bluuebunny/crossref_metadata_2025 huggingface dataset:
Stochastic expression and epigenetic memory at the yeast
HO
promoter
Authors: Zhang Qian , Yoon Youngdae , Yu Yaxin , Parnell Emily J. , Garay Juan Antonio Raygoza , Mwangi Michael M. , Cross Frederick R. , Stillman David J. , Bai Lu
Published: July 2013

Eukaryotic gene regulation usually involves sequence-specific transcription factors and sequence-nonspecific cofactors. A large effort has been made to understand how these factors affect the average gene expression level among a population. However, little is known about how they regulate gene expression in individual cells. In this work, we address this question by mutating multiple factors in the regulatory pathway of the yeast
HO
promoter (
HOpr
) and probing the corresponding promoter activity in single cells using time-lapse fluorescence microscopy. We show that the
HOpr
fires in an “on/off” fashion in WT cells as well as in different genetic backgrounds. Many chromatin-related cofactors that affect the average level of
HO
expression do not actually affect the firing amplitude of the
HOpr
; instead, they affect the firing frequency among individual cell cycles. With certain mutations, the bimodal expression exhibits short-term epigenetic memory across the mitotic boundary. This memory is propagated in “cis” and reflects enhanced activator binding after a previous “on” cycle. We present evidence that the memory results from slow turnover of the histone acetylation marks.
General topology meets model theory, on 𝔭 and 𝔱
Authors: Malliaris Maryanthe , Shelah Saharon
Published: July 2013

Cantor proved in 1874 [Cantor G (1874)
J Reine Angew Math
77:258–262] that the continuum is uncountable, and Hilbert’s first problem asks whether it is the smallest uncountable cardinal. A program arose to study cardinal invariants of the continuum, which measure the size of the continuum in various ways. By Gödel [Gödel K (1939)
Proc Natl Acad Sci USA
25(4):220–224] and Cohen [Cohen P (1963)
Proc Natl Acad Sci USA
50(6):1143–1148], Hilbert’s first problem is independent of ZFC (Zermelo-Fraenkel set theory with the axiom of choice). Much work both before and since has been done on inequalities between these cardinal invariants, but some basic questions have remained open despite Cohen’s introduction of forcing. The oldest and perhaps most famous of these is whether “

,” which was proved in a special case by Rothberger [Rothberger F (1948)
Fund Math
35:29–46], building on Hausdorff [Hausdorff (1936)
Fund Math
26:241–255]. In this paper we explain how our work on the structure of Keisler’s order, a large-scale classification problem in model theory, led to the solution of this problem in ZFC as well as of an a priori unrelated open question in model theory.
Functional genomic screen of human stem cell differentiation reveals pathways involved in neurodevelopment and neurodegeneration
Authors: Zhang Ying , Schulz Vincent P. , Reed Brian D. , Wang Zheng , Pan Xinghua , Mariani Jessica , Euskirchen Ghia , Snyder Michael P. , Vaccarino Flora M. , Ivanova Natalia , Weissman Sherman M. , Szekely Anna M.
Published: July 2013

Human embryonic stem cells (hESCs) can be induced and differentiated to form a relatively homogeneous population of neuronal precursors in vitro. We have used this system to screen for genes necessary for neural lineage development by using a pooled human short hairpin RNA (shRNA) library screen and massively parallel sequencing. We confirmed known genes and identified several unpredicted genes with interrelated functions that were specifically required for the formation or survival of neuronal progenitor cells without interfering with the self-renewal capacity of undifferentiated hESCs. Among these are several genes that have been implicated in various neurodevelopmental disorders (i.e., brain malformations, mental retardation, and autism). Unexpectedly, a set of genes mutated in late-onset neurodegenerative disorders and with roles in the formation of RNA granules were also found to interfere with neuronal progenitor cell formation, suggesting their functional relevance in early neurogenesis. This study advances the feasibility and utility of using pooled shRNA libraries in combination with next-generation sequencing for a high-throughput, unbiased functional genomic screen. Our approach can also be used with patient-specific human-induced pluripotent stem cell-derived neural models to obtain unparalleled insights into developmental and degenerative processes in neurological or neuropsychiatric disorders with monogenic or complex inheritance.
DNA-binding specificity changes in the evolution of forkhead transcription factors
Authors: Nakagawa So , Gisselbrecht Stephen S. , Rogers Julia M. , Hartl Daniel L. , Bulyk Martha L.
Published: July 2013

The evolution of transcriptional regulatory networks entails the expansion and diversification of transcription factor (TF) families. The forkhead family of TFs, defined by a highly conserved winged helix DNA-binding domain (DBD), has diverged into dozens of subfamilies in animals, fungi, and related protists. We have used a combination of maximum-likelihood phylogenetic inference and independent, comprehensive functional assays of DNA-binding capacity to explore the evolution of DNA-binding specificity within the forkhead family. We present converging evidence that similar alternative sequence preferences have arisen repeatedly and independently in the course of forkhead evolution. The vast majority of DNA-binding specificity changes we observed are not explained by alterations in the known DNA-contacting amino acid residues conferring specificity for canonical forkhead binding sites. Intriguingly, we have found forkhead DBDs that retain the ability to bind very specifically to two completely distinct DNA sequence motifs. We propose an alternate specificity-determining mechanism whereby conformational rearrangements of the DBD broaden the spectrum of sequence motifs that a TF can recognize. DNA-binding bispecificity suggests a previously undescribed source of modularity and flexibility in gene regulation and may play an important role in the evolution of transcriptional regulatory networks.
Zinc-finger antiviral protein mediates retinoic acid inducible gene I–like receptor-independent antiviral response to murine leukemia virus
Authors: Lee Hanna , Komano Jun , Saitoh Yasunori , Yamaoka Shoji , Kozaki Tatsuya , Misawa Takuma , Takahama Michihiro , Satoh Takashi , Takeuchi Osamu , Yamamoto Naoki , Matsuura Yoshiharu , Saitoh Tatsuya , Akira Shizuo
Published: July 2013

When host cells are infected by an RNA virus, pattern-recognition receptors (PRRs) recognize the viral RNA and induce the antiviral innate immunity. Toll-like receptor 7 (TLR7) detects the genomic RNA of incoming murine leukemia virus (MLV) in endosomes and mediates the antiviral response. However, the RNA-sensing PRR that recognizes the MLV in the cytosol is not fully understood. Here, we definitively demonstrate that zinc-finger antiviral protein (ZAP) acts as a cytosolic RNA sensor, inducing the degradation of the MLV transcripts by the exosome, an RNA degradation system, on RNA granules. Although the retinoic acid inducible gene I (RIG-I)–like receptors (RLRs) RIG-I and melanoma differentiation-associated protein 5 detect various RNA viruses in the cytosol and induce the type I IFN-dependent antiviral response, RLR loss does not alter the replication efficiency of MLV. In sharp contrast, the loss of ZAP greatly enhances the replication efficiency of MLV. ZAP localizes to RNA granules, where the processing-body and stress-granule proteins assemble. ZAP induces the recruitment of the MLV transcripts and exosome components to the RNA granules. The CCCH-type zinc-finger domains of ZAP, which are RNA-binding motifs, mediate its localization to RNA granules and MLV transcripts degradation by the exosome. Although ZAP was known as a regulator of RIG-I signaling in a human cell line, ZAP deficiency does not affect the RIG-I–dependent production of type I IFN in mouse cells. Thus, ZAP is a unique member of the cytosolic RNA-sensing PRR family that targets and eliminates intracellular RNA viruses independently of TLR and RLR family members.
Evolutionary diversification of the multimeric states of proteins
Authors: Lynch Michael
Published: July 2013

Significance

Rather than operating as single units, most proteins assemble as multimers, usually with all subunits derived from the same gene. In contrast to patterns of gene structure and genome organization, which typically exhibit substantial increases in complexity from unicellular to multicellular organisms, the structural complexity of orthologous proteins appears roughly constant over the tree of life. The interfaces of multimers also often shift dramatically over evolutionary time. To explain these observations, a model is presented for the stochastic origin of variation in the multimeric states of proteins via the joint processes of mutation, random genetic drift, and constant directional selection.
Phage ϕ29 protein p1 promotes replication by associating with the FtsZ ring of the divisome in
Bacillus subtilis
Authors: Ballesteros-Plaza David , Holguera Isabel , Scheffers Dirk-Jan , Salas Margarita , Muñoz-Espín Daniel
Published: July 2013

During evolution, viruses have optimized the interaction with host factors to increase the efficiency of fundamental processes such as DNA replication. Bacteriophage ϕ29 protein p1 is a membrane-associated protein that forms large protofilament sheets that resemble eukaryotic tubulin and bacterial filamenting temperature-sensitive mutant Z protein (FtsZ) polymers. In the absence of protein p1, phage ϕ29 DNA replication is impaired. Here we show that a functional fusion of protein p1 to YFP localizes at the medial region of
Bacillus subtilis
cells independently of other phage-encoded proteins. We also show that ϕ29 protein p1 colocalizes with the
B. subtilis
cell division protein FtsZ and provide evidence that FtsZ and protein p1 are associated. Importantly, the midcell localization of YFP-p1 was disrupted in a strain that does not express FtsZ, and the fluorescent signal was distributed all over the cell. Depletion of penicillin-binding protein 2B (PBP2B) in
B. subtilis
cells did not affect the subcellular localization of YFP-p1, indicating that its distribution does not depend on septal wall synthesis. Interestingly, when ϕ29 protein p1 was expressed,
B. subtilis
cells were about 1.5-fold longer than control cells, and the accumulation of ϕ29 DNA was higher in mutant
B. subtilis
cells with increased length. We discuss the biological role of p1 and FtsZ in the ϕ29 growth cycle.
Somatotype, training and performance in Ironman athletes
Authors: Kandel Michel , Baeyens Jean Pierre , Clarys Peter
Published: July 2013

The aim of this study was to describe the physiques of Ironman athletes and the relationship between Ironman's performance, training and somatotype. A total of 165 male and 22 female competitors of the Ironman Switzerland volunteered in this study. Ten anthropometric dimensions were measured, and 12 training and history variables were recorded with a questionnaire. The variables were compared with the race performance. The somatotype was a strong predictor of Ironman performance (R=0.535; R2=0.286; sign. p<0.001) in male athletes. The endomorphy component was the most substantial predictor. Reductions in endomorphy by one standard deviation as well as an increased ectomorphy value by one standard deviation lead to significant and substantial improvement in Ironman performance (28.1 and 29.8 minutes, respectively). An ideal somatotype of 1.7–4.9–2.8 could be established. Age and quantitative training effort were not significant predictors on Ironman performance. In female athletes, no relationship between somatotype, training and performance was found. The somatotype of a male athlete defines for 28.6% variance in Ironman performance. Athletes not having an ideal somatotype of 1.7–4.9–2.8 could improve their performance by altering their somatotype. Lower rates in endomorphy, as well as higher rates in ectomorphy, resulted in a significant better race performance. The impact of somatotype was the most distinguished on the run discipline and had a much greater impact on the total race time than the quantitative training effort. These findings could not be found in female athletes.
The joint impact of drought conditions and media coverage on the Colorado rafting industry
Authors: Schoengold Karina , Shrestha Prabhakar , Eiswerth Mark
Published: July 2013

Decreased instream flows are thought to negatively impact river recreation, such as whitewater rafting. Runoff declines are often accompanied by high temperatures, wildfires, and associated media coverage. Very few studies have examined the impact of these accompanying factors, and none have disentangled their influence. Using regression analysis of data from the Arkansas River in Colorado, we find that reduced flows usually decrease the number of whitewater rafting customers, although very high flows also deter rafting activities. More importantly, negative media coverage of wildfires also appears to have adverse impacts on rafting tourism, controlling for instream flows and weather.
Climate change opportunities for Idaho's irrigation supply and deliveries
Authors: Qualls Russell J. , Taylor R. Garth , Hamilton Joel , Arogundade Ayodeji B.
Published: July 2013

The Snowmelt Runoff Model (SRM) was used to simulate timing and magnitude of runoff for six climate scenarios (2030 and 2080 ‘Wet’, ‘Middle’, and ‘Dry’). The water supply results from SRM were run through a Southern Idaho reservoir operation and water rights allocation model (MODSIM). The 2030-Dry and 2080-Dry scenarios produce supply deficits relative to the current climate of 5.4%, and 1.9%, respectively, for which the corresponding irrigation water delivery reductions were 1.7% and 2.7%. In contrast, the 2030-Wet, 2030-Mid, 2080-Wet, and 2080-Mid climate change scenarios increased water supply by 13.4%, 0.5%, 19.5%, and 5%, respectively, for which water deliveries increased by 0.41%, 0.04%, 0.34% and 0.14%, respectively. Idaho's irrigation delivery and storage system can ameliorate the risk of dry climate change, but is incapable of storing and delivering the increased water supplied by the wet climate change scenarios. This is an opportunity worth exploring.
A converse of the Gale-Klee-Rockafellar theorem: Continuity of convex functions at the boundary of their domains
Authors: Ernst Emil
Published: July 2013

Given

x
0

x_0

, a point of a convex subset

C
C

of a Euclidean space, the two following statements are proven to be equivalent: (i) every convex function

f
:
C
→

R

f:C\to \mathbb {R}

is upper semi-continuous at

x
0

x_0

, and (ii)

C
C

is polyhedral at

x
0

x_0

. In the particular setting of closed convex functions and

F
σ

F_\sigma

domains, we prove that every closed convex function

f
:
C
→

R

f:C\to \mathbb {R}

is continuous at

x
0

x_0

if and only if

C
C

is polyhedral at

x
0

x_0

. This provides a converse to the celebrated Gale-Klee-Rockafellar theorem.
On hyperbolicity and tautness modulo an analytic subset of Hartogs domains
Authors: Thai Do , Thomas Pascal , Trao Nguyen , Duc Mai
Published: July 2013

LetXXbe a complex space andHHa positive homogeneous plurisubharmonic functionHHonX×CmX\times \mathbb {C}^m. Consider the Hartogs-type domain<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="normal upper Omega Subscript upper H Baseline left-parenthesis upper X right-parenthesis colon equals StartSet left-parenthesis z comma w right-parenthesis element-of upper X times double-struck upper C Superscript m Baseline colon upper H left-parenthesis z comma w right-parenthesis greater-than 1 EndSet">ΩH(X):={(z,w)∈X×Cm:H(z,w)>1}\Omega _{H}(X):=\{(z,w)\in X\times \mathbb {C}^m:H(z,w)>1 \}. LetSSbe an analytic subset ofXX. We give necessary and sufficient conditions for hyperbolicity and tautness moduloS×CmS\times \mathbb {C}^mofΩH(X)\Omega _{H}(X), with the obvious corollaries for the special case of Hartogs domains.
The Effect of Transitional Organic Production Practices on Soilborne Pests of Tomato in a Simulated Microplot Study
Authors: Chellemi Dan O. , Rosskopf Erin N. , Kokalis-Burelle Nancy
Published: July 2013

The perceived risk of pest resurgence upon transition from conventional to organic-based farming systems remains a critical obstacle to expanding organic vegetable production, particularly where chemical fumigants have provided soilborne pest and disease control. Microplots were used to study the effects of soil amendments and cropping sequences applied over a 2-year transitional period from conventional to organic tomato (Solanum lycopersicum) cultivation on the incidence of bacterial wilt caused by Ralstonia solanacearum, purple nutsedge (Cyperus rotundus) reproduction, root galling by Meloidogyne incognita, and soil nematode populations. A continuation of tomato monoculture during the transitional period resulted in a disease incidence of 33%, as compared with 9% in microplots that were rotated with sunn hemp (Crotalaria juncea) and Japanese millet (Echinochloa crusgalli var. frumentacea). The benefits of disease control from a crop rotation extended into to a second season of organic tomato cultivation season, where bacterial wilt declined from 40% in microplots with a tomato monoculture to 17% in plots with a crop rotation sequence. Combining applications of urban plant debris with a continued tomato monoculture increased the incidence of bacterial wilt to 60%. During the transition period, tomato plants following a cover crop regime also had significantly lower levels of root galling from root-knot nematode infection compared with plants in the continuous tomato monoculture. Nutsedge tuber production was significantly increased in plots amended with broiler litter but not urban plant debris. Compared with a continuous monoculture, the results illustrate the importance of a systems-based approach to implementing transitional organic practices that is cognizant of their interactive effects on resident soilborne disease, weed, and pest complexes.
Lagged Association Between Powdery Mildew Leaf Severity, Airborne Inoculum, Weather, and Crop Losses in Strawberry
Authors: Carisse O. , Morissette-Thomas V. , Van der Heyden H.
Published: July 2013

Knowledge about epidemiology and the impact of disease on yield is fundamental for establishing effective management strategies. The purpose of this study was to investigate the relationship between foliar strawberry mildew severity, Podosphaera aphanis airborne inoculum concentration, weather, and subsequent crop losses for day-neutral strawberry. The experiment was conducted at three, five, and four sites in 2006, 2007, and 2008, respectively, for a total of 12 epidemics. At each site, data were collected on 25 plants at 2-day intervals from the end of May to early October for a total of 60 to 62 samplings annually. First, seasonal crop losses were statistically described; then, a lagged regression model was developed to describe crop losses from the parameters that were significantly associated with losses. There was a strong positive linear relationship between seasonal crop losses and the area under the leaf disease progress curve (R2 = 0.90) and daily mean airborne conidia concentration (R2 = 0.86), and a negative linear relationship between crop losses and time to 5% loss (R2 = 0.76) and time to 5% leaf area diseased (R2 = 0.61). Among the 53 monitoring- and weather-based variables analyzed, percent leaf area diseased, log10-transformed airborne inoculum concentration, and weather variables related to temperature were significantly associated with crop losses. However, polynomial distributed lag regression models built with weather variables were not accurate in predicting losses, with the exception of a model based on a combined temperature and humidity variable, which provided accurate prediction of the data used to construct the model but not of independent data. Overall, the model based on log10-transformed airborne inoculum concentration did not provide accurate crop loss predictions. The model built using percent leaf area diseased with a time lag of 8 days (n = 4) and a polynomial degree of 2 provided a good description of the crop-loss data used to construct the model (r = 0.99 and 0.90) and of independent data (r = 0.92). For the 12 epidemics studied, 5% crop loss was reached when an average of 17% leaf area diseased was observed since the beginning of symptom development. These results indicate that information on foliar powdery mildew must be considered when making strawberry powdery mildew management decisions.
Spinal Stenosis
Authors: Roszell Karin , Sandella Danielle , Haig Andrew J. , Yamakawa Karen S.J.
Published: July 2013

Study Design:

Prospective noninterventional observation.

Objective:

To examine factors that influence a patient’s real decision to accept the offer of surgery for lumbar spinal stenosis in a relatively controlled situation.

Summary of Background Data:

A patient’s decision to undergo spine surgery might be influenced by factors other than pathology. However, there is limited research exploring the decision.

Methods:

A study performed for other purposes recruited persons aged 55–90 years with medical record evidence of an offer of surgery for spinal stenosis by a university faculty surgeon. Inclusion criteria included neurogenic claudication, subjectively positive imaging, and difficulty walking 200 yards. Potential subjects with additional disabling conditions (eg, lower limb amputation), conditions that might mimic stenosis (eg, polyneuropathy), or some contraindications to invasive treatment (eg, anticoagulation) were excluded. Subjects filled out questionnaires on function, quality of life, pain, and health, and were examined by a spine surgeon masked to diagnostic category (Other recruits had back pain or no symptoms). Telephone follow-up 6–12 months later determined whether surgery was done.

Results:

Of 39 qualifying subjects, 20 followed through with surgery. A binary logistic regression revealed that significant factors that influence patient decision making included SF-36 measures of “Comparative Health” and “Role Limit Emotional” as well as the subject’s overall perception of their quality of life. The combination of all 3 factors yielded a predictive model (P=0.031). Individually, however, only “Comparative Health” was significant and able to predict a decision to proceed with surgery (P=0.036).

Conclusions:

In this population with significant disability, uncomplicated medical history, and a relatively clear diagnosis, the decision to accept surgical intervention was influenced by issues of perceived overall health and quality of life. Interventions to change real or perceived overall health may impact patient acceptance of surgery.
Maltase‐Glucoamylase Modulates Gluconeogenesis and Sucrase‐Isomaltase Dominates Starch Digestion Glucogenesis
Authors: Diaz‐Sotomayor Maricela , Quezada‐Calvillo Roberto , Avery Stephen E. , Chacko Shaji K. , Yan Li‐ke , Lin Amy Hui‐Mei , Ao Zi‐hua , Hamaker Bruce R. , Nichols Buford L.
Published: July 2013

Objectives:

Six enzyme activities are needed to digest starch to absorbable free glucose; 2 luminal α‐amylases (AMY) and 4 mucosal maltase‐glucoamylase (MGAM) and sucrase‐isomaltase (SI) subunit activities are involved in the digestion. The AMY activities break down starch to soluble oligomeric dextrins; mucosal MGAM and SI can either directly digest starch to glucose or convert the post‐α‐amylolytic dextrins to glucose. We hypothesized that MGAM, with higher maltase than SI, drives digestion on ad limitum intakes and SI, with lower activity but more abundant amount, constrains ad libitum starch digestion.

Methods:

Mgam null and wild‐type (WT) mice were fed with starch diets ad libitum and ad limitum. Fractional glucogenesis (fGG) derived from starch was measured and fractional gluconeogenesis and glycogenolysis were calculated. Carbohydrates in small intestine were determined.

Results:

After ad libitum meals, null and WT had similar increases of blood glucose concentration. At low intakes, null mice had less fGG (P = 0.02) than WT mice, demonstrating the role of Mgam activity in ad limitum feeding; null mice did not reduce fGG responses to ad libitum intakes demonstrating the dominant role of SI activity during full feeding. Although fGG was rising after feeding, fractional gluconeogenesis fell, especially for null mice.

Conclusions:

The fGNG (endogenous glucogenesis) in null mice complemented the fGG (exogenous glucogenesis) to conserve prandial blood glucose concentrations. The hypotheses that Mgam contributes a high‐efficiency activity on ad limitum intakes and SI dominates on ad libitum starch digestion were confirmed.
Bibliometric Study of the Quality of Celiac Disease Research Publications
Authors: Master Samuel , Lebwohl Benjamin , Ludvigsson Jonas F. , Green Peter H.
Published: July 2013

Celiac disease (CD) is common and occurs in both children and adults. A recent bibliometric study revealed that the journal with the most CD articles was the Journal of Pediatric Gastroenterology and Nutrition followed by the American Journal of Gastroenterology, a journal predominantly concerned with adult issues. To assess the quality and complexity of CD, research appearing in these journals used strict published criteria to assess the quality of the research in the 30 most recent research articles in each journal. The authors found that the research reported in these articles was of similar high quality and complexity.
Advancing the long view of ecological change in tundra systems
Authors: Post Eric , Høye Toke T.
Published: July 2013

Despite uncertainties related to sustained funding, ideological rivalries and the turnover of research personnel, long-term studies and studies espousing a long-term perspective in ecology have a history of contributing landmark insights into fundamental topics, such as population- and community dynamics, species interactions and ecosystem function. They also have the potential to reveal surprises related to unforeseen events and non-stationary dynamics that unfold over the course of ongoing observation and experimentation. The unprecedented rate and magnitude of current and expected abiotic changes in tundra environments calls for a synthetic overview of the scope of ecological responses these changes have elicited. In this special issue, we present a series of contributions that advance the long view of ecological change in tundra systems, either through sustained long-term research, or through retrospective or prospective modelling. Beyond highlighting the value of long-term research in tundra systems, the insights derived herein should also find application to the study of ecological responses to environmental change in other biomes as well.
Phenological response of tundra plants to background climate variation tested using the International Tundra Experiment
Authors: Oberbauer S. F. , Elmendorf S. C. , Troxler T. G. , Hollister R. D. , Rocha A. V. , Bret-Harte M. S. , Dawes M. A. , Fosaa A. M. , Henry G. H. R. , Høye T. T. , Jarrad F. C. , Jónsdóttir I. S. , Klanderud K. , Klein J. A. , Molau U. , Rixen C. , Schmidt N. M. , Shaver G. R. , Slider R. T. , Totland Ø. , Wahren C.-H. , Welker J. M.
Published: July 2013

The rapidly warming temperatures in high-latitude and alpine regions have the potential to alter the phenology of Arctic and alpine plants, affecting processes ranging from food webs to ecosystem trace gas fluxes. The International Tundra Experiment (ITEX) was initiated in 1990 to evaluate the effects of expected rapid changes in temperature on tundra plant phenology, growth and community changes using experimental warming. Here, we used the ITEX control data to test the phenological responses to background temperature variation across sites spanning latitudinal and moisture gradients. The dataset overall did not show an advance in phenology; instead, temperature variability during the years sampled and an absence of warming at some sites resulted in mixed responses. Phenological transitions of high Arctic plants clearly occurred at lower heat sum thresholds than those of low Arctic and alpine plants. However, sensitivity to temperature change was similar among plants from the different climate zones. Plants of different communities and growth forms differed for some phenological responses. Heat sums associated with flowering and greening appear to have increased over time. These results point to a complex suite of changes in plant communities and ecosystem function in high latitudes and elevations as the climate warms.
Complex biotic interactions drive long-term vegetation dynamics in a subarctic ecosystem
Authors: Olofsson Johan , te Beest Mariska , Ericson Lars
Published: July 2013

Predicting impacts of global warming requires understanding of the extent to which plant biomass and production are controlled by bottom-up and top-down drivers. By annually monitoring community composition in grazed control plots and herbivore-free exclosures at an Arctic location for 15 years, we detected multiple biotic interactions. Regular rodent cycles acted as pulses driving synchronous fluctuations in the biomass of field-layer vegetation; reindeer influenced the biomass of taller shrubs, and the abundance of plant pathogenic fungi increased when densities of their host plants increased in exclosures. Two outbreaks of geometrid moths occurred during the study period, with contrasting effects on the field layer: one in 2004 had marginal effects, while one in 2012 severely reduced biomass in the control plots and eliminated biomass that had accumulated over 15 years in the exclosures. The latter was followed by a dramatic decline of the dominant understory dwarf-shrubEmpetrum hermaphroditum, driven by an interaction between moth herbivory on top buds and leaves, and increased disease severity of a pathogenic fungus. We show that the climate has important direct and indirect effects on all these biotic interactions. We conclude that long time series are essential to identify key biotic interactions in ecosystems, since their importance will be influenced by climatic conditions, and that manipulative treatments are needed in order to obtain the mechanistic understanding needed for robust predictions of future ecosystem changes and their feedback effects.
Nonlinear flowering responses to climate: are species approaching their limits of phenological change?
Authors: Iler Amy M. , Høye Toke T. , Inouye David W. , Schmidt Niels M.
Published: July 2013

Many alpine and subalpine plant species exhibit phenological advancements in association with earlier snowmelt. While the phenology of some plant species does not advance beyond a threshold snowmelt date, the prevalence of such threshold phenological responses within plant communities is largely unknown. We therefore examined the shape of flowering phenology responses (linear versus nonlinear) to climate using two long-term datasets from plant communities in snow-dominated environments: Gothic, CO, USA (1974–2011) and Zackenberg, Greenland (1996–2011). For a total of 64 species, we determined whether a linear or nonlinear regression model best explained interannual variation in flowering phenology in response to increasing temperatures and advancing snowmelt dates. The most common nonlinear trend was for species to flower earlier as snowmelt advanced, with either no change or a slower rate of change when snowmelt was early (average 20% of cases). By contrast, some species advanced their flowering at a faster rate over the warmest temperatures relative to cooler temperatures (average 5% of cases). Thus, some species seem to be approaching their limits of phenological change in response to snowmelt but not temperature. Such phenological thresholds could either be a result of minimum springtime photoperiod cues for flowering or a slower rate of adaptive change in flowering time relative to changing climatic conditions.
Analyses of a Gravistimulation-Specific Ca2+ Signature in Arabidopsis using Parabolic Flights
Authors: Toyota Masatsugu , Furuichi Takuya , Sokabe Masahiro , Tatsumi Hitoshi
Published: July 2013

Gravity is a critical environmental factor affecting the morphology and functions of organisms on the Earth. Plants sense changes in the gravity vector (gravistimulation) and regulate their growth direction accordingly. In Arabidopsis (Arabidopsis thaliana) seedlings, gravistimulation, achieved by rotating the specimens under the ambient 1g of the Earth, is known to induce a biphasic (transient and sustained) increase in cytoplasmic calcium concentration ([Ca2+]c). However, the [Ca2+]c increase genuinely caused by gravistimulation has not been identified because gravistimulation is generally accompanied by rotation of specimens on the ground (1g), adding an additional mechanical signal to the treatment. Here, we demonstrate a gravistimulation-specific Ca2+ response in Arabidopsis seedlings by separating rotation from gravistimulation by using the microgravity (less than 10−4  g) conditions provided by parabolic flights. Gravistimulation without rotating the specimen caused a sustained [Ca2+]c increase, which corresponds closely to the second sustained [Ca2+]c increase observed in ground experiments. The [Ca2+]c increases were analyzed under a variety of gravity intensities (e.g. 0.5g, 1.5g, or 2g) combined with rapid switching between hypergravity and microgravity, demonstrating that Arabidopsis seedlings possess a very rapid gravity-sensing mechanism linearly transducing a wide range of gravitational changes (0.5g–2g) into Ca2+ signals on a subsecond time scale.
Drivers of in‐group and out‐of‐group electronic word‐of‐mouth (eWOM)
Authors: Luís Abrantes José , Seabra Cláudia , Raquel Lages Cristiana , Jayawardhena Chanaka
Published: July 2013

Purpose

The purpose of this study is to address a recent call for additional research on electronic word‐of‐mouth (eWOM). In response to this call, this study draws on the social network paradigm and the uses and gratification theory (UGT) to propose and empirically test a conceptual framework of key drivers of two types of eWOM, namely in‐group and out‐of‐group.

Design/methodology/approach

The proposed model, which examines the impact of usage motivations on eWOM in‐group and eWOM out‐of‐group, is tested in a sample of 302 internet users in Portugal.

Findings

Results from the survey show that the different drivers (i.e. mood‐enhancement, escapism, experiential learning and social interaction) vary in terms of their impact on the two different types of eWOM. Surprisingly, while results show a positive relationship between experiential learning and eWOM out‐of‐group, no relationship is found between experiential learning and eWOM in‐group.

Research limitations/implications

This is the first study investigating the drivers of both eWOM in‐group and eWOM out‐of‐group. Additional research in this area will contribute to the development of a general theory of eWOM.

Practical implications

By understanding the drivers of different eWOM types, this study provides guidance to marketing managers on how to allocate resources more efficiently in order to achieve the company's strategic objectives.

Originality/value

No published study has investigated the determinants of these two types of eWOM. This is the first study offering empirical considerations of how the various drivers differentially impact eWOM in‐group and eWOM out‐of‐group.
The impact of online user reviews on cameras sales
Authors: Zhang Lin , Ma Baolong , Cartwright Debra K.
Published: July 2013

Purpose

The purpose of this research is to help better understand the impact of online user reviews on sales of search goods.

Design/methodology/approach

This research is based on digital camera sales data collected from amazon.com and two studies are included in this research. The first study is based on a static model and sample data from one time stamp. The second study is based on two sample data collected from two different time stamps, and a dynamic model is proposed.

Findings

The results from the first study reveal that the average online customer review, the number of online reviews, the price and the camera's physical properties such as the number of pixels and the optimal zoom number (but not LCD screen size) have significant influence on digital camera sales. The results from the second study show that the sales from the previous period are an important indicator for future sales. In addition, change in price, change in average online review rating and change in the total number of online reviews are all significantly associated with future sales.

Research limitations/implications

The research reveals that there is a significant relationship between the online user review and sales of search goods, and the influence of online user reviews on search goods sales is different from that on experience goods. It also recognizes that the product specifications influence the sales of search goods. In addition, the research on search goods shows that price at the specific time and price changes are significant factors affecting sales.

Practical implications

The research indicates that retailers should provide channels for, and encourage, customer online reviews for search goods to improve sales. It is also beneficial for online retailers to provide detailed product attributes to help their customers make the purchase decision. Carefully designed and executed price promotions could also be effective ways to improve sales of searchable goods.

Originality/value

This study is one of the first attempts to investigate the impact of online user reviews on sales of search goods.
Event‐based cooperative control of a high‐speed bar‐tacking sewing machine
Authors: Xie Xiaohui , Ma Cui , Sun Qiang , Du Ruxu
Published: July 2013

Purpose

Bar‐tacking is a specialized sewing stitch designed to provide immense tensile strength to the garment which requires a high‐speed precision bar‐tacking sewing machine. This paper aims to present an event‐driven multi‐axis cooperative control method for a bar‐tacking sewing machine.

Design/methodology/approach

The control method consists of two parts: the multi‐axis cooperative control and the needle stop positioning control. The challenges include the high speed and the precision. For example, the needle must stop at a set position in milliseconds.

Findings

The presented multi‐axis cooperative control can ensure the high speed response and the precision of the cooperative control. The needle stop positioning control is based on a combination of the velocity control and the position control with velocity feed‐forward and limitation.

Research limitations/implications

The bar‐tacking sewing machine requires high‐speed start and stop response and coordination of displacement and velocity only at some given points. Therefore, the conventional multi‐axis cooperative control methods are not suitable. In addition, it requires high‐speed precision control under varying loading conditions.

Practical implications

While there are a number of commercial textile machines available in the market, designing a smart bar‐tacking sewing machine with good speed and precision performance remains a challenge.

Originality/value

The bar‐tacking sewing machine requires highly accurate multi‐axes cooperative control. The presented event‐driven multi‐axis control method is effective. It has not only the required high accuracy but also the fast time response.
Business regulation, inward foreign direct investment, and economic growth in the new European Union member states
Authors: Allen Matthew M.C. , Aldred Maria L.
Published: July 2013

Purpose

The purpose of this paper is to assess the extent to which institutional convergence has taken place in the new European Union (EU) member states. It does so by contrasting arguments that are inspired by transaction‐cost economics within the mainstream international‐business literature and contentions within the comparative‐capitalisms perspective. A corollary of arguments within the former is that those countries that have less transparent ways of doing business will post poorer economic growth records than those with more predictable and less costly regulations. By contrast, contentions within the comparative‐capitalisms literature lead to expectations that a broader set of institutional factors will shape economic growth.

Design/methodology/approach

The article adopts a fuzzy‐set qualitative comparative analysis approach to examine the necessary and sufficient causal conditions for economic growth in the region.

Findings

There is a great deal of institutional diversity within the new EU member states in Central and Eastern Europe. There are no clusters of countries around a specific variety of capitalism or an economic model that has above‐average economic growth rates and that is characterized by institutions that lower the costs of market transacting. This, in turn, suggests that convergence pressures are not as great as the mainstream international‐business literature has argued.

Research limitations/implications

Future research could complement this study by adopting a cross‐country, comparative micro‐ or firm‐level approach to examine the ways in which different institutional factors, both individually and collectively, shape the growth of businesses and consequently, economies.

Originality/value

Mainstream international business tends to focus on regulation and market‐supporting institutions to explain growth in developing economies. This research has shown that a broader view of institutions needs to be adopted, as some countries have been able to post strong economic growth figures despite institutional environments that do not lower the costs of market‐based contracting.
Cognitive automation strategy for reconfigurable and sustainable assembly systems
Authors: Fasth‐Berglund Åsa , Stahre Johan
Published: July 2013

Purpose

The paper aims to discuss the importance of considering both the physical and cognitive automation when aiming for a flexible or reconfigurable assembly system. This is done in order to handle the increased demand for mass customized production and to maintain or improve the social sustainability within the company.

Design/methodology/approach

The methodologies used in this paper are a theoretical review about task allocation and levels of automation and a methodology called DYNAMO++ for the industrial case studies.

Findings

The paper provides both theoretical and empirical insights about the importance of considering both the cognitive and physical automation when aiming for a reconfigurable assembly system.

Research limitations/implications

The paper will only discuss the cognitive strategy from a social sustainability perspective and not from an economical or environmental angle.

Practical implications

The paper presents data from three industrial case studies, mostly in the automotive industry. The result points towards a need for a more structured and quantitative method when choosing automation solutions, furthermore an increased use of cognitive automation solution.

Social implications

The results from the case studies show that when the complexity and variety of products increases, a cognitive support for the operators is needed. This strengthens the theory of a need for a cognitive automation strategy within companies.

Originality/value

The paper demonstrates an advance in the state of the art in task allocation. The concept model and the DYNAMO++ method can be seen as a step closer towards quantitative measures of task allocation (i.e. changes in both physical and cognitive LoA) and dynamic changes over time.
3D vision based quality inspection with computational intelligence
Authors: Yu Quan , Wang Kesheng
Published: July 2013

Purpose

Product quality inspection is of importance in manufacturing industries to ensure that low quality or unqualified products are not delivered to the consumer. Human inspection has many limitations such as low accuracy or speed due to factors such as tiredness and boredom. Traditional 2D vision inspection also has limitations of product shape complexity or flexibility. Thus, automated 3D vision inspection is anticipated to meet the requirements of higher applicability. This paper seeks to address these issues.

Design/methodology/approach

In many product quality inspection problems, geometrical parameters of the industrial parts are commonly used as the basis of quality inspection. Machine vision is widely applied to acquire such kind of parameters. Comparing to traditional 2D vision, 3D vision can acquire 3D coordinates of the object directly, so that the inspection can be accomplished which is difficult to do with 2D vision. As an active vision technique, structure light system (SLS) is applied to acquire the 3D coordinate information of inspected object in this paper. On the basis of point cloud and regression analysis, features relative to quality are defined and extracted as the attributes for the product classification. Three data mining techniques are applied to accomplish the classification in this paper, which include decision trees, artificial neural networks and support vector machine.

Findings

A new intelligent automated 3D vision quality inspection for assembly lines has been developed, which comprises structure light system (SLS) and data mining approaches such as decision tree, artificial neutral networks and support vector machine.

Originality/value

The combination of structure light system (SLS) and data mining approaches makes the automated quality inspection available. The proposed system is easy to be implemented and flexible for different types of products.
Assembly model and design thinking: a study of assembly scheme based on gene model
Authors: Yixiong Feng , Yicong Gao , Zeyu Mai , Jianrong Tan
Published: July 2013

Purpose

Existing models of product assembly scheme design often ignore the constraint relations among design thinking. In order to grasp the functions of each part and the constraint relations among them in product assembly system macroscopically, further design and variation of product assembly system should be made according to design thinking. This paper seeks to address these issues.

Design/methodology/approach

Through analyzing the similarity between biological organization system and product system and taking biology knowledge for reference, product assembly system was expressed as product function gene, product constraint gene, product function protein, product constraint protein and product cell and so on in this paper. The product gene model composed of product function gene groups and constraint genes was established and a modeling method based on it was proposed.

Findings

The author applied this method to model the 5‐DOF manipulator of complex diamond manufacturing special equipment with good results which proved the effectiveness of this modeling method.

Originality/value

By identifying constraint relations and design thinking in the gene model, the system makes the modification process which is conducted by the designers automatically identified and varied to achieve computer‐aided design and assembly.