Showing papers by "University of Nevada, Reno published in 2012"

Words as Tools: Learning Academic Vocabulary as Language Acquisition

Abstract: There is a growing awareness of the importance of academic vocabulary, and more generally, of academic language proficiency, for students’ success in school. There is also a growing body of research on the nature of the demands that academic language places on readers and writers, and on interventions to help students meet these demands. In this review, we discuss the role of academic vocabulary within academic language, examine recent research on instruction in academic vocabulary, considering both general academic words and discipline-specific words, and offer our perspective on the current state of this research and recommendations on how to continue inquiry and to improve practice in this area. We use the metaphor of ‘words as tools’ to reflect our understanding that instruction in academic vocabulary must approach words as means for communicating and thinking about disciplinary content, and must therefore provide students with opportunities to use the instructed words for these purposes as they are learning them.

Allergic Rhinitis and its Impact on Asthma (ARIA): Achievements in 10 years and future needs

Abstract: Allergic rhinitis (AR) and asthma represent global health problems for all age groups. Asthma and rhinitis frequently coexist in the same subjects. Allergic Rhinitis and its Impact on Asthma (ARIA) was initiated during a World Health Organization workshop in 1999 (published in 2001). ARIA has reclassified AR as mild/moderate-severe and intermittent/persistent. This classification closely reflects patients' needs and underlines the close relationship between rhinitis and asthma. Patients, clinicians, and other health care professionals are confronted with various treatment choices for the management of AR. This contributes to considerable variation in clinical practice, and worldwide, patients, clinicians, and other health care professionals are faced with uncertainty about the relative merits and downsides of the various treatment options. In its 2010 Revision, ARIA developed clinical practice guidelines for the management of AR and asthma comorbidities based on the Grading of Recommendation, Assessment, Development and Evaluation (GRADE) system. ARIA is disseminated and implemented in more than 50 countries of the world. Ten years after the publication of the ARIA World Health Organization workshop report, it is important to make a summary of its achievements and identify the still unmet clinical, research, and implementation needs to strengthen the 2011 European Union Priority on allergy and asthma in children.

Invited review article: high-speed flexure-guided nanopositioning: mechanical design and control issues.

Abstract: Recent interest in high-speed scanning probe microscopy for high-throughput applications including video-rate atomic force microscopy and probe-based nanofabrication has sparked attention on the development of high-bandwidth flexure-guided nanopositioning systems (nanopositioners). Such nanopositioners are designed to move samples with sub-nanometer resolution with positioning bandwidth in the kilohertz range. State-of-the-art designs incorporate uniquely designed flexure mechanisms driven by compact and stiff piezoelectric actuators. This paper surveys key advances in mechanical design and control of dynamic effects and nonlinearities, in the context of high-speed nanopositioning. Future challenges and research topics are also discussed.

Randomized Clinical Trial of Cognitive Behavioral Therapy (CBT) versus Acceptance and Commitment Therapy (ACT) for Mixed Anxiety Disorders

Abstract: Objective: Randomized comparisons of acceptance-based treatments with traditional cognitive behavioral therapy (CBT) for anxiety disorders are lacking. To address this gap, we compared acceptance and commitment therapy (ACT) to CBT for heterogeneous anxiety disorders. Method: One hundred twenty-eight individuals (52% female, mean age 38, 33% minority) with 1 or more DSM–IV anxiety disorders began treatment following randomization to CBT or ACT; both treatments included behavioral exposure. Assessments at pre-treatment, post-treatment, and 6- and 12-month follow-up measured anxiety-specific (principal disorder Clinical Severity Ratings [CSRs], Anxiety Sensitivity Index, Penn State Worry Questionnaire, Fear Questionnaire avoidance) and non-anxiety-specific (Quality of Life Index [QOLI], Acceptance and Action Questionnaire–16 [AAQ]) outcomes. Treatment adherence, therapist competency ratings, treatment credibility, and co-occurring mood and anxiety disorders were investigated. Results: CBT and ACT improved similarly across all outcomes from pre- to post-treatment. During follow-up, ACT showed steeper linear CSR improvements than CBT (p .05, d 1.26), and at 12-month follow-up, ACT showed lower CSRs than CBT among completers (p .05, d 1.10). At 12-month follow-up, ACT reported higher AAQ than CBT (p .08, d 0.42; completers: p .05, d 0.56), whereas CBT reported higher QOLI than ACT (p .05, d 0.42). Attrition and comorbidity improvements were similar; ACT used more non-study psychotherapy at 6-month follow-up. Therapist adherence and competency were good; treatment credibility was higher in CBT. Conclusions: Overall improvement was similar between ACT and CBT, indicating that ACT is a highly viable treatment for anxiety disorders.

Part-based multiple-person tracking with partial occlusion handling

Abstract: Single camera-based multiple-person tracking is often hindered by difficulties such as occlusion and changes in appearance. In this paper, we address such problems by proposing a robust part-based tracking-by-detection framework. Human detection using part models has become quite popular, yet its extension in tracking has not been fully explored. Our approach learns part-based person-specific SVM classifiers which capture the articulations of the human bodies in dynamically changing appearance and background. With the part-based model, our approach is able to handle partial occlusions in both the detection and the tracking stages. In the detection stage, we select the subset of parts which maximizes the probability of detection, which significantly improves the detection performance in crowded scenes. In the tracking stage, we dynamically handle occlusions by distributing the score of the learned person classifier among its corresponding parts, which allows us to detect and predict partial occlusions, and prevent the performance of the classifiers from being degraded. Extensive experiments using the proposed method on several challenging sequences demonstrate state-of-the-art performance in multiple-people tracking.

Acceptance and Commitment Therapy as a Unified Model of Behavior Change

Abstract: The present article summarizes the assumptions, model, techniques, evidence, and diversity/social justice commitments of Acceptance and Commitment Therapy (ACT). ACT focused on six processes (acceptance, defusion, self, now, values, and action) that bear on a single overall target (psychological flexibility). The ACT model of behavior change has been shown to have positive outcomes across a broad range of applied problems and areas of growth. Process and outcome evidence suggest that the psychological flexibility model underlying ACT provides a unified model of behavior change and personal development that fits well with the core assumptions of counseling psychology.

Gas-particle partitioning of atmospheric Hg(II) and its effect on global mercury deposition

Abstract: Atmospheric deposition of Hg(II) represents a major input of mercury to surface environments. The phase of Hg(II) (gas or particle) has important implications for deposition. We use long-term observations of reactive gaseous mercury (RGM, the gaseous component of Hg(II)), particle-bound mercury (PBM, the particulate component of Hg(II)), fine particulate matter (PM 2.5), and temperature (T ) at five sites in North America to derive an empirical gas-particle partitioning relationship log 10(K 1 ) = (10±1)- (2500±300)/T where K = (PBM/PM2.5)/RGM with PBM and RGM in common mixing ratio units, PM2.5 in µg m 3 , and T in K. This relationship is within the range of previ- ous work but is based on far more extensive data from mul- tiple sites. We implement this empirical relationship in the GEOS-Chem global 3-D Hg model to partition Hg(II) be- tween the gas and particle phases. The resulting gas-phase fraction of Hg(II) ranges from over 90 % in warm air with lit- tle aerosol to less than 10 % in cold air with high aerosol. Hg deposition to high latitudes increases because of more effi- cient scavenging of particulate Hg(II) by precipitating snow. Model comparison to Hg observations at the North Ameri- can surface sites suggests that subsidence from the free tro- posphere (warm air, low aerosol) is a major factor driving the seasonality of RGM, while elevated PBM is mostly associ- ated with high aerosol loads. Simulation of RGM and PBM at these sites is improved by including fast in-plume reduc- tion of Hg(II) emitted from coal combustion and by assum- ing that anthropogenic particulate Hg(p) behaves as semi- volatile Hg(II) rather than as a refractory particulate compo- nent. We improve the simulation of Hg wet deposition fluxes in the US relative to a previous version of GEOS-Chem; this largely reflects independent improvement of the washout al- gorithm. The observed wintertime minimum in wet depo- sition fluxes is attributed to inefficient snow scavenging of gas-phase Hg(II).

Prions in Yeast

Abstract: The concept of a prion as an infectious self-propagating protein isoform was initially proposed to explain certain mammalian diseases. It is now clear that yeast also has heritable elements transmitted via protein. Indeed, the “protein only” model of prion transmission was first proven using a yeast prion. Typically, known prions are ordered cross-β aggregates (amyloids). Recently, there has been an explosion in the number of recognized prions in yeast. Yeast continues to lead the way in understanding cellular control of prion propagation, prion structure, mechanisms of de novo prion formation, specificity of prion transmission, and the biological roles of prions. This review summarizes what has been learned from yeast prions.

A two-dimensional polymer prepared by organic synthesis.

Abstract: Synthetic polymers are widely used materials, as attested by a production of more than 200 millions of tons per year, and are typically composed of linear repeat units. They may also be branched or irregularly crosslinked. Here, we introduce a two-dimensional polymer with internal periodicity composed of areal repeat units. This is an extension of Staudinger's polymerization concept (to form macromolecules by covalently linking repeat units together), but in two dimensions. A well-known example of such a two-dimensional polymer is graphene, but its thermolytic synthesis precludes molecular design on demand. Here, we have rationally synthesized an ordered, non-equilibrium two-dimensional polymer far beyond molecular dimensions. The procedure includes the crystallization of a specifically designed photoreactive monomer into a layered structure, a photo-polymerization step within the crystal and a solvent-induced delamination step that isolates individual two-dimensional polymers as free-standing, monolayered molecular sheets.

An insect-specific P450 oxidative decarbonylase for cuticular hydrocarbon biosynthesis

Abstract: Insects use hydrocarbons as cuticular waterproofing agents and as contact pheromones. Although their biosynthesis from fatty acyl precursors is well established, the last step of hydrocarbon biosynthesis from long-chain fatty aldehydes has remained mysterious. We show here that insects use a P450 enzyme of the CYP4G family to oxidatively produce hydrocarbons from aldehydes. Oenocyte-directed RNAi knock-down of Drosophila CYP4G1 or NADPH-cytochrome P450 reductase results in flies deficient in cuticular hydrocarbons, highly susceptible to desiccation, and with reduced viability upon adult emergence. The heterologously expressed enzyme converts C18-trideuterated octadecanal to C17-trideuterated heptadecane, showing that the insect enzyme is an oxidative decarbonylase that catalyzes the cleavage of long-chain aldehydes to hydrocarbons with the release of carbon dioxide. This process is unlike cyanobacteria that use a nonheme diiron decarbonylase to make alkanes from aldehydes with the release of formate. The unique and highly conserved insect CYP4G enzymes are a key evolutionary innovation that allowed their colonization of land.

Morphometric indices of body condition in birds: a review

Abstract: Morphometric estimates of body condition are widely used by ornithologists, but which estimates work best is a matter of debate. We review morphometric approaches (body mass, ratio and residual condition indices, predictive regression models, fat scoring, and abdominal profiles) for estimating body condition (defined as fat mass) in birds. We describe the strengths and weaknesses of each approach. Across diverse indices and species (~200 estimates total), the mean r 2 relating condition indices to mass of body fat was 0.55, and 64% of the r 2 values were greater than 0.50. But despite their generally good performance, condition indices sometimes perform poorly (i.e., r 2 is low). The data indicate that: (1) no single index was clearly best, (2) on average body mass alone, fat scores, and predictive multiple regression equations explained slightly more than 50% of the variation in fat content, (3) on average, ratio and residual indices explained slightly less than 50% of the variation in fat content, and (4) body mass alone, a variable that can be easily and reliably measured, is as good or nearly as good an indicator of fat content as any other condition index. We recommend that: (1) morphometric indicators of condition be empirically validated, (2) researchers publish their body composition data in sufficient detail that they can be used in future analyses exploring the relative merits of different condition indices, and (3) multiple regression directly on measured traits be used instead of condition indices whenever the condition index is not empirically validated.

Design and Control of a Three-Axis Serial-Kinematic High-Bandwidth Nanopositioner

Abstract: The development of a high-performance three-axis serial-kinematic nanopositioning stage is presented. The stage is designed for high-bandwidth applications that include video-rate scanning probe microscopy and high-throughput probe-based nanofabrication. Specifically, the positioner employs vertically stiff, double-hinged serial flexures for guiding the motion of the sample platform to minimize parasitic motion (runout) and off-axis effects compared to previous designs. Finite element analysis (FEA) predicts the dominant resonances along the fast ( x-axis) and slow (y-axis) scanning axes at 25.9 and 6.0 kHz, respectively. The measured dominant resonances of the prototype stage in the fast and slow scanning directions are 24.2 and 6.0 kHz, respectively, which are in good agreement with the FEA predictions. In the z-direction, the measured dominant resonance is approximately 70 kHz. The lateral and vertical positioning ranges are approximately 9 μm × 9 μm and 1 μm, respectively. Four approaches to control the lateral motion of the stage are evaluated for precision tracking at high-scan rates: (1) open-loop smooth inputs; (2) PID feedback; (3) discrete-time repetitive control implemented using field-programmable gate array (FPGA) hardware; and (4) model-based feed forward control. The stage is integrated with a commercial scan-by-probe atomic force microscope (AFM) and imaging and tracking results up to a line rate of 7 kHz are presented. At this line rate, 70 frames/s atomic force microscope video (100 × 100 pixels resolution) can be achieved.

Regulation of gastrointestinal motility—insights from smooth muscle biology

Abstract: Gastrointestinal motility results from coordinated contractions of the tunica muscularis, the muscular layers of the alimentary canal. Throughout most of the gastrointestinal tract, smooth muscles are organized into two layers of circularly or longitudinally oriented muscle bundles. Smooth muscle cells form electrical and mechanical junctions between cells that facilitate coordination of contractions. Excitation-contraction coupling occurs by Ca(2+) entry via ion channels in the plasma membrane, leading to a rise in intracellular Ca(2+). Ca(2+) binding to calmodulin activates myosin light chain kinase; subsequent phosphorylation of myosin initiates cross-bridge cycling. Myosin phosphatase dephosphorylates myosin to relax muscles, and a process known as Ca(2+) sensitization regulates the activity of the phosphatase. Gastrointestinal smooth muscles are 'autonomous' and generate spontaneous electrical activity (slow waves) that does not depend upon input from nerves. Intrinsic pacemaker activity comes from interstitial cells of Cajal, which are electrically coupled to smooth muscle cells. Patterns of contractile activity in gastrointestinal muscles are determined by inputs from enteric motor neurons that innervate smooth muscle cells and interstitial cells. Here we provide an overview of the cells and mechanisms that generate smooth muscle contractile behaviour and gastrointestinal motility.

Acceptance and Commitment Therapy

Abstract: ACT is an example of a third wave behavior therapy that saves direct change strategies for overt behaviors and utilizes contextual and experiential methods such as mindfulness and acceptance to address cognitive process that hinder and limit overt behavioral change. The treatment is informed by RFT and is based on the philosophical position of functional contextualism. ACT seeks to undermine the literal grip of language (relational framing) that fosters experiential avoidance, cognitive fusion, and behavioral inflexibility, through the application of six core psychological techniques: acceptance, defusion, contact with the present moment, self-as as-context, values, and commitment to behavior change. Homework can play an integral role in the application of these techniques, by supporting the in-session therapy. Homework can be especially useful because it allows the client to utilize these principles in situations that cannot be created in the therapy sessions, such as public situation for someone who struggles with anxiety. As with most therapies, ACT has its own homework assignments, but therapists often create new techniques to serve the clients needs.

Slow and steady wins the race: a randomized clinical trial of acceptance and commitment therapy targeting shame in substance use disorders.

Abstract: Objective Shame has long been seen as relevant to substance use disorders, but interventions have not been tested in randomized trials. This study examined a group-based intervention for shame based on the principles of acceptance and commitment therapy (ACT) in patients (N = 133; 61% female; M = 34 years old; 86% Caucasian) in a 28-day residential addictions treatment program. Method Consecutive cohort pairs were assigned in a pairwise random fashion to receive treatment as usual (TAU) or the ACT intervention in place of 6 hr of treatment that would have occurred at that same time. The ACT intervention consisted of three 2-hr group sessions scheduled during a single week. Results Intent-to-treat analyses demonstrated that the ACT intervention resulted in smaller immediate gains in shame, but larger reductions at 4-month follow-up. Those attending the ACT group also evidenced fewer days of substance use and higher treatment attendance at follow-up. Effects of the ACT intervention on treatment utilization at follow-up were statistically mediated by posttreatment levels of shame, in that those evidencing higher levels of shame at posttreatment were more likely to be attending treatment at follow-up. Intervention effects on substance use at follow-up were mediated by treatment utilization at follow-up, suggesting that the intervention may have had its effects, at least in part, through improving treatment attendance. Conclusions These results demonstrate that an approach to shame based on mindfulness and acceptance appears to produce better treatment attendance and reduced substance use.

Contextual behavioral science: Creating a science more adequate to the challenge of the human condition.

Abstract: The present article describes the nature, scope, and purpose of Contextual Behavioral Science (CBS). Emerging from behavioral psychology but expanding from those roots, CBS is based on contextual assumptions regarding the centrality of situated action, the nature of epistemology versus ontology, and a pragmatic truth criterion linked to the specific goal of predicting-and-influencing psychological events with precision, scope, and depth. These assumptions and goals explain the characteristic features of CBS including its environmentalism, focus on theory and principles, and its reticulated or networked program of theory development, research and practice. Domains of development include increased linkage to multi-dimensional and multi-level evolution science; development of principles that describe the interaction of behavior and symbolic events with genetic, epigenetic, and cultural dimensions; expansion of theoretical and model development to a broader range of areas of human complexity; advances in measurement theory and practice; the development of techniques and components linked to contextual processes and principles; broad testing of these methods; additional research on mediation and moderation; more concern for effectiveness and training; and enhancement of a diverse development community.

Synthesis of System Dynamics Tools for Holistic Conceptualization of Water Resources Problems

Abstract: Out-of-context analysis of water resources systems can result in unsustainable management strategies. To address this problem, systems thinking seeks to understand interactions among the subsystems driving a system’s overall behavior. System dynamics, a method for operationalizing systems thinking, facilitates holistic understanding of water resources systems, and strategic decision making. The approach also facilitates participatory modeling, and analysis of the system’s behavioral trends, essential to sustainable management. The field of water resources has not utilized the full capacity of system dynamics in the thinking phase of integrated water resources studies. We advocate that the thinking phase of modeling applications is critically important, and that system dynamics offers unique qualitative tools that improve understanding of complex problems. Thus, this paper describes the utility of system dynamics for holistic water resources planning and management by illustrating the fundamentals of the approach. Using tangible examples, we provide an overview of Causal Loop and Stock and Flow Diagrams, reference modes of dynamic behavior, and system archetypes to demonstrate the use of these qualitative tools for holistic conceptualization of water resources problems. Finally, we present a summary of the potential benefits as well as caveats of qualitative system dynamics for water resources decision making.

Revisiting the Evolution of Ecological Specialization, With Emphasis on Insect-Plant Interactions

Abstract: Ecological specialization is a fundamental and well-studied concept, yet its great reach and complexity limit current understanding in important ways. More than 20 years after the publication of D. J. Futuyma and G. Moreno's oft-cited, major review of the topic, we synthesize new developments in the evolution of ecological specialization. Using insect–plant interactions as a model, we focus on important developments in four critical areas: genetic architecture, behavior, interaction complexity, and macroevolution. We find that theory based on simple genetic trade-offs in host use is being replaced by more subtle and complex pictures of genetic architecture, and multitrophic interactions have risen as a necessary framework for understanding specialization. A wealth of phylogenetic data has made possible a more detailed consideration of the macroevolutionary dimension of specialization, revealing (among other things) bidirectionality in transitions between generalist and specialist lineages. Technological advances, including genomic sequencing and analytical techniques at the community level, raise the possibility that the next decade will see research on specialization spanning multiple levels of biological organization in non-model organisms, from genes to populations to networks of interactions in natural communities. Finally, we offer a set of research questions that we find to be particularly pressing and fruitful for future research on ecological specialization.

Single-ion nuclear clock for metrology at the 19th decimal place.

Abstract: The 76(5) eV nuclear magnetic-dipole transition in a single 229Th3+ ion may provide the foundation for an optical clock of superb accuracy A virtual clock transition composed of stretched states within the 5F(5/2) electronic ground level of both nuclear ground and isomeric manifolds is proposed It is shown to offer unprecedented systematic shift suppression, allowing for clock performance with a total fractional inaccuracy approaching 1×10(-19)

Spatial patterns and drivers of fire occurrence and its future trend under climate change in a boreal forest of Northeast China

Abstract: Understanding the spatial patterns of fire occurrence and its response to climate change is vital to fire risk mitigation and vegetation management. Focusing on boreal forests in Northeast China, we used spatial point pattern analysis to model fire occurrence reported from 1965 to 2009. Our objectives were to quantitate the relative importance of biotic, abiotic, and human influences on patterns of fire occurrence and to map the spatial distribution of fire occurrence density (number of fires occurring over a given area and time period) under current and future climate conditions. Our results showed human-caused fires were strongly related to human activities (e.g. landscape accessibility), including proximity to settlements and roads. In contrast, fuel moisture and vegetation type were the most important controlling factors on the spatial pattern of lightning fires. Both current and future projected spatial distributions of the overall (human- + lightning-caused) fire occurrence density were strongly clustered along linear components of human infrastructure. Our results demonstrated that the predicted change in overall fire occurrence density is positively related to the degree of temperature and precipitation change, although the spatial pattern of change is expected to vary spatially according to proximity to human ignition sources, and in a manner inconsistent with predicted climate change. Compared to the current overall fire occurrence density (median value: 0.36 fires per 1000 km2 per year), the overall fire occurrence density is projected to increase by 30% under the CGCM3 B1 scenario and by 230% under HadCM3 A2 scenario in 2081–2100, respectively. Our results suggest that climate change effects may not outweigh the effects of human influence on overall fire occurrence over the next century in this cultural landscape. Accurate forecasts of future fire-climate relationships should account for anthropogenic influences on fire ignition density, such as roads and proximity to settlements.

Major Earthquakes Occur Regularly on an Isolated Plate Boundary Fault

Abstract: The scarcity of long geological records of major earthquakes, on different types of faults, makes testing hypotheses of regular versus random or clustered earthquake recurrence behavior difficult. We provide a fault-proximal major earthquake record spanning 8000 years on the strike-slip Alpine Fault in New Zealand. Cyclic stratigraphy at Hokuri Creek suggests that the fault ruptured to the surface 24 times, and event ages yield a 0.33 coefficient of variation in recurrence interval. We associate this near-regular earthquake recurrence with a geometrically simple strike-slip fault, with high slip rate, accommodating a high proportion of plate boundary motion that works in isolation from other faults. We propose that it is valid to apply time-dependent earthquake recurrence models for seismic hazard estimation to similar faults worldwide.

Performance of Nonstructural Components during the 27 February 2010 Chile Earthquake

Abstract: The 27 February 2010 Chile earthquake caused widespread nonstructural damage in practically all types of buildings. While few commercial, residential, office, and industrial buildings suffered stru...

Radar-Enabled Recovery of the Sutter’s Mill Meteorite, a Carbonaceous Chondrite Regolith Breccia

Abstract: Doppler weather radar imaging enabled the rapid recovery of the Sutter’s Mill meteorite after a rare 4-kiloton of TNT–equivalent asteroid impact over the foothills of the Sierra Nevada in northern California. The recovered meteorites survived a record high-speed entry of 28.6 kilometers per second from an orbit close to that of Jupiter-family comets (Tisserand’s parameter = 2.8 ± 0.3). Sutter’s Mill is a regolith breccia composed of CM (Mighei)–type carbonaceous chondrite and highly reduced xenolithic materials. It exhibits considerable diversity of mineralogy, petrography, and isotope and organic chemistry, resulting from a complex formation history of the parent body surface. That diversity is quickly masked by alteration once in the terrestrial environment but will need to be considered when samples returned by missions to C-class asteroids are interpreted.

Air pollution, oxidative stress, and Alzheimer's disease.

Abstract: Alzheimer's disease (AD) is the most common form of dementia affecting millions of people worldwide and will continue to affect millions more with population aging on the rise. AD causality is multifactorial. Known causal factors include genetic predisposition, age, and sex. Environmental toxins such as air pollution (AP) have also been implicated in AD causation. Exposure to AP can lead to chronic oxidative stress (OS), which is involved in the pathogenesis of AD. Whereas AP plays a role in AD pathology, the epidemiological evidence for this association is limited. Given the significant prevalence of AP exposure combined with increased population aging, epidemiological evidence for this link is important to consider. In this paper, we examine the existing evidence supporting the relationship between AP, OS, and AD and provide recommendations for future research on the population level, which will provide evidence in support of public health interventions.

Double-ended calibration of fiber-optic Raman spectra distributed temperature sensing data

Abstract: Over the past five years, Distributed Temperature Sensing (DTS) along fiber optic cables using Raman backscattering has become an important tool in the environmental sciences. Many environmental applications of DTS demand very accurate temperature measurements, with typical RMSE < 0.1 K. The aim of this paper is to describe and clarify the advantages and disadvantages of double-ended calibration to achieve such accuracy under field conditions. By measuring backscatter from both ends of the fiber optic cable, one can redress the effects of differential attenuation, as caused by bends, splices, and connectors. The methodological principles behind the double-ended calibration are presented, together with a set of practical considerations for field deployment. The results from a field experiment are presented, which show that with double-ended calibration good accuracies can be attained in the field.