bluuebunny/crossref_metadata_2025_split huggingface dataset:
The causes and countermeasures of Chinese graduate entrepreneurship dilemma
Authors: Zhao Xiuzhai 
Published: September 2011

PurposeThe purpose of this paper is to find out the causes of Chinese graduate entrepreneurship dilemma (both the Chinese graduate entrepreneurship rate and the Chinese graduates' entrepreneurship low success rate) and then to propose some suggestions to the dilemma.Design/methodology/approachThe study is conducted on the basis of 20 graduate entrepreneurship cases to summarize the necessary qualifications for graduates to start new businesses and then uses Global Entrepreneurship Monitor's (GEM) theory of entrepreneurial climate to analyze the entrepreneurial climate faced by Chinese graduates.FindingsThis paper points out the internal and external causes of Chinese graduate entrepreneurship dilemma: the internal one is that most graduates do not have the qualifications for entrepreneurship; the external one is that the present entrepreneurial climate in China is poor, resulting in difficulties for Chinese graduates to start new ventures.Practical implicationsThe paper proposes the following countermeasures to help Chinese graduates get out of the entrepreneurship dilemma: undergraduates actively participating in social practice activities, establishing and improving the entrepreneurship education system, perfecting government policies and creating a strong entrepreneurial culture, respectively.Originality/valueNowadays, there is much research into the causes of the Chinese graduate entrepreneurship dilemma from various viewpoints. However, an analysis of the causes using GEMs theory of entrepreneurial climate is rare. This paper analyzes the problem from this aspect.
Building an integrative framework for national systems of innovation
Authors: Wang Yuandi , Zhou Zhao 
Published: September 2011

PurposeThis paper proposes a way to integrate three different analytical approaches into a consistent framework of national systems of innovation that can benefit academia and policy makers. The approaches include the traditional structural method of national systems of innovation, the new development of functional view of national systems of innovation, and the effective approach.Design/methodology/approachAs a theoretical research paper, the paper reviews and analyses intensive literature on national system of innovation from the perspectives of functional, structural, and effectiveness approaches.FindingsThe paper argues that these three approaches reflect different perspectives of national systems of innovation. Instead of contradicting each other, they could be integrated into a coherent framework.Originality/valueThe paper builds an integrative framework to bring different methods of national systems of innovation together. It provides an integrative framework for academy and policy makers to more comprehensively understand the concept of national systems of innovation and further policy design and implementation.
Firm‐level productivity and exporting in Uganda's manufacturing sector
Authors: Bbaale Edward 
Published: September 2011

PurposeThis paper aims to investigate firm‐level interactions between productivity and exporting in Uganda's manufacturing sector.Design/methodology/approachThe paper empirically tested two hypotheses that relate to the dynamic gains from trade and also have tended to dominate the literature; self‐selection and learning‐by‐exporting hypotheses. It employs proxies of self‐selection and learning‐by‐exporting obtained from indices of path dependence to fit maximum likelihood estimates of export behavior.FindingsThe results provide support for both hypotheses and it is also found that more experienced exporters reap more productivity gains from learning effects which is in line with the view that knowledge spillovers to exporting firms increase with the level of interaction in the global market place. Thus, learning‐by‐exporting is not a “short term” occurrence which takes place only in the first few years of entry in export markets after which it would fizzle out as a firm's exporting experience increases but rather, it is a cumulative process.Practical implicationsThis paper generates a number of insights that can guide policy makers in designing policies to promote firm productivity growth that is an engine of growth in the private sector and by extension, would fuel up overall economic growth and poverty reduction.Originality/valuePrevious studies on exports and growth in Uganda have been basically focused on macro‐data analysis; yet, promoting rapid expansion of manufactured exports may require more than just a good macroeconomic policy environment. This study fills the research gap by relating firm‐level productivity performance to the microeconomic environment in which manufacturing firms operate.
The effect mechanism of credit constraint on cycle's formation
Authors: Chen Kunting , Zhong Changbiao 
Published: September 2011

PurposeThis paper aims to study the formation and amplification mechanism of the financial crisis and business cycle and also discuss the related optimal rules for the central bank and government.Design/methodology/approachThis study is developed basically on a simple financial business cycle model by embedding credit constrains into the DSGE model.FindingsThe model in this paper puts forward an explanation for the mechanism of cycles' formation. Using this it finds that: the financial lever in modern economy is the offender of the USA financial crisis, which created the cycles and amplified it into the crisis when the financial lever multiple was increased to much greater levels, and that the traditional policy rule is not good enough for a long running growth process.Research limitations/implicationsThe findings in this study suggest that to keep the financial lever multiple under a safe level and to reform the policy rule to be good enough for a long run growth process is necessary.Practical implicationsAccording to the model's principle, the paper claims that: the development of the financial and credit markets during recent years has increased the volatility of the economic cycle – excessive credit abuse has become the root cause of the instability of the economy system; the proportion of the mortgage loan and similar financial products in the economy should be controlled strictly; it is necessary to recheck the traditional standpoint of the monetary policy. Rule policy by the Keynesian model exists as a short‐term problem, thus it is not sufficient to study the questions related to technological shocks.Originality/valueThe model in this paper explains well the mechanism of cycles and crisis' formation. The findings under the modeling economy give a safe level for financial lever multiples for the first time. The financial business cycle model being used in studying the Chinese economy is a pioneering and exploratory experiment.
Impact of in‐patient research participation on subsequent heroin use patterns: implications for ethics and public health
Authors: Roux Perrine , Tindall Claudia , Fugon Lionel , Murray Janet , Vosburg Suzanne K. , Saccone Phillip , Sullivan Maria A. , Manubay Jeanne M. , Cooper Ziva D. , Jones Jermaine D. , Foltin Richard W. , Comer Sandra D. 
Published: September 2011

ABSTRACTAims  Research on drug dependence often involves the administration of drugs of abuse to experienced drug users under controlled laboratory conditions. The primary objective of this study was to assess whether participation in such research alters the frequency of heroin use by non‐treatment‐seeking opioid‐dependent volunteers after study completion.Design  Data were examined from four in‐patient studies involving controlled opioid administration.Setting  Substance Use Research Center at Columbia University, New York State Psychiatric Institute.Participants  Sixty‐nine heroin‐dependent volunteers.Measurements  Participants' self‐reported heroin use prior to and 1 month after study participation was compared using a Wilcoxon test. Because a number of participants reported that they had stopped using heroin, a logistic regression was used to identify correlates of heroin cessation 1 month after study completion.Findings  One hundred and one participants entered laboratory studies and 69 completed them. Self‐reported heroin use significantly decreased 1 month after study participation [1.7 (±2.0) bags per day] compared to baseline [6.8 (±4.2) bags per day], P < 0.001 among the 69 completers. In addition, 42% of the completers were heroin‐abstinent 1 month after study completion. Being African American, having a history of opioid dependence treatment, reporting heavier heroin use at baseline and a longer history of heroin use were correlated with cessation of heroin use.Conclusions  Participation in opioid administration studies does not increase subsequent heroin use and for some individuals leads to accessing opioid dependence treatment and cessation of heroin use in the short term.
Fabrication of Porous Hydroxyapatite Ceramic Scaffolds with High Flexural Strength Through the Double Slip‐Casting Method Using Fine Powders
Authors: Zhang Yin , Kong Deshuang , Yokogawa Yoshiyuki , Feng Xia , Tao Yaqiu , Qiu Tai 
Published: September 2011

The formation of sufficiently large three‐dimensional nano/macroporosity in bone scaffolds remains a challenge despite the numerous fabrication methods reported in literature. The presence of such porosity is required for tissue ingrowth and for the concurrent degradation of implanted structure. A new technique of combining the slip casting and polymer sponge methods using the slips with different powders was introduced in the study to prepare hydroxyapatite scaffolds with bimodal pore sizes. This technique provided better control over the microstructures of scaffolds and enhanced their mechanical properties compared to traditional methods. With this technique, we were able to produce scaffolds with mechanical and structural properties that could not be attained by the polymer sponge or slip‐casting method alone. The scaffolds were prepared with an open, uniform, and interconnected porous structure with a bimodal pore size of 100–300 μm. The bimodal porous hydroxyapatite scaffold sintered at 1200°C had a large flexural strength of 73.3 MPa and a porosity of 52.5 vol%. These bioscaffolds hold promise for applications in hard tissue engineering.
Linking Specific Heterotrophic Bacterial Populations to Bioreduction of Uranium and Nitrate in Contaminated Subsurface Sediments by Using Stable Isotope Probing
Authors: Akob Denise M. , Kerkhof Lee , Küsel Kirsten , Watson David B. , Palumbo Anthony V. , Kostka Joel E. 
Published: September 2011

ABSTRACT

Shifts in terminal electron-accepting processes during biostimulation of uranium-contaminated sediments were linked to the composition of stimulated microbial populations using DNA-based stable isotope probing. Nitrate reduction preceded U(VI) and Fe(III) reduction in [
13
C]ethanol-amended microcosms. The predominant, active denitrifying microbial groups were identified as members of the
Betaproteobacteria
, whereas
Actinobacteria
dominated under metal-reducing conditions.
Improvement of Glyphosate Resistance through Concurrent Mutations in Three Amino Acids of the Ochrobactrum 5-Enopyruvylshikimate-3-Phosphate Synthase
Authors: Tian Yong-Sheng , Xu Jing , Xiong Ai-Sheng , Zhao Wei , Fu Xiao-Yan , Peng Ri-He , Yao Quan-Hong 
Published: September 2011

ABSTRACT

A mutant of 5-enopyruvylshikimate-3-phosphate synthase from
Ochrobactrum anthropi
was identified after four rounds of DNA shuffling and screening. Its ability to restore the growth of the mutant ER2799 cell on an M9 minimal medium containing 300 mM glyphosate led to its identification. The mutant had mutations in seven amino acids: E145G, N163H, N267S, P318R, M377V, M425T, and P438L. Among these mutations, N267S, P318R, and M425T have never been previously reported as important residues for glyphosate resistance. However, in the present study they were found by site-directed mutagenesis to collectively contribute to the improvement of glyphosate tolerance. Kinetic analyses of these three mutants demonstrated that the effectiveness of these three individual amino acid alterations on glyphosate tolerance was in the order P318R > M425T > N267S. The results of the kinetic analyses combined with a three-dimensional structure modeling of the location of P318R and M425T demonstrate that the lower hemisphere's upper surface is possibly another important region for glyphosate resistance. Furthermore, the transgenic
Arabidopsis
was obtained to confirm the potential of the mutant in developing glyphosate-resistant crops.
Scandium Stimulates the Production of Amylase and Bacilysin in Bacillus subtilis
Authors: Inaoka Takashi , Ochi Kozo 
Published: September 2011

ABSTRACT

We investigated the effects of rare earth elements on enzyme production and secondary metabolism in
Bacillus subtilis
. Addition of scandium to the growth medium stimulated the production of both amylase and bacilysin at the transcriptional level, thus showing scandium to have a remarkable impact in
B. subtilis
.
SagS Contributes to the Motile-Sessile Switch and Acts in Concert with BfiSR To Enable Pseudomonas aeruginosa Biofilm Formation
Authors: Petrova Olga E. , Sauer Karin 
Published: September 2011

ABSTRACTThe interaction ofPseudomonas aeruginosawith surfaces has been described as a two-stage process requiring distinct signaling events and the reciprocal modulation of small RNAs (sRNAs). However, little is known regarding the relationship between sRNA-modulating pathways active under planktonic or surface-associated growth conditions. Here, we demonstrate that SagS (PA2824), the cognate sensor of HptB, links sRNA-modulating activities via the Gac/HptB/Rsm system postattachment to the signal transduction network BfiSR, previously demonstrated to be required for the development ofP. aeruginosa. Consistent with the role of SagS in the GacA-dependent HtpB signaling pathway, inactivation ofsagSresulted in hyperattachment, an HptB-dependent increase inrsmYZ, increased Psl polysaccharide production, and increased virulence. Moreover,sagSinactivation rescued attachment but abrogated biofilm formation by the ΔgacAand ΔhptBmutant strains. The ΔsagSstrain was impaired in biofilm formation at a stage similar to that of the previously described two-component system BfiSR. Expression ofbfiRbut notbfiSrestored ΔsagSbiofilm formation independently ofrsmYZ. We demonstrate that SagS interacts directly with BfiS and only indirectly with BfiR, with the direct and specific interaction between these two membrane-bound sensors resulting in the modulation of the phosphorylation state of BfiS in a growth-mode-dependent manner. SagS plays an important role inP. aeruginosavirulence in a manner opposite to that of BfiS. Our findings indicate that SagS acts as a switch by linking the GacA-dependent sensory system under planktonic conditions to the suppression of sRNAs postattachment and to BfiSR, required for the development ofP. aeruginosabiofilms, in a sequential and stage-specific manner.
Identification of the Amidotransferase AsnB1 as Being Responsible for
meso
-Diaminopimelic Acid Amidation in Lactobacillus plantarum Peptidoglycan
Authors: Bernard Elvis , Rolain Thomas , Courtin Pascal , Hols Pascal , Chapot-Chartier Marie-Pierre 
Published: September 2011

ABSTRACT

The peptidoglycan (PG) of
Lactobacillus plantarum
contains amidated
meso
-diaminopimelic acid (mDAP). The functional role of this PG modification has never been characterized in any bacterial species, except for its impact on PG recognition by receptors of the innate immune system.
In silico
analysis of loci carrying PG biosynthesis genes in the
L. plantarum
genome revealed the colocalization of the
murE
gene, which encodes the ligase catalyzing the addition of mDAP to UDP-
N
-muramoyl-
d
-glutamate PG precursors, with
asnB1
, which encodes a putative asparagine synthase with an N-terminal amidotransferase domain. By gene disruption and complementation experiments, we showed that
asnB1
is the amidotransferase involved in mDAP amidation. PG structural analysis revealed that mDAP amidation plays a key role in the control of the
l,d
-carboxypeptidase DacB activity. In addition, a mutant strain with a defect in mDAP amidation is strongly affected in growth and cell morphology, with filamentation and cell chaining, while a DacB-negative strain displays a phenotype very similar to that of a wild-type strain. These results suggest that mDAP amidation may play a critical role in the control of the septation process.
VasH Is a Transcriptional Regulator of the Type VI Secretion System Functional in Endemic and Pandemic Vibrio cholerae
Authors: Kitaoka Maya , Miyata Sarah T. , Brooks Teresa M. , Unterweger Daniel , Pukatzki Stefan 
Published: September 2011

ABSTRACTThe Gram-negative bacteriumVibrio choleraeis the etiological agent of cholera, a disease characterized by the release of high volumes of watery diarrhea. Many medically important proteobacteria, includingV. cholerae, carry one or multiple copies of the gene cluster that encodes the bacterial type VI secretion system (T6SS) to confer virulence or interspecies competitiveness. Structural similarity and sequence homology between components of the T6SS and the cell-puncturing device of T4 bacteriophage suggest that the T6SS functions as a molecular syringe to inject effector molecules into prokaryotic and eukaryotic target cells. Although our understanding of how the structural T6SS apparatus assembles is developing, little is known about how this system is regulated. Here, we report on the contribution of the activator of the alternative sigma factor 54, VasH, as a global regulator of theV. choleraeT6SS. Using bioinformatics and mutational analyses, we identified domains of the VasH polypeptide that are essential for its ability to initiate transcription of T6SS genes and established a universal role for VasH in endemic and pandemicV. choleraestrains.
Biochemical and Cellular Characterization of Helicobacter pylori RecA, a Protein with High-Level Constitutive Expression
Authors: Orillard Emilie , Radicella J. Pablo , Marsin Stéphanie 
Published: September 2011

ABSTRACT

Helicobacter pylori
is a bacterial pathogen colonizing half of the world's human population. It has been implicated in a number of gastric diseases, from asymptomatic gastritis to cancer. It is characterized by an amazing genetic variability that results from high mutation rates and efficient DNA homologous recombination and transformation systems. Here, we report the characterization of
H. pylori
RecA (HpRecA), a protein shown to be involved in DNA repair, transformation, and mouse colonization. The biochemical characterization of the purified recombinase reveals activities similar to those of
Escherichia coli
RecA (EcRecA). We show that in
H. pylori
, HpRecA is present in about 80,000 copies per cell during exponential growth and decreases to about 50,000 copies in stationary phase. The amount of HpRecA remains unchanged after induction of DNA lesions, suggesting that HpRecA is always expressed at a high level in order to repair DNA damage or facilitate recombination. We performed HpRecA localization analysis by adding a Flag tag to the protein, revealing two different patterns of localization. During exponential growth, RecA-Flag presents a diffuse pattern, overlapping with the DAPI (4′,6-diamidino-2-phenylindole) staining of DNA, whereas during stationary phase, the protein is present in more defined areas devoid of DAPI staining. These localizations are not affected by inactivation of competence or DNA recombination genes. Neither UV irradiation nor gamma irradiation modified HpRecA localization, suggesting the existence of a constitutive DNA damage adaptation system.
Peroxide Stimulon and Role of PerR in Group A Streptococcus
Authors: Grifantini Renata , Toukoki Chadia , Colaprico Annalisa , Gryllos Ioannis 
Published: September 2011

ABSTRACT

We have characterized group A
Streptococcus
(GAS) genome-wide responses to hydrogen peroxide and assessed the role of the peroxide response regulator (PerR) in GAS under oxidative stress. Comparison of transcriptome changes elicited by peroxide in wild-type bacteria with those in a
perR
deletion mutant showed that 76 out of 237 peroxide-regulated genes are PerR dependent. Unlike the PerR-mediated upregulation of peroxidases and other peroxide stress defense mechanisms previously reported in Gram-positive species, PerR-dependent genes in GAS were almost exclusively downregulated and encoded proteins involved in purine and deoxyribonucleotide biosynthesis, heme uptake, and amino acid/peptide transport, but they also included a strongly activated putative transcriptional regulator (
SPy1198
). Of the 161 PerR-independent loci, repressed genes (86 of 161) encoded proteins with functions similar to those coordinated by PerR, in contrast to upregulated loci that encoded proteins that function in DNA damage repair, cofactor metabolism, reactive oxygen species detoxification, pilus biosynthesis, and hypothetical proteins. Complementation of the
perR
deletion mutant with wild-type PerR restored PerR-dependent regulation, whereas complementation with either one of two PerR variants carrying single mutations in two predicted metal-binding sites did not rescue the mutant phenotype. Metal content analyses of the recombinant wild type and respective PerR mutants, in addition to regulation studies in metal-supplemented and iron-depleted media, showed binding of zinc and iron by PerR and an iron requirement for optimal responses to peroxide. Our findings reveal a novel physiological contribution of PerR in coordinating DNA and protein metabolic functions in peroxide and identify GAS adaptive responses that may serve to enhance oxidative stress resistance and virulence in the host.
FraH Is Required for Reorganization of Intracellular Membranes during Heterocyst Differentiation in Anabaena sp. Strain PCC 7120
Authors: Merino-Puerto Victoria , Mariscal Vicente , Schwarz Heinz , Maldener Iris , Mullineaux Conrad W. , Herrero Antonia , Flores Enrique 
Published: September 2011

ABSTRACT

In the filamentous, heterocyst-forming cyanobacteria, two different cell types, the CO
2
-fixing vegetative cells and the N
2
-fixing heterocysts, exchange nutrients and regulators for diazotrophic growth. In the model organism
Anabaena
sp. strain PCC 7120, inactivation of
fraH
produces filament fragmentation under conditions of combined nitrogen deprivation, releasing numerous isolated heterocysts. Transmission electron microscopy of samples prepared by either high-pressure cryo-fixation or chemical fixation showed that the heterocysts of a Δ
fraH
mutant lack the intracellular membrane system structured close to the heterocyst poles, known as the honeycomb, that is characteristic of wild-type heterocysts. Using a green fluorescent protein translational fusion to the carboxyl terminus of FraH (FraH-C-GFP), confocal microscopy showed spots of fluorescence located at the periphery of the vegetative cells in filaments grown in the presence of nitrate. After incubation in the absence of combined nitrogen, localization of FraH-C-GFP changed substantially, and the GFP fluorescence was conspicuously located at the cell poles in the heterocysts. Fluorescence microscopy and deconvolution of images showed that GFP fluorescence originated mainly from the region next to the cyanophycin plug present at the heterocyst poles. Intercellular transfer of the fluorescent tracers calcein (622 Da) and 5-carboxyfluorescein (374 Da) was either not impaired or only partially impaired in the Δ
fraH
mutant, suggesting that FraH is not important for intercellular molecular exchange. Location of FraH close to the honeycomb membrane structure and lack of such structure in the Δ
fraH
mutant suggest a role of FraH in reorganization of intracellular membranes, which may involve generation of new membranes, during heterocyst differentiation.