1,207 research outputs found
The effects of contract detail and prior ties on contract change : a learning perspective
Despite the large literature on alliance contract design, we know little about how transacting parties change and amend their underlying contracts during the execution of strategic alliances. Drawing on existing research in the alliance contracting literature, we develop the empirical question of how contract detail and prior ties influence the amount, direction, and type of change in such agreements during the collaboration. We generated a sample of 115 joint ventures (JVs) by distributing a survey to JV board members or top managers and found that the amount of contract change is negatively associated with the level of detail in the initial contract but is positively associated with the number of prior ties between alliance partners. In relation to the direction of contract change, we find that the level of detail of the initial agreements negatively correlates with the likelihood of removing or weakening existing provisions and that prior collaborative experience positively correlates with the likelihood of strengthening of existing provisions or adding of new ones. We also find that prior ties affect the type of change in that JV parents prefer to change enforcement provisions more so than the coordination provisions in the contract. Our paper generates new insights on the complementarities between relational governance and transaction cost economics perspectives on alliance contracting
Mechanics of biofilms formed of bacteria with fimbriae appendages
Gram-negative bacteria, as well as some Gram-positive bacteria, possess hair-like appendages known as fimbriae, which play an important role in adhesion of the bacteria to surfaces or to other bacteria. Unlike the sex pili or flagellum, the fimbriae are quite numerous, with of order 1000 fimbriae appendages per bacterial cell. In this paper, a recently developed hybrid model for bacterial biofilms is used to examine the role of fimbriae tension force on the mechanics of bacterial biofilms. Each bacterial cell is represented in this model by a spherocylindrical particle, which interact with each other through collision, adhesion, lubrication force, and fimbrial force. The bacterial cells absorb water and nutrients and produce extracellular polymeric substance (EPS). The flow of water and EPS, and nutrient diffusion within these substances, is computed using a continuum model that accounts for important effects such as osmotic pressure gradient, drag force on the bacterial cells, and viscous shear. The fimbrial force is modeled using an outer spherocylinder capsule around each cell, which can transmit tensile forces to neighboring cells with which the fimbriae capsule collides. We find that the biofilm structure during the growth process is dominated by a balance between outward drag force on the cells due to the EPS flow away from the bacterial colony and the inward tensile fimbrial force acting on chains of cells connected by adhesive fimbriae appendages. The fimbrial force also introduces a large rotational motion of the cells and disrupts cell alignment caused by viscous torque imposed by the EPS flow. The current paper characterizes the competing effects of EPS drag and fimbrial force using a series of computations with different values of the ratio of EPS to bacterial cell production rate and different numbers of fimbriae per cell
Cash on the Table? Imperfect Take-up of Tax Incentives and Firm Investment Behavior
We investigate whether tax incentives are effective in stimulating private investment in less developed countries, by exploiting the introduction of accelerated depreciation for fixed assets investment in China as a natural experiment. In contrast to the large positive impact of similar tax incentives in the U.S. and U.K. found in recent studies, accelerated depreciation appeared ineffective in stimulating Chinese firms’ investment. Using confidential corporate tax returns from a large province, we find that firms fail to claim the tax benefits on over 80 percent of eligible investments. Firms’ take-up of the tax incentive is significantly influenced by their taxable positions and tax sophistication. Information transmission and resources of local tax authorities also play a significant role. Our study contributes to the understanding of conditions under which tax-based investment incentives can be effective
Accurately Detecting Flirting: Error Management Theory, the Traditional Sexual Script, and Flirting Base Rate
The present manuscript reports two studies on the accuracy of flirting detection. In Study 1, 52 pairs (N = 104) of opposite-sex heterosexual strangers interacted for 10-12 minutes, then self-reported flirting and perceived partner flirting. The results indicated that interactions where flirting did not occur were more accurately perceived than interactions where flirting occurred. In Study 2, 26 one minute video clips drawn from Study 1 were randomly assigned to one of eight experimental conditions that varied flirting base rate and the traditional sexual script. Participant observers (N = 261) attempted to determine if flirting occurred. Results indicated that base rate affected accuracy; flirting was more accurately detected in clips where flirting did not occur than in clips where flirting occurred. Study 2 also indicated that female targets’ flirting was more accurately judged than male targets’ flirting. Findings are discussed in relation to accuracy and courtship context
A Large Nonmetastatic Anaplastic Thyroid Cancer with Complete Thyroidal Confinement
Anaplastic thyroid cancer (ATC) is rare but extremely aggressive, which accounts for
about 2% of all thyroid cancers yet nearly 50% of thyroid-cancer-associated deaths
in the United States. The median survival time from diagnosis is 5 months, with a
1-year survival rate of only 20%. We report here a case of ATC in a 56-year-old man
who survived a large ATC. Preoperative fine-needle aspiration biopsy study to a
large right thyroid mass suggested ATC. Total thyroidectomy with radical lateral
neck and central neck dissection removed a well-circumscribed 9.5 cm tumor
without extrathyroidal extension or lymphovascular invasion. All 73 lymph nodes
removed were negative for metastasis. The tumor consisted of highly pleomorphic,
undifferentiated cells with large zones of necrosis and loss of thyroid
transcription factor-1 and thyroglobulin expression. A focal well-differentiated
component and PAX8 expression confirmed its thyroid follicular cell origin. Nine
months after postsurgical adjuvant concurrent radiation therapy and chemotherapy,
the patient remained well without clinical, biochemical, and radiographical evidence
for cancer recurrence. This is an unusual case of ATC in that it is one of the
largest ATC tumors reported to display mild pathologic behavior and relatively
long-term patient survival
Transcriptome landscape of the human placenta
<p>Abstract</p> <p>Background</p> <p>The placenta is a key component in understanding the physiological processes involved in pregnancy. Characterizing genes critical for placental function can serve as a basis for identifying mechanisms underlying both normal and pathologic pregnancies. Detailing the placental tissue transcriptome could provide a valuable resource for genomic studies related to placental disease.</p> <p>Results</p> <p>We have conducted a deep RNA sequencing (RNA-Seq) study on three tissue components (amnion, chorion, and decidua) of 5 human placentas from normal term pregnancies. We compared the placental RNA-Seq data to that of 16 other human tissues and observed a wide spectrum of transcriptome differences both between placenta and other human tissues and between distinct compartments of the placenta. Exon-level analysis of the RNA-Seq data revealed a large number of exons with differential splicing activities between placenta and other tissues, and 79% (27 out of 34) of the events selected for RT-PCR test were validated. The master splicing regulator <it>ESRP1 </it>is expressed at a proportionately higher level in amnion compared to all other analyzed human tissues, and there is a significant enrichment of ESRP1-regulated exons with tissue-specific splicing activities in amnion. This suggests an important role of alternative splicing in regulating gene function and activity in specific placental compartments. Importantly, genes with differential expression or splicing in the placenta are significantly enriched for genes implicated in placental abnormalities and preterm birth. In addition, we identified 604-1007 novel transcripts and 494-585 novel exons expressed in each of the three placental compartments.</p> <p>Conclusions</p> <p>Our data demonstrate unique aspects of gene expression and splicing in placental tissues that provide a basis for disease investigation related to disruption of these mechanisms. These data are publicly available providing the community with a rich resource for placental physiology and disease-related studies.</p
Inhibition of RNA-binding protein HuR reduces glomerulosclerosis in experimental nephritis
Recent identification of an RNA-binding protein (HuR) that regulates mRNA turnover and translation of numerous transcripts via binding to an ARE in their 3′-UTR involved in inflammation and is abnormally elevated in varied kidney diseases offers a novel target for the treatment of renal inflammation and subsequent fibrosis. Thus, we hypothesized that treatment with a selective inhibition of HuR function with a small molecule, KH-3, would down-regulate HuR-targeted proinflammatory transcripts thereby improving glomerulosclerosis in experimental nephritis, where glomerular cellular HuR is elevated. Three experimental groups included normal and diseased rats treated with or without KH-3. Disease was induced by the monoclonal anti-Thy 1.1 antibody. KH-3 was given via daily intraperitoneal injection from day 1 after disease induction to day 5 at the dose of 50 mg/kg BW/day. At day 6, diseased animals treated with KH-3 showed significant reduction in glomerular HuR levels, proteinuria, podocyte injury determined by ameliorated podocyte loss and podocin expression, glomerular staining for periodic acid-Schiff positive extracellular matrix proteins, fibronectin and collagen IV and mRNA and protein levels of profibrotic markers, compared with untreated disease rats. KH-3 treatment also reduced disease-induced increases in renal TGFβ1 and PAI-1 transcripts. Additionally, a marked increase in renal NF-κB-p65, Nox4, and glomerular macrophage cell infiltration observed in disease control group was largely reversed by KH-3 treatment. These results strongly support our hypothesis that down-regulation of HuR function with KH-3 has therapeutic potential for reversing glomerulosclerosis by reducing abundance of pro-inflammatory transcripts and related inflammation
Strain prioritization and genome mining for enediyne natural products
The enediyne family of natural products has had a profound impact on modern chemistry, biology, and medicine, and yet only 11 enediynes have been structurally characterized to date. Here we report a genome survey of 3,400 actinomycetes, identifying 81 strains that harbor genes encoding the enediyne polyketide synthase cassettes that could be grouped into 28 distinct clades based on phylogenetic analysis. Genome sequencing of 31 representative strains confirmed that each clade harbors a distinct enediyne biosynthetic gene cluster. A genome neighborhood network allows prediction of new structural features and biosynthetic insights that could be exploited for enediyne discovery. We confirmed one clade as new C-1027 producers, with a significantly higher C-1027 titer than the original producer, and discovered a new family of enediyne natural products, the tiancimycins (TNMs), that exhibit potent cytotoxicity against a broad spectrum of cancer cell lines. Our results demonstrate the feasibility of rapid discovery of new enediynes from a large strain collection.
IMPORTANCE Recent advances in microbial genomics clearly revealed that the biosynthetic potential of soil actinomycetes to produce enediynes is underappreciated. A great challenge is to develop innovative methods to discover new enediynes and produce them in sufficient quantities for chemical, biological, and clinical investigations. This work demonstrated the feasibility of rapid discovery of new enediynes from a large strain collection. The new C-1027 producers, with a significantly higher C-1027 titer than the original producer, will impact the practical supply of this important drug lead. The TNMs, with their extremely potent cytotoxicity against various cancer cells and their rapid and complete cancer cell killing characteristics, in comparison with the payloads used in FDA-approved antibody-drug conjugates (ADCs), are poised to be exploited as payload candidates for the next generation of anticancer ADCs. Follow-up studies on the other identified hits promise the discovery of new enediynes, radically expanding the chemical space for the enediyne family
- …