63 research outputs found
Future agricultural conditions in the Nepal Himalaya - A fuzzy logic approach using high resolution climate scenarios
Until the end of the 21st century, ongoing climate change is expected to trigger major changes in site conditions and vertical species distributions in high mountain regions such as the Himalaya. Altitudinal ranges of species used as staple crops in Himalayan agriculture and currently suitable cultivation areas will be affected as well. Changing climatic variables such as temperature and precipitation will modify agricultural land-use options, and assessments of future crop growth conditions are in high demand. This GIS-based approach utilizes high resolution climate data of the present and two future scenarios and relates them to bioclimatic requirements of the five most important crops grown in Nepal: rice, maize, wheat, finger millet and potato. It takes into account soil pH as a basic constraint for the individual crop. The three factors temperature, precipitation,and soil pH are then combined using a fuzzy logic algorithm. The assessment visualizes the expected shifts in suitable cultivation zones for the individual crops. The results show that wheat is likely to experience the most severe loss of crop suitability until the end of the 21st century, while the cultivation of rice is likely to benefit
Climate change-induced shift of tree growth sensitivity at a central Himalayan treeline ecotone
Himalayan treelines are exposed to above average climate change impact, resulting in complex tree growth-climate relationships for Himalayan Silver Fir (Abies spectabilis (D. Don) Spach) at central Himalayan treelines. The majority of recent studies detected current tree growth sensitivity to dry conditions during pre-monsoon seasons. The aim of this study was to analyze growth-climate relationships for more than a century for a treeline ecotone in east-central Nepal and to test for Blue Intensity (BI; used as a surrogate of maximum late wood density) as climate proxy. We determined the relationships of Abies spectabilis radial tree growth and BI to climate by correlating both to temperature, precipitation and drought index data. The results showed a significantly unstable dendroclimatic signal over time. Climate warming-induced moisture deficits during pre-monsoon seasons became a major factor limiting radial tree growth during recent decades. Earlier in time, the dendroclimatic signal was weaker, predominantly reflecting a positive relationship of tree growth and summer temperature. Compared to radial tree growth, BI showed a different but strong climate signal. Temporally unstable correlations may be attributed to increasing effects of above-average rates of climate warming. An extended network of Himalayan tree-ring sites is needed to further analyze cause-effect relationships and to solve this attribution problem
The Spinal Transcriptome after Cortical Stroke: In Search of Molecular Factors Regulating Spontaneous Recovery in the Spinal Cord
In response to cortical stroke and unilateral corticospinal tract degeneration, compensatory sprouting of spared corticospinal fibers is associated with recovery of skilled movement in rodents. To date, little is known about the molecular mechanisms orchestrating this spontaneous rewiring. In this study, we provide insights into the molecular changes in the spinal cord tissue after large ischemic cortical injury in adult female mice, with a focus on factors that might influence the reinnervation process by contralesional corticospinal neurons. We mapped the area of cervical gray matter reinnervation by sprouting contralesional corticospinal axons after unilateral photothrombotic stroke of the motor cortex in mice using anterograde tracing. The mRNA profile of this reinnervation area was analyzed using whole-genome sequencing to identify differentially expressed genes at selected time points during the recovery process. Bioinformatic analysis revealed two phases of processes: early after stroke (4-7 d post-injury), the spinal transcriptome is characterized by inflammatory processes, including phagocytic processes as well as complement cascade activation. Microglia are specifically activated in the denervated corticospinal projection fields in this early phase. In a later phase (28-42 d post-injury), biological processes include tissue repair pathways with upregulated genes related to neurite outgrowth. Thus, the stroke-denervated spinal gray matter, in particular its intermediate laminae, represents a growth-promoting environment for sprouting corticospinal fibers originating from the contralesional motor cortex. This dataset provides a solid starting point for future studies addressing key elements of the post-stroke recovery process, with the goal to improve neuroregenerative treatment options for stroke patients. SIGNIFICANCE STATEMENT We show that the molecular changes in the spinal cord target tissue of the stroke-affected corticospinal tract are mainly defined by two phases: an early inflammatory phase during which microglia are specifically activated in the target area of reinnervating corticospinal motor neurons; and a late phase during which growth-promoting factors are upregulated which can influence the sprouting response, arborization, and synapse formation. By defining for the first time the endogenous molecular machinery in the stroke-denervated cervical spinal gray matter with a focus on promotors of axon growth through the growth-inhibitory adult CNS, this study will serve as a basis to address novel neuroregenerative treatment options for chronic stroke patients
Drug-induced mild therapeutic hypothermia obtained by administration of a transient receptor potential vanilloid type 1 agonist
<p>Abstract</p> <p>Background</p> <p>The use of mechanical/physical devices for applying mild therapeutic hypothermia is the only proven neuroprotective treatment for survivors of out of hospital cardiac arrest. However, this type of therapy is cumbersome and associated with several side-effects. We investigated the feasibility of using a transient receptor potential vanilloid type 1 (TRPV1) agonist for obtaining drug-induced sustainable mild hypothermia.</p> <p>Methods</p> <p>First, we screened a heterogeneous group of TRPV1 agonists and secondly we tested the hypothermic properties of a selected candidate by dose-response studies. Finally we tested the hypothermic properties in a large animal. The screening was in conscious rats, the dose-response experiments in conscious rats and in cynomologus monkeys, and the finally we tested the hypothermic properties in conscious young cattle (calves with a body weight as an adult human). The investigated TRPV1 agonists were administered by continuous intravenous infusion.</p> <p>Results</p> <p>Screening: Dihydrocapsaicin (DHC), a component of chili pepper, displayed a desirable hypothermic profile with regards to the duration, depth and control in conscious rats. Dose-response experiments: In both rats and cynomologus monkeys DHC caused a dose-dependent and immediate decrease in body temperature. Thus in rats, infusion of DHC at doses of 0.125, 0.25, 0.50, and 0.75 mg/kg/h caused a maximal ΔT (°C) as compared to vehicle control of -0.9, -1.5, -2.0, and -4.2 within approximately 1 hour until the 6 hour infusion was stopped. Finally, in calves the intravenous infusion of DHC was able to maintain mild hypothermia with ΔT > -3°C for more than 12 hours.</p> <p>Conclusions</p> <p>Our data support the hypothesis that infusion of dihydrocapsaicin is a candidate for testing as a primary or adjunct method of inducing and maintaining therapeutic hypothermia.</p
Enhanced axonal response of mitochondria to demyelination offers neuroprotection:implications for multiple sclerosis
Axonal loss is the key pathological substrate of neurological disability in demyelinating disorders, including multiple sclerosis (MS). However, the consequences of demyelination on neuronal and axonal biology are poorly understood. The abundance of mitochondria in demyelinated axons in MS raises the possibility that increased mitochondrial content serves as a compensatory response to demyelination. Here, we show that upon demyelination mitochondria move from the neuronal cell body to the demyelinated axon, increasing axonal mitochondrial content, which we term the axonal response of mitochondria to demyelination (ARMD). However, following demyelination axons degenerate before the homeostatic ARMD reaches its peak. Enhancement of ARMD, by targeting mitochondrial biogenesis and mitochondrial transport from the cell body to axon, protects acutely demyelinated axons from degeneration. To determine the relevance of ARMD to disease state, we examined MS autopsy tissue and found a positive correlation between mitochondrial content in demyelinated dorsal column axons and cytochrome c oxidase (complex IV) deficiency in dorsal root ganglia (DRG) neuronal cell bodies. We experimentally demyelinated DRG neuron-specific complex IV deficient mice, as established disease models do not recapitulate complex IV deficiency in neurons, and found that these mice are able to demonstrate ARMD, despite the mitochondrial perturbation. Enhancement of mitochondrial dynamics in complex IV deficient neurons protects the axon upon demyelination. Consequently, increased mobilisation of mitochondria from the neuronal cell body to the axon is a novel neuroprotective strategy for the vulnerable, acutely demyelinated axon. We propose that promoting ARMD is likely to be a crucial preceding step for implementing potential regenerative strategies for demyelinating disorders.</p
Enhanced axonal response of mitochondria to demyelination offers neuroprotection:implications for multiple sclerosis
Axonal loss is the key pathological substrate of neurological disability in demyelinating disorders, including multiple sclerosis (MS). However, the consequences of demyelination on neuronal and axonal biology are poorly understood. The abundance of mitochondria in demyelinated axons in MS raises the possibility that increased mitochondrial content serves as a compensatory response to demyelination. Here, we show that upon demyelination mitochondria move from the neuronal cell body to the demyelinated axon, increasing axonal mitochondrial content, which we term the axonal response of mitochondria to demyelination (ARMD). However, following demyelination axons degenerate before the homeostatic ARMD reaches its peak. Enhancement of ARMD, by targeting mitochondrial biogenesis and mitochondrial transport from the cell body to axon, protects acutely demyelinated axons from degeneration. To determine the relevance of ARMD to disease state, we examined MS autopsy tissue and found a positive correlation between mitochondrial content in demyelinated dorsal column axons and cytochromecoxidase (complex IV) deficiency in dorsal root ganglia (DRG) neuronal cell bodies. We experimentally demyelinated DRG neuron-specific complex IV deficient mice, as established disease models do not recapitulate complex IV deficiency in neurons,and found that these mice are able to demonstrate ARMD, despite the mitochondrial perturbation.Enhancement of mitochondrial dynamics in complex IV deficient neurons protects the axon upon demyelination. Consequently, increased mobilisation of mitochondria from the neuronal cell body to the axon is a novel neuroprotective strategy for the vulnerable, acutely demyelinated axon. We propose that promoting ARMD is likely to be a crucial preceding step for implementing potential regenerative strategies for demyelinating disorders.</p
Landnutzungsveränderungen in den Hochgebirgen der Erde
Die Landnutzungssysteme in den Hochgebirgen der Erde sind im Anthropozän durch dynamische Transformationsprozesse gekennzeichnet, in denen Anpassungsformen und –strategien an vielfältige Veränderungen der sozioökonomischen Rahmenbedingungen im Zuge der beschleunigten Globalisierung wie auch an klimawandelbedingte naturräumliche Veränderungen zum Ausdruck kommen. Traditionelle Lebensweisen und Wirtschaftsformen werden insbesondere durch veränderte Mobilitätsmuster der Gebirgsbevölkerung und durch Erweiterung des Einkommensspektrums (v.a. Tourismus) modifiziert. Arbeitskräftemangel infolge weitverbreiteter Abwanderungstendenzen in urbane Zentren und Tiefländer führt in den meisten Hochgebirgen zu einem graduellen Bedeutungsverlust der Berglandwirtschaft, vor allem des Pastoralismus. Der Strukturwandel von Agrar- zu Dienstleistungsgesellschaften ist insbesondere in den europäischen Alpen weit fortgeschritten.
Land use changes in the world’s mountains: In the Anthropocene, land use systems in the world‘s mountains are characterized by dynamic transformation processes, manifested in forms and strategies of adaptation to diverse changes in the socioeconomic framework in the course of accelerated globalization as well as to climate change-induced changes in the natural environment. Traditional lifestyles and economies are being modified in particular by changes in the mobility patterns of the mountain population and by the diversification of the income spectrum (especially tourism). In most high mountain regions, labor shortages due to widespread migration trends to urban centers and lowlands are leading to a gradual loss of importance of mountain agriculture, especially pastoralism. In the European Alps, the structural change from an agricultural to a service society is already well advanced.
Cambios en el uso del suelo en las altas montañas de la tierra: Los sistemas de uso del suelo en las altas montañas de la tierra se caracterizan por procesos de transformación dinámica en el Antropoceno, en los cuales formas y estrategias de adaptación a diversos cambios en el marco socio-económico condicionan en Se expresa el curso de la globalización acelerada así como los cambios en el espacio natural debido al cambio climático. Los modos de vida tradicionales y las formas económicas se están modificando, en particular, al cambiar los patrones de movilidad de la población de las montañas y al ampliar el espectro de ingresos (especialmente el turismo). La escasez de mano de obra como resultado de la migración generalizada a los centros urbanos y las tierras bajas conduce a una disminución gradual de la importancia de la agricultura de montaña, especialmente el pastoreo, en la mayoría de las montañas altas. El cambio estructural de sociedades agrícolas a sociedades de servicios está particularmente avanzado en los Alpes europeos
Alpine Waldgrenzen im Klimawandel – Wie sind die heterogenen Reaktionsmuster zu erklären?
Die klimatischen Waldgrenzen in den Hochgebirgen der Erde sind wärmemangelbedingte Höhengrenzen, die sich im Zuge des Klimawandels in höhere Lagen verschieben werden, sofern nicht-thermische Standortsfaktoren dies nicht verhindern. Empirische Untersuchungen aus vielen Hochgebirgen zeigen bisher einen Anstieg, in vielen Fällen jedoch auch eine weitgehende Persistenz dieser Höhengrenzen. Die heterogenen Reaktionsmuster lassen sich grob nach Waldgrenztypen und –formen gliedern, eine hohe Responsvariabilität weisen jedoch auch physiognomisch vergleichbare Formen wie diffuse Waldgrenzen oder solche mit Krummholzgürtel auf. Zur Erklärung müssen die vielfältigen Interaktionen zwischen der Klimaerwärmung als globale/regionale Einflussgröße und den Komplexen der abiotischen und biotischen Standortsfaktoren sowie anthropogener Einflüsse bzw. deren Wechselwirkungen auf lokaler Ebene herangezogen werden.
Alpine treelines under climate change - How to explain heterogeneous response patterns? Climatic treelines in the world’s high mountains are altitudinal limits caused by heat deficiency. They will shift to higher elevations in the course of climate change, unless not prevented by non-thermal site factors. Empirical studies from many high mountain ranges have so far shown a treeline advance, but in many cases also a distinct persistence of treeline elevations. These heterogeneous response patterns can be roughly classified according to treeline types and forms, however, physiognomically comparable treeline forms such as diffuse treelines or those with a krummholz belt still show high response variability. In order to explain inconsistent response patterns, many-faceted interactions between global warming as a global/regional input variable and the complexes of abiotic and biotic site factors as well as anthropogenic influences and their interrelationships at the local level have to be analyse
Detection of the Earth's rotation using superfluid phase coherence
It has long been recognized that the macroscopic quantum properties of superfluid helium could form the basis of a technique for measuring the state of absolute rotation of the containment vessel: circulation of superfluid helium is quantized, so providing a reference state of zero rotation with respect to inertial space. Here we provide experimental proof of this concept by detecting the rotation of the Earth using the spatial phase coherence of superfluid ^4He, thus providing independent corroboration of an earlier report that demonstrated the feasibility of making such a measurement. Our superfluid container is constructed on a centimetre-size silicon wafer, and has an essentially toroidal geometry but with the flow path interrupted by partition incorporating a sub-micrometre aperture. Rotation of the container induces a measurable flow velocity through the aperture in order to maintain coherence in the quantum phase of the super-fluid. Using this device, we determine the Earth's rotation rate to a precision of 0.5% with a measurement time of one hour, and argue that improvements in sensitivity of several orders of magnitude should be feasible
- …