Innovation network Acemoglu, Daron; Akcigit, Ufuk; Kerr, William R.
Proceedings of the National Academy of Sciences - PNAS,
10/2016, Letnik:
113, Številka:
41
Journal Article
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Technological progress builds upon itself, with the expansion of invention in one domain propelling future work in linked fields. Our analysis uses 1.8 million US patents and their citation ...properties to map the innovation network and its strength. Past innovation network structures are calculated using citation patterns across technology classes during 1975–1994. The interaction of this preexisting network structure with patent growth in upstream technology fields has strong predictive power on future innovation after 1995. This pattern is consistent with the idea that when there is more past upstream innovation for a particular technology class to build on, then that technology class innovates more.
Entrepreneurship as Experimentation Kerr, William R.; Nanda, Ramana; Rhodes-Kropf, Matthew
The Journal of economic perspectives,
07/2014, Letnik:
28, Številka:
3
Journal Article
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Entrepreneurship research is on the rise but many questions about the fundamental nature of entrepreneurship still exist. We argue that entrepreneurship is about experimentation; the probabilities of ...success are low, extremely skewed, and unknowable until an investment is made. At a macro level, experimentation by new firms underlies the Schumpeterian notion of creative destruction. However, at a micro level, investment and continuation decisions are not always made in a competitive Darwinian contest. Instead, a few investors make decisions that are impacted by incentive, agency, and coordination problems, often before a new idea even has a chance to compete in a market. We contend that costs and constraints on the ability to experiment alter the type of organizational form surrounding innovation and influence when innovation is more likely to occur. These factors not only govern how much experimentation is undertaken in the economy, but also the trajectory of experimentation, with potentially very deep economic consequences.
This study explores the role of U.S. ethnic scientific and entrepreneurial communities for international technology transfer to their home countries. U.S. ethnic researchers are quantified through an ...ethnic-name database and individual patent records. International patent citations confirm knowledge diffuses through ethnic networks, and manufacturing output in foreign countries increases with an elasticity of 0.1-0.3 to stronger scientific integration with the U.S. frontier. Specifications exploiting exogenous changes in U.S. immigration quotas address reverse-causality concerns. Exercises further differentiate responses by development stages in home countries. Ethnic technology transfers are particularly strong in high-tech industries and among Chinese economies.
Human parvovirus B19 is a single-stranded DNA virus which preferentially targets the erythroblasts in the bone marrow. B19 infection commonly causes erythema infectiosum, arthralgia, fetal death, ...transient aplastic crisis in patients with shortened red cell survival, and persistent infection in people who are immunocompromised. Less common clinical manifestations include atypical skin rashes, neurological syndromes, cardiac syndromes, and various cytopenias. B19 infection has also been associated with development of a variety of different autoimmune diseases, including rheumatological, neurological, neuromuscular, cardiovascular, haematological, nephrological and metabolic. Production of a variety of autoantibodies has been demonstrated to occur during B19 infection and these have been shown to be key to the pathogenesis of the particular disease process in a significant number of cases, for example, production of rheumatoid factor in cases of B19-associated rheumatoid arthritis and production of anti-glutamic acid decarboxylase (GAD) in patients with B19-associated type 1 diabetes mellitus. B19 infection has also been associated with the development of multiple autoimmune diseases in 12 individuals. Documented mechanisms in B19-associated autoimmunity include molecular mimicry (IgG antibody to B19 proteins has been shown to cross react with a variety of recognised human autoantigens, including collagen II, keratin, angiotensin II type 1 receptor, myelin basic protein, cardiolipin, and platelet membrane glycoprotein IIb/IIIa), B19-induced apoptosis with presentation of self-antigens to T lymphocytes, and the phospholipase activity of the B19 unique VP1 protein.
This study evaluates the impact of high‐skilled immigrants on U.S. technology formation. We use reduced‐form specifications that exploit large changes in the H‐1B visa program. Higher H‐1B admissions ...increase immigrant science and engineering (SE) employment and patenting by inventors with Indian and Chinese names in cities and firms dependent upon the program relative to their peers. Most specifications find limited effects for native SE employment or patenting. We are able to rule out displacement effects, and small crowding‐in effects may exist. Total SE employment and invention increases with higher admissions primarily through direct contributions of immigrants.
Background We have developed a multimodal technique for the control of pain following knee and hip surgery, called "local infiltration analgesia" (LIA). It is based on systematic infiltration of a ...mixture of ropiva-caine, ketorolac, and adrenaline into the tissues around the surgical field to achieve satisfactory pain control with little physiological disturbance. The technique allows virtually immediate mobilization and earlier discharge from hospital.
Patients and methods In this open, nonrandomized case series, we used LIA to manage postoperative pain in all 325 patients presenting to our service from Jan 1, 2005 to Dec 31,2006 for elective hip resurfacing (HRA), primary total hip replacement (THR), or primary total knee replacement arthroplasty (TKR). We recorded pain scores, mobilization times, and morphine usage for the entire group.
Results Pain control was generally satisfactory (numerical rating scale pain score range 0-3). No morphine was required for postoperative pain control in two-thirds of the patients. Most patients were able to walk with assistance between 5 and 6 h after surgery and independent mobility was achieved 13-22 h after surgery. Orthostatic hypotension, nausea, and vomiting were occasionally associated with standing for the first time, but other side effects were unremarkable. 230 (71%) of the 325 patients were discharged directly home after a single overnight stay in hospital.
Interpretation Local infiltration analgesia is simple, practical, safe, and effective for pain management after knee and hip surgery.
CpG islands (CGIs) are prominent in the mammalian genome owing to their GC-rich base composition and high density of CpG dinucleotides. Most human gene promoters are embedded within CGIs that lack ...DNA methylation and coincide with sites of histone H3 lysine 4 trimethylation (H3K4me3), irrespective of transcriptional activity. In spite of these intriguing correlations, the functional significance of non-methylated CGI sequences with respect to chromatin structure and transcription is unknown. By performing a search for proteins that are common to all CGIs, here we show high enrichment for Cfp1, which selectively binds to non-methylated CpGs in vitro. Chromatin immunoprecipitation of a mono-allelically methylated CGI confirmed that Cfp1 specifically associates with non-methylated CpG sites in vivo. High throughput sequencing of Cfp1-bound chromatin identified a notable concordance with non-methylated CGIs and sites of H3K4me3 in the mouse brain. Levels of H3K4me3 at CGIs were markedly reduced in Cfp1-depleted cells, consistent with the finding that Cfp1 associates with the H3K4 methyltransferase Setd1 (refs 7, 8). To test whether non-methylated CpG-dense sequences are sufficient to establish domains of H3K4me3, we analysed artificial CpG clusters that were integrated into the mouse genome. Despite the absence of promoters, the insertions recruited Cfp1 and created new peaks of H3K4me3. The data indicate that a primary function of non-methylated CGIs is to genetically influence the local chromatin modification state by interaction with Cfp1 and perhaps other CpG-binding proteins.
Despite an overwhelming scientific consensus, a sizable minority of people doubt that human activity is causing climate change. Communicating the existence of a scientific consensus has been ...suggested as a way to correct individuals' misperceptions about human-caused climate change and other scientific issues, though empirical support is mixed. We report an experiment in which psychology students were presented with consensus information about two issues, and subsequently reported their perception of the level of consensus and extent of their endorsement of those issues. We find that messages about scientific consensus on the reality of anthropogenic climate change and the safety of genetically modified food shift perceptions of scientific consensus. Using mediation models we also show that, for both these issues, high consensus messages also increase reported personal agreement with the scientific consensus, mediated by changes in perceptions of a scientific consensus. This confirms the role of perceived consensus in informing personal beliefs about climate change, though results indicate the impact of single, one-off messages may be limited.
Microencapsulation of living cells is a field that has been heavily investigated by many researchers over the past two decades. Numerous experimental setups have been developed to encapsulate living ...cells in microbeads using different microfluidic devices and materials. Previous studies have investigated different microfluidic devices and materials for use in cancer treatment, drug delivery, environmental remediation, food production, and cell culture contexts. Some of the current challenges to these setups are maintaining reasonable levels of cell viability, cell leaching, nutrient and oxygen diffusion, and ensuring uniform microbead shape and size distribution. Addressing these issues and identifying the most reproducible and convenient setup enables researchers to efficiently encapsulate living cells and further advance the biomedical field. The efficiency of microencapsulation in terms of cell viability and uniform microbead shape and size distribution are directly related to the type of device used and the cross-linking method applied. Hence, the focus of this review is to assess the effects of using T-junction, flow-focusing, and co-flow microfluidic devices as well as thermal, ionic, and photo cross-linking methods for the microencapsulation of living cells. Recent applications of bacteria microencapsulation using microfluidic systems since 2017 are presented.
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•Flow-focusing enables high bead production frequency and narrow size distribution.•Co-flow exhibits simple fabrication and generates large microbeads.•Thermal cross-linking enables fast gelation and produces beads of adequate strength.•Ionically cross-linked beads can be mechanically enhanced using polymer blends.•Photo cross-linked beads show high mechanical strength and long-term cell viability.
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