A Fitting Agenda for Arctic's Next Forty Years

... The ambitions of all of the circumpolar powers - Canada, the U.S., the Soviet Union, the Scandinavian countries - converge in the Arctic. Their activities, now and in the future, threaten the arctic environment. Offshore drilling in arctic waters, diversion of arctic rivers, accumulation of arctic haze can offer enormous risks to arctic marine life and weather systems. ... A concept of collective stewardship must be developed if we are to ensure the protection of the arctic environment. The Reagan administration's determination to open up the calving grounds of the Porcupine caribou herd along the arctic coast of Alaska to oil and gas exploration and production threatens the future of a herd that is an international environmental resource and threatens as well the future of Inuit and Dene villages on both sides of the international boundary. The pursuit of one nation's goals can cause social and environmental havoc. Let's not permit the debate about the Arctic to be cast in terms of sovereignty, of national ambition. We should not allow the sterile goals of the nation-state to define the future of the Arctic. National sovereignty is a limited and limiting concept. Sovereignty is a national issue, stewardship an international issue. Beyond sovereignty comes the concept of stewardship by all of the circumpolar powers over the circumpolar basin. In the Arctic an attempt ought even to be made to transcend the particularities of the Cold War. It is in the Arctic that the survival of the Native subsistence economy is essential; it is there that the place of Native peoples within our polities will be determined; it is there that our commitment to environmental goals and international cooperation will be tested: a fitting agenda for Arctic's next 40 years

Timing and Precision of Spike Initiation in Layer V Pyramidal Cells of the Rat Somatosensory Cortex

The timing and location of action potential initiation in layer V pyramidal cells of the rat somatosensory cortex depends on different ligand-gated and intrinsic conductances. In order to assess the shunting effect of GABAA receptor activation and Ih on the summative properties of these neurons, we recorded simultaneously from their somata and dendrites and induced combined excitatory and inhibitory postsynaptic potentials using extracellular stimulation. Three major consequences of GABAA receptor activation on the integration properties were found: (i) the action potential could be initiated in the distal apical dendrite, if GABAA receptors were simultaneously activated in the soma; (ii) GABAA receptor activation narrowed the time window for suprathreshold summation of two coincident excitatory synaptic inputs by a factor of 3.4; and (iii) uneven weights of the GABAergic components between two inputs could lead to unbalanced shunting and consequently to a time shift in the peak of the coincidence detection window. Blockade of Ih practically abolished coincidence detection within a time window of 30 ms. Location of spike initiation and summation of coincident inputs in pyramidal cells is determined by at least two shunting mechanisms: activation of the presynaptic inhibitory network and modulation of Ih as a function of the postsynaptic membrane potentia

Modification of Charge Trapping at Particle/Particle Interfaces by Electrochemical Hydrogen Doping of Nanocrystalline TiO2

Particle/particle interfaces play a crucial role in the functionality and performance of nanocrystalline materials such as mesoporous metal oxide electrodes. Defects at these interfaces are known to impede charge separation via slow-down of transport and increase of charge recombination, but can be passivated via electrochemical doping (i.e., incorporation of electron/proton pairs), leading to transient but large enhancement of photoelectrode performance. Although this process is technologically very relevant, it is still poorly understood. Here we report on the electrochemical characterization and the theoretical modeling of electron traps in nanocrystalline rutile TiO2 films. Significant changes in the electrochemical response of porous films consisting of a random network of TiO2 particles are observed upon the electrochemical accumulation of electron/proton pairs. The reversible shift of a capacitive peak in the voltammetric profile of the electrode is assigned to an energetic modification of trap states at particle/particle interfaces. This hypothesis is supported by first-principles theoretical calculations on a TiO2 grain boundary, providing a simple model for particle/particle interfaces. In particular, it is shown how protons readily segregate to the grain boundary (being up to 0.6 eV more stable than in the TiO2 bulk), modifying its structure and electron-trapping properties. The presence of hydrogen at the grain boundary increases the average depth of traps while at the same time reducing their number compared to the undoped situation. This provides an explanation for the transient enhancement of the photoelectrocatalytic activity toward methanol photooxidation which is observed following electrochemical hydrogen doping of rutile TiO2 nanoparticle electrodes

FACS purification and transcriptome analysis of drosophila neural stem cells reveals a role for Klumpfuss in self-renewal

Drosophila neuroblasts (NBs) have emerged as a model for stem cell biology that is ideal for genetic analysis but is limited by the lack of cell-type-specific gene expression data. Here, we describe a method for isolating large numbers of pure NBs and differentiating neurons that retain both cell-cycle and lineage characteristics. We determine transcriptional profiles by mRNA sequencing and identify 28 predicted NB-specific transcription factors that can be arranged in a network containing hubs for Notch signaling, growth control, and chromatin regulation. Overexpression and RNA interference for these factors identify Klumpfuss as a regulator of self-renewal. We show that loss of Klumpfuss function causes premature differentiation and that overexpression results in the formation of transplantable brain tumors. Our data represent a valuable resource for investigating Drosophila developmental neurobiology, and the described method can be applied to other invertebrate stem cell lineages as well

Homotransplantation of multiple visceral organs

It was technically possible to perform simultaneous homotransplantation of multiple visceral organs including the liver, spleen, pancreas, omentum and the entire gastrointestinal tract. Arterialization of the cooled graft was accomplished through the donor aorta which was removed with the graft and attached to that of the recipient dog. Gastrointestinal hemorrhage after surgery accounted for a high operative mortality and was thought to be due to denervation of the graft. The five dogs which survived the immediate trauma of surgery lived for five and a half to nine days. After the second day, these animals were physically active and able to resume oral alimentation. In three dogs, there was metabolic evidence of rejection of the liver. In two others, jaundice did not develop. These observations were compared with chemical, hematologic and pathologic data obtained in previous experiments involving homotransplantation of the liver alone. In some cases, there was less evidence of host versus graft rejection after the multiple organ transplants. Other data in the present study suggested the possibility that a significant graft versus host reaction may have been an important contributory cause of death. © 1962

Investigating emotion regulation and social information processing as mechanisms linking adverse childhood experiences with psychosocial functioning in young swiss adults: the FACE epidemiological accelerated cohort study.

BACKGROUND Adverse childhood experiences increase the risk for psychological disorders and lower psychosocial functioning across the lifespan. However, less is known about the processes through which ACE are linked to multiple negative outcomes. The aim of the FACE epidemiological study is to investigate emotion regulation (emotional reactivity, perseverative thinking and self-efficacy for managing emotions) and social information processing (rejection sensitivity, interpretation biases and social understanding) as potential mechanisms linking adverse childhood experiences and psychosocial functioning in a large population sample of young adults. It is embedded in a larger project that also includes an ecological momentary assessment of emotion regulation and social information processing and informs the development and evaluation of an online self-help intervention for young adults with a history of ACE. METHODS The study plans to recruit 5000 young adults aged 18 to 21 from the German-speaking Swiss population. Addresses are provided by Swiss Federal Statistical Office and participants are invited by mail to complete a self-report online survey. If the targeted sample size will not be reached, a second additional sample will be recruited via educational facilities such as universities or teacher training colleges or military training schools. Three follow-ups are planned after 1 year, 2 years and 3 years, resulting in ages 18-24 being covered. The main exposure variable is self-reported adverse childhood experiences before the age of 18, measured at the baseline. Primary outcomes are psychosocial functioning across the study period. Secondary outcomes are social information processing, emotion regulation and health care service use. Statistical analyses include a range of latent variable models to identify patterns of adverse childhood experiences and patterns and trajectories of psychosocial adaptation. DISCUSSION The results will contribute to the understanding of the underlying mechanisms that link ACE with psychosocial functioning which is crucial for an improved insight into risk and resilience processes and for tailoring interventions. Furthermore, the identification of factors that facilitate or hinder service use among young adults with ACE informs healthcare policies and the provision of appropriate healthcare services. TRIAL REGISTRATION NUMBER NCT05122988. The study was reviewed and authorized by the ethical committee of Northwestern and Central Switzerland (BASEC number 2021-01204)

Zero dynamics and stabilization for analytic linear systems

The feedback stabilization problem is studied for time-varying real analytic systems. We investigate structural properties of the zero dynamics in terms of a system operator over a skew polynomial ring. The concept of (A,B)-invariant time-varying subspaces included in the kernel of C is used to obtain a condition for stabilizability. This condition is equivalent to autonomy of the zero dynamics in case of time-invariant systems. We derive a zero dynamics form for systems which satisfy an assumption close to autonomous zero dynamics; this in some sense resembles the Byrnes-Isidori form for systems with strict relative degree. Some aspects of the latter are also proved. Finally, we show for square systems with autonomous zero dynamics that there exists a linear state feedback such that the Lyapunov exponent of the closed-loop system equals the Lyapunov exponent of the zero dynamics; some boundedness conditions are required, too. If the zero dynamics are exponentially stable this implies that the system can be exponentially stabilized. These results are to some extent also new for time-invariant systems