were significantly better than those of the control group ( P<0.05), and there was no significant difference in HKA between the two groups ( t=1.54， P=0.13). Gait analysis at 1 year after operation showed that the walking speed, stride length, knee extension at mid-stance, and flexion at swing in the UKA group were significantly better than those in the TKA group ( P<0.05); there was no significant difference in cadence, knee flexion at initial contact, and knee flexion at loading response between the two groups ( P>0.05). The ASI of bilateral knee flexion in the UKA group was significantly greater than that in the TKA group during the initial contact and loading response period ( P<0.05). Compared with TKA, UKA has the advantages of small incision, less blood loss, and quicker functional recovery. The early gait after UKA is mainly manifested as the increase in walking speed, stride length, knee flexion at swing, and extension at mid-stance phase. From the analysis of gait symmetry, during the initial contact and loading response phase, the operation side after UKA undertakes more shock absorption and joint stabilization functions than the contralateral side.

Batch-scale remediation of toluene contaminated groundwater using PRB system with tyre crumb rubber and sand mixture

The objective of the study is to examine the potential of TCR (tyre crumb rubber) particles to remediate toluene contaminated aquifers by using them as the reactive constituent of permeable reactive barriers (PRB). The objective is achieved by performing laboratory experiments to identify toluene adsorption capacity and rate of toluene removal of the optimal TCR-sand mix. Adsorption isotherms and Kc-Co relations (Kc: distribution coefficient, Co: initial toluene concentration) identified the optimum mix (2.5 % TCR-97.5 % sand mix) for remediation of toluene contaminated water. Batch experiments showed that toluene adsorption by TCR particles is endothermic and is energetically favoured at higher temperature. Adsorption of the non-polar molecule by TCR particles obeyed bi-linear, pseudo first order kinetics. The carbon-black component of TCR particles adsorbed significant amount of toluene during the initial contact period (10−60 min). Scatchard analysis, Freundlich isotherm and DR (Dubinin-Radushkevich) equation indicated that toluene is adsorbed by van der Waals attraction at energetically heterogenous sites of TCR particles. The near irreversible toluene adsorption in the laboratory experiment is attributed to physical entrapment of the non-polar molecules in the medium and fine pores of TCR particles. Batch experiment results predict that unit PRB column constructed with 2.5 % TCR-97.5 % sand mix can remediate 11,013 K L of toluene contaminated (0.15 mg/L) groundwater near instantaneously.

The Effect of Internships on Computer Science Engineering Capstone Projects

Contribution: Internships designed to provide training and an initial period of contact with industry, prior to a computer science engineering capstone project, have a very positive impact on both industry and academic capstone projects. Background: Internships and capstone projects are widely used to integrate work-related learning in computer engineering curricula. Both activities offer numerous benefits for students, industry, and academia. Although their effects have been extensively studied separately, the interaction between them remains unexplored. Research Questions: What is the effect of internships on the development of a subsequent capstone project? Methodology: The hypothesis was that the completion of an internship will have positive effects on several aspects of the capstone projects: 1) improved student competencies; 2) improved capstone project outcomes; and 3) decreased supervision effort. Further, these positive effects were expected to be greater in industry-based projects than in academic projects. The hypothesis was tested through a quantitative study of data collected from 274 computer science engineering capstone projects. A period of time with internships was compared with another period without internships, and differentiating between academic and industry projects. Findings: Internships prior to capstone projects improve student skills in autonomy, technology, methodology, and project management; increase the complexity and technological novelty of the resulting projects; and reduce advisor involvement in practical (technology, execution) and keep-the-project-alive issues, and increase advisor involvement in monitoring student work (meetings, reports, and initial arrangements). This effect was observed in both industrial and academic projects.

Ground reaction forces during a drop vertical jump: Impact of external load training

External load training (ELT) is a supplemental training method used to potentially improve high intensity task performance. However, biomechanical parameters such as ground reaction forces (GRF), ground contact time, and time to peak GRF during a drop vertical jump (DVJ) following an ELT intervention have yet to be examined. Therefore, this study investigated the impact of ELT on certain biomechanical parameters of a DVJ task. Well-trained females stratified into two groups (ELT = 9, Control = 10) completed a DVJ from a 45.72 cm box onto a force platform at baseline, post-ELT, and post-detraining (DET). ELT consisted of wearing weight vests (WV) with 8% body mass for 32 h/week during daily living and 3 training sessions/week for 3 weeks. After ELT, a 3 week DET phase was completed. The control group replicated procedures without ELT intervention. The vertical, medial/lateral, and anterior/posterior components of the GRF were assessed during the initial contact, minimum force following initial contact, push-off, and second landing periods. Dependent variables were analyzed using a 2 (group) × 3 (time) mixed model ANOVA (p < .05). Significantly greater peak vertical GRF during the initial contact period was identified for the ELT group. Significant increases in the minimum vertical GRF following the initial contact period from baseline to post-ELT following the were observed for the ELT group, while significant increases in peak vertical GRF during the second landing period at post-ELT and post-DET in comparison to baseline was observed for both groups. The combination of greater vertical GRF during the initial contact period and the period following initial contact suggests that ELT may increase GRFs during a DVJ in comparison to routine training without a weighted vest.

Removal of methylene blue from aqueous solutions using alum Sludge: Sorption optimization by response surface methodology

A sorption process on low cost sorbents is one the promising methods for removing of these pollutants from aqueous solutions. This report describes use of drinking water treatment sludge which is abundantly available from drinking water treatment plants, to remove methylene blue (MB) dye from aqueous solutions. The main objective of this work is to determine the optimum conditions for removal of MB dye, a common compound that is used as a model for organic chemicals. Response surface methodology (RSM) is used in the optimization of the sorption process. Six independent important factors which are temperature of treatment, pH of solution, dosage of sorbent, initial dye concentration, contact period and temperature of sorption were investigated using batch sorption technique with a 26 half factorial faced centered central composite design

Adhesion strength of a living cell to various substrates measured using a cup-attached atomic force microscopy chip

Cell adhesion strengths to various substrates were quantitatively measured using atomic force microscopy (AFM). A cup-shaped metal hemisphere was attached to the apex of the AFM cantilever, the “cup-chip” approached a cell (FP10SC2) to pick it up, the captured cell approached any one of six different substrates [gold (Au), nickel (Ni), bovine serum albumin (BSA), an amino group (NH2), poly(tetrafluoroethylene) (PTFE), and structured PTFE (sPTFE)], and the cell adhesion strength at the initial contact period was evaluated by detaching the cell from the substrate. The results obtained showed that the force needed to detach the cell from the NH2 substrate was more than 3-fold larger than that of metal substrates (Au and Ni), more than 15-fold larger than that of biochemically treated substrates (BSA), and more than 20-fold larger than that of hydrophobic substrates (PTFE and sPTFE). Using differences in adhesion strengths, a cell on a sPTFE substrate was picked up using a BSA-coated cup-chip, placed on a NH2 substrate, repeating this cell manipulation five times, and line patterning of cells was achieved. These results indicate that measurements of cell adhesion strength are fundamental to fabricate desired cell networks and the cup-chip is a useful tool for achieving easy cell manipulation.

Effect of Carbon Dissolution Reaction on Wetting Behaviour of Molten Fe–C Alloy on Graphite Substrate in the Initial Contact Period

Effect of Carbon Dissolution Reaction on Wetting Behaviour of Molten Fe–C Alloy on Graphite Substrate in the Initial Contact Period

Stiffness-reflecting energy-bounding approach for improving transparency of delayed haptic interaction systems

The ultimate objective of this study is to produce an interaction system haptically transparent to the human operator while guaranteeing interaction stability. In delayed haptic interaction systems (HIS) such as the bilateral teleoperation system (TS) and networked haptic virtual environments (NHVE), time delay over networks is a major cause of instability and transparency degradation. It has been proved that the passivity based energybounding approach (EBA) can guarantee robust stable interaction of the delayed HIS. However, transparency of the EBA has not been fully addressed, especially in terms of environment stiffness. This paper analyzes EBA transparency for the delayed HIS followed by experimental validation. This study demonstrates that the EBA in the delayed HIS can transparently display the environment stiffness regardless of the time delay by setting the second control parameter in the EBA to the environment stiffness value if the environment stiffness is less than the stable displayable stiffness by the EBA. For a very short period of initial contact with the very stiff environments, the stable displayable impedance range of the EBA can also be significantly increased by using the time-varying first control parameter. Experimental results show the effectiveness of the proposed approach.

Landing strategies focusing on the control of tibial rotation in the initial contact period of one-leg forward hops.

Anterior cruciate ligament (ACL) reconstruction (ACLR) surgeries successfully restore anterior tibial translation but not tibial rotation. This study aimed to explore landing strategies focusing on the control of tibial rotation at landing when the ACL is most vulnerable. Three groups of male subjects (50 ACLRs, 26 basketball players, and 31 controls) participated in one-leg forward hop tests for determining the tibial rotatory landing strategies adopted during the initial landing phase. The differences in knee kinematics and muscle activities between internal and external tibial rotatory (ITR, ETR) landing strategies were examined. A higher proportion of basketball players (34.6%) were found to adopt ITR strategies (controls: 6.5%), exhibiting significantly greater hopping distance and knee strength. After adjusting for hopping distance, subjects adopting ITR strategies were found to hop faster with straighter knees at foot contact and with greater ITR and less knee adduction angular displacement during the initial landing phase. However, significantly greater angular displacement in knee flexion, greater medial hamstring activities, and greater co-contraction index of hamstrings and medial knee muscles were also found during initial landing. Our results support the importance of the recruitments of medial hamstrings or the local co-contraction in assisting the rotatory control of the knee during initial landing for avoiding ACL injuries.

Health Consequences of European Contact in the Great Plains: A Comparison of Systemic Stress Levels in Pre‐ and Post‐Contact Arikara Populations

AbstractThe biocultural effects of European contact varied considerably throughout the Americas. Some populations were decimated by colonialism, while others benefited from trade relationships and access to new technologies. It has been suggested that initial contact with European fur traders and explorers was economically favourable for Plains village populations, thereby facilitating a period of cultural florescence. In this study, we evaluate the hypothesis that Plains groups were better off than their predecessors during the initial contact period by comparing frequencies of enamel hypoplasia, cribra orbitalia, and porotic hyperostosis in pre‐ and post‐contact Arikara skeletal assemblages. We included both juveniles and adults in our sample to capture variation in the stress experience of different segments of the population. Our analysis revealed similarly low frequencies of cribra orbitalia in the pre‐ and post‐contact groups and no observed cases of porotic hyperostosis. Enamel hypoplasia, however, was significantly more prevalent among post‐contact Arikara villagers when compared to their pre‐contact counterparts, which suggests that stress levels were higher after European contact. Additionally, enamel hypoplasia was most common among post‐contact juveniles. The elevated frequency of enamel hypoplasia in the post‐contact sample combined with the low frequencies of cribra orbitalia and porotic hyperostosis suggests that disease stress, rather than nutritional deficiencies, was likely responsible for the decline in overall health following European contact. These results also suggest that juveniles are sensitive indicators of systemic stress within a population and should be included in bioarchaeological analyses of prehistoric health when available. Copyright © 2015 John Wiley &amp; Sons, Ltd.

Searching for Scandinavians in pre-Viking Scotland: molecular fingerprinting of Early Medieval combs

The character and chronology of Norse colonisation in Early Medieval northern Scotland (8th–10th centuries AD) is hotly debated. The presence of reindeer antler raw material in ‘native’ or ‘Pictish’ type combs from the Orkney Isles, northern Scotland has been put forward as evidence for a long and largely peaceful initial period of cultural contact, as opposed to a shorter, more polarised period probably in the late ninth century. Here this hypothesis is tested using a minimally-destructive collagen peptide mass fingerprinting method (ZooMS) to speciate the raw material of 20 combs. Eleven were identified as red deer, four as reindeer and one as whale. The accuracy and gentleness of this method was tested by the subsequent application of ancient DNA (aDNA) methods to fourteen of the same samples: in ten, amplification was successful and all supported the preliminary ZooMS identification. All ‘native’-type combs in the sample are identified as red deer, and all Norse types as reindeer. These results challenge previous species identifications for these combs' raw materials. The balance of evidence no longer supports the existence of a long period of cultural contact between Atlantic Scotland and Scandinavian settlers before the late 9th century. ZooMS is shown to have considerable potential for identification of worked bone and antler artefacts, with applications in archaeology and wildlife/art-history forensics.

Aluminum (hydr)oxide coated pumice for fluoride removal from drinking water: Synthesis, equilibrium, kinetics and mechanism

Intake of excess fluoride (beyond 1.5mg/L, WHO guideline) for long periods can result in the incidence of fluorosis. Adsorption is widely considered the most appropriate technology for water defluoridation, if a suitable adsorbent is available. Several studied adsorbents have shown certain degrees of adsorption capacity, however, applicability of most is limited either due to lack of socio-cultural acceptance, high cost or effectiveness only in extreme pH conditions. The search for alternative adsorbents thus remains of interest. Modification of pumice particle surfaces by aluminum oxide coating was found effective in creating hard surface sites for fluoride adsorption, in accordance with the hard and soft acids and bases (HSAB) concept. Aluminum oxide coated pumice (AOCP) reduced fluoride concentration in model water from 5.0±0.2mg/L to 1.5mg/L in approximately 1h, using an adsorbent dose of 10mg/L. Contrary to expectations, thermal treatment of AOCP aimed at further improving its performance, instead reduced the fluoride removal efficiency. The equilibrium adsorption of fluoride by AOCP conformed reasonably to five isotherm models in the order: Generalized model>Langmuir type 2>BET>Temkin>Dubinin–Radushkevich; with a maximum capacity of 7.87mg/g. AOCP exhibited good fluoride adsorption within the pH range, 6–9, which makes it possible to avoid pH adjustment with the associated cost and operational difficulties, especially if it is to be used in remote areas of developing countries. Based on results from kinetic adsorption experiments, it was observed that at a neutral pH of 7.0±0.1 which is a more suitable condition for groundwater treatment, fluoride adsorption by AOCP was quite comparable or perhaps fairly faster in the initial period of contact than that of activated alumina (AA), the commonly used adsorbent for water defluoridation. AOCP is thus promising and could also possibly be a useful fluoride adsorbent.

Heat Transfer Between Colliding Surfaces and Particles

Collisional heat transfer between two contacting curved surfaces is investigated computationally using a finite difference method and analytically using various asymptotic methods. Transformed coordinates that scale with the contact radius and the diffusion length are used for the computations. Hertzian contact theory of elasticity is used to characterize the contact area as a function of time. For an axisymmetric contact area, a two-dimensional self-similar solution for the thermal field during the initial period of contact is obtained, and it serves as an initial condition for the heat transfer simulation throughout the entire duration of collision. A two-dimensional asymptotic heat transfer result is obtained for small Fourier number. For finite Fourier numbers, local analytical solutions are presented to elucidate the nature of the singularity of the thermal field and heat flux near the contact point. From the computationally determined heat transfer during the collision, a closed-form formula is developed to predict the heat transfer as a function of the Fourier number, the thermal diffusivity ratio, and the thermal conductivity ratio of the impacting particles.

Native Americans: The First Conservationists? An Examination of Shepard Krech III's Hypothesis with Respect to the Western Shoshone

The well-known argument by Shepard Krech (1999) that Native Americans were not in fact first conservationists is tackled by examining the Western Shoshone as they were documented in the most intensive period of initial contact: 1828-1870. Particular attention is paid to their uses of fire, fish, pine nuts, antelope, and beaver. Reference is made to a model developed by Eric Smith and Mark Wishnie (2000) in which several key concepts are salient: ecosystem engineering, taking a short-term loss in order to reap a long-term gain, and effective conservation. On the basis of this case study, examination of factors such as resources that could neither be predicted nor controlled, proprietary rights that were defended, tracts with open access where communal management was the norm, and the existence of resource-procurement directions in future studies is crucial for determining the extent of Native American conservationism.