1,327 research outputs found
A Bibliometric Study on Innovation and Firm Performance: Building a Research Framework
In response to a rising interest in the connection between innovation and firm performance, this paper examines the body of research on this link and takes a closer look into the influences on innovation, firm performance or both. The basis for this study is a bibliometric analysis of 3,462 scientific publications. We identified 27 innovation domains with an influence on firm performance, showed the rising interest in the topic and found that most types of innovation have a positive impact on firm performance. We provide an overview of which indicators researchers used to measure innovativeness and firm performance and what methods they used to establish the link between the two. Additionally, we stress the importance of sustainable innovation and show that these also positively influence firm performance. In the end, we structure all research fronts into three different groups and based on that, develop a framework that visualizes research on innovation and firm performances
A new perspective on the competent programmer hypothesis through the reproduction of bugs with repeated mutations
The competent programmer hypothesis states that most programmers are
competent enough to create correct or almost correct source code. Because this
implies that bugs should usually manifest through small variations of the
correct code, the competent programmer hypothesis is one of the fundamental
assumptions of mutation testing. Unfortunately, it is still unclear if the
competent programmer hypothesis holds and past research presents contradictory
claims. Within this article, we provide a new perspective on the competent
programmer hypothesis and its relation to mutation testing. We try to re-create
real-world bugs through chains of mutations to understand if there is a direct
link between mutation testing and bugs. The lengths of these paths help us to
understand if the source code is really almost correct, or if large variations
are required. Our results indicate that while the competent programmer
hypothesis seems to be true, mutation testing is missing important operators to
generate representative real-world bugs.Comment: Submitted and under revie
Making the Newsvendor Smart – Order Quantity Optimization with ANNs for a Bakery Chain
Accurate demand forecasting is particularly crucial for products with short shelf life like bakery products. Over- and underestimation of customer demand affects not only profit margins of bakeries but is also responsible for 600,000 metric tons of food waste every year in Germany. To solve this problem, we develop an IT artifact based on artificial neural networks, which is automating the manual order process and capable of reducing costs as well as food waste. To test and evaluate our artifact, we cooperated with an SME bakery chain from Germany. The bakery chain runs 40 points of sale (POS) in southern Germany. After algorithm based reconstructing and cleaning of the censored sales data, we compare two different data-driven newsvendor approaches for this inventory problem. We show that both models are able to significantly improve the forecast quality (cost savings up to 30%) compared to human planners
On viscosity, conduction and sound waves in the intracluster medium
Recent X-ray and optical observations of the Perseus cluster indicate that
the viscous and conductive dissipation of sound waves is the mechanism
responsible for heating the intracluster medium and thus balancing radiative
cooling of cluster cores. We discuss this mechanism more generally and show how
the specific heating and cooling rates vary with temperature and radius. It
appears that the heating mechanism is most effective above 10^7K, which allows
for radiative cooling to proceed within normal galaxy formation but will stifle
the growth of very massive galaxies. The scaling of the wavelength of sound
waves with cluster temperature and feedback in the system are investigated.Comment: 5 pages, 4 figures, MNRAS accepte
Serial imaging of micro-agents and cancer cell spheroids in a microfluidic channel using multicolor fluorescence microscopy
Multicolor fluorescence microscopy is a powerful technique to fully visualize many biological phenomena by acquiring images from different spectrum channels. This study expands the scope of multicolor fluorescence microscopy by serial imaging of polystyrene micro-beads as surrogates for drug carriers, cancer spheroids formed using HeLa cells, and microfluidic channels. Three fluorophores with different spectral characteristics are utilized to perform multicolor microscopy. According to the spectrum analysis of the fluorophores, a multicolor widefield fluorescence microscope is developed. Spectral crosstalk is corrected by exciting the fluorophores in a round-robin manner and synchronous emitted light collection. To report the performance of the multicolor microscopy, a simplified 3D tumor model is created by placing beads and spheroids inside a channel filled with the cell culture medium is imaged at varying exposure times. As a representative case and a method for bio-hybrid drug carrier fabrication, a spheroid surface is coated with beads in a channel utilizing electrostatic forces under the guidance of multicolor microscopy. Our experiments show that multicolor fluorescence microscopy enables crosstalk-free and spectrally-different individual image acquisition of beads, spheroids, and channels with the minimum exposure time of 5.5 ms. The imaging technique has the potential to monitor drug carrier transportation to cancer cells in real-time
Towards Vascularized Tissue Blocks Using a Suspension Bioprinted Blood Vessel
In order for engineered tissue grafts and eventually organs to successfully integrate in a clinical setting, a functional vascular network is imperative. Without vasculature, the tissue constructs cannot receive nutrients essential for their survival, but also lack the stimuli that determine the tissue’s biophysical properties i.e. cell fate determination, cell to cell junctions, and cell orientation. In order for the vascular network to functionally connect to the patient, a hierarchical organization, resembling the vascular tree, is important. From previous studies it is known that fluid flow is a crucial component in controlling the formation of the vascular tree, and that the organization of the vascular network can be further controlled using gradients of angiogenic growth factors such as VEGF. By utilizing spheroid bioprinting within a microgel suspension, an artificial vessel structure was assembled. The deposited spheroids maintained viability and fused over time into perfusable vessels.The subsequent formation of small-diameter vascular structures and capillaries was regulated by an on-demand flow through the bioprinted vessel, resulting in controllable fluid flow shear stresses. Furthermore, VEGF was spatially patterned in the tissue block by locally doping the suspension with growth factor releasing microparticles. By varying both these stimuli, the location of vascular sprout formation and subsequent growth of the new vascular structures could be influenced. This spheroid 3D bioprinting platform offers a dynamic, customizable and accurate method to trigger and control the process of angiogenesis in vitro. By stimulating an artificial blood vessel with controlled fluid flow and growth factor gradients, a vascular complex vascular network can be produced and modulated. The combination of this approach with a gradual replacement of the microgel suspension with cells, can pave the way for the production of vascularized tissue blocks
Connectivity and tree structure in finite graphs
Considering systems of separations in a graph that separate every pair of a
given set of vertex sets that are themselves not separated by these
separations, we determine conditions under which such a separation system
contains a nested subsystem that still separates those sets and is invariant
under the automorphisms of the graph.
As an application, we show that the -blocks -- the maximal vertex sets
that cannot be separated by at most vertices -- of a graph live in
distinct parts of a suitable tree-decomposition of of adhesion at most ,
whose decomposition tree is invariant under the automorphisms of . This
extends recent work of Dunwoody and Kr\"on and, like theirs, generalizes a
similar theorem of Tutte for .
Under mild additional assumptions, which are necessary, our decompositions
can be combined into one overall tree-decomposition that distinguishes, for all
simultaneously, all the -blocks of a finite graph.Comment: 31 page
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A Bioeconomic View on Size-Related Harvesting: Does Size Matter?
The individual size of fish as a proxy for life-history traits and market
value displays an important, yet in bioeconomic modelling often ignored
biological and economic parameter. This raises the question if and to what
extent the consideration of a pricing related to the individual size
influences optimal harvest strategies. We demonstrate here that the
magnitude of size-dependency in the pricing clearly causes a quantitative
impact on the outcome of optimizing the harvest strategy. Resulting is not
only a shift regarding the potentially achieved revenues, but mainly a
correlation regarding the optimal fishing pattern and the catch weights. The
observed qualitative tendency towards a reduction in the fishing mortality
simultaneously yielding higher catch weights with increasing size-dependent
price effects can be generalized and is insensitive of additional
economic factors like the discount rate or demand functions. These
findings suggest that size-dependent pricing has a certain impact on the
harvest strategy if one is aiming for maximum economic yield (MEY) and
hence it should be more often accounted for in bioeconomic modelling.Keywords: Fisheries Modeling, Modeling and Economic Theory, Fisheries Economic
Myocardial Work Assessment for the Prediction of Prognosis in Advanced Heart Failure
Objectives: The aim of this study was to investigate whether echocardiographic
assessment of myocardial work is a predictor of outcome in advanced heart failure.
Background: Global work index (GWI) and global constructive work (GCW) are
calculated bymeans of speckle tracking, blood pressuremeasurement, and a normalized
reference curve. Their prognostic value in advanced heart failure is unknown.
Methods: Cardiopulmonary exercise testing and echocardiography with assessment
of GWI and GCW was performed in patients with advanced heart failure caused by
ischemic heart disease or dilated cardiomyopathy (n = 105). They were then followed up
repeatedly. The combined endpoint was all-cause death, implantation of a left ventricular
assist device, or heart transplantation.
Results: The median patient age was 54 years (interquartile range [IQR]: 48–59.9). The
mean left ventricular ejection fraction was 27.8 ± 8.2%, the median NT-proBNP was
1,210 pg/ml (IQR: 435–3,696). The mean GWI was 603 ± 329 mmHg% and the mean
GCW was 742 ± 363 mmHg%. The correlation between peak oxygen uptake and GWI
as well as GCW was strongest in patients with ischemic cardiomyopathy (r = 0.56, p
= 0.001 and r = 0.53, p = 0.001, respectively). The median follow-up was 16 months
(IQR: 12–18.5). Thirty one patients met the combined endpoint: Four patients died, eight
underwent transplantation, and 19 underwent implantation of a left ventricular assist
device. In themultivariate Cox regression analysis, only NYHA class, NT-proBNP and GWI
(hazard ratio [HR] for every 50 mmHg%: 0.85; 95% CI: 0.77–0.94; p = 0.002) as well as
GCW (HR for every 50 mmHg%: 0.86; 95% CI: 0.79–0.94; p = 0.001) were identified as
independent predictors of the endpoint. The cut-off value for predicting the outcome was
455 mmHg% for GWI (AUC: 0.80; p < 0.0001; sensitivity 77.4%; specificity 71.6%) and
530 mmHg% for GCW (AUC: 0.80; p < 0.0001; sensitivity 74.2%; specificity 78.4%).
Conclusions: GWI and GCW are powerful predictors of outcome in patients with
advanced heart failure
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