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Operating experience from fusion research shows how Spitzer resistivity may render ohmic heating in the chromosphere self limiting and thus serve to define the lower margin of the transition region. Its upper margin is at about 6000 K, where radiative cooling of He:H plasma decelerates sharply. The third and last stage in the proposed scheme is expansion into the tenuous plasma of space, which leads to the acceleration of ions to high energies, long recorded by spacecraft instruments. There is thus dynamic continuity all the way from the solar interior, the energy source for spinning columns in the Rayleigh Benard setting of the convection zone, to the coronal exhalation of the solar wind, a finding which should benefit the analysis of space weather, witness the association between helium in the solar wind and the incidence of coronal mass ejections., 8 pages and 4 figures

The Namie (Japan) 2016.11.21 Mw 6.9 earthquake (d = 9.0 km) initiated a tsunami which, contrary to forecasts of up to 3 m based on preliminary earthquake magnitude, nowhere exceeded 1.4 m. The hypocentre of the main shock was bordered in the succeeding 24 h by a tight cluster of 24 M ≤4.5 shallow (d ≤ 20 km) earthquakes. Two of them nucleated close to a M4.6 tremor that had preceded the main earthquake by 2.34 h, raising the possibility that a single structure hosted all three. Granted the ultimate cause was subduction at the Japan Trench, these events reaffirm the need for focused seafloor monitoring and fault history to supplement teleseismic data for realistic tsunami forecasting. Earthquake clustering in the 24 h after the main earthquake may also reflect a mode of megathrust segmentation which discourages the generation of great (Mw ∼ 9) earthquakes.

The history of human environments in Saudi Arabia is often depicted purely as an alternation of more or less arid interludes. However, access to and through the peninsula, and the range and quality of the resources it offered at different times, has owed much to tectonics and sea level oscillations as well as to changes in the atmospheric circulation, and the outcome was rarely the same throughout the peninsula. The Kingdom’s archaeological record thus reflects global as well as local geological and climatic events, and large-scale geophysical and solar fluctuations as well as minor atmospheric disturbances. Human influence is generally dwarfed by these natural processes but in some areas it has been profound and not always beneficial.

Stars have long been classified on the basis of their brightness; variability was a secondary consideration but eventually proved an important clue to stellar dynamics as well as a means of classification. The Sun’s ~11-year activity cycle, identified mainly from sunspots and other surface features, is superimposed on both longer and shorter periodicities which are manifested in luminosity and internal processes to different degrees. Solar observation thus makes increasing demands on the versatility and sensitivity of observatories, observers and their archives, and rules out an all-purpose definition of the present-day Sun.

In 1911 the Sun shed its unique role in humanity’s universe and joined the ranks of several million G2V yellow dwarf stars; whatever the resulting loss of prestige by association, humanity has thereby gained greatly in its understanding of solar history and probable future by analogy with kindred stars and the calibration of models of solar evolution. The Sun’s composition and inner workings were revealed by spectroscopy and nuclear physics; advances in solar physics and chemistry illuminate other stars, solar systems and galaxies, to the benefit of our cosmic understanding. Numerous devices now monitor the Sun, their development prompted by necessity as well as curiosity.

Our grasp of the solar factor in weather remains imperfect, to the detriment of forecasting and palaeoclimatic analysis, but there is progress on several novel fronts, and the study of exoplanet atmospheres provides useful pointers. The influence of galactic cosmic rays on cloud cover is being assessed experimentally. Phytochemistry allows the broadbrush lessons of ecology to be refined. Ozone monitoring and palaeohydrology shed light on the impact of solar UV on the global circulation.

The accepted scheme for the solar interior is a core powered by nuclear fusion primarily via the p-p reaction. The validity of the Standard Solar Model for the Sun’s related metabolism can be assessed by reference to the associated flux of neutrinos. A temperature of 15 million K at the core falls to ~6000 K at the photosphere and rises to 20,000 K at the chromosphere and to 1–2 million K or more at the outer margins of the solar corona; most of the mechanisms currently favoured for this progression hinge on magnetic reconnection or on wave heating, whereas the scheme advanced here is a stepwise sequence, with induction heating at the photosphere, the Joule-Thomson effect in the chromosphere, and plasma expansion in the corona, a tripartite solution which also explains the threefold structure of the solar atmosphere.

In the 1960s localised oscillations of the Sun’s surface were found to represent acoustic and other internal waves which were to reveal many features and processes of the solar interior. In contrast, despite prolonged observation of the Sun from telescopes, balloons and orbiting satellites, there is uncertainty over any surface evidence for gravitational interplay with the planets, the Schwabe and other activity cycles, and the mass loss expected from the solar wind and nuclear fusion. But the variegated ramifications of the subject, including relativity and stellar evolution, guarantee further astrometric innovations and refinements.

The M w 7.7 earthquake that struck SE Pakistan on 24 September 2013 at 11.29.48 UTC was a sinistral strike-slip event on a branch of the Ornach-Nal-Chaman fault system which hereabouts separates the Eurasian Plate from the Indian Plate. Although the focus was at a depth of 15 km and 400 km inland the earthquake was accompanied by the emergence of an island off the Makran coast and the generation of a tsunami with a peak amplitude of 27 cm at Muscat (Oman) and 20 cm at Chah Bahar (Iran). At DART marine buoy 23228 in the Indian Ocean 500 km to the south a series of seismic Rayleigh waves about 4 min after the main shock was followed 54 min later by a tsunami with a peak amplitude of 1 cm. The Rayleigh series is here attributed to seafloor vibration during accelerated subduction of the Arabian Plate beneath the Eurasian Plate, and the tsunami to the development or reactivation of one or more reverse faults on the seaward portion of the Makran imbricate fan. As in the 2010.2.27 M w 8.8 Maule (Chile), the 2004.12.26 M w 9.2 Sumatra–Andaman, the 2005.3.28 M w 8.7 Nias (Indonesia) and the 2011.3.11 M w 9.0 Tohoku (Japan) earthquakes, the link between tsunami generation and slip on the megathrust is thus very indirect, to the detriment of attempts to mitigate coastal hazards using teleseismic data when nearshore seafloor monitoring would probably prove more effective.

The recurring mismatch between the magnitude of subduction earthquakes and related tsunamis hinders hazard assessment. A tsunami which accompanied the 2014.04.01 Mw 8.2 Iquique earthquake and attained ≤2.11 m on the north Chilean coast is generally attributed to slip at a depth of 23 km on the megathrust between the Nazca and South American plates but, as at some other such sites, elastic seafloor deformation resulting from interplate displacements may have been supplemented if not overshadowed as the primary tsunamigenic agent by upper plate faulting. The evidence for suitable structures includes foreshocks M ≤ 5.8 dating from the preceding month and, during the 24 h immediately after the main shock, aftershocks M ≤ 5.6.

The Royal Geographical Society (with the Institute of British Geographers) annual Medals and Awards recognise achievements in researching, communicating and teaching a wide range of geographical knowledge. The speeches and citations are a record of the ceremony of 2012. With comments by the BBC's Alastair Fothergill, and Professors Charles Withers, Gillian Rose, Stuart Lane and Claudio Vita-Finzi, the speeches encompass historical geography, inspiring audiences, domestic visual culture, flood hazards and climate change. President Michael Palin introduces the ceremony, emphasising the breadth and relevance of geographical research.

During the last half century, advances in geomorphology—abetted by conceptual and technical developments in geophysics, geochemistry, remote sensing, geodesy, computing and ecology—have enhanced the potential value of fluvial history for reconstructing erosional and depositional sequences on the Earth and on Mars and for evaluating climatic and tectonic changes, the impact of fluvial processes on human settlement and health, and the problems faced in managing unstable fluvial systems.

The history of sea level within the Red Sea basin impinges on several areas of research. For archaeology and prehistory, past sea levels of the southern sector define possible pathways of human dispersal out of Africa. For tectonics, the interglacial sea levels provide estimates of rates for vertical tectonics. For global sea level studies, the Red Sea sediments contain a significant record of changing water chemistry with implications on the mass exchange between oceans and ice sheets during glacial cycles. And, because of its geometry and location, the Red Sea provides a test laboratory for models of glacio-hydro-isostasy. The Red Sea margins contain incomplete records of sea level for the Late Holocene, for the Last Glacial Maximum, for the Last Interglacial and for earlier interglacials. These are usually interpreted in terms of tectonics and ocean volume changes but it is shown here that the glacio-hydro-isostatic process is an additional important component with characteristic spatial variability. Through an iterative analysis of the Holocene and interglacial evidence a separation of the tectonic, isostatic and eustatic contributions is possible and we present a predictive model for palaeo-shorelines and water depths for a time interval encompassing the period proposed for migrations of modern humans out of Africa. Principal conclusions include the following. (i) Late Holocene sea level signals evolve along the length of the Red Sea, with characteristic mid-Holocene highstands not developing in the central part. (ii) Last Interglacial sea level signals are also location dependent and, in the absence of tectonics, are not predicted to occur more than 1–2 m above present sea level. (iii) For both periods, Red Sea levels at ‘expected far-field’ elevations are not necessarily indicative of tectonic stability and the evidence points to a long-wavelength tectonic uplift component along both the African and Arabian northern and central sides of the Red Sea. (iv) The observational evidence is consistent with tectonic and isostatic processes both operating over the past 300,000 years without requiring changes in the time averaged (over a few thousand years) tectonic rates. (v) Recent bathymetric data for the Bab al Mandab region have been compiled to confirm the location and depth of the sill controlling flow in and out of the Red Sea. Throughout the last 400,000 years the Red Sea has remained open to the Gulf of Aden with cross sectional areas at times of glacial maxima about 2% of that today. (vi) The minimum channel widths connecting the Red Sea to the Gulf of Aden at times of lowstand occur south of the Hanish Sill. The channels are less than 4 km wide and remain narrow for as long as local sea levels are below −50 m. This occurs for a number of sustained periods during the last two glacial cycles and earlier. (vii) Periods suitable for crossing between Africa and Arabia without requiring seaworthy boats or seafaring skills occurred periodically throughout the Pleistocene, particularly at times of favourable environmental climatic conditions that occurred during times of sea level lowstand.

Tsunami intensity is poorly correlated with earthquake magnitude. The distribution of aftershocks that immediately followed the 2010 Maule (Chile), the 2004 Sumatra–Andaman and the 2005 Nias (Indonesia) events supports the view that faulting within an accretionary wedge or an outer rise can sometimes disrupt the seafloor more effectively than a megathrust even if the associated seismicity is minor. Monitoring offshore faults would thus seem an effective way to supplement modes of tsunami early warning which hinge on instrumental earthquake detection or wave height and period.

St Peter and St Paul Rocks (SPSPR) are emergent portions of a peridotitic mass within the St Paul fracture zone of the Equatorial Mid-Atlantic Ridge, where local seismicity is dominated by strike-slip mechanisms. We used subtidal red algae in living position, death assemblages in intertidal conglomerates, and marine terraces as sea-level markers. The highest deposits correspond to a marine terrace with a shoreline angle at 8 ± 1 m asl that formed ca. 6400–6200 cal. yr BP. After correction for the sea-level changes derived by glacioisostatic modelling, AMS and radiometric 14 C age measurements on the Holocene sea-level markers indicate emergence during the last 6600 a at a minimum average rate of ∼ 1.5 mm/a. We propose that uplift resulted from peridotite emplacement by extrusion, rather than volcanic activity or fault slip, with the implication that the ridge has been subject to compression during the Holocene.

Measurements of solar EUV irradiance show, besides the ∼11-year Schwabe cycle, a series of oscillations with a ∼27-day period. They are generally explained by the passage of active regions across the solar surface resulting from the Sun's rotation, but the calculated amplitude underestimates the observed long-term variation in irradiance (Lean 1991). The variant of this model proposed here is modulation of EUV emission from the corona by rotation of the Sun's radiative zone. The response would be immediate, raising the prospect of short-term forecasting of EUV effects on space weather and on the Earth's atmospheric circulation.

The term cataclastic diapirism is proposed for the low-temperature extrusion of highly fractured rocks through more competent strata to produce domed topographies at the surface. The process is illustrated by reference to the geomorphology, neotectonics and microseismicity of the Pie de Palo, an elongated ridge in the western Sierras Pampeanas of Argentina composed of shattered and sheared Lower Palaeozoic rocks and subject to coseismic uplift. The Pie de Palo is conventionally interpreted as a fault-driven basement fold linked to low-angle eastward subduction of the Nazca plate beneath South America; the diapiric model implies instead that deformation is powered by regional compression from west-verging, near-surface, crustal shortening which results ultimately from Atlantic spreading.

The peptide corresponding to the (66-104) sequence of horse heart cytochrome c and its carboxyamide analog, selectively modified at the critical Met80 residue, have been synthesized by stepwise solid-phase methods on PAM and BHA resins respectively. The correctness of the growing peptide chain as well as the homogeneity of the final products have been monitored by several analytical methods including quantitative Edman degradation. After HF cleavage both peptides were purified by semipreparative HPLC. The overall yields were 24% for the native (66-104) and 10% for the carboxyamide analog. The homogeneity of the purified synthetic peptides have been determined by different criteria including HPLC, amino acid composition, Edman degradation, electrophoresis, and tryptic peptide mapping. The synthetic fragments have been utilized for preliminary semisynthesis experiments with the native [Hse greater than 65] (1-65)H heme-sequence.

A comparative study on thermolysin from Bacillus thermoproteolyticus and neutral protease from Bacillus subtilis involving (far- and near-ultraviolet circular dichroism (CD) and immunological techniques is reported. These enzymes are homologous metalloendopeptidases, having similar size, kinetic behaviour, substrate specificity and susceptibility to inhibitors. The far-ultraviolet CD spectrum of each protein shows a minimum at 208 and a shoulder near 220 nm; differences in the extent of ellipticity, however, have been observed. Estimates of secondary structure obtained by quantitation of the far-ultraviolet CD spectra indicated a higher helicity of neutral protease relative to thermolysin. In the presence of ethylenediaminetetraacetic acid, which removes calcium and the functional zinc ion from the metalloenzymes, neutral protease is immediately denatured, whereas thermolysin maintains a globular structure, although thermolabile. On the other hand, the zinc-specific chelating agent tetraethylenepentamine does not have measurable effects on the conformation and conformational stability of either protein. Marked higher stability to temperature and guanidine hydrochloride were observed for thermolysin as compared with neutral protease, as indicated by monitoring conformational transitions with CD measurements at 220 nm. Antisera prepared in rabbits using thermolysin as immunogen do not cross-react with neutral protease, indicating differences of surface structure between the two proteins. On the basis and limitations of the techniques employed, it is proposed that the two sequentially and functionally homologous metalloendopeptidases may have similar conformations at specific regions (active and binding sites, at least) of the polypeptide chain essential for biological function, while some variability in the structure of other regions may be tolerated.

The molecule of thermolysin was shown by X-ray crystallography to be composed of two structural domains of equal size comprising residues 1-157 and 158-316. In order to explore the possibility that these domains correspond to globular fragments able to refold autonomously, we have investigated the conformational and stability properties of fragment 121-316, which was obtained by limited chemical cleavage of thermolysin with cyanogen bromide. As judged by far-ultraviolet circular dichroism measurements, in aqueous solution under neutral conditions the fragment maintains a relative amount of helical structure which is comparable to that exhibited by the corresponding region in native thermolysin. The secondary structure attained by the fragment appears remarkably stable to the denaturing action of heat. By measuring the temperature dependence of the dichroic signal at 220 nm a Tm near 74 degrees was obtained. Immunodiffusion analyses indicated that the fragment recognizes and precipitates antibodies raised in rabbits using native thermolysin as immunogen. The overall conformational and immunochemical data indicate that fragment 121-316 of thermolysin is able to refold into a stable structure of native-like characteristics independently of the rest of the molecule. The results of this study complement those previously reported for fragment 206-316 (Vita, C., Fontana, A., Seeman, J.R. & Chaiken, I.M. (1979) Biochemistry 18, 3023-3031).

Coseismic and interseismic deformation of the outer-arc islands of Nias and Simeulue associated with the great Indonesian earthquakes of 2004.12.26 and 2005.3.28 is generally ascribed to elastic stress storage and release on the interface between the Indian and Eurasian plates at the Java trench. However, the nature of the associated shallow seismicity and the pattern of Holocene deformation of the islands suggest that there has also been substantial activity on imbricate faults within the sediment prism behind the trench. The distinction between the two kinds of seismicity is of practical as well as theoretical significance because, in contrast with the megathrust, outer-arc faulting is not subject to appreciable postseismic relaxation and is, moreover, well placed to generate tsunami.

The Sun, which embodies much of the mass of our solar system, has evolved substantially since its coagulation from the nebula. It is at the heart of the solar system in many ways besides its obvious gravitational role, notably through the radiation it emits at a range of wavelengths, the magnetic heliosphere and the solar wind. All fluctuate periodically, irregularly and cumulatively in response to factors working within the Sun or externally, notably orbital cycles, interaction between bodies, and interstellar matter.

We examine some long-standing assumptions about the early use of coastlines and marine resources and their contribution to the pattern of early human dispersal, and focus on the southern Red Sea Basin and the proposed southern corridor of movement between Africa and Arabia across the Bab al-Mandab Straits. We reconstruct relative sea levels in light of isostatic and tectonic effects, and evaluate their paleogeographical impact on the distribution of resources and human movement. We conclude that the crossing of the Bab al-Mandab posed little significant or long-lasting physical or climatic barrier to human transit during the Pleistocene and that the emerged continental shelf during periods of low sea level enhanced the possibilities for human settlement and dispersal around the coastlines of the Arabian Peninsula. We emphasize the paleogeographical and paleoenvironmental significance of Pleistocene sea-level change and its relationship with changes in paleoclimate, and identify the exploration of...

In order to search for new anti-tumor and anti-viral agents, a series of α-aminophosphonate conjugates of 3-O-β-acetyl ursolic acid were prepared. Their biological activities as cytotoxic and anti-HIV agents were evaluated. The preliminary bioassays indicate that synthesized compounds 7a–j have anti-HIV activity (targeting HIV-1 gp120 and CD4) and no cytotoxicity on HT-29 cells (human colon adenocarcinoma cell line).

Four caves on the SW flank of Mt. Carmel, es Skhul, el Wad, el Jaml and et Tabun, were first excavated in the 1930s by a team led by Dorothy Garrod. They yielded human remains whose age and evolutionary status remain controversial partly because the complexity of the cave deposits invites conflicting interpretations. The abrasion of artefacts and pebbles in el Wad and es Skhul, which was originally ascribed to spring flow within the caves, is explained here by wave action, with the implication that during part of the Middle Palaeolithic the caves were on the shoreline rather than being separated from it—as they now are—by several kilometres of coastal plain and a height difference of some 45 m. U-series, thermoluminescence (TL) and electron spin resonance (ESR) dating suggests that this occurred about 120,000 years ago, when sea level in the eastern Mediterranean stood 5–6 m above its present position. It follows that Mt. Carmel has subsequently undergone some 40 m of uplift. During the period of maximum submergence, the coastal route between Africa and the northern Mediterranean would have been partly blocked, but the loss of the coastal plain for transit and as a source of animal food was offset by easier access from the caves to marine resources.

Palaeostress analysis of spreading oceanic ridges requires data on extension over time and at different locations along strike so that mechanical models can be formulated and tested. The seafloor palaeomagnetic record provides average spreading rates but as the last (normal) chron measures 790,000 years an alternative method is required for identifying episodes of spreading at time scales of 8.3 in the RedSea-Dead Sea rift system Other isotopes may prove to be more sensitive and therefore responsive to smaller deformation.

A 33-amino acid peptide corresponding to the helix-loop-helix motif of the calcium binding site I of the protein calmodulin from Paramecium Tetraurelia has been synthesized its binding properties with heavy metal ions have been studied. Herein, we demonstrate that two mutations of two aspartic acid residues in the peptide sequence gave access to a new peptide, which was selective for the uranyl ion UO2 2+. This new peptide can be useful for the development of selective uranyl biosensors to monitor the presence of uranium in contaminated environments.

A set of engineered peptides (33 amino acids long) corresponding to the helix-turn-helix (EF-Hand) motif of the metal-binding site I of the protein calmodulin from paramecium tetraurelia have been synthesized. A disulfide bridge has been introduced in the native sequence in order to stabilize a native-like conformation. The calcium-binding carboxylate residues in positions 20, 22, 24, and 31 were mutated into other amino acids and the influence of such mutations on the binding affinity of the peptides for calcium and lanthanides have been studied. It was shown that the binding affinity for terbium ions can be modulated with dissociation constants ranging from 40 nmolar to 40 mmolar. The study of the influence of the mutations on the terbium affinity showed that the residue in position 24 played a key role on the capability of the peptides to bind lanthanides and that the affinity could be enhanced by mutations on non-coordinating positions. Such peptides with high affinity for lanthanides may facilitate the development of new highly sensitive biosensors to monitor the metal pollution in the environment.

Neotectonic data may indicate whether stored elastic energy will be dissipated or released destructively. The Hengchun Peninsula of Taiwan is the southern extremity of the Central Range of Taiwan and thus an emergent part of the accretionary wedge resulting from subduction of Eurasia beneath the Philippine Sea plate at the Manila Trench. Radiocarbon dating of fossil shorelines on the peninsula shows that it has been uplifted at an average rate of 3.8 mm/yr during the Holocene. About 1 / 3 of the uplift is due to deformation along the Hengchun reverse fault but, in contrast with the Chelungpu and other low angle reverse faults west of the Central Range, it accommodates strain principally by aseismic creep. To cite this article: C. Vita-Finzi, J.-C. Lin, C. R. Geoscience 337 (2005).

The waste products of stone tool making and isolated artifacts found on land surfaces can illuminate aspects of human culture and of landscape evolution even though they lack stratigraphic context. Quartzite artifacts and debris occurring on pediments near Pinedale (Wyoming) include cobbles from which multiple flakes have been removed by percussion. Some of the specimens have been polished and abraded by wind-blown sand. Neither feature is represented in the material excavated at the local Holocene site of Trappers Point. The location of the surface finds in relation to topography and the products of glaciation suggests that occupation in Paleo-Indian or perhaps earlier times was more pervasive in Wyoming than suggested by the few settlement or kill sites on the valley floors. It also shows that relying on sealed sites to date the pattern of human movement across the landscape risks underestimating its antiquity.

The binding surface on CD4 for the HIV-1 gp120 envelope glycoprotein has been transplanted previously onto a scorpion-toxin scaffold. Here, we use X-ray crystallography to characterize atomic-level details of gp120 with this transplant, CD4M33. Despite known envelope flexibility, the conformation of gp120 induced by CD4M33 was so similar to that induced by CD4 that localized measures were required to distinguish ligand-induced differences from lattice variation. To investigate relationships between structure, function, and mimicry, an F23 analog of CD4M33 was devised. Structural and thermodynamic analyses showed F23 to be a better molecular mimic of CD4 than CD4M33. F23 also showed increased neutralization breadth, against diverse isolates of HIV-1, HIV-2, and SIVcpz. Our results lend insight into the stability of the CD4 bound conformation of gp120, define measures that quantify molecular mimicry as a function of evolutionary distance, and suggest how such evaluations might be useful in developing mimetic antagonists with increased neutralization breadth.

We have identified numerous well-preserved elutriation and fluidization structures probably induced by liquefaction in Quaternary gravels and gravelly sediments of braided fluvial channel deposits in the Rio Grande do Norte and Ceara states, northeastern Brazil. They show evidence of upward-directed water escape after sediment deposition and before sediment compaction. Among the several types of structures observed, the most frequent are pillars, pockets and dikes. These structures range in width from a few centimeters to as much as 4 m, and in height from 60 cm to 4 m. Dikes, pillars and pockets are systematically associated. Clastic dikes vented large quantities of sand to the upper layers or the surface; pebbles and cobbles from the host rock sank into the dikes and formed pillars and pockets. Pockets form the root part; pillars form the intermediate part and dike, the upper part of the composite structure. The morphology of the structures in sectional and plan views indicates a 3D geometry composed of a tabular dike and pillar that present a downward continuous transition to a bowl-shaped pocket. This “stratigraphy” of liquefaction features is different from that usually presented in the current literature. Field data suggest that both the location and the geometry of the features were controlled by sedimentary properties rather than joints and small faults. The size and abundance of these features suggest that they were formed by great events rather than localized mechanisms. Field evidence also indicates that these features are the product of fluidization and elutriation and may have been induced by liquefaction processes associated with seismic shaking. A nonseismic origin related to elutriation processes, however, cannot be ruled out for some of the features.