Major shifts at the range edge of marine forests: the combined effects of climate changes and limited dispersal

Global climate change is likely to constrain low latitude range edges across many taxa and habitats. Such is the case for NE Atlantic marine macroalgal forests, important ecosystems whose main structuring species is the annual kelp Saccorhiza polyschides. We coupled ecological niche modelling with simulations of potential dispersal and delayed development stages to infer the major forces shaping range edges and to predict their dynamics. Models indicated that the southern limit is set by high winter temperatures above the physiological tolerance of overwintering microscopic stages and reduced upwelling during recruitment. The best range predictions were achieved assuming low spatial dispersal (5 km) and delayed stages up to two years (temporal dispersal). Reconstructing distributions through time indicated losses of ~30% from 1986 to 2014, restricting S. polyschides to upwelling regions at the southern edge. Future predictions further restrict populations to a unique refugium in northwestern Iberia. Losses were dependent on the emissions scenario, with the most drastic one shifting ~38% of the current distribution by 2100. Such distributional changes might not be rescued by dispersal in space or time (as shown for the recent past) and are expected to drive major biodiversity loss and changes in ecosystem functioning.

DAΦNE operation with electron-cloud-clearing electrodes

The effects of an electron cloud (e-cloud) on beam dynamics are one of the major factors limiting performances of high intensity positron, proton, and ion storage rings. In the electron-positron collider DAΦNE, namely, a horizontal beam instability due to the electron-cloud effect has been identified as one of the main limitations on the maximum stored positron beam current and as a source of beam quality deterioration. During the last machine shutdown in order to mitigate such instability, special electrodes have been inserted in all dipole and wiggler magnets of the positron ring. It has been the first installation all over the world of this type since long metallic electrodes have been installed in all arcs of the collider positron ring and are currently used during the machine operation in collision. This has allowed a number of unprecedented measurements (e-cloud instabilities growth rate, transverse beam size variation, tune shifts along the bunch train) where the e-cloud contribution is clearly evidenced by turning the electrodes on and off. In this Letter we briefly describe a novel design of the electrodes, while the main focus is on experimental measurements. Here we report all results that clearly indicate the effectiveness of the electrodes for e-cloud suppression.

Test of "crab-waist" collisions at the DAPhiNE Phi factory

The electron-positron collider DAPhiNE, the Italian Phi factory, has been recently upgraded in order to implement an innovative collision scheme based on large crossing angle, small beam sizes at the crossing point, and compensation of beam-beam interaction by means of sextupole pairs creating a "crab-waist" configuration in the interaction region. Experimental tests of the novel scheme exhibited an increase by a factor of 3 in the peak luminosity of the collider with respect to the performances reached before the upgrade. In this Letter we present the new collision scheme, discuss its advantages, describe the hardware modifications realized for the upgrade, and report the results of the experimental tests carried out during commissioning of the machine in the new configuration and standard operation for the users.

[Occupational backache: crossover study]

The authors briefly review the risk factors for the spine involved in working activities. Three hundred workers doing different jobs were studied for their general physical condition, job-related postures, the site of any back pain, and motor activity practiced. In line with other studies, data confirm that no worker category is immune from back problems, but highlight the positive role of motor activity in pain perception.

Transarticular repair of the brachial plexus. Case report

This paper illustrates the repair of a complex and unusually placed iatrogenic injury of the brachial plexus. The authors present the case of a 36-year old woman, musician (piano solista), with a dumbbell tumour of the brachial plexus. A general surgeon performed a gross total removal of the tumour, cutting it flush with the exit of the neuroforamen and this resulted in a severe upper brachial plexus injury. Four months later, the brachial plexus was repaired with a nerve graft, using a double extraforaminal and preforaminal approach via the transarticular route. The surgical procedure proved to be effective and without significant consequences for the patient.

[Vibration, back pain and physical exercise in high-risk professionals: a cross-sectional study]

Repeated loads and vibration stress in professional settings are relevant risk factors for back pain. Aim of this cross-sectional study was to estimate: a) the prevalence of back pain in two high-risk professional samples (helicopter pilots and bus drivers); b) the association between physical/sports exercise and back pain subjective perception across age. Prevalence of back pain is 94% in helicopter pilots and 74% in bus drivers; prevalence of back pain significantly increases with age. The positive effect of regular physical/sports exercise on subjective back pain significantly decreases with age. Physical or sports exercise adapted to structural characteristic of patients can result effective in diminishing personal impairment in subjects at professional risk.

Ultrarelativistic-positron-beam transport through meter-scale plasmas

We report on the first study of the dynamic transverse forces imparted to an ultrarelativistic positron beam by a long plasma in the underdense regime. Focusing of the 28.5 GeV beam is observed from time-resolved beam profiles after the 1.4 m plasma. The strength of the imparted force varies along the approximately 12 ps full length of the bunch as well as with plasma density. Computer simulations substantiate the longitudinal aberration seen in the data and reveal mechanisms for emittance degradation.

Transverse envelope dynamics of a 28.5-GeV electron beam in a long plasma

The transverse dynamics of a 28.5-GeV electron beam propagating in a 1.4 m long, (0-2)x10(14) cm(-3) plasma are studied experimentally in the underdense or blowout regime. The transverse component of the wake field excited by the short electron bunch focuses the bunch, which experiences multiple betatron oscillations as the plasma density is increased. The spot-size variations are observed using optical transition radiation and Cherenkov radiation. In this regime, the behavior of the spot size as a function of the plasma density is well described by a simple beam-envelope model. Dynamic changes of the beam envelope are observed by time resolving the Cherenkov light.

X-ray emission from betatron motion in a plasma wiggler

The successful utilization of an ion channel in a plasma to wiggle a 28.5-GeV electron beam to obtain broadband x-ray radiation is reported. The ion channel is induced by the electron bunch as it propagates through an underdense 1.4-meter-long lithium plasma. The quadratic density dependence of the spontaneously emitted betatron x-ray radiation and the divergence angle of approximately (1-3)x10(-4) radian of the forward-emitted x-rays as a consequence of betatron motion in the ion channel are in good agreement with theory. The absolute photon yield and the peak spectral brightness at 14.2-keV photon energy are estimated.

Observation of plasma focusing of a 28.5 GeV positron beam

The observation of plasma focusing of a 28.5 GeV positron beam is reported. The plasma was formed by ionizing a nitrogen jet only 3 mm thick. Simultaneous focusing in both transverse dimensions was observed with effective focusing strengths of order tesla per micron. The minimum area of the beam spot was reduced by a factor of 2.0+/-0.3 by the plasma. The longitudinal beam envelope was measured and compared with numerical calculations.

Novel final focus design for future linear colliders

The length, complexity, and cost of the present final focus designs for linear colliders grow very quickly with the beam energy. In this Letter, a novel final focus system is presented and compared with the one proposed for the Next Linear Collider (NLC Zeroth-Order Design Report, edited by T. O. Raubenheimer, SLAC Report No. 474, 1996). This new design has fewer optical elements and is much shorter, nonetheless achieving better chromatic properties. Moreover, the new system is more suitable for operation over a larger energy range.

Reverse dorsal digital island flap

The anatomic and clinical bases for a reliable and versatile homodigital flap for covering difficult distal dorsal and dorsolateral wounds of the long fingers are presented. This one-step procedure, which uses the dorsal skin of the first or second phalanx transposed as a reverse island flap, preserving the collateral nerve and artery to the fingertip, has proved valuable in salvaging the severely injured digits of nine patients (for a total of 12 flaps). It would seem to be a relatively simple way of achieving early recovery because it does not require distant flap reconstruction, the immobilization of adjacent digits, or homodigital flaps that might jeopardize an already injured finger. Furthermore, it reduces the time of hospitalization and improves patient welfare.

D-dimer plasma concentration in various clinical conditions: implication for the use of this test in the diagnostic approach of venous thromboembolism

Plasma measurement of D-Dimer (DD) represents a definite aid in the diagnostic approach of outpatients with suspected venous thromboembolism (VTE). However, the high sensitivity (about 95%) of the test which allows to rule out VTE when concentrations are below a given cutoff (500 micrograms/L as measured by the ELISA technique) is counterbalanced by a poor specificity (about 40%). Because the specificity might even be lower in patients who are hospitalized we determined the DD plasma concentration in 255 patients who were consecutively admitted in general internal medicine wards with various pathological conditions. The proportion of patients who had DD levels below the cutoff of 500 micrograms/L was 6% (1/18) in patients with VTE and 22% (52/237) in hospitalized patients without VTE: the figure was 21% in patients with pulmonary infections, 14% in patients with other infections, 11% in patients with neoplastic diseases, 34% in patients with coronary or cerebrovascular disease, 19% in patients with cardiac failure, 69% in patients with rheumatologic disease and in 16% in subjects with miscellaneous clinical conditions. The high rate of elevated plasma DD in hospitalized patients questions the usefulness of this test in the diagnostic approach of VTE in aged patients who present with concomitant disease like infections, neoplasia, cardiac failure and many other pathological conditions, except rheumatologic affections and coronary or cerebrovascular diseases.

Alkaline Waterflooding for Wettability Alteration-Evaluating a Potential Field Application

This procedure, in which the wettability change is assumed to be the important enhanced recovery mechanism, is recommended for determining the applicability alkaline waterflooding in specific light-oil reservoir systems.

Introduction

The wettability of petroleum reservoir rock, its estimation in laboratory tests, and its effect on the displacement of oil by water have been the subject of a considerable and growing body of literature. Craig presented an excellent review of developments in this presented an excellent review of developments in this field so another discussion will not be given here. Recent investigators generally agree that preferred wettability is not a discrete-valued function, oil-wet or water-wet, but can span a continuum between these extremes. It has been demonstrated with artificial wettability systems using low-viscosity oils that waterflooding to a given water-oil ratio (WOR) becomes increasingly more efficient as a sand becomes more water-wet. It is not altogether certain, however, that waterflooding under strongly water-wet conditions is always most efficient in real reservoir systems. An example of this is given by Salathiel, who found lower residual oil saturations in mixed wettability systems than would occur under strongly water-wet conditions. This effect was attributed to gravity drainage across bedding planes. Most recently, Treiber el al. noted that a large number of reservoirs are more oil-wet than water-wet.It has generally been found, however, that causing a reservoir to become more water-wet by chemical means during the course of a waterflood results in an increase in oil recovery over that of an unaltered displacement by water alone. This has been demonstrated by Wagner and Leach, and by Leach et al. using a refined oil containing an amine to simulate an oil-wet system and an aqueous acid solution to reverse wettability. Mungan and Emery et al. obtained the same result using a sodium hydroxide (NaOH) solution to alter the wettability of a crude oil-brine-sand system. Alkaline waterflooding has been found under certain circumstances to increase oil production by low interfacial tension displacement and by rigid film breaking as well as by favorable wettability alteration.Two types of screening procedures for recovery estimation have been reported, both of which attempt to duplicate reservoir wettability by contacting oil, water, and mineral for long periods of time. A contact-angle measurement technique was described for wettability and wettability alteration estimation and for wettability estimation alone. The measurement is made after water displaces oil from a plane mineral surface in contact with the oil for various times. To obtain no further changes, the aging times required varied from 200 to 2,400 hours for different reservoir systems. The amount of additional oil obtainable by an alkaline waterflood is inferred from the difference between the normal water-oil-solid and alkaline water-oil-solid contact angles. This type of test can only estimate wettability-change increased production. production. JPT

P. 1335