684 research outputs found

    Viewing time affects overspecification:Evidence for two strategies of attribute selection during reference production

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    Speakers often produce definite referring expressions that are overspecified: they tend to include more attributes than necessary to distinguish the target referent. The current paper investigates how the occurrence of overspecification is affected by viewing time. We conducted an experiment in which speakers were asked to refer to target objects in visual domains. Half of the speakers had unlimited time to inspect the domains, while viewing time was limited (1000 ms) for the other half. The results reveal that limited viewing time induces the occurrence of overspecification. We conjecture that limited viewing time caused speakers to rely heavily on quick heuristics during attribute selection, which urge them to select attributes that are perceptually salient. In the case of unlimited inspection time, speakers seem to rely on a combination of heuristic and more deliberate selection strategies

    Frequent activity on Vulcano (Italy) spanning the last 80 ky: New insights from the chemo-stratigraphy of the Brown Tuffs

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    The Brown Tuffs (BT) are widespread reddish-brown to grey, ash-rich pyroclastic deposits recognized in the stratigraphic sequences of the Aeolian Islands and Capo Millazzo peninsula (Sicily) that span the last 80 ky. They have very homogeneous lithological, textural and sedimentological features which make it difficult to reliably correlate units on the islands to proximal units in the source areas. Here we carefully re-interpret the stratigraphic profiles of the BT on Vulcano and Lipari where the deposits are thickest and present the most complete succession. The investigation is based on a large dataset of major and minor element geochemistry of juvenile glass components for the majority of the recognized BT depositional units, whilst also providing new radiocarbon ages. The distinctive chemical groupings observed within the glass analyses, both temporally and spatially, allow us to fingerprint the three main stratigraphically defined macro-units in which the BT succession can be sub-divided using prominent tephra marker beds, the Ischia Tephra (Monte Epomeo Green Tuff; 56 ky) and Monte Guardia pyroclastics from Lipari (herein radiocarbon dated to 27\u201326 ky). The Lower (80\u201356 ky; LBT), Intermediate (56\u201327 ky; IBT) and Upper BT (here dated at 24\u20136 ky; UBT) macro-units display K-series volcanic glasses ranging from basaltic trachy-andesites, through trachy-andesites, to more evolved trachytes, all consistent with an origin on Vulcano. The UBT are clearly distinguished from the lower macro units by their higher-SiO2 trachy-andesite to trachytic glasses, which extend to noticeably lower TiO2, CaO and MgO contents. These features make it possible to re-define the geochemical-evolutionary boundary between IBT and UBT as corresponding to the 24 ky Spiaggia Lunga scoria bed on Vulcano, which is stratigraphically higher (and younger) than the previous boundary marker (Monte Guardia). The glass compositions of the LBT, IBT and UBT are used to: (1) assess links to known proximal eruption units outcropping on Vulcano; (2) validate medial-distal BT occurrences across the Aeolian archipelago (Salina, Filicudi and Panarea) and on Capo Millazzo; (3) confirm that the BT are responsible for distal volcanic ash layers preserved in Central Mediterranean marine sedimentary archives. Interestingly, the glass compositions of the UBT are very similar to those of the Punte Nere unit, the earliest pyroclastic products erupted from the currently active La Fossa cone on Vulcano, indicating the corresponding magmatic system has likely erupted similar melts and products over the last 24 ky and thus extending its life cycle. Such information is crucial for evaluating the long-term eruption scenarios underpinning hazard assessment of the La Fossa caldera magmatic system

    La Valoración del Análisis de la Marcha en la Planificación de la Osteotomía Alta de Tibia

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    El objetivo de este trabajo ha sido el de valorar una nueva metódica clínica y biomecánica de los pacientes que presentan un genu varo y tratados quirúrgicamente mediante osteotomía tibial alta. De acuerdo a la metódica de Andriacchi e Insall y de nuestra pequeña experiencia hemos aplicado el estudio mediante "gait analysis" a estos pacientes preoperatoriamente. El cálculo preoperatorio del "momento adductor" parece ser discriminativo con respecto a los pacientes que tendrán un buen o mal resultado debido a la recidiva de la deformidad, dolor, etc. Tomando como referencia los resultados de estos estudios sugerimos algunas indicaciones pre y postoperatorias con referencia a la rehabilitación y la orientación quirúrgica más adecuada según el valor del momento adductor (alto o bajo) que presenten este tipo de pacientes.The purpose of this study has been to assess a new clinical and biomechanical approach of genu varum patients treated by high tibial osteotomy. According to Andriacchi, Insall, and their awn small experienc e the author s apply gait analysis to study the genu varum of patients pre-operatively. The assessment during preoperative gait of the adductor moment (high or low value s with respec t to the normal) seems to be discriminant in define patien that are goint to have good or bad results due to the recurrence of the pathology: pain, varus deformity, etc. Starting from the results the studies the authors suggest some indications in the pre and postoperative with reference to rehabilitation and surgical orientation taking in account the high or low level of preoperative the adductor moment

    Neutron Halo Isomers in Stable Nuclei and their Possible Application for the Production of Low Energy, Pulsed, Polarized Neutron Beams of High Intensity and High Brilliance

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    We propose to search for neutron halo isomers populated via γ\gamma-capture in stable nuclei with mass numbers of about A=140-180 or A=40-60, where the 4s1/24s_{1/2} or 3s1/23s_{1/2} neutron shell model state reaches zero binding energy. These halo nuclei can be produced for the first time with new γ\gamma-beams of high intensity and small band width (≤\le 0.1%) achievable via Compton back-scattering off brilliant electron beams thus offering a promising perspective to selectively populate these isomers with small separation energies of 1 eV to a few keV. Similar to single-neutron halo states for very light, extremely neutron-rich, radioactive nuclei \cite{hansen95,tanihata96,aumann00}, the low neutron separation energy and short-range nuclear force allows the neutron to tunnel far out into free space much beyond the nuclear core radius. This results in prolonged half lives of the isomers for the γ\gamma-decay back to the ground state in the 100 ps-μ\mus range. Similar to the treatment of photodisintegration of the deuteron, the neutron release from the neutron halo isomer via a second, low-energy, intense photon beam has a known much larger cross section with a typical energy threshold behavior. In the second step, the neutrons can be released as a low-energy, pulsed, polarized neutron beam of high intensity and high brilliance, possibly being much superior to presently existing beams from reactors or spallation neutron sources.Comment: accepted for publication in Applied Physics

    Geochemical and isotopic insights into the assembly, evolution and disruption of a magmatic plumbing system before and after a cataclysmic caldera-collapse eruption at Ischia volcano (Italy)

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    New geochemical and isotopic data on volcanic rocks spanning the period ~75–50 ka BP on Ischia volcano, Italy, shed light on the evolution of the magmatic system before and after the catastrophic, caldera-forming Monte Epomeo Green Tuff (MEGT) eruption. Volcanic activity during this period was influenced by a large, composite and differentiating magmatic system, replenished several times with isotopically distinct magmas of deep provenance. Chemical and isotopic variations highlight that the pre-MEGT eruptions were fed by trachytic/phonolitic magmas from an isotopically zoned reservoir that were poorly enriched in radiogenic Sr and became progressively less radiogenic with time. Just prior to the MEGT eruption, the magmatic system was recharged by an isotopically distinct magma, relatively more enriched in radiogenic Sr with respect to the previously erupted magmas. This second magma initially fed several SubPlinian explosive eruptions and later supplied the climactic, phonolitic-to-trachytic MEGT eruption(s). Isotopic data, together with erupted volume estimations obtained for MEGT eruption(s), indicate that >5–10 km3 of this relatively enriched magma had accumulated in the Ischia plumbing system. Geochemical modelling indicates that it accumulated at shallow depths (4–6 km), over a period of ca. 20 ka. After the MEGT eruption, volcanic activity was fed by a new batch of less differentiated (trachyte-latite) magma that was slightly less enriched in radiogenic Sr. The geochemical and Sr–Nd-isotopic variations through time reflect the upward flux of isotopically distinct magma batches, variably contaminated by Hercynian crust at 8–12 km depth. The deep-sourced latitic to trachytic magmas stalled at shallow depths (4–6 km depth), differentiated to phonolite through crystal fractionation and assimilation of a feldspar-rich mush, or ascended directly to the surface and erupted

    Melflufen for relapsed and refractory multiple myeloma

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    Introduction: The overall survival of patients with multiple myeloma has improved with the advent of novel agents; however, multiple myeloma remains incurable. Combinations of standard-of-care agents such as immunomodulators, proteasome inhibitors, and anti-CD38 monoclonal antibodies are increasingly used in earlier lines of therapy. Patients with disease that is refractory to multiple novel agents represent a population with high unmet medical need and for whom therapies with new mechanisms of action could be beneficial. Melphalan flufenamide (melflufen) has demonstrated encouraging activity in patients with relapsed and refractory multiple myeloma. Areas covered: This review provides an overview of the mechanism of action of melflufen, a first-in-class peptide-drug conjugate that targets aminopeptidases and rapidly delivers alkylating agents into tumor cells. It reviews key Phase I and II clinical trial data for melflufen in combination with dexamethasone as well as in triplet combinations with daratumumab or bortezomib. The safety profile of melflufen, which is characterized primarily by clinically manageable hematologic adverse events, is described. Expert opinion: Melflufen has potential to fill a gap in the myeloma treatment landscape by providing a new mechanism of action with clinically meaningful efficacy and a favorable safety profile in patients refractory to multiple novel agents

    Localization from quantum interference in one-dimensional disordered potentials

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    We show that the tails of the asymptotic density distribution of a quantum wave packet that localizes in the the presence of random or quasiperiodic disorder can be described by the diagonal term of the projection over the eingenstates of the disordered potential. This is equivalent of assuming a phase randomization of the off-diagonal/interference terms. We demonstrate these results through numerical calculations of the dynamics of ultracold atoms in the one-dimensional speckle and quasiperiodic potentials used in the recent experiments that lead to the observation of Anderson localization for matter waves [Billy et al., Nature 453, 891 (2008); Roati et al., Nature 453, 895 (2008)]. For the quasiperiodic case, we also discuss the implications of using continuos or discrete models.Comment: 5 pages, 3 figures; minor changes, references update

    Evidence for a large-magnitude Holocene eruption of Mount Rittmann (Antarctica): A volcanological reconstruction using the marine tephra record

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    In Antarctica, the near-source exposures of volcanic eruption deposits are often limited as they are not well preserved in the dynamic glacial environment, thus making volcanological reconstructions of explosive eruptions extremely challenging. Fortunately, pyroclastic deposits from explosive eruptions are preserved in Southern Ocean sediments surrounding Antarctica, and the tephrostratigraphy of these sequences offers crucial volcanological information including the timing and tempo of past eruptions, their magnitude, and eruption dynamics. Here we report the results of a tephrostratigraphy and tephrochronology study focused on four sediment cores recovered from the Wood Bay area in the western Ross Sea, Antarctica. In all these sedimentary sequences, we found a well-stratified primary tephra of considerable thickness, up to 80 cm, hereafter named the Aviator Tephra (AVT). According to the characteristics of the tephra deposit and its distribution, the AVT was associated with an eruption of considerable intensity, potentially representing one of the largest Holocene eruptions recorded in Antarctica. Based on the major and trace element geochemistry and the mineral assemblage of the tephra, Mount Rittmann was identified as the source of the AVT. A Holocene age of ∼11 ka was determined by radiocarbon dating organic material within the sediments and 40Ar-39Ar dating of alkali-feldspar crystals included in the tephra. Eruption dynamics were initially dominated by hydromagmatic magma fragmentation conditions producing a sustained, relatively wet and ash-rich eruptive cloud. The eruption then evolved into a highly energetic, relatively dry magmatic Plinian eruption. The last phase was characterized by renewed efficient magma-water interaction and/or collapse of the eruptive column producing pyroclastic density currents and associated co-ignimbritic plumes. The distal tephra deposits might be linked to the widespread lag breccia layer previously identified on the rim of the Mount Rittmann caldera which share the same geochemical composition. Diatoms found in the sediments surrounding the AVT and the primary characteristics of the tephra indicate that the Wood Bay area was open sea at the time of the eruption, which is much earlier than previously thought. AVT is also an excellent tephrostratigraphic marker for the Wood Bay area, in the Ross Sea, and a useful marker for future synchronization of continental ice and marine archives in the region
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