bluuebunny/crossref_metadata_2025 huggingface dataset:
Extracting samples of high diversity from thematic collections of large gene banks using a genetic-distance based approach
Authors: Pessoa-Filho Marco , Rangel Paulo HN , Ferreira Marcio E
Published: June 2010

Background

Breeding programs are usually reluctant to evaluate and use germplasm accessions other than the elite materials belonging to their advanced populations. The concept of core collections has been proposed to facilitate the access of potential users to samples of small sizes, representative of the genetic variability contained within the gene pool of a specific crop. The eventual large size of a core collection perpetuates the problem it was originally proposed to solve. The present study suggests that, in addition to the classic core collection concept, thematic core collections should be also developed for a specific crop, composed of a limited number of accessions, with a manageable size.

Results

The thematic core collection obtained meets the minimum requirements for a core sample - maintenance of at least 80% of the allelic richness of the thematic collection, with, approximately, 15% of its size. The method was compared with other methodologies based on the M strategy, and also with a core collection generated by random sampling. Higher proportions of retained alleles (in a core collection of equal size) or similar proportions of retained alleles (in a core collection of smaller size) were detected in the two methods based on the M strategy compared to the proposed methodology. Core sub-collections constructed by different methods were compared regarding the increase or maintenance of phenotypic diversity. No change on phenotypic diversity was detected by measuring the trait "Weight of 100 Seeds", for the tested sampling methods. Effects on linkage disequilibrium between unlinked microsatellite loci, due to sampling, are discussed.

Conclusions

Building of a thematic core collection was here defined by prior selection of accessions which are diverse for the trait of interest, and then by pairwise genetic distances, estimated by DNA polymorphism analysis at molecular marker loci. The resulting thematic core collection potentially reflects the maximum allele richness with the smallest sample size from a larger thematic collection. As an example, we used the development of a thematic core collection for drought tolerance in rice. It is expected that such thematic collections increase the use of germplasm by breeding programs and facilitate the study of the traits under consideration. The definition of a core collection to study drought resistance is a valuable contribution towards the understanding of the genetic control and the physiological mechanisms involved in water use efficiency in plants.
Characterization of SQUAMOSA-like genes in Gerbera hybrida, including one involved in reproductive transition
Authors: Ruokolainen Satu , Ng Yan Peng , Broholm Suvi K , Albert Victor A , Elomaa Paula , Teeri Teemu H
Published: June 2010

Background

The flowering process in plants proceeds through the induction of an inflorescence meristem triggered by several pathways. Many of the genes associated with both the flowering process and floral architecture encode transcription factors of the MADS domain family. Gerbera, a member of the sunflower family, Asteraceae, bears compressed inflorescence heads (capitula) with three different flower types characterized by differences in both sexuality and floral symmetry. To understand how such a complex inflorescence structure is achieved at the molecular level, we have characterized the array of Gerbera MADS box genes. The high number of SQUAMOSA-like genes in Gerbera compared to other model species raised the question as to whether they may relate to Gerbera's complex inflorescence structure and whether or not a homeotic A function is present.

Results

In this paper we describe six Gerbera genes related to the SQUAMOSA/APETALA1/FRUITFULL genes of snapdragon and Arabidopsis. Based on phylogenetic analysis of the entire gene lineage, our data indicates that GSQUA1 and GSQUA3 are members of the SQUA/AP1 clade, while GSQUA2, GSQUA4, GSQUA5 and GSQUA6 are co-orthologs of the Arabidopsis FUL gene. GSQUA1/GSQUA3 and GSQUA4/GSQUA5/GSQUA6, respectively, represent several gene duplication events unknown in the model systems that may be specific to either Gerbera or Asteraceae. GSQUA genes showed specific expression profiles. GSQUA1, GSQUA2, and GSQUA5 were inflorescence abundant, while GSQUA3, GSQUA4, and GSQUA6 expression was also detected in vegetative organs. Overexpression of GSQUA2 in Gerbera led to accelerated flowering, dwarfism and vegetative abnormalities, all new and specific phenomena observed in transgenic Gerbera plants with modified MADS box gene expression.

Conclusions

Based on expression patterns, none of the Gerbera SQUA-like genes are likely to control flower organ identity in the sense of the floral A function. However, our data shows that the FUL-like gene GSQUA2 plays a vital role in meristem transition. The roles of other GSQUA-genes in Gerbera floral development are intriguing, but require still further study.
Metals detected by ICP/MS in wound tissue of war injuries without fragments in Gaza
Authors: Skaik Sobhi , Abu-Shaban Nafiz , Abu-Shaban Nasser , Barbieri Mario , Barbieri Maurizio , Giani Umberto , Manduca Paola
Published: June 2010

Background

The amount and identity of metals incorporated into "weapons without fragments" remain undisclosed to health personnel. This poses a long-term risk of assumption and contributes to additional hazards for victims because of increased difficulties with clinical management. We assessed if there was evidence that metals are embedded in "wounds without fragments" of victims of the Israeli military operations in Gaza in 2006 and 2009.

Methods

Biopsies of "wounds without fragments" from clinically classified injuries, amputation (A), charred (C), burns (B), multiple piercing wounds by White Phosphorus (WP) (M), were analyzed by ICP/MS for content in 32 metals.

Results

Toxic and carcinogenic metals were detected in folds over control tissues in wound tissues from all injuries: in A and C wounds (Al, Ti, Cu, Sr, Ba, Co, Hg, V, Cs and Sn), in M wounds (Al, Ti, Cu, Sr, Ba, Co and Hg) and in B wounds (Co, Hg, Cs, and Sn); Pb and U in wounds of all classes; B, As, Mn, Rb, Cd, Cr, Zn in wounds of all classes, but M; Ni was in wounds of class A. Kind and amounts of metals correlate with clinical classification of injuries, exposing a specific metal signature, similar for 2006 and 2009 samples.

Conclusions

The presence of toxic and carcinogenic metals in wound tissue is indicative of the presence in weapon inducing the injury. Metal contamination of wounds carries unknown long term risks for survivors, and can imply effects on populations from environmental contamination. We discuss remediation strategies, and believe that these data suggest the need for epidemiological and environmental surveys.
Hyperinsulinemia improves ischemic LV function in insulin resistant subjects
Authors: Heck Patrick M , Hoole Stephen P , Khan Sadia N , Dutka David P
Published: June 2010

Background

Glucose is a more efficient substrate for ATP production than free fatty acid (FFA). Insulin resistance (IR) results in higher FFA concentrations and impaired myocardial glucose use, potentially worsening ischemia. We hypothesized that metabolic manipulation with a hyperinsulinemic euglycemic clamp (HEC) would affect a greater improvement in left ventricular (LV) performance during dobutamine stress echo (DSE) in subjects with IR.

Methods

24 subjects with normal LV function and coronary disease (CAD) awaiting revascularization underwent 2 DSEs. Prior to one DSEs they underwent an HEC, where a primed infusion of insulin (rate 43 mU/m2/min) was co-administered with 20% dextrose at variable rates to maintain euglycemia. At steady-state the DSE was performed and images of the LV were acquired with tissue Doppler at each stage for offline analysis. Segmental peak systolic velocities (Vs) were recorded, as well as LV ejection fraction (EF). Subjects were then divided into two groups based on their insulin sensitivity during the HEC.

Results

HEC changed the metabolic environment, suppressing FFAs and thereby increasing glucose use. This resulted in improved LV performance at peak stress, measured by EF (IS group mean difference 5.3 (95% CI 2.5-8) %, p = 0.002; IR group mean difference 8.7 (95% CI 5.8-11.6) %, p < 0.0001) and peak Vsin ischemic segments (IS group mean improvement 0.7(95% CI 0.07-1.58) cm/s, p = 0.07; IR group mean improvement 1.0 (95% CI 0.54-1.5) cm/s, p < 0.0001),that was greater in the subjects with IR.

Conclusions

Increased myocardial glucose use induced by HEC improves LV function under stress in subjects with CAD and IR. Cardiac metabolic manipulation in subjects with IR is a promising target for future therapy.
The small molecule curcumin analog FLLL32 induces apoptosis in melanoma cells via STAT3 inhibition and retains the cellular response to cytokines with anti-tumor activity
Authors: Bill Matthew A , Fuchs James R , Li Chenglong , Yui Jennifer , Bakan Courtney , Benson Don M , Schwartz Eric B , Abdelhamid Dalia , Lin Jiayuh , Hoyt Dale G , Fossey Stacey L , Young Gregory S , Carson William E , Li Pui-Kai , Lesinski Gregory B
Published: June 2010

Background

We characterized the biologic effects of a novel small molecule STAT3 pathway inhibitor that is derived from the natural product curcumin. We hypothesized this lead compound would specifically inhibit the STAT3 signaling pathway to induce apoptosis in melanoma cells.

Results

FLLL32 specifically reduced STAT3 phosphorylation at Tyr705 (pSTAT3) and induced apoptosis at micromolar amounts in human melanoma cell lines and primary melanoma cultures as determined by annexin V/propidium iodide staining and immunoblot analysis. FLLL32 treatment reduced expression of STAT3-target genes, induced caspase-dependent apoptosis, and reduced mitochondrial membrane potential. FLLL32 displayed specificity for STAT3 over other homologous STAT proteins. In contrast to other STAT3 pathway inhibitors (WP1066, JSI-124, Stattic), FLLL32 did not abrogate IFN-γ-induced pSTAT1 or downstream STAT1-mediated gene expression as determined by Real Time PCR. In addition, FLLL32 did not adversely affect the function or viability of immune cells from normal donors. In peripheral blood mononuclear cells (PBMCs), FLLL32 inhibited IL-6-induced pSTAT3 but did not reduce signaling in response to immunostimulatory cytokines (IFN-γ, IL 2). Treatment of PBMCs or natural killer (NK) cells with FLLL32 also did not decrease viability or granzyme b and IFN-γ production when cultured with K562 targets as compared to vehicle (DMSO).

Conclusions

These data suggest that FLLL32 represents a lead compound that could serve as a platform for further optimization to develop improved STAT3 specific inhibitors for melanoma therapy.
Immunohistochemical expression of epidermal growth factor receptor (EGFR) in oral squamous cell carcinoma in relation to proliferation, apoptosis, angiogenesis and lymphangiogenesis
Authors: Sarkis Seta A , Abdullah Bashar H , Abdul Majeed Ban A , Talabani Nazar G
Published: June 2010

Objectives

Squamous cell carcinoma (SCC) is by far the most common malignant neoplasm of the oral cavity. A number of etiologic factors have been implicated in its development. During the past few decades, a particular focus has been placed on the investigation of valid biomarkers predictive of cancer behavior and cervical lymph node metastasis in head and neck Squamous cell carcinoma (HNSCC).The present study was designed to investigate the expression of epidermal growth factor in these tumors in relation to proliferation, apoptosis, angiogenesis and lymphangiogenesis.

Materials and methods

Immunohistochemical (IHC) evaluation of epidermal growth factor receptor (EGFR) expression in 40 retrospective OSCC specimens and its correlation with proliferating cell nuclear antigen (PCNA), antiapoptotic antibody (P53), vascular endothelial growth factor (VEGF), and D2-40 monoclonal antibodies (Mab), in relation to the clinicopathological parameters.

Results

Data revealed positive EGFR immunoreactivity in 35(87.5%) cases. There was a statistically significant correlation regarding EGFR extent score with respect to intratumoral lymphatic vessel density (ILVD) (r = 0.35) as well as EGFR intensity score with respect to ILVD and peritumoral lymphatic vessel density (PLVD) (r = 0.33, r = 0.36 respectively). EGFR expression was not correlated with the clinicopathological parameters. Conclusions: EGFR is expressed by most of the cases. EGFR correlation with D2- 40 positive lymphatic vessels suggests a higher tendency of OSCC for lymphatic dissemination. Lack of correlation among the studied markers suggests their independent effect on tumor behavior.
Co-variation between autotrophy and heterotrophy in the Mediterranean coralCladocora caespitosa
Authors: Hoogenboom Mia , Rodolfo-Metalpa Riccardo , Ferrier-Pagès Christine
Published: June 2010

This study quantifies the relative contributions of autotrophy and heterotrophy to the energy budget of the temperate scleractinian species Cladocora caespitosa Linnaeus 1767. Colonies were incubated under different light and feeding regimes, and changes in carbon acquisition through photosynthesis and feeding were measured during a 2-month time period. This approach allowed us to quantify the rate at which adjustments to physiology occurred, as well as the magnitude of up- or downregulation of both feeding modes. In addition, we explored how shifts in carbon acquisition mode influenced tissue biomass (protein content), energy stores (lipid content) and colony growth (calcification). Increases in feeding capacity during prolonged exposure to darkness were correlated with decreases in photosynthetic capacity. However, feeding effort did not decrease when photosynthesis was high. In fact, feeding was maximal under high light conditions when food was not available. During starvation, colonies used their lipid stores to partially meet their metabolic requirements. Colonies kept in low light used nutrients from feeding to supplement calcification, whereas those kept at high light converted carbon from feeding into tissue biomass. This work provides the first estimates of rates of adjustment of heterotrophic feeding capacity in a Mediterranean scleractinian coral. For the study species, flexibility in carbon acquisition through heterotrophy was approximately equal to flexibility in photosynthesis both in magnitude and in the rate at which physiological adjustments occurred. The ability to alter feeding effort rapidly and strongly may explain the wide depth distribution of C. caespitosa, and its ability to survive in turbid coastal waters where light is often limited.
Selection of entomopathogenic nematodes for enhanced responsiveness to a volatile root signal helps to control a major root pest
Authors: Hiltpold Ivan , Baroni Mariane , Toepfer Stefan , Kuhlmann Ulrich , Turlings Ted C. J.
Published: June 2010

The efficacy of natural enemies as biological control agents against insect pests can theoretically be enhanced by artificial selection for high responsiveness to foraging cues. The recent discovery that maize roots damaged by the western corn rootworm (WCR) emit a key attractant for insect-killing nematodes has opened the way to explore whether a selection strategy can improve the control of root pests. The compound in question, (E)-β-caryophyllene, is only weakly attractive to Heterorhabditis bacteriophora, one of the most infectious nematodes against WCR. To overcome this drawback, we used a six-arm below-ground olfactometer to select for a strain of H. bacteriophora that is more readily attracted to (E)-β-caryophyllene. After six generations of selection, the selected strain responded considerably better and moved twice as rapidly towards a (E)-β-caryophyllene source than the original strain. There was a minor trade-off between this enhanced responsiveness and nematode infectiveness. Yet, in subsequent field tests, the selected strain was significantly more effective than the original strain in reducing WCR populations in plots with a maize variety that releases (E)-β-caryophyllene, but not in plots with a maize variety that does not emit this root signal. These results illustrate the great potential of manipulating natural enemies of herbivores to improve biological pest control.
Object preference by walking fruit flies,Drosophila melanogaster, is mediated by vision and graviperception
Authors: Robie Alice A. , Straw Andrew D. , Dickinson Michael H.
Published: June 2010

Walking fruit flies, Drosophila melanogaster, use visual information to orient towards salient objects in their environment, presumably as a search strategy for finding food, shelter or other resources. Less is known, however, about the role of vision or other sensory modalities such as mechanoreception in the evaluation of objects once they have been reached. To study the role of vision and mechanoreception in exploration behavior, we developed a large arena in which we could track individual fruit flies as they walked through either simple or more topologically complex landscapes. When exploring a simple, flat environment lacking three-dimensional objects, flies used visual cues from the distant background to stabilize their walking trajectories. When exploring an arena containing an array of cones, differing in geometry, flies actively oriented towards, climbed onto, and explored the objects, spending most of their time on the tallest, steepest object. A fly's behavioral response to the geometry of an object depended upon the intrinsic properties of each object and not a relative assessment to other nearby objects. Furthermore, the preference was not due to a greater attraction towards tall, steep objects, but rather a change in locomotor behavior once a fly reached and explored the surface. Specifically, flies are much more likely to stop walking for long periods when they are perched on tall, steep objects. Both the vision system and the antennal chordotonal organs (Johnston's organs) provide sufficient information about the geometry of an object to elicit the observed change in locomotor behavior. Only when both these sensory systems were impaired did flies not show the behavioral preference for the tall, steep objects.
Jumping mechanisms and performance of pygmy mole crickets (Orthoptera, Tridactylidae)
Authors: Burrows M. , Picker M. D.
Published: June 2010

Pygmy mole crickets live in burrows at the edge of water and jump powerfully to avoid predators such as the larvae and adults of tiger beetles that inhabit the same microhabitat. Adults are 5–6 mm long and weigh 8 mg. The hind legs are dominated by enormous femora containing the jumping muscles and are 131% longer than the body. The ratio of leg lengths is: 1:2.1:4.5 (front:middle:hind, respectively). The hind tarsi are reduced and their role is supplanted by two pairs of tibial spurs that can rotate through 180 deg. During horizontal walking the hind legs are normally held off the ground. Jumps are propelled by extension of the hind tibiae about the femora at angular velocities of 68,000 deg s−1 in 2.2 ms, as revealed by images captured at rates of 5000 s−1. The two hind legs usually move together but can move asynchronously, and many jumps are propelled by just one hind leg. The take-off angle is steep and once airborne the body rotates backwards about its transverse axis (pitch) at rates of 100 Hz or higher. The take-off velocity, used to define the best jumps, can reach 5.4 m s−1, propelling the insect to heights of 700 mm and distances of 1420 mm with an acceleration of 306 g. The head and pronotum are jerked rapidly as the body is accelerated. Jumping on average uses 116 μJ of energy, requires a power output of 50 mW and exerts a force of 20 mN. In jumps powered by one hind leg the figures are about 40% less.
The role of the anterior lateral eyes in the vision-based behaviour of jumping spiders
Authors: Zurek Daniel B. , Taylor Alan J. , Evans Christopher S. , Nelson Ximena J.
Published: June 2010

Jumping spiders, or salticids, sample their environment using a combination of two types of eyes. The forward-facing pair of ‘principal’ eyes have narrow fields of view, but exceptional spatial resolution, while the two or three pairs of ‘secondary’ eyes have wide fields of view and function especially well as motion analysers. Motion detected by the secondary eyes may elicit an orienting response, whereupon the object of interest is examined further using the high-acuity principal eyes. The anterior lateral (AL) eyes are particularly interesting, as they are the only forward-facing pair of secondary eyes. In this study, we aimed to determine characteristics of stimuli that elicit orienting responses mediated by the AL eyes. After covering all eyes except the AL eyes, we measured orienting responses to dot stimuli that varied in size and contrast, and moved at different speeds. We found that all stimulus parameters had significant effects on orientation propensity. When tethered flies were used as prey, we found that visual information from the AL eyes alone was sufficient to elicit stalking behaviour. These results suggest that, in terms of overall visual processing, the relevance of spatial vision in the AL eyes has been underestimated in the literature. Our results also show that female spiders are significantly more responsive than males. We found that hunger caused similar increases in orientation propensity in the two sexes, but females responded more often than males both when sated and when hungry. A higher propensity by females to orient toward moving objects may be related to females tending to experience higher nutritional demands than males.
Hysteresis in the production of force by larval Dipteran muscle
Authors: Paterson Bethany A. , Anikin Ilya Marko , Krans Jacob L.
Published: June 2010

We describe neuromuscular hysteresis – the dependence of muscle force on recent motoneuron activity – in the body wall muscles of larval Sarcophaga bullata and Drosophila melanogaster. In semi-intact preparations, isometric force produced by a train of nerve impulses at a constant rate was significantly less than that produced by the same train of stimuli with a brief (200 ms) high-frequency burst of impulses interspersed. Elevated force did not decay back to predicted values after the burst but instead remained high throughout the duration of the stimulus train. The increased force was not due to a change in excitatory junction potentials (EJPs); EJP voltage and time course before and after the high-frequency burst were not statistically different. Single muscle and semi-intact preparations exhibited hysteresis similarly, suggesting that connective tissues of the origin or insertion are not crucial to the mechanism of hysteresis. Hysteresis was greatest at low motoneuron rates – yielding a ~100% increase over predicted values based on constant-rate stimulation alone – and decreased as impulse rate increased. We modulated motoneuron frequency rhythmically across rates and cycle periods similar to those observed during kinematic analysis of larval crawling. Positive force hysteresis was also evident within these more physiological activation parameters.
Neuromuscular control of wingbeat kinematics in Anna's hummingbirds (Calypte anna)
Authors: Altshuler Douglas L. , Welch Kenneth C. , Cho Brian H. , Welch Danny B. , Lin Amy F. , Dickson William B. , Dickinson Michael H.
Published: June 2010

Hummingbirds can maintain the highest wingbeat frequencies of any flying vertebrate – a feat accomplished by the large pectoral muscles that power the wing strokes. An unusual feature of these muscles is that they are activated by one or a few spikes per cycle as revealed by electromyogram recordings (EMGs). The relatively simple nature of this activation pattern provides an opportunity to understand how motor units are recruited to modulate limb kinematics. Hummingbirds made to fly in low-density air responded by moderately increasing wingbeat frequency and substantially increasing the wing stroke amplitude as compared with flight in normal air. There was little change in the number of spikes per EMG burst in the pectoralis major muscle between flight in normal and low-density heliox (mean=1.4 spikes cycle−1). However the spike amplitude, which we take to be an indication of the number of active motor units, increased in concert with the wing stroke amplitude, 1.7 times the value in air. We also challenged the hummingbirds using transient load lifting to elicit maximum burst performance. During maximum load lifting, both wing stroke amplitude and wingbeat frequency increased substantially above those values during hovering flight. The number of spikes per EMG burst increased to a mean of 3.3 per cycle, and the maximum spike amplitude increased to approximately 1.6 times those values during flight in heliox. These results suggest that hummingbirds recruit additional motor units (spatial recruitment) to regulate wing stroke amplitude but that temporal recruitment is also required to maintain maximum stroke amplitude at the highest wingbeat frequencies.
Building Bridges between Structural and Program Evaluation Approaches to Evaluating Policy
Authors: Heckman James J
Published: June 2010

This paper compares the structural approach to economic policy analysis with the program evaluation approach. It offers a third way to do policy analysis that combines the best features of both approaches. I illustrate the value of this alternative approach by making the implicit economics of LATE explicit, thereby extending the interpretability and range of policy questions that LATE can answer. (JEL C21, E61)
Instruments, Randomization, and Learning about Development
Authors: Deaton Angus
Published: June 2010

There is currently much debate about the effectiveness of foreign aid and about what kind of projects can engender economic development. There is skepticism about the ability of econometric analysis to resolve these issues or of development agencies to learn from their own experience. In response, there is increasing use in development economics of randomized controlled trials (RCTs) to accumulate credible knowledge of what works, without overreliance on questionable theory or statistical methods. When RCTs are not possible, the proponents of these methods advocate quasi-randomization through instrumental variable (IV) techniques or natural experiments. I argue that many of these applications are unlikely to recover quantities that are useful for policy or understanding: two key issues are the misunderstanding of exogeneity and the handling of heterogeneity. I illustrate from the literature on aid and growth. Actual randomization faces similar problems as does quasi-randomization, notwithstanding rhetoric to the contrary. I argue that experiments have no special ability to produce more credible knowledge than other methods, and that actual experiments are frequently subject to practical problems that undermine any claims to statistical or epistemic superiority. I illustrate using prominent experiments in development and elsewhere. As with IV methods, RCT-based evaluation of projects, without guidance from an understanding of underlying mechanisms, is unlikely to lead to scientific progress in the understanding of economic development. I welcome recent trends in development experimentation away from the evaluation of projects and toward the evaluation of theoretical mechanisms. (JEL C21, F35, O19)
Online Demand Under Limited Consumer Search
Authors: Kim Jun B. , Albuquerque Paulo , Bronnenberg Bart J.
Published: June 2010

Using aggregate product search data from Amazon.com, we jointly estimate consumer information search and online demand for consumer durable goods. To estimate the demand and search primitives, we introduce an optimal sequential search process into a model of choice and treat the observed market-level product search data as aggregations of individual-level optimal search sequences. The model builds on the dynamic programming framework by Weitzman [Weitzman, M. L. 1979. Optimal search for the best alternative. Econometrica 47(3) 641–654] and combines it with a choice model. It can accommodate highly complex demand patterns at the market level. At the individual level, the model has a number of attractive properties in estimation, including closed-form expressions for the probability distribution of alternative sets of searched goods and breaking the curse of dimensionality. Using numerical experiments, we verify the model's ability to identify the heterogeneous consumer tastes and search costs from product search data. Empirically, the model is applied to the online market for camcorders and is used to answer manufacturer questions about market structure and competition and to address policy-maker issues about the effect of selectively lowered search costs on consumer surplus outcomes. We demonstrate that the demand estimates from our search model predict the actual product sales ranks. We find that consumer search for camcorders at Amazon.com is typically limited to 10–15 choice options and that this affects estimates of own and cross elasticities. In a policy simulation, we also find that the vast majority of the households benefit from Amazon.com's product recommendations via lower search costs.
The Economics of Buyer Uncertainty: Advance Selling vs. Probabilistic Selling
Authors: Fay Scott , Xie Jinhong
Published: June 2010

Although advance selling and probabilistic selling differ in both motivation and implementation, we argue that they share a common characteristic—both offer consumers a choice involving buyer uncertainty. We develop a formal model to examine the general economics of purchase options that involve buyer uncertainty, explore the differences in buyer uncertainty created via these two strategies, and derive conditions under which one dominates the other. We show that the seller can address unobservable buyer heterogeneity by inducing sales involving buyer uncertainty via two different mechanisms: (1) homogenizing heterogeneous consumers and (2) separating heterogeneous consumers. Offering advance sales encourages customers to purchase while they are uncertain about their consumption states (more homogeneous), but offering probabilistic goods encourages customers to reveal their heterogeneity via self-selecting whether or not to purchase the uncertain product. The relative attractiveness of these two selling strategies depends on the degree of two types of buyer heterogeneity: (1) Max_Value-Heterogeneity, which is the variation in consumers' valuations for their preferred good, and (2) Strength-Heterogeneity, which is the variation in the strength of consumers' preferences. Neither strategy is advantageous unless the market exhibits sufficient Max_Value-Heterogeneity. However, whereas Strength-Heterogeneity can destroy the profit advantage of advance selling, a mid-range of Strength-Heterogeneity is necessary for probabilistic selling to be advantageous.
Optimal Reverse-Pricing Mechanisms
Authors: Spann Martin , Zeithammer Robert , Häubl Gerald
Published: June 2010

Reverse pricing is a market mechanism under which a consumer's bid for a product leads to a sale if the bid exceeds a hidden acceptance threshold the seller has set in advance. The seller faces two key decisions in designing such a mechanism. First, he must decide where in the process to collect the revenue—that is, whether to commit to a minimum markup above cost (and thus define the bid-acceptance threshold given cost) and whether to set a fee for the consumer's right to bid. Second, the seller must decide whether to facilitate or hinder consumer learning about the current bid-acceptance threshold. We analyze these decisions for a profit-maximizing small intermediary retailer selling to consumers who can also purchase the product in an outside posted-price market. The optimal revenue model is to charge a fee for the right to bid and then accept all bids above cost, rather than to set a positive minimum markup above cost. Avoiding minimum markups in favor of a bidding fee is more profitable because of increased efficiency arising from more entry by consumers and higher bids by the entrants. When consumers learn about the bid-acceptance threshold before they enter the market, efficiency increases further, and generating revenue through a bidding fee can compensate the seller for his loss of information rent when the competition from the outside posted-price firm is relatively weak.
Optimal Reverse Channel Structure for Consumer Product Returns
Authors: Shulman Jeffrey D. , Coughlan Anne T. , Savaskan R. Canan
Published: June 2010

Consumers often return a product to a retailer because they learn after purchase that the product does not match as well with preferences as had been expected. This is a costly issue for retailers and manufacturers—in fact, it is estimated that the U.S. electronics industry alone spent $13.8 billion dollars in 2007 to restock returned products [Lawton, C. 2008. The war on returns. Wall Street Journal (May 8) D1]. The bulk of these returns were nondefective items that simply were not what the consumer wanted. To eliminate returns and to recoup the cost of handling returns, many retailers are adopting the practice of charging restocking fees to consumers as a penalty for making returns. This paper employs an analytical model of a bilateral monopoly to examine the impact of reverse channel structure on the equilibrium return policy and profit. More specifically, we examine how the return penalty is affected by whether returns are salvaged by the manufacturer or by the retailer. Interestingly, we find that the return penalty may be more severe when returns are salvaged by a channel member who derives greater value from a returned unit. Also, the manufacturer may earn greater profit by accepting returns even if the retailer has a more efficient outlet for salvaging units.
The Seeds of Dissolution: Discrepancy and Incoherence in Buyer–Supplier Exchange
Authors: Wang Qiong , Kayande Ujwal , Jap Sandy
Published: June 2010

In this research, we examine a novel mechanism of interorganizational relationship dissolution: incoherence in a partner's behavior. We propose that the discrepancy between an exchange partner's opportunistic behavior and the focal firm's expectations may create a state of incoherence and uncertainty and that this effect can be damaging to the exchange even when the partner's behavior is better than expected. Using nearly 500 longitudinal, confidential reports of industrial buyers and sellers, we find supportive evidence that (1) the net effect of the discrepancy is initially positive when behavior is better than expected but becomes rapidly negative thereafter, and (2) the net effect of the discrepancy is always negative when behavior is worse than expected. Thus, these effects will generally damage the exchange even as the partner tries to improve the relationship. This gives insight into why exchange relationships that hit a downward spiral can be difficult, if not impossible, to salvage. We also show that the dysfunctional consequences of discrepancy are mitigated through exchange structures such as the magnitude of dependence on an organizational partner, the development phase of the relationship, and the presence of bilateral idiosyncratic investments. Implications for theory and the management of interorganizational relationships are developed.
Detection of Androgen Receptor Mutations in Circulating Tumor Cells in Castration-Resistant Prostate Cancer
Authors: Jiang Yuqiu , Palma John F , Agus David B , Wang Yixin , Gross Mitchell E
Published: June 2010

BACKGROUND

Coding mutations in the AR (androgen receptor) gene have been identified in tissue samples from patients with advanced prostate cancer and represent a possible mechanism underlying the development of castration-resistant prostate cancer (CRPC). There is a paucity of tumor-derived tissue available for molecular studies of CRPC patients. Circulating tumor cells (CTCs) in the blood of CRPC patients represent a possible avenue for interrogating the disease of such patients.

METHODS

Circulating tumor cells were captured with the CellSearch® Circulating Tumor Cell (CTC) Kit and with the CellSearch Profile Kit plus Qiagen's AllPrep DNA/RNA Micro Kit for the measurement of the CTC count per 7.5 mL of blood and for the isolation of nucleic acids, respectively. The AR gene was amplified by the PCR, and mutation status and relative abundance were analyzed by applying Transgenomic's WAVE® denaturing HPLC technology followed by direct sequencing.

RESULTS

AR mutations were detected in 20 of 35 CRPC patients; 19 missense mutations, 2 silent mutations, 5 deletions, and 1 insertion were observed. The relative abundance of the mutants in the amplified products ranged from 5% to 50%. Many of the AR mutations were identified in surgical biopsies or at autopsy and were associated with resistance to androgen-directed therapies.

CONCLUSIONS

AR mutations can be identified in CTC-enriched peripheral blood samples from CRPC patients. This approach has the potential to open new perspectives in understanding CTCs and the mechanisms for tumor progression and metastasis in CRPC.
VKORC1 haplotypes influence the performance characteristics of PIVKAII for screening of hepatocellular carcinoma
Authors: Wang Yibo , Luo Fang , Zheng Yi , Fan Xiaohan , Chen Jinxing , Zhang Yu , Hui Rutai
Published: June 2010

Background: PIVKAII (protein induced by vitamin K absence), used for screening for hepatocellular carcinoma (HCC), is influenced by vitamin K epoxide reductase complex subunit 1 (VKORC1). VKORC1 haplotype frequency is significantly different in ethnic groups. We evaluated whether VKORC1 haplotypes could influence the performance characteristics of PIVKAII in screening for HCC.

Methods: A total 228 HCC patients and 258 patients with hepatitis B were recruited. Tumor size was measured in 76 patients with HCC. Serum PIVKAII concentrations and VKORC1 haplotype were determined in the cohort. Youden's index and ROC curves were used to compare the performance characteristics of PIVKAII in screening for HCC.

Results: In the HCC group and in patients with hepatitis B, serum PIVKAII concentrations were higher in VKORC1 rs2395612 TT carriers than in CC/CT carriers (50.34±72.18 vs. 11.98±27.45, p<0.05 in HCC group and 1.92±0.52 vs. 1.48±0.36, p<0.01). The estimated optimal cut-off value of PIVKAII for screening HCC was 2.0 and 3.0 ng/mL in CC/CT carriers and TT carriers, respectively. Furthermore, VKORC1 haplotypes also influenced the association of serum PIVKAII concentrations with HCC tumor size in patients with HCC.

Conclusions:
VKORC1 haplotypes influence the performance characteristics of PIVKAII for screening of HCC. Thus, measurement could be complementary for PIVKAII in HCC screening.

Clin Chem Lab Med 2010;48:1475–9.
Defining Overfished Stocks: Have We Lost the Plot?
Authors: Hilborn Ray , Stokes Kevin
Published: June 2010

In recent years, there has been increasing emphasis on prevention of overfishing and agencies such as the National Oceanic and Atmospheric Administration now report the proportion of stocks that are overfished as a primary indicator of the agencies' performance. Almost all national and international legislation makes specific reference to maximum sustainable yield (MSY) and most definitions of overfishing are related in some way to achievement of MSY. We show that many of the definitions of overfishing now being adopted by fisheries agencies are increasingly unrelated to achievement of MSY and have become, to a great extent, arbitrary. We argue that overfishing definitions and management targets are generally better based on levels of historical stock size rather than the growing trend to setting targets in relation to theoretical unfished stock sizes.

Resumen

Recientemente se le ha dado especial énfasis a la prevención de la sobrepesca y agencias como la Nacional de Administración Oceánica y Atmosférica reportan como su principal indicador de desempeño, la proporción de stocks sobreexplotados. Casi toda la legislación existente, nacional e internacional, hace referencia específica al Rendimiento Máximo Sostenible (RMS) y la mayor parte de las definiciones de sobrepesca se relacionan de alguna forma a la adquisición de dicho nivel de rendimiento. En la presente contribución se muestra que muchas de las definiciones de sobrepesca que adoptan las agencias de pesquerías, se alejan cada vez más del nivel de RMS y que se han convertido, en buena medida, en algo arbitrario. Se discute que las definiciones de sobrepesca y objetivos de manejo generalmente tienen una mejor base en los niveles históricos del tamaño del stock que en la tendencia creciente de establecerlos en relación al tamaño teórico del stock en estado virgen.
A Novel Technique for Mapping Habitat in Navigable Streams Using Low-cost Side Scan Sonar
Authors: Kaeser Adam J. , Litts Thomas L.
Published: June 2010

An inexpensive and rapid technique for mapping instream habitat of navigable rivers is needed by natural resource professionals. Unlike more expensive side scan sonar devices, the Humminbird® Side Imaging system employs a boat-mounted transducer enabling the survey of shallow, rocky streams. This device can be used to obtain high resolution, georeferenced images of underwater habitat. We developed a technique employing geographic information systems (GIS) to transform raw sonar images to fit the configuration of a stream channel. The end product is a GIS layer that can be interpreted to map instream habitat. We demonstrated this approach by mapping substrate and large woody debris in a southwest Georgia stream, and evaluated the technique through a comprehensive accuracy assessment. An overall classification accuracy of 77% was observed for substrate mapping and sonar estimates of large woody debris were correlated (r2 = 0.79) with actual wood abundance. Sonar mapping generated estimates of reach and substrate area comparable to a traditional field approach, and reduced the time investment by 90%. Applications for high resolution habitat maps are widespread and numerous; the ability to produce these maps at low cost is now within the grasp of researchers and managers alike.

Los estudiosos de los recursos naturales requieren de una técnica rápida y económica para mapear hábitats en ríos navegables. A diferencia de la mayoría de los escáneres sonares, el sistema de imágenes Humminbird® emplea un transductor montable en una embarcación que permite hacer sondeos en ríos rocosos y someros. Este dispositivo puede utilizarse para obtener imágenes subacuáticas del hábitat, de alta resolución y geo-referenciadas. Se desarrolló una técnica que emplea información de los Sistemas de Información Geográfica (SIG) para transformar las imágenes originales de sonar de forma tal que se ajusten a la configuración de los canales fluviales. El producto final es una capa de SIG que puede ser interpretada para mapear hábitats en los ríos. Este enfoque se demuestra mediante el mapeo del sustrato y escombros de madera en un río del suroeste de Georgia, y también se evaluó su precisión. En cuanto al mapeo del sustrato se observó una precisión del 77% y la estimación realizada mediante el sonar de la abundancia de los escombros de madera se correlacionó con la abundancia real de la madera (r2 = 0.79). Los mapeos con sonar generaron estimaciones tanto de alcance como de área de sustrato, comparables con los obtenidos con los enfoques tradicionales, y redujeron el tiempo de las operaciones en un 90%. Las aplicaciones de mapas de hábitat de alta resolución son variadas y numerosas; la habilidad de producir estos mapas a un bajo costo se encuentra en este momento al alcance tanto de investigadores como de manejadores.
Extracellular superoxide dismutase is a thyroid differentiation marker down-regulated in cancer
Authors: Laatikainen Lilja E , Castellone Maria D , Hebrant Aline , Hoste Candice , Cantisani Maria C , Laurila Juha P , Salvatore Giuliana , Salerno Paolo , Basolo Fulvio , Näsman Johnny , Dumont Jacques E , Santoro Massimo , Laukkanen Mikko O
Published: June 2010

Reactive oxygen species, specifically hydrogen peroxide (H2O2), have a significant role in hormone production in thyroid tissue. Although recent studies have demonstrated that dual oxidases are responsible for the H2O2 synthesis needed in thyroid hormone production, our data suggest a pivotal role for superoxide dismutase 3 (SOD3) as a major H2O2-producing enzyme. According to our results, Sod3 is highly expressed in normal thyroid, and becomes even more abundant in rat goiter models. We showed TSH-stimulated expression of Sod3 via phospholipase C–Ca2+ and cAMP–protein kinase A, a pathway that might be disrupted in thyroid cancer. In line with this finding, we demonstrated an oncogene-dependent decrease in Sod3 mRNA expression synthesis in thyroid cancer cell models that corresponded to a similar decrease in clinical patient samples, suggesting that SOD3 could be used as a differentiation marker in thyroid cancer. Finally, the functional analysis in thyroid models indicated a moderate role for SOD3 in regulating normal thyroid cell proliferation being in line with our previous observations.
Full Scale Advanced Oxidation Treatment Plant for Groundwater
Authors: Werderitsch Markus
Published: June 2010

Vienna Waterworks installed a new innovative treatment plant in the Waterworks Moosbrunn to improve the safety and reliability of the water supply system in case of failure or necessary repairs on either of the two spring water supply mains or during times of increased water demand. The abstracted raw water is groundwater, which is contaminated by chlorinated hydrocarbons, such as tetrachloroethene and trichloroethene. Different treatment possibilities were evaluated before the project started. One of the most suitable processes was the combined use of ozone and hydrogen peroxide (advanced oxidation process). This innovative process is installed for the first time on a full-scale basis and with a daily capacity of 64.000 m3/d it also is the biggest treatment plant in Austria. The treatment plant has been running to the complete satisfaction of Vienna Waterworks since start-up.
Hong Kong Sludge Treatment Facilities
Authors: Leong Echo , Kwan Alex , Yuen Priscilla
Published: June 2010

At present, all dewatered sewage sludge generated by sewage treatment works (STW) is disposed of at landfills. This current practice of sludge disposal at landfill is not sustainable from both environmental and technical perspectives. The Hong Kong sludge contains high content of chloride due to use of seawater flushing in most of the Hong Kong areas and Hong Kong is a densely populated city. This unique condition has limited its selection of the alternative sludge treatment technology. The Sludge Treatment Facilities (STF) adopting fluidized bed incineration technology is a sustainable alternative for sludge disposal in Hong Kong. The design capacity of the STF is 2000 wet tonnes per day. The STF will be implemented under a Design-Build-and-Operate contract arrangement with a contractual operation period of 15 years and is scheduled to be commissioned by 2012.
Study on Application of BOT model in Sewage Sludge Treatment and disposal of China
Authors: Tian Xin , Chang Miao
Published: June 2010

Sewage sludge treatment and disposal is becoming an essential issue in China. By analyzing current situation and problems in sludge treatment and disposal sector, this paper presented the feasibility of BOT model in sludge treatment and disposal facilities construction, and further established a specific BOT framework for sewage sludge treatment and disposal. This study identified two different BOT operational modes according to the sewage sludge production status in China. Based on summarizing the current challenges in China's sludge treatment and disposal BOT projects, suggestions were proposed.