The Alaska Peninsula is a landscape defined by volcanic, tectonic, and glacial processes, and life throughout is conditioned on the interactions among them. During the middle Holocene (ca. 4100–3600 yr ago), intense caldera-forming eruptions of the Aniakchak and Veniaminof volcanoes changed the shape of the central portion of the Peninsula dramatically, and had significant and perhaps devastating impacts on both terrestrial and marine biota. Here we evaluate the severity of these impacts by tracking human settlement patterns using 75 unique radiocarbon (14C) age determinations on buried cultural features from the central Alaska Peninsula. Coastal regions were re-colonized within a few hundred years while river systems most proximate to the volcanoes were uninhabited for up to 1500 years following the most severe eruptions. Patterns of human settlement may also document previously unrecorded landscape change throughout the region, and further contribute to our understanding of post-volcanic ecological succession.

Recent observations suggest that the energy release in solar flares may occur in many small bursts. If these bursts give rise to plasma heating, a large number of collisionless shocks will be generated. These shocks can individually heat plasma and accelerate particles, but the interaction of particles with many shocks as well, as of shocks with each other can give rise to further heating and acceleration.

A large fraction of the electrons which are accelerated during the impulsive phase of solar flares stream towards the chromosphere and are unstable to the growth of plasma waves. The linear and nonlinear evolution of plasma waves as a function of time is analyzed with the use of a set of rate equations that follow in time the non-linearly coupled system of plasma waves-ion fluctuations. The nonthermal tail formed during the stabilization of the precipitated electrons can stabilize the Anomalous Doppler Resonance instability and prevent the isotropization of the energetic electrons. The precipitating electrons modify the way the return current is carried by the background plasma. In particular, the return current is not carried by the bulk of the electrons but by a small number of high velocity electrons. For beam/plasma densities ≳ 10−3, this can reduce the effects of collisions and heating by the return current. For higher density beams where the return current could be unstable to current driven instabilities, the effects of strong turbulence anomalous resistivity is shown to prevent the appearance of such instabilities. Our main conclusion is that the beam-return current system is interconnected and how the return current is carried is determined by the beam generated strong turbulence.

In the last decades, numerous observational and computational studies have shown that the global flare distribution is a power-law with a slope less than 2. In these studies, active regions are treated as statistically indistinguishable. To test this, we identify and separately analyze the flares produced by ten individual active regions (2006-2016). In five regions, we find a single power-law distribution, with a slope of a < 2. In the other five, we find a broken double power-law distribution, with slopes a1 < 2 and a2 > 2.

Explanations for the use of pots as practical domestic tools permeate the literature of technological adoption and change. While many arguments focus on the economic merits of pots, few have attempted to trace the conditions that promote or deter the adoption of pottery. This is especially true for the use of pottery by mobile peoples. We adapt an established model of technological investment to draw attention to three key variables affecting pottery adoption: manufacturing time, utility, and use time. We use the logic of this model to examine how social and environmental contexts, specifically residential mobility in marginal environments, impacts use of and investment in ceramic technology. We further illustrate how the model can be used to reveal seasonal patterns of behavior from the spatial distribution of pottery discarded by mobile foragers and herders.

The objective of the study was to investigate the effect of season on the fatty acid and terpene composition in ewe milk. A total of 760 samples of bulk sheep milk were collected during winter (147 samples), spring (314 samples) and summer (299 samples) of 2011, from 90 commercial farms of dairy sheep from the prefecture of Grevena, Greece. Regarding fatty acid composition, summer samples had higher concentrations of α-linolenic acid, cis-9, trans 11- CLA, trans-11, C18 : 1 and PUFAs but lower content of saturated fatty acids particularly C12 : 0, C14 : 0 and C16 : 0. The winter milk had the lowest content of terpenes, in particular sesquiterpenes, compared to spring and summer milk. The terpene profile of milk samples, in all three seasons, revealed the presence of monoterpenes: a-pinene, b-pinene and D-limonene, especially with a higher frequency of appearance in summer. The most common and abundant sesquiterpenes found in milk samples were β-caryophyllene and α-caryophyllene with a higher frequency of appearance in summer. In conclusion, the available pastures in semi-extensive farming systems can contribute to the production of high quality milk.

A review of recently published temporal data from Shuidonggou Locality 1 indicates that a 40–43 cal ka date for the inception of Initial Upper Paleolithic (IUP) blade-oriented technologies in East Asia is warranted. Comparison of the dates from Shuidonggou to other Asian IUP dates in Korea, Siberia, and Mongolia supports this assertion, indicating that the initial appearance of the IUP in East Asia generally corresponds in time to the fluorescence of the IUP in eastern Europe and western Asia. This conclusion preliminarily suggests that either a version of the IUP originated independently in East Asia just prior to 40 cal ka, or more likely, that an early, initial diffusion of the IUP into East Asia occurred ∼41 cal ka, a hypothesis consistent with current estimates for the evolution or arrival of modern humans in the region.

Particle acceleration during solar flares is a complex process where the main ‘actors’ (Direct (D.C.) or turbulent electric fields) are hidden from us. It is easy to construct a successful particle accelertion model if we are allowed to impose on the flaring region arbitrary conditions (e.g., strength and scale length of the D.C. or turbulent electric fields), but then we have not solved the acceleration problem; we have simply re-defined it. We outline in this review three recent observations which indicate that the following physical processes may happen during solar flares : (1) Release of energy in a large number of microflares ; (2) short time-scales; (3) small length scales; and (4) coherent radiation and acceleration sources. We propose that these new findings force us to reformulate the acceleration process inside a flaring active region assuming that a large number of reconnection sites will burst almost simultaneously. All the well-known acceleration mechanisms (electric fields, turbulent fields, shock waves, etc.) reviewed briefly here, can be used in a statistical model where each particle is gaining energy through its interaction with many small reconnection sites.

The heliosphere could be divided in three major acceleration Laboratories, the solar surface (Laboratory 1), the interplanetary medium (Laboratory 2) and Earth and Planetary magnetospheres (Laboratory 3). Our understanding of the acceleration process depends strongly on the nature of the drivers and the energy dissipation process. The energy gain by a particle with velocity where is the variation of the electric field in space and time. All three Laboratories mentioned above share a common characteristic, the drivers and the energy dissipation processes are closely connected to fully developed MHD turbulence. We can show that our understanding of particle acceleration depends strongly on the interaction of particles with fields resulting from fully developed MHD turbulence.

For all n > 1, the characteristic function of the unit ball in ℝ2n is not the symbol of a bounded bilinear multiplier operator from Lp (ℝn ) × Lq (ℝn ) to Lr (ℝn ) when 1/p + 1/q = 1/r and exactly one of p, q, or r′ = r/(r – 1) is less than 2.

We discuss the microwave emission from a flaring loop (Spicer 1977). In particular we examine the following question: What will be the characteristics of the radio emission at centimeter wavelengths from a small compact flaring loop (average plasma density ne ≃ 1010 cm−3, average magnetic field at the footpoint of the loop Bℓ ≃ 500 gauss and Bt ≃ 100 gauss at the top of the loop and length of the loop, L = 109 cm), when the mechanism which pumps magnetic energy into the plasma in the form of heating and/or electron acceleration satisfies the following conditions. a. The magnetic energy is released in a small volume, (the energy release volume (ERV)), compared to the volume of the loop, and the rate at which magnetic energy is transformed into plasma energy is faster than the energy losses from the same volume. This causes a local enhancement of the temperature by as much as one or two orders of magnitude above the coronal temperature. b). The bulk of the energy released goes into heating the plasma and heats primarily the electrons (Te > Ti). Using these two assumptions one can easily show (Brown, Melrose and Spicer 1979, Vlahos and Papadopoulos 1979) that the high energy electrons in the tail of the velocity distribution in the ERV will instantaneously run away from this volume, and the resulting charge imbalance between the ERV and its surroundings (which still have average coronal temperatures ~ 106 K), will drive a return current, with velocity VD. When VD reaches the value of the local sound speed Cs ≃ 107 cm/sec low frequency ion acoustic waves will be excited at the interface of the ERV and its surroundings. It has been shown that the heat flow along the magnetic field lines is greatly reduced due to the presence of ion-acoustic turbulence (cf. Manheimer 1977). The bulk of the electrons in the ERV have electron-wave collision times **τw << 10–100 sec, longer than the impulsive phase of the flare. But since τw ~ v3 for those electrons with velocity v > ve (see Rudakov and Korablev 1966) the electrons in the tail will not “see” the ion sound waves and will stream freely towards the chromosphere.

Here we report findings to optimize and standardize conditions to attenuate metacercariae of Opisthorchis viverrini by ionizing radiation to elicit protective immune responses to challenge infection. Metacercariae were gamma-irradiated and the ability of irradiated metacercariae to prevent patent infection of challenge metacercariae in hamsters was determined, as well as their ability to induce a host antibody response. Metacercariae irradiated in a dose-dependent manner, with 3, 5, 10, 12, 20, 25 and 50 Gray, were used to infect Syrian golden hamsters by stomach gavage to ascertain the effect of irradiation on ability of the worms to establish infection. In addition, other hamsters were infected with metacercariae irradiated with 20–50 Gray, followed by challenge with intact/wild-type (non-irradiated) metacercariae to determine the protective effect as established by the numbers of adult flukes, eggs of O. viverrini in hamster faeces and anti-O. viverrini antibody titres. Significantly fewer worms were recovered from hamsters immunized with metacercariae irradiated at 20, 25 and 50 Gray than from control hamsters infected with intact metacercariae or 0 Gray, and the worms showed damaged reproductive organs. Faecal egg numbers were decreased significantly in hamsters immunized with 25 and 50 Gray metacercariae of O. viverrini. Moreover, hamsters administered metacercariae that were protected elicited a robust, specific anti-fluke immunoglobulin G response compared to control hamsters, suggesting a role for antibody in protection elicited by radiation-attenuated metacercariae.

In this paper we prove a certain ${{L}^{2}}$ -estimate for multilinear Fourier multiplier operators with multipliers of limited smoothness. As a consequence, we extend the result of Calderón and Torchinsky in the linear theory to the multilinear case. The sharpness of our results and some related estimates in Hardy spaces are also discussed.