821 research outputs found

    Unified Growth Based on the Specific Factors Model

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    The two-sector specific factor model is typically used in the theory of international trade where it helps to clarify the principle of comparative advantage. Instead, we use this model as explicit theoretical framework to explain major trends of long-run economic development. Combined with endogenous technical progress functions which assume that knowledge accumulates as a by-product of agricultural and manufacturing experience, the two-sector specific factors model can explain major historical trends and structural turnarounds. The technical progress functions establish the link between the agricultural and the manufacturing sector through the land-labour ratio, which is determined by the savings propensities of wage-earners, landlords and capitalists. This result is achieved by making use of the traditional investment = savings condition, without reference to complicated micro-based models of human capital accumulation.Economic development, growth, Industrial Revolution, income distribution

    Unified Growth Based on the Specific Factors Model

    Get PDF
    The two-sector specific factor model is typically used in the theory of international trade where it helps to clarify the principle of comparative advantage. Instead, we use this model as explicit theoretical framework to explain major trends of long-run economic development. Combined with endogenous technical progress functions which assume that knowledge accumulates as a by-product of agricultural and manufacturing experience, the two-sector specific factors model can explain major historical trends and structural turnarounds. The technical progress functions establish the link between the agricultural and the manufacturing sector through the land-labour ratio, which is determined by the savings propensities of wage-earners, landlords and capitalists. This result is achieved by making use of the traditional investment = savings condition, without reference to complicated micro-based models of human capital accumulation

    Chemical-Biology-derived in vivo Sensors: Past, Present, and Future.

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    To understand the complex biochemistry and biophysics of biological systems, one needs to be able to monitor local concentrations of molecules, physical properties of macromolecular assemblies and activation status of signaling pathways, in real time, within single cells, and at high spatio-temporal resolution. Here we look at the tools that have been / are being / need to be provided by chemical biology to address these challenges. In particular, we highlight the utility of molecular probes that help to better measure mechanical forces and flux through key signalling pathways. Chemical biology can be used to both build biosensors to visualize, but also actuators to perturb biological processes. An emergent theme is the possibility to multiplex measurements of multiple cellular processes. Advances in microscopy automation now allow us to acquire datasets for 1000's of cells. This produces high dimensional datasets that require computer vision approaches that automate image analysis. The high dimensionality of these datasets are often not immediately accessible to human intuition, and, similarly to 'omics technologies, require statistical approaches for their exploitation. The field of biosensor imaging is therefore experiencing a multidisciplinary transition that will enable it to realize its full potential as a tool to provide a deeper appreciation of cell physiology

    Mid-term treatment-related cognitive sequelae in glioma patients

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    Purpose: Cognitive functioning represents an essential determinant of quality of life. Since significant advances in neuro-oncological treatment have led to prolonged survival it is important to reliably identify possible treatment-related neurocognitive dysfunction in brain tumor patients. Therefore, the present study specifically evaluates the effects of standard treatment modalities on neurocognitive functions in glioma patients within two years after surgery. Methods: Eighty-six patients with World Health Organization (WHO) grade 1-4 gliomas were treated between 2004 and 2012 and prospectively followed within the German Glioma Network. They received serial neuropsychological assessment of attention, memory and executive functions using the computer-based test battery NeuroCog FX. As the primary outcome the extent of change in cognitive performance over time was compared between patients who received radiotherapy, chemotherapy or combined radio-chemotherapy and patients without any adjuvant therapy. Additionally, the effect of irradiation and chemotherapy was assessed in subgroup analyses. Furthermore, the potential impact of the extent of tumor resection and histopathological characteristics on cognitive functioning were referred to as secondary outcomes. Results: After a median of 16.8 (range 5.9-31.1) months between post-surgery baseline neuropsychological assessment and follow-up assessment, all treatment groups showed numerical and often even statistically significant improvement in all cognitive domains. The extent of change in cognitive functioning showed no difference between treatment groups. Concerning figural memory only, irradiated patients showed less improvement than non-irradiated patients (p = 0.029, η2 = 0.06). Resected patients, yet not patients with biopsy, showed improvement in all cognitive domains. Compared to patients with astrocytomas, patients with oligodendrogliomas revealed a greater potential to improve in attentional and executive functions. However, the heterogeneity of the patient group and the potentially selected cohort may confound results. Conclusion: Within a two-year post-surgery interval, radiotherapy, chemotherapy or their combination as standard treatment did not have a detrimental effect on cognitive functions in WHO grade 1-4 glioma patients. Cognitive performance in patients with adjuvant treatment was comparable to that of patients without. Keywords: Glioma; NeuroCog FX; Neuropsychological assessment; Prospective; Treatment-related neurotoxicit

    LITOS: a versatile LED illumination tool for optogenetic stimulation.

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    Optogenetics has become a key tool to manipulate biological processes with high spatio-temporal resolution. Recently, a number of commercial and open-source multi-well illumination devices have been developed to provide throughput in optogenetics experiments. However, available commercial devices remain expensive and lack flexibility, while open-source solutions require programming knowledge and/or include complex assembly processes. We present a LED Illumination Tool for Optogenetic Stimulation (LITOS) based on an assembled printed circuit board controlling a commercially available 32 × 64 LED matrix as illumination source. LITOS can be quickly assembled without any soldering, and includes an easy-to-use interface, accessible via a website hosted on the device itself. Complex light stimulation patterns can easily be programmed without coding expertise. LITOS can be used with different formats of multi-well plates, petri dishes, and flasks. We validated LITOS by measuring the activity of the MAPK/ERK signaling pathway in response to different dynamic light stimulation regimes using FGFR1 and Raf optogenetic actuators. LITOS can uniformly stimulate all the cells in a well and allows for flexible temporal stimulation schemes. LITOS's affordability and ease of use aims at democratizing optogenetics in any laboratory

    Evaluation of business travel as a potential customer field of a local AAM market

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    Several studies examine Advanced Air Mobility (AAM) demand focusing on commuting and airport shuttle trips at this moment. Little activities are concentrating on business travel in general nor for AAM demand in special. Business travel as a generic term for any corporate purposed transport consists of four categories: Meetings, Incentives, Conventions and Exhibitions (MICE). Every business traffic comes along with its own character which has to be considered when modelling. After the transport generation based on their travel purpose and location, a discrete choice model evaluates different modes of transport to determine the market share for AAM. As business travel is expected to have a greater value of time, the modal share of AAM is anticipated be higher compared to more cost-sensitive use cases such as commuting. On the other hand, however, the market size of the overall business traffic could weaken this group of potential AAM passengers. In the field of this poorly investigated demand share, this approach presents a possibility of modeling local business traffic. Furthermore, this study assumes an adopted AAM mode of transport for this passenger group, which helps to understand the characteristics of future AAM demand

    Two Distinct Filopodia Populations at the Growth Cone Allow to Sense Nanotopographical Extracellular Matrix Cues to Guide Neurite Outgrowth

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    The process of neurite outgrowth is the initial step in producing the neuronal processes that wire the brain. Current models about neurite outgrowth have been derived from classic two-dimensional (2D) cell culture systems, which do not recapitulate the topographical cues that are present in the extracellular matrix (ECM) in vivo. Here, we explore how ECM nanotopography influences neurite outgrowth

    Optogenetic actuator - ERK biosensor circuits identify MAPK network nodes that shape ERK dynamics.

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    Combining single-cell measurements of ERK activity dynamics with perturbations provides insights into the MAPK network topology. We built circuits consisting of an optogenetic actuator to activate MAPK signaling and an ERK biosensor to measure single-cell ERK dynamics. This allowed us to conduct RNAi screens to investigate the role of 50 MAPK proteins in ERK dynamics. We found that the MAPK network is robust against most node perturbations. We observed that the ERK-RAF and the ERK-RSK2-SOS negative feedback operate simultaneously to regulate ERK dynamics. Bypassing the RSK2-mediated feedback, either by direct optogenetic activation of RAS, or by RSK2 perturbation, sensitized ERK dynamics to further perturbations. Similarly, targeting this feedback in a human ErbB2-dependent oncogenic signaling model increased the efficiency of a MEK inhibitor. The RSK2-mediated feedback is thus important for the ability of the MAPK network to produce consistent ERK outputs, and its perturbation can enhance the efficiency of MAPK inhibitors

    Flavonoids from Ericameria nauseosa inhibiting PI3K/AKT pathway in human melanoma cells.

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    The PI3K/AKT and MAPK/ERK pathways are frequently mutated in metastatic melanoma. In a screen of over 2500 plant extracts, the dichloromethane extract of Ericameria nauseosa significantly inhibited oncogenic activity of AKT in MM121224 human melanoma cells. This extract was analyzed by analytical HPLC, and the column effluent was fractionated and tested for activity to generate the so-called HPLC-based activity profile. Compounds eluting within active time-windows of the chromatogram were subsequently isolated in a larger scale to afford 11 flavones (1-11), four flavanones (12-15), two diterpenes (16, 17), and a seco-caryophyllene (18). All isolated compounds were tested for activity, whereby only flavonoids were found active. Of these, flavones were shown to be more active than the flavanones. The most potent flavone was compound 9, that was displaying an IC50 of 14.7 ± 1.4 µM on AKT activity in MM121224 cells. The terpenoids (16-18) were found to be inactive in the assay. Both diterpenes, a grindelic acid derivative (16) and an ent-neo-clerodane (17) were identified as new natural products. Their absolute configuration was established by ECD. Compound 17 is the first description of a clerodane type diterpene in the genus Ericameria
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