bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular hyperdiversity and evolution in very large populations
Authors: Cutter Asher D. , Jovelin Richard , Dey Alivia
Published: March 2013

The genomic density of sequence polymorphisms critically affects the sensitivity of inferences about ongoing sequence evolution, function and demographic history. Most animal and plant genomes have relatively low densities of polymorphisms, but some species are hyperdiverse with neutral nucleotide heterozygosity exceeding 5%. Eukaryotes with extremely large populations, mimicking bacterial and viral populations, present novel opportunities for studying molecular evolution in sexually reproducing taxa with complex development. In particular, hyperdiverse species can help answer controversial questions about the evolution of genome complexity, the limits of natural selection, modes of adaptation and subtleties of the mutation process. However, such systems have some inherent complications and here we identify topics in need of theoretical developments. Close relatives of the model organismsCaenorhabditis elegansandDrosophila melanogasterprovide known examples of hyperdiverse eukaryotes, encouraging functional dissection of resulting molecular evolutionary patterns. We recommend how best to exploit hyperdiverse populations for analysis, for example, in quantifying the impact of noncrossover recombination in genomes and for determining the identity and micro‐evolutionary selective pressures on noncoding regulatory elements.
Paths to selection on life history loci in different natural environments across the native range of Arabidopsis thaliana
Authors: Fournier‐Level Alexandre , Wilczek Amity M. , Cooper Martha D. , Roe Judith L. , Anderson Jillian , Eaton Deren , Moyers Brook T. , Petipas Renee H. , Schaeffer Robert N. , Pieper Bjorn , Reymond Matthieu , Koornneef Maarten , Welch Stephen M. , Remington David L. , Schmitt Johanna
Published: March 2013

Selection on quantitative trait loci (QTL) may vary among natural environments due to differences in the genetic architecture of traits, environment‐specific allelic effects or changes in the direction and magnitude of selection on specific traits. To dissect the environmental differences in selection on life history QTL across climatic regions, we grew a panel of interconnected recombinant inbred lines (RILs) of Arabidopsis thaliana in four field sites across its native European range. For each environment, we mapped QTL for growth, reproductive timing and development. Several QTL were pleiotropic across environments, three colocalizing with known functional polymorphisms in flowering time genes (CRY2, FRI and MAF2‐5), but major QTL differed across field sites, showing conditional neutrality. We used structural equation models to trace selection paths from QTL to lifetime fitness in each environment. Only three QTL directly affected fruit number, measuring fitness. Most QTL had an indirect effect on fitness through their effect on bolting time or leaf length. Influence of life history traits on fitness differed dramatically across sites, resulting in different patterns of selection on reproductive timing and underlying QTL. In two oceanic field sites with high prereproductive mortality, QTL alleles contributing to early reproduction resulted in greater fruit production, conferring selective advantage, whereas alleles contributing to later reproduction resulted in larger size and higher fitness in a continental site. This demonstrates how environmental variation leads to change in both QTL effect sizes and direction of selection on traits, justifying the persistence of allelic polymorphism at life history QTL across the species range.
Functional genomic and phenotypic responses to desiccation in natural populations of a desert drosophilid
Authors: Rajpurohit Subhash , Oliveira Cássia C. , Etges William J. , Gibbs Allen G.
Published: March 2013

We used whole‐transcriptome microarrays to assess changes in gene expression and monitored mortality rates and epicuticular hydrocarbons (CHCs) in response to desiccation stress in four natural populations of Drosophila mojavensis from Baja California and mainland Mexico. Desiccation had the greatest effect on gene expression, followed by biogeographical variation at regional and population levels. Genes involved in environmental sensing and cuticular structure were up‐regulated in dry conditions, while genes involved in transcription itself were down‐regulated. Flies from Baja California had higher expression of reproductive and mitochondrial genes, suggesting that these populations have greater fecundity and higher metabolic rates. Host plant differences had a surprisingly minor effect on the transcriptome. In most cases, desiccation‐caused mortality was greater in flies reared on fermenting cactus tissues than that on laboratory media. Water content of adult females and males was significantly different and was lower in Baja California males. Different groups of CHCs simultaneously increased and decreased in amounts due to desiccation exposure of 9 and 18 h and were population‐specific and dependent on larval rearing substrates. Overall, we observed that changes in gene expression involved a coordinated response of behavioural, cuticular and metabolic genes. Together with differential expression of cuticular hydrocarbons, this study revealed some of the mechanisms that have allowed D. mojavensis to exploit its harsh desert conditions. Certainly, for D. mojavensis that uses different host plants, population‐level understanding of responses to stressors associated with future climate change in desert regions must be evaluated across geographical and local ecological scales.
Fleas associated with non‐flying small mammal communities from northern and central Chile: with new host and locality records
Authors: BAZÁN‐LEÓN E. A. , LARESCHI M. , SANCHEZ J. , SOTO‐NILO G. , LAZZONI I. , VENEGAS C. I. , POBLETE Y. , VÁSQUEZ R. A.
Published: March 2013

Fleas associated with small mammals from seven localities from northern and central Chile were assessed. We captured 352 small mammals belonging to 12 species from which we obtained 675 fleas belonging to 15 different species. The most frequently captured flea species wereNeotyphloceras crassispina crassispina(n = 198) andN. chilensis(n = 175). High values of flea species richness and diversity were found in Fray Jorge National Park (NP), a north‐central Chilean site, whereas the highest values of mean abundance (MA) and prevalence were found in three diverse sites that include Los Molles River, a high altitude site located in north‐central Chile, Fray JorgeNPand Dichato, in south‐central Chile. On the other hand, high values of flea richness and diversity were found on two rodent species,Abrothrix olivaceaandA. longipilis, whereas the highest values ofMAand prevalence were found onOligoryzomys longicaudatus,A. longipilisandPhyllotis xanthopygus. A total of three new host recordings, nine new localities and nine new host species and locality recordings are reported. Also, this study represents the first known record ofTetrapsyllus(Tetrapsyllus)comisin Chile and the first ecological analysis ofNeotyphloceras chilensis.
Utility of galactomannan antigen detection in bronchoalveolar lavage fluid in immunocompromised patients
Authors: Brownback Kyle R. , Pitts Lucas R. , Simpson Steven Q.
Published: March 2013

Diagnosis of invasive pulmonary aspergillosis (IPA) is a challenging process in immunocompromised patients. Galactomannan (GM) antigen detection in bronchoalveolar lavage (BAL) fluid is a method to detect IPA with improved sensitivity over conventional studies. We sought to determine the diagnostic yield of BAL GM assay in a diverse population of immunocompromised patients. A retrospective review of 150 fiberoptic bronchoscopy (FOB) with BAL for newly diagnosed pulmonary infiltrate in immunocompromised patients was performed. Patient information, procedural details and laboratory studies were collected. BAL and serum samples were evaluated for GM using enzyme‐linked immunoassay. Of 150 separate FOB with BAL, BAL GM was obtained in 143 samples. There were 31 positive BAL GM assays. In those 31 positive tests, 13 were confirmed as IPA, giving a positive predictive value of 41.9%. There was one false negative BAL GM. Of the 18 false positive BAL GM, 4 were receiving piperacillin–tazobactam and 11 were receiving an alternative beta‐lactam antibiotic. BAL GM assay shows excellent sensitivity for diagnosing IPA. There was a significant number of false positive BAL GM assays and several of those patients were receiving beta‐lactam antibiotics at the time of bronchoscopy.
SUB1A‐mediated submergence tolerance response in rice involves differential regulation of the brassinosteroid pathway
Authors: Schmitz Aaron J. , Folsom Jing J. , Jikamaru Yusuke , Ronald Pamela , Walia Harkamal
Published: March 2013

Submergence 1A (SUB1A), is an ethylene response factor (ERF) that confers submergence tolerance in rice (Oryza sativa) via limiting shoot elongation during the inundation period. SUB1A has been proposed to restrict shoot growth by modulating gibberellic acid (GA) signaling.

Our transcriptome analysis indicated that SUB1A differentially regulates genes associated with brassinosteroid (BR) synthesis during submergence. Consistent with the gene expression data, the SUB1A genotype had higher brassinosteroid levels after submergence compared to the intolerant genotype. Tolerance to submergence can be activated in the intolerant genotype by pretreatment with exogenous brassinolide, which results in restricted shoot elongation during submergence.

BR induced a GA catabolic gene, resulting in lower GA levels in SUB1A plants. BR treatment also induced the DELLA protein SLR1, a known repressor of GA responses such as shoot elongation. We propose that BR limits GA levels during submergence in the SUB1A rice through a GA catabolic enzyme as part of an early response and may repress GA responses by inducing SLR1 after several days of submergence.

Our results suggest that BR biosynthesis is regulated in a SUB1A‐dependent manner during submergence and is involved in modulating the GA signaling and homeostasis.
Photosynthetic performance of submerged macrophytes from lowland stream and lake habitats with contrasting CO2 availability
Authors: Baattrup‐Pedersen Annette , Madsen Tom Vindbæk , Riis Tenna , Cavalli Giulia
Published: March 2013

We examine the photosynthetic response of submerged plants from streams and lakes with contrasting free‐CO2 and nitrogen (N) availability. We hypothesized that: the photosynthetic capacity of stream plants is higher because of higher N availability; the photosynthetic N‐use efficiency (PNUE) is also higher because stream plants are acclimated to higher free‐CO2; and PNUE is lower in aquatic compared to terrestrial plants.

We tested these hypotheses by measuring tissue‐N, photosynthetic capacity and inorganic C extraction capacity in plants collected from streams and lakes and by comparing the PNUE of aquatic plants with previously published PNUE of terrestrial plants.

We found that the organic N content was consistently higher in stream (3.8–6.3% w/w) than in lake plants (1.2–4.3% w/w). The photosynthetic capacity correlated positively with tissue‐N. The relationships were similar for stream and lake plants, indicating that N allocation patterns were similar despite variability in free‐CO2 between the two habitats.

The slope of the relationship between photosynthetic capacity and tissue‐N was lower than found for terrestrial plants, whereas the compensatory N content for photosynthesis was similar. This suggests that PNUE is lower in aquatic plants, perhaps reflecting that the selection pressure for a high C fixation rate per unit N is reduced as a result of low inorganic C availability in the aquatic environment.
Zinc Finger Protein 6 (ZFP6) regulates trichome initiation by integrating gibberellin and cytokinin signaling in Arabidopsis thaliana
Authors: Zhou Zhongjing , Sun Lili , Zhao Yongqin , An Lijun , Yan An , Meng Xiaofang , Gan Yinbo
Published: March 2013

The Arabidopsis trichome is a model system for studying cell development, cell differentiation and the cell cycle in plants. Our previous studies have shown that the ZINC FINGER PROTEIN5 (ZFP5) controls shoot maturation and epidermal cell fate through GA signaling in Arabidopsis.

We have identified a novel C2H2 zinc finger protein ZINC FINGER PROTEIN 6 (ZFP6) which plays a key role in regulating trichome development in Arabidopsis.

Overexpression of ZFP6 results in ectopic trichomes on carpels and other inflorescence organs. Gain‐ and loss‐of‐function analyses have shown that the zfp6 mutant exhibits a reduced number of trichomes in sepals of flowers, cauline leaves, lateral branch and main inflorescence stems in comparison to wild‐type plants.

Molecular and genetic analyses suggest that ZFP6 functions upstream of GIS, GIS2, ZFP8, ZFP5 and key trichome initiation regulators GL1 and GL3.We reveal that ZFP6 and ZFP5 mediate the regulation of trichome initiation by integrating GA and cytokinin signaling in Arabidopsis. These findings provide new insights into the molecular mechanism of plant hormone control of epidermal trichome patterning through C2H2 transcriptional factors.
Silicon alleviates iron deficiency in cucumber by promoting mobilization of iron in the root apoplast
Authors: Pavlovic Jelena , Samardzic Jelena , Maksimović Vuk , Timotijevic Gordana , Stevic Nenad , Laursen Kristian H. , Hansen Thomas H. , Husted Søren , Schjoerring Jan K. , Liang Yongchao , Nikolic Miroslav
Published: March 2013

Root responses to lack of iron (Fe) have mainly been studied in nutrient solution experiments devoid of silicon (Si). Here we investigated how Si ameliorates Fe deficiency in cucumber (Cucumis sativus) with focus on the storage and utilization of Fe in the root apoplast.

A combined approach was performed including analyses of apoplastic Fe, reduction‐based Fe acquisition and Fe‐mobilizing compounds in roots along with the expression of related genes.

Si‐treated plants accumulated higher concentrations of root apoplastic Fe, which rapidly decreased when Fe was withheld from the nutrient solution. Under Fe‐deficient conditions, Si also increased the accumulation of Fe‐mobilizing compounds in roots. Si supply stimulated root activity of Fe acquisition at the early stage of Fe deficiency stress through regulation of gene expression levels of proteins involved in Fe acquisition. However, when the period of Fe deprivation was extended, these reactions further decreased as a consequence of Si‐induced enhancement of the Fe status of the plants.

This work provides new evidence for the beneficial role of Si in plant nutrition and clearly indicates that Si‐mediated alleviation of Fe deficiency includes an increase of the apoplastic Fe pool in roots and an enhancement of Fe acquisition.
Functional dissection of the PROPEP2 and PROPEP3 promoters reveals the importance of WRKY factors in mediating microbe‐associated molecular pattern‐induced expression
Authors: Logemann Elke , Birkenbihl Rainer P. , Rawat Vimal , Schneeberger Korbinian , Schmelzer Elmon , Somssich Imre E.
Published: March 2013

In Arabidopsis thaliana, small peptides (AtPeps) encoded by PROPEP genes act as damage‐associated molecular patterns (DAMPs) that are perceived by two leucine‐rich repeat receptor kinases, PEPR1 and PEPR2, to amplify defense responses. In particular, expression of PROPEP2 and PROPEP3 is strongly and rapidly induced by AtPeps, in response to bacterial, oomycete, and fungal pathogens, and microbe‐associated molecular patterns (MAMPs).

The cis‐regulatory modules (CRMs) within the PROPEP2 and PROPEP3 promoters that mediate MAMP responsiveness were delineated, employing parsley (Petroselinum crispum) protoplasts and transgenic A. thaliana plants harboring promoter‐reporter constructs. By chromatin immunoprecipitation in vivo, DNA interactions with a specific transcription factor were detected. Furthermore, the phastCons program was used to identify conserved regions of the PROPEP3 locus in different Brassicaceae species.

The major MAMP‐responsive CRM within the PROPEP2 promoter is composed of several W boxes and an as1/OCS (activation sequence‐1/octopine synthase) enhancer element, while in the PROPEP3 promoter the CRM is comprised of six W boxes. The WRKY33 transcription factor binds in vivo to these promoter regions in a MAMP‐dependent manner. Both the position and orientation of the six W boxes are conserved within the PROPEP3 promoters of four other Brassicaceae family members.

WRKY factors are the major regulators of MAMP‐induced PROPEP2 and PROPEP3 expression.
Combined phosphate and nitrogen limitation generates a nutrient stress transcriptome favorable for arbuscular mycorrhizal symbiosis in Medicago truncatula
Authors: Bonneau Laurent , Huguet Stéphanie , Wipf Daniel , Pauly Nicolas , Truong Hoai‐Nam
Published: March 2013

Arbuscular mycorrhizal (AM) symbiosis is stimulated by phosphorus (P) limitation and contributes to P and nitrogen (N) acquisition. However, the effects of combined P and N limitation on AM formation are largely unknown.

Medicago truncatula plants were cultivated in the presence or absence of Rhizophagus irregularis (formerly Glomus intraradices) in P‐limited (LP), N‐limited (LN) or combined P‐ and N‐limited (LPN) conditions, and compared with plants grown in sufficient P and N.

The highest AM formation was observed in LPN, linked to systemic signaling by the plant nutrient status. Plant free phosphate concentrations were higher in LPN than in LP, as a result of cross‐talk between P and N. Transcriptome analyses suggest that LPN induces the activation of NADPH oxidases in roots, concomitant with an altered profile of plant defense genes and a coordinate increase in the expression of genes involved in the methylerythritol phosphate and isoprenoid‐derived pathways, including strigolactone synthesis genes.

Taken together, these results suggest that low P and N fertilization systemically induces a physiological state of plants favorable for AM symbiosis despite their higher P status. Our findings highlight the importance of the plant nutrient status in controlling plant–fungus interaction.
Chromium supplementation in overweight and obesity: a systematic review and meta‐analysis of randomized clinical trials
Authors: Onakpoya I. , Posadzki P. , Ernst E.
Published: March 2013

The increased prevalence of obesity has made the use of dietary supplements as weight reducing agents highly popular, but their efficacy has not been proven. One such supplement is chromium. The purpose of this review was to evaluate the evidence for or against the efficacy of chromium supplementation in overweight and obese individuals. Electronic searches were conducted in Medline, Embase, Amed and The Cochrane Library. The bibliographies of located articles were also searched. No age, gender or language restrictions were imposed. The reporting quality of identified randomized clinical trials (RCTs) was assessed using a methodological checklist adapted from the Consolidated Standard of Reporting Trials Statement and Preferred Reporting Items for Systematic Reviews and Meta‐Analyses guidelines. Thirty‐nine trials were identified and 20 were included. There were variations in reporting quality of included studies. A meta‐analysis of 11 studies showed a statistically significant difference in weight loss favouring chromium over placebo (mean difference (MD): −0.50 kg; 95% confidence interval (CI): −0.97, −0.03). There was a high statistical heterogeneity. Adverse events included watery stools, vertigo, headaches and urticaria. The evidence from available RCTs shows that chromium supplementation generates statistically significant reductions in body weight. The magnitude of the effect is small, and the clinical relevance is uncertain. Future trials should last at least 16 weeks and greater uniformity in the measuring and assessment tools for body composition is recommended.
Adiponectin and incident coronary heart disease and stroke. A systematic review and meta‐analysis of prospective studies
Authors: Kanhai D. A. , Kranendonk M. E. , Uiterwaal C. S. P. M. , van der Graaf Y. , Kappelle L. J. , Visseren F. L. J.
Published: March 2013

The plasma concentration of adiponectin, an adipokine that has anti‐inflammatory, anti‐atherogenic and insulin sensitizing properties, is lower in obese subjects and could therefore be a target for therapy. In order to review and meta‐analyse prospective cohort studies investigating adiponectin concentration and the risk for incident coronary heart disease (CHD) or stroke, a systematic search of MEDLINE, EMBASE and Cochrane databases was performed. Two independent reviewers selected prospective cohort studies investigating the relationship between adiponectin level and incident CHD or stroke using ‘adiponectin’ and ‘cardiovascular disease’ or ‘stroke’ and their synonyms, excluding patients with clinically manifest vascular disease. Random‐effects models were used to calculate pooled relative risks (RRs) and 95% confidence intervals (95% CI). Generalized least squares regression was used to assess dose–response relationships for adiponectin concentrations from studies that provided RRs solely based upon categorical data regression. In total, 16 prospective cohort studies, comprising 23,919 patients and 6,870 CHD or stroke outcome events, were included in the meta‐analyses. An increase of 1 standard deviation in log‐transformed adiponectin did not lower the risk for CHD (RR 0.97; 95% CI 0.86–1.09). A 10 μg mL–1 increase in adiponectin conferred a RR of 0.91 (95% CI 0.80–1.03) for CHD and a RR 1.01 (95% CI 0.97–1.06) for stroke. In conclusion, plasma adiponectin is not related to the risk for incident CHD or stroke.
Oral manifestations and their treatment in Sjögren′s syndrome
Authors: González S , Sung H , Sepúlveda D , González MJ , Molina C
Published: March 2013

Sjögren's syndrome (SS) is a complex, chronic, systemic, autoimmune disease that mainly affects the exocrine glands, especially the salivary and lacrimal glands, leading to dryness of the oral and ocular mucosae. Several factors have been studied that could explain the glandular hypofunction primarily related to water transport. Recent reports have shown alterations in secretory route and trafficking in labial salivary glands, explaining alterations in the saliva quality. The decrease in salivary flow and qualitative alterations in saliva could explain many of the oral manifestations. The exocrine manifestations and systemic involvement significantly impact the patient's perception of health‐related quality of life. For this reason and given its systemic nature, the treatment of these patients should be multidisciplinary. This review addresses some particular oral health aspects of SS patients and focuses on relevant topics concerning the treatment and prevention of common oral disorders associated with this disease.
Distorted Transmissions. Towards a Material Reading of Thomas Pynchon's The Crying of Lot 49
Authors: Andersen Tore Rye
Published: March 2013

Drawing on various theories of the materiality and mediality of literature, the essay argues that a focus on the material history of any given literary work can provide a more nuanced understanding of various literary historical processes than traditional textual analysis. Taking different physical editions of Thomas Pynchon's The Crying of Lot 49 as its starting point, the essay traces the constantly evolving exchanges between the progressive material incarnations of Pynchon's novel and the cultural context, laying bare some of the complex literary historical, cultural, and institutional processes that contributed to the canonization of The Crying of Lot 49.
Modernism Becomes Contrapuntal. Eeva‐Liisa Manner's Poetic Intermediality
Authors: Kaunonen Leena
Published: March 2013

Eeva‐Liisa Manner (1921–1995), a prominent Finnish poet, made her modernist breakthrough after the Second World War. By focusing on Manner's poetic musicalization of literature I will offer an example of how Finnish modernism became contrapuntal. To understand the aesthetics of Manner, it is informative to place it against the background of modernism's interest in the phenomenon of intermediality that has contributed to the writing of modernist poetry associated with music. It is equally important to examine the impact of cultural periodicals that contributed to making intermedial vocabulary known to readers and thus helped in disseminating new trends across the domestic cultural scene. I also situate Manner's poetics in relation to T. S. Eliot's musical analogies. Finally, the interpretations of Manner's poems entitledBachandThe Chromatic Levelswill sum up my examination of Manner's preoccupation with adapting international models for the musicalization of literature.
Fasciola hepatica tegumental coat antigen suppresses MAPK signalling in dendritic cells and up‐regulates the expression of SOCS3
Authors: Vukman K. V. , Adams P. N. , O'Neill S. M.
Published: March 2013

Fasciola hepatica tegumental coat antigen (FhTeg) suppresses dendritic cell maturation and function by inhibiting IL‐6, tumour necrosis factor (TNF)‐α, IL‐10 and IL‐12 production and CD80, CD86 and CD40 cell surface marker expression in TLR4‐stimulated dendritic cells. Fasciola hepatica also impairs dendritic cell function by inhibiting its phagocytic capacity and its ability to prime T cells. We have shown previously that activation of mast cells with bacterial ligands is also inhibited by FhTeg. Fasciola hepatica suppresses LPS‐induced NF‐κB and MAPK pathway (ERK) activation in these cells. Previously, we demonstrated that FhTeg induces expression of suppressor of cytokine signalling (SOCS)3, a negative regulator of the TLR pathway in mast cells. In this study, we show the same inhibitory effect of FhTeg on the activation of the other members of the MAPKs pathway (ERK, p38, JNK) in dendritic cells and demonstrate an enhanced expression of SOCS3, but not SOCS1, SOCS5 or PIAS3 in this process. These studies enhance our understanding of the immunomodulatory effect of helminth molecules on the TLR pathway.
Organic matter fractions and N mineralization in vegetable‐cropped sandy soils
Authors: Jegajeevagan K. , Sleutel S. , Ameloot N. , Kader M. A. , De Neve S.
Published: March 2013

Soil organic nitrogen mineralization rates and possible predictors thereof were investigated for vegetable‐growing soils in Belgium. Soil organic matter (SOM) was fractionated into sand (> 53 μm) and silt+clay (< 53 μm) fractions. The latter fraction was further separated into 6%NaOCl‐oxidation labile (6%NaOCl‐ox) and resistant N and C and subsequently into 10%HF‐extractable (mineral bound) and resistant (recalcitrant) N and C. The N mineralization turnover rate (% of soil N/year) correlated with several of the investigated N or C fractions and stepwise linear regression confirmed that the 6%NaOCl‐ox N was the best predictor. However, the small R² (0.42) of the regression model suggests that soil parameters other than the soil fractions isolated here would be required to explain the significant residual variation in N mineralization rate. A next step could be to look for alternative SOM fractionations capable of isolating bioavailable N. However, it would appear that the observed relationships between N fractions and N mineralization may not be causal but indirect. The number of vegetable crops per rotation did not influence N mineralization, but it did influence 6%NaOCl‐ox N, probably as an effect of differences in crop residues returned and organic manure supply. However, the nature of this relation between management, SOM quality and N mineralization is not clear. Explanation of correlations between N mineralization and presumed bioavailable N fractions, like the 6%NaOCl‐ox N, requires further mechanistic elucidation of the N mineralization process.
Tourism, modernity and the consumption of home in China
Authors: Su Xiaobo
Published: March 2013

Tourists have long been neglected in the literature on home and mobility, although they constitute a massive mobile population within and across national borders. Addressing this gap, this paper advances geography's critical engagement with home in relation to mobility and modernity, and questions the binary distinction between home and unhomeliness in tourist mobility. It focuses on the alienation of Chinese modernity and how one group of domestic tourists negotiates this alienation through their imagination and consumption of home in a popular tourist site (i.e. Lijiang, a World Heritage site in Yunnan province) within the context of China's transformation, which started in 1978. This paper has two objectives. First, it examines why home is woven into the touristic imagination of Lijiang; and second, it links tourists' personal experiences with China's broad sociospatial transformation in order to explore individuals' resistance against and compliance with modernity. I argue that the imagination and consumption of home generates intensely contradictory configurations of struggle that simultaneously push tourists towards an ideal of home for inner freedom and premodern paradise, yet pull them back into the whirling vortex of ‘modern’ life and commercial forces. The paper sheds light on micro‐geographies of people's lives in the context of China's rapid transformation.
NORMAL REGIONAL DISTRIBUTION OF CEREBRAL BLOOD FLOW IN DOGS: COMPARISON BETWEEN 99mTc‐ETHYLCYSTEINATE DIMER AND 99mTc‐ HEXAMETHYLPROPYLENE AMINE OXIME SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY
Authors: Adriaens Antita , Polis Ingeborgh , Waelbers Tim , Vandermeulen Eva , Dobbeleir André , De Spiegeleer Bart , Peremans Kathelijne
Published: March 2013

Functional imaging provides important insights into canine brain pathologies such as behavioral problems. Two 99mTc‐labeled single photon emission computed tomography (SPECT) cerebral blood flow tracers—ethylcysteinate dimer (ECD) and hexamethylpropylene amine oxime (HMPAO)—are commonly used in human medicine and have been used previously in dogs but intrasubject comparison of both tracers in dogs is lacking. Therefore, this study investigated whether regional distribution differences between both tracers occur in dogs as is reported in humans. Eight beagles underwent two SPECT examinations first with 99mTc‐ECD and followed by 99mTc‐HMPAO. SPECT scanning was performed with a triple head gamma camera equipped with ultrahigh resolution parallel hole collimators. Images were reconstructed using filtered backprojection with a Butterworth filter. Emission data were fitted to a template permitting semiquantification using predefined regions or volumes of interest (VOIs). For each VOI, perfusion indices were calculated by normalizing the regional counts per voxel to total brain counts per voxel. The obtained perfusion indices for each region for both tracers were compared with a paired Student's T‐test. Significant (P < 0.05) regional differences were seen in the subcortical region and the cerebellum. Both tracers can be used to visualize regional cerebral blood flow in dogs, however, due to the observed regional differences, they are not entirely interchangeable.
IMAGING DIAGNOSIS—AORTIC ANEURYSM AND URETERAL OBSTRUCTION SECONDARY TO UMBILICAL ARTERY ABSCESSATION IN A 5‐WEEK‐OLD FOAL
Authors: Nogradi Nora , Magdesian K. Gary , Whitcomb Mary Beth , Church Molly , Spriet Mathieu
Published: March 2013

A 5‐week‐old foal was evaluated for fever and hematuria of 3 days duration. Cystoscopy localized the blood to be originating from the left ureter. Abdominal ultrasonography revealed left hydronephrosis, hydroureter, and omphaloarteritis of the left umbilical artery with abscess formation that communicated with an arterial structure. Computed tomography (CT) revealed a large aortic aneurysm within the center of the abscess. An exploratory celiotomy was performed and the infection was nonresectable. The prognosis for life was grave; therefore the colt was euthanized. Necropsy findings confirmed the antemortem diagnosis. Ultrasound and CT imaging in this case provided an accurate antemortem diagnosis.
Filtering free resolutions
Authors: Eisenbud David , Erman Daniel , Schreyer Frank-Olaf
Published: March 2013

A recent result of Eisenbud–Schreyer and Boij–Söderberg proves that the Betti diagram of any graded module decomposes as a positive rational linear combination of pure diagrams. When does this numerical decomposition correspond to an actual filtration of the minimal free resolution? Our main result gives a sufficient condition for this to happen. We apply it to show the non-existence of free resolutions with some plausible-looking Betti diagrams and to study the semigroup of quiver representations of the simplest ‘wild’ quiver.
Koszul, Ringel and Serre duality for strict polynomial functors
Authors: Krause Henning
Published: March 2013

This is a report on recent work of Chałupnik and Touzé. We explain the Koszul duality for the category of strict polynomial functors and make explicit the underlying monoidal structure which seems to be of independent interest. Then we connect this to Ringel duality for Schur algebras and describe Serre duality for strict polynomial functors.
Versatile Rb vapor cells with long lifetimes
Authors: Hulbert John F. , Giraud-Carrier Matthieu , Wall Tom , Hawkins Aaron R. , Bergeson Scott , Black Jennifer , Schmidt Holger
Published: March 2013

The authors report on an approach to the construction of long-lasting rubidium atomic vapor cells. The method uses pinch-off copper cold-welds, low temperature solders, and electroplated copper to create long-lasting hermetic seals between containment chambers of dissimilar geometries and materials. High temperature epoxy, eutectic lead/tin solder, and indium solder were considered as sealing materials. These seals were analyzed using accelerated lifetime testing techniques. Vapor cells with epoxy and bare metal solder seals had a decrease in the rubidium atomic density within days after being heated to elevated temperatures. They also exhibited broadened spectra as a result of rubidium reacting with the seals. However, indium solder seals with a passivation coating of electroplated copper did not exhibit a significant decrease in linewidth or atomic density after being held at 95 °C for 30 days. The authors conclude that this particular seal has no rubidium chemical reaction failure mode and when used in combination with copper cold welding has the potential to create multiplatform vapor cells with extremely long lifetimes.
A method to measure paddle and detector pressures and footprints in mammography
Authors: Hogg Peter , Szczepura Katy , Darlington Alison , Maxwell Anthony
Published: March 2013

Purpose:

Compression is necessary in mammography to improve image quality and reduce radiation burden. Maximizing the amount of breast in contact with the image receptor (IR) is important. To achieve this, for the craniocaudal projection, there is no consensus within the literature regarding how the IR should be positioned relative to the inframammary fold (IMF). No information exists within the literature to describe how pressure balancing between IR and paddle, and IR breast footprint, might be optimized. This paper describes a novel method for measuring the respective pressures applied to the breast from the IR and the paddle and a method to simultaneously measure the breast footprints on the IR and the paddle.

Methods:

Using a deformable breast phantom and electronic pressure‐sensitive mat, area and pressure readings were gathered from two mammography machines and four paddles at 60, 80, and 100 N with the IR positioned at −2, −1, 0, +1, and +2 cm relative to the IMF (60 combinations in total).

Results:

Paddle and IR footprints were calculated along with a uniformity index (UI). For all four paddle/machine/pressure combinations the greatest IR footprint was achieved at IMF +2 cm. The UI indicates that the best pressure/footprint balance is achieved at IMF +1 cm.

Conclusions:

The authors’ method appears to be suited to measuring breast footprints and pressures on IR and paddle and a human female study is planned.
Microionization chamber air‐kerma calibration coefficients as a function of photon energy for x‐ray spectra in the range of 20–250 kVp relative to 60Co
Authors: Snow J. R. , Micka J. A. , DeWerd L. A.
Published: March 2013

Purpose:

To investigate the applicability of a wide range of microionization chambers for reference dosimetry measurements in low‐ and medium‐energy x‐ray beams.

Methods:

Measurements were performed with six cylindrical microchamber models, as well as one scanning chamber and two Farmer‐type chambers for comparison purposes. Air‐kerma calibration coefficients were determined at the University of Wisconsin Accredited Dosimetry Calibration Laboratory for each chamber for a range of low‐ and medium‐energy x‐ray beams (20–250 kVp), with effective energies ranging from 11.5 keV to 145 keV, and a60Co beam. A low‐Z proof‐of‐concept microchamber was developed and calibrated with and without a high‐Z silver epoxy on the collecting electrode.

Results:

All chambers composed of low‐Z materials (Z ≤ 13), including the Farmer‐type chambers, the scanning chamber, and the PTW TN31014 and the proof‐of‐concept microchambers, exhibited air‐kerma calibration coefficients with little dependence on the quality of the beam. These chambers typically exhibited variations in calibration coefficients of less than 3% with the beam quality, for medium energy beams. However, variations in air‐kerma calibration coefficients of greater than 50% were measured over the range of medium‐energy x‐ray beams for each of the microchambers containing high‐Z collecting electrodes (Z > 13). For these high‐Z chambers, which include the Exradin A14SL and A16 chambers, the PTW TN31006 chamber, the IBA CC01 chamber, and the proof‐of‐concept chamber containing silver, the average variation in air‐kerma calibration coefficients between any two calibration beams was nearly 25% over the entire range of beam qualities investigated.

Conclusions:

Due to the strong energy dependence observed with microchambers containing high‐Z components, these chambers may not be suitable dosimeters for kilovoltage x‐ray applications, as they do not meet the TG‐61 requirements. It is recommended that only microchambers containing low‐Z materials (Z ≤ 13) be considered for air‐kerma calibrations for reference dosimetry in low‐ and medium‐energy x‐ray beams.
Prediction of human observer performance in a 2‐alternative forced choice low‐contrast detection task using channelized Hotelling observer: Impact of radiation dose and reconstruction algorithms
Authors: Yu Lifeng , Leng Shuai , Chen Lingyun , Kofler James M. , Carter Rickey E. , McCollough Cynthia H.
Published: March 2013

Purpose:

Efficient optimization of CT protocols demands a quantitative approach to predicting human observer performance on specific tasks at various scan and reconstruction settings. The goal of this work was to investigate how well a channelized Hotelling observer (CHO) can predict human observer performance on 2‐alternative forced choice (2AFC) lesion‐detection tasks at various dose levels and two different reconstruction algorithms: a filtered‐backprojection (FBP) and an iterative reconstruction (IR) method.

Methods:

A 35 × 26 cm2 torso‐shaped phantom filled with water was used to simulate an average‐sized patient. Three rods with different diameters (small: 3 mm; medium: 5 mm; large: 9 mm) were placed in the center region of the phantom to simulate small, medium, and large lesions. The contrast relative to background was −15 HU at 120 kV. The phantom was scanned 100 times using automatic exposure control each at 60, 120, 240, 360, and 480 quality reference mAs on a 128‐slice scanner. After removing the three rods, the water phantom was again scanned 100 times to provide signal‐absent background images at the exact same locations. By extracting regions of interest around the three rods and on the signal‐absent images, the authors generated 21 2AFC studies. Each 2AFC study had 100 trials, with each trial consisting of a signal‐present image and a signal‐absent image side‐by‐side in randomized order. In total, 2100 trials were presented to both the model and human observers. Four medical physicists acted as human observers. For the model observer, the authors used a CHO with Gabor channels, which involves six channel passbands, five orientations, and two phases, leading to a total of 60 channels. The performance predicted by the CHO was compared with that obtained by four medical physicists at each 2AFC study.

Results:

The human and model observers were highly correlated at each dose level for each lesion size for both FBP and IR. The Pearson's product‐moment correlation coefficients were 0.986 [95% confidence interval (CI): 0.958–0.996] for FBP and 0.985 (95% CI: 0.863–0.998) for IR. Bland‐Altman plots showed excellent agreement for all dose levels and lesions sizes with a mean absolute difference of 1.0% ± 1.1% for FBP and 2.1% ± 3.3% for IR.

Conclusions:

Human observer performance on a 2AFC lesion detection task in CT with a uniform background can be accurately predicted by a CHO model observer at different radiation dose levels and for both FBP and IR methods.
A classroom demonstration of reciprocal space
Authors: Hannibal Madsen Morten , Høpfner Louise , Rasmussen Nina , Stolborg Mikkel , Nygård Jesper , Feidenhans'l Robert , Thomsen Jan W.
Published: March 2013

An array of nanowires and a laser pointer are used for a simple visualization of two-dimensional reciprocal space. The experiment can be performed without any preparation and in any classroom. It aids the teaching of scattering experiments, and illustrates the underlying principles of electron, x-ray, and neutron scattering. A detailed study of the diffraction pattern was performed by mounting the sample with nanowires on a stage designed for x-ray scattering. The setup is well suited for undergraduate students, who get training in sample alignment in a small lab instead of at a large-scale facility. The exact positions of the diffraction spots are calculated and monitored experimentally for a 360° rotation of the sample. By fitting to this set of images, it is possible to determine the lattice vectors of the artificial crystal with an uncertainty of less than 1%.
The pilot-wave perspective on quantum scattering and tunneling
Authors: Norsen Travis
Published: March 2013

The de Broglie-Bohm “pilot-wave” theory replaces the paradoxical wave-particle duality of ordinary quantum theory with a more mundane and literal kind of duality: each individual photon or electron comprises a quantum wave (evolving in accordance with the usual quantum mechanical wave equation) and a particle that, under the influence of the wave, traces out a definite trajectory. The definite particle trajectory allows the theory to account for the results of experiments without the usual recourse to additional dynamical axioms about measurements. Instead, one need simply assume that particle detectors click when particles arrive at them. This alternative understanding of quantum phenomena is illustrated here for two elementary textbook examples of one-dimensional scattering and tunneling. We introduce a novel approach to reconcile standard textbook calculations (made using unphysical plane-wave states) with the need to treat such phenomena in terms of normalizable wave packets. This approach allows for a simple but illuminating analysis of the pilot-wave theory's particle trajectories and an explicit demonstration of the equivalence of the pilot-wave theory predictions with those of ordinary quantum theory.
Coupled second-quantized oscillators
Authors: Bhattacharya M. , Shi H. , Preble S.
Published: March 2013

Second quantization is a powerful technique for describing quantum mechanical processes in which the number of excitations of a single particle is not conserved. A textbook example of second quantization is the presentation of the simple harmonic oscillator in terms of creation and annihilation operators, which, respectively, represent addition or removal of quanta of energy from the oscillator. Our aim in this article is to bolster this textbook example. Accordingly, we explore the physics of coupled second-quantized oscillators. These explorations are phrased as exactly solvable eigenvalue problems, the mathematical structure providing a framework for the physical understanding. The examples we present can be used to enhance the discussion of second-quantized harmonic oscillators in the classroom, to make a connection to the classical physics of coupled oscillators, and to acquaint students with systems employed at the frontiers of contemporary physics research.
Towards the Kelvin wake and beyond
Authors: Likar Andrej , Razpet Nada
Published: March 2013

The difference between wave propagation in dispersive and non-dispersive media can be effectively demonstrated by observing the wave patterns invoked by uniformly moving surface disturbances. Although the dispersion relation of surface waves on water is complicated, there are some frequency intervals where the phase velocity of the waves reduces to the simple power law behavior cp∝ωκ. Among these cases are gravity waves short compared to the depth of the water (κ=−1), short capillary waves (κ=1/3), and long waves in shallow water (κ≈0). Making use of this power-law behavior, we vary the exponent and visualize the smooth transition from a non-dispersive to a dispersive medium.
Distortion product otoacoustic emissions upon ear canal pressurization
Authors: Zebian Makram , Schirkonyer Volker , Hensel Johannes , Vollbort Sven , Fedtke Thomas , Janssen Thomas
Published: March 2013

The purpose of this study was to quantify the change in distortion product otoacoustic emission (DPOAE) level upon ear canal pressurization. DPOAEs were measured on 12 normal-hearing human subjects for ear canal static pressures between −200 and +200 daPa in (50 ± 5) daPa steps. A clear dependence of DPOAE levels on the pressure was observed, with levels being highest at the maximum compliance of the middle ear, and decreasing on average by 2.3 dB per 50 daPa for lower and higher pressures. Ear canal pressurization can serve as a tool for improving the detectability of DPOAEs in the case of middle-ear dysfunction.
Scalable synthesis of the pink gypsy moth Lymantria mathura sex pheromone (–)-mathuralure
Authors: Mowat Jeffrey , Senior James , Kang Baldip , Britton Robert
Published: March 2013

Mathuralure (1) is the major sex pheromone component of the pink gypsy moth Lymantria mathura, a potentially devastating invasive species to North America. To support population monitoring of this moth, a gram-scale synthesis of (–)-mathuralure (1) was developed. This process relies on coupling an alkynyl lithium species with a chloroepoxide and provides access to the natural product in a 10% yield over 10 steps.