1,155 research outputs found
Why Supply Chain Collaboration Fails: The Socio-Structural View Of Resistance To Collaboration Strategies
Purpose
The relational view posits that supply chain integration can be a source of competitive advantage. Few firms, however, successfully co-create value to attain supernormal relational rents. We therefore elaborate theory regarding the reasons why collaboration strategies fail.
Design/methodology/approach
This study employs a quasi-longitudinal, multi-case interview methodology to explore the reasons why collaboration strategies fail to deliver intended results. We interviewed managers at 49 companies in Period 1 and managers at 57 companies in Period 2. Fifteen companies participated in both rounds of interviews.
Findings
This paper builds and describes a taxonomy of relational resistors. We then explore how sociological and structural resistors reinforce each other to undermine collaborative behavior. Specifically, the interplay among resistors 1) obscures the true sources of resistance, 2) exacerbates a sense of vulnerability to non-collaborative behavior that reduces the willingness to invest in relational architecture, and 3) inhibits the development of essential relational skills and organizational routines.
Originality/value
This research identifies and describes the behaviors and processes that impede successful supply chain alliances. By delving into the interplay among relational resistors, the research explains the detail and nuance of inter-firm rivalry and supply chain complexity. Ultimately, it is the re-enforcing nature of various resistors that make it so difficult for firms have to realize relational rents
Alterations in cellular metabolism modulate CD1d-mediated NKT-cell responses
Natural killer T (NKT) cells play a critical role in the host's innate immune response. CD1d-mediated presentation of glycolipid antigens to NKT cells has been established; however, the mechanisms by which NKT cells recognize infected or cancerous cells remain unclear. 5′-AMP activated protein kinase (AMPK) is a master regulator of lipogenic pathways. We hypothesized that activation of AMPK during infection and malignancy could alter the repertoire of antigens presented by CD1d and serve as a danger signal to NKT cells. In this study, we examined the effect of alterations in metabolism on CD1d-mediated antigen presentation to NKT cells and found that an infection with lymphocytic choriomeningitis virus rapidly increased CD1d-mediated antigen presentation. Hypoxia inducible factors (HIF) enhance T-cell effector functions during infection, therefore antigen presenting cells pretreated with pharmacological agents that inhibit glycolysis, induce HIF and activate AMPK were assessed for their ability to induce NKT-cell responses. Pretreatment with 2-deoxyglucose, cobalt chloride, AICAR and metformin significantly enhanced CD1d-mediated NKT-cell activation. In addition, NKT cells preferentially respond to malignant B cells and B-cell lymphomas express HIF-1α. These data suggest that targeting cellular metabolism may serve as a novel means of inducing innate immune responses
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The ocean's gravitational potential energy budget in a coupled climate model
This study examines, in a unified fashion, the budgets of ocean gravitational potential energy (GPE) and available gravitational potential energy (AGPE) in the control simulation of the coupled atmosphere–ocean general
circulation model HadCM3. Only AGPE can be converted into kinetic energy by adiabatic processes. Diapycnal mixing supplies GPE, but not AGPE, whereas the reverse is true of the combined effect of surface buoyancy forcing and convection. Mixing and buoyancy forcing, thus, play complementary roles in sustaining the large scale circulation. However, the largest globally integrated source of GPE is resolved advection (+0.57 TW) and the largest sink is through parameterized eddy transports (-0.82 TW). The effect of these adiabatic processes on AGPE is identical to their effect on GPE, except for
perturbations to both budgets due to numerical leakage exacerbated by non-linearities in the equation of state
Monomeric PcrA helicase processively unwinds plasmid lengths of DNA in the presence of the initiator protein RepD
The helicase PcrA unwinds DNA during asymmetric replication of plasmids, acting with an initiator protein, in our case RepD. Detailed kinetics of PcrA activity were measured using bulk solution and a single-molecule imaging technique to investigate the oligomeric state of the active helicase complex, its processivity and the mechanism of unwinding. By tethering either DNA or PcrA to a microscope coverslip surface, unwinding of both linear and natural circular plasmid DNA by PcrA/RepD was followed in real-time using total internal reflection fluorescence microscopy. Visualization was achieved using a fluorescent single-stranded DNA-binding protein. The single-molecule data show that PcrA, in combination with RepD, can unwind plasmid lengths of DNA in a single run, and that PcrA is active as a monomer. Although the average rate of unwinding was similar in single-molecule and bulk solution assays, the single-molecule experiments revealed a wide distribution of unwinding speeds by different molecules. The average rate of unwinding was several-fold slower than the PcrA translocation rate on single-stranded DNA, suggesting that DNA unwinding may proceed via a partially passive mechanism. However, the fastest dsDNA unwinding rates measured in the single-molecule unwinding assays approached the PcrA translocation speed measured on ssDNA
The secreted triose phosphate isomerase of Brugia malayi is required to sustain microfilaria production in vivo
Human lymphatic filariasis is a major tropical disease transmitted through mosquito vectors which take up microfilarial larvae from the blood of infected subjects. Microfilariae are produced by long-lived adult parasites, which also release a suite of excretory-secretory products that have recently been subject to in-depth proteomic analysis. Surprisingly, the most abundant secreted protein of adult Brugia malayi is triose phosphate isomerase (TPI), a glycolytic enzyme usually associated with the cytosol. We now show that while TPI is a prominent target of the antibody response to infection, there is little antibody-mediated inhibition of catalytic activity by polyclonal sera. We generated a panel of twenty-three anti-TPI monoclonal antibodies and found only two were able to block TPI enzymatic activity. Immunisation of jirds with B. malayi TPI, or mice with the homologous protein from the rodent filaria Litomosoides sigmodontis, failed to induce neutralising antibodies or protective immunity. In contrast, passive transfer of neutralising monoclonal antibody to mice prior to implantation with adult B. malayi resulted in 60–70% reductions in microfilarial levels in vivo and both oocyte and microfilarial production by individual adult females. The loss of fecundity was accompanied by reduced IFNγ expression by CD4+ T cells and a higher proportion of macrophages at the site of infection. Thus, enzymatically active TPI plays an important role in the transmission cycle of B. malayi filarial parasites and is identified as a potential target for immunological and pharmacological intervention against filarial infections
Assessment of Surface Water Contamination from Coalbed Methane Fracturing-Derived Volatile Contaminants in Sullivan County, Indiana, USA
There is a growing concern over the contamination of surface water and the associated environmental and public health consequences from the recent proliferation in hydraulic fracturing in the USA. Petroleum hydrocarbon-derived contaminants of concern [benzene, toluene, ethylbenzene, and xylene (BTEX)] and various dissolved cations and anions were spatially determined in surface waters around 14 coalbed methane fracking wells in Sullivan County, IN, USA. At least one BTEX was detected in 69% of sampling sites (n=13) and 23% of sampling sites were found to be contaminated with all of the BTEX. Toluene was the most common BTEX compound detected across all sites, both upstream and downstream from coalbed methane fracking sites. The calcium (~60 ppm) and sulfates (~175 ppm) were the dominant cations and anions, respectively, in surface water around the fracking sites. This study represents the first report of BTEX contamination in surface water from coalbed methane hydraulic fracturing wells
The Enigmatic Young Low-Mass Variable TWA 30
TWA 30 is a remarkable young (7+/-3 Myr), low-mass (0.12+/-0.04 Msun),
late-type star (M5+/-1) residing 42+/-2 pc away from the sun in the TW Hydrae
Association. It shows strong outflow spectral signatures such as [S II], [O I],
[O II], [O III], and Mg I], while exhibiting weak Halpha emission (-6.8+/-1.2
Angstroms). Emission lines of [S II] and [O I] are common to T Tauri stars
still residing in their natal molecular clouds, while [O III] and Mg I]
emission lines are incredibly rare in this same population; in the case of TWA
30, these latter lines may arise from new outflow material colliding into older
outflow fronts. The weak Halpha emission and small radial velocity shifts of
line emission relative to the stellar frame of rest (generally <=10 km/s)
suggest that the disk is viewed close to edge-on and that the stellar axis may
be inclined to the disk, similar to the AA Tau system, based on its temporal
changes in emission/absorption line strengths/profiles and variable reddening
(A_V=1.5-9.0). The strong Li absorption (0.61+/-0.13 Angstroms) and common
kinematics with members of the TWA confirm its age and membership to the
association. Given the properties of this system such as its proximity, low
mass, remarkable outflow signatures, variability, and edge-on configuration,
this system is a unique case study at a critical time in disk evolution and
planet-building processes.Comment: ApJ in press, 51 pages, 8 tables, 12 figures; converted to preprint
style since emulateapj version cut off Tables 4-
The ataxia protein sacsin is a functional co-chaperone that protects against polyglutamine-expanded ataxin-1
An extensive protein–protein interaction network has been identified between proteins implicated in inherited ataxias. The protein sacsin, which is mutated in the early-onset neurodegenerative disease autosomal recessive spastic ataxia of Charlevoix-Saguenay, is a node in this interactome. Here, we have established the neuronal expression of sacsin and functionally characterized domains of the 4579 amino acid protein. Sacsin is most highly expressed in large neurons, particularly within brain motor systems, including cerebellar Purkinje cells. Its subcellular localization in SH-SY5Y neuroblastoma cells was predominantly cytoplasmic with a mitochondrial component. We identified a putative ubiquitin-like (UbL) domain at the N-terminus of sacsin and demonstrated an interaction with the proteasome. Furthermore, sacsin contains a predicted J-domain, the defining feature of DnaJ/Hsp40 proteins. Using a bacterial complementation assay, the sacsin J-domain was demonstrated to be functional. The presence of both UbL and J-domains in sacsin suggests that it may integrate the ubiquitin–proteasome system and Hsp70 function to a specific cellular role. The Hsp70 chaperone machinery is an important component of the cellular response towards aggregation prone mutant proteins that are associated with neurodegenerative diseases. We therefore investigated the effects of siRNA-mediated sacsin knockdown on polyglutamine-expanded ataxin-1. Importantly, SACS siRNA did not affect cell viability with GFP-ataxin-1[30Q], but enhanced the toxicity of GFP-ataxin-1[82Q], suggesting that sacsin is protective against mutant ataxin-1. Thus, sacsin is an ataxia protein and a regulator of the Hsp70 chaperone machinery that is implicated in the processing of other ataxia-linked proteins
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