15 research outputs found
Coherent methods in the X-ray sciences
X-ray sources are developing rapidly and their coherent output is growing
extremely rapidly. The increased coherent flux from modern X-ray sources is
being matched with an associated rapid development in experimental methods.
This article reviews the literature describing the ideas that utilise the
increased brilliance from modern X-ray sources. It explores how ideas in
coherent X-ray science are leading to developments in other areas, and vice
versa. The article describes measurements of coherence properties and uses this
discussion as a base from which to describe partially-coherent diffraction and
X-ray phase contrast imaging, with its applications in materials science,
engineering and medicine. Coherent diffraction imaging methods are reviewed
along with associated experiments in materials science. Proposals for
experiments to be performed with the new X-ray free-electron-lasers are briefly
discussed. The literature on X-ray photon correlation spectroscopy is described
and the features it has in common with other coherent X-ray methods are
identified. Many of the ideas used in the coherent X-ray literature have their
origins in the optical and electron communities and these connections are
explored. A review of the areas in which ideas from coherent X-ray methods are
contributing to methods for the neutron, electron and optical communities is
presented.Comment: A review articel accepted by Advances in Physics. 158 pages, 29
figures, 3 table
Whispering to the Deaf: Communication by a Frog without External Vocal Sac or Tympanum in Noisy Environments
Atelopus franciscus is a diurnal bufonid frog that lives in South-American tropical rain forests. As in many other frogs, males produce calls to defend their territories and attract females. However, this species is a so-called âearlessâ frog lacking an external tympanum and is thus anatomically deaf. Moreover, A. franciscus has no external vocal sac and lives in a sound constraining environment along river banks where it competes with other calling frogs. Despite these constraints, male A. franciscus reply acoustically to the calls of conspecifics in the field. To resolve this apparent paradox, we studied the vocal apparatus and middle-ear, analysed signal content of the calls, examined sound and signal content propagation in its natural habitat, and performed playback experiments. We show that A. franciscus males can produce only low intensity calls that propagate a short distance (<8 m) as a result of the lack of an external vocal sac. The species-specific coding of the signal is based on the pulse duration, providing a simple coding that is efficient as it allows discrimination from calls of sympatric frogs. Moreover, the signal is redundant and consequently adapted to noisy environments. As such a coding system can be efficient only at short-range, territory holders established themselves at short distances from each other. Finally, we show that the middle-ear of A. franciscus does not present any particular adaptations to compensate for the lack of an external tympanum, suggesting the existence of extra-tympanic pathways for sound propagation
Recommended from our members
Afatinib versus methotrexate in older patients with second-line recurrent and/or metastatic head and neck squamous cell carcinoma: subgroup analysis of the LUX-Head & Neck 1 trial.
BackgroundIn the phase III LUX-Head & Neck 1 (LHN1) trial, afatinib significantly improved progression-free survival (PFS) versus methotrexate in recurrent and/or metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) patients progressing on/after platinum-based therapy. This report evaluates afatinib efficacy and safety in prespecified subgroups of patients aged â„65 and <65 years.Patients and methodsPatients were randomized (2:1) to 40 mg/day oral afatinib or 40 mg/m(2)/week intravenous methotrexate. PFS was the primary end point; overall survival (OS) was the key secondary end point. Other end points included: objective response rate (ORR), patient-reported outcomes, tumor shrinkage, and safety. Disease control rate (DCR) was also assessed.ResultsOf 483 randomized patients, 27% (83 afatinib; 45 methotrexate) were aged â„65 years (older) and 73% (239 afatinib; 116 methotrexate) <65 years (younger) at study entry. Similar PFS benefit with afatinib versus methotrexate was observed in older {median 2.8 versus 2.3 months, hazard ratio (HR) = 0.68 [95% confidence interval (CI) 0.45-1.03], P = 0.061} and younger patients [2.6 versus 1.6 months, HR = 0.79 (0.62-1.01), P = 0.052]. In older and younger patients, the median OS with afatinib versus methotrexate was 7.3 versus 6.4 months [HR = 0.84 (0.54-1.31)] and 6.7 versus 6.2 months [HR = 0.98 (0.76-1.28)]. ORRs with afatinib versus methotrexate were 10.8% versus 6.7% and 10.0% versus 5.2%; DCRs were 53.0% versus 37.8% and 47.7% versus 38.8% in older and younger patients, respectively. In both subgroups, the most frequent treatment-related adverse events were rash/acne (73%-77%) and diarrhea (70%-80%) with afatinib, and stomatitis (43%) and fatigue (31%-34%) with methotrexate. Fewer treatment-related discontinuations were observed with afatinib (each subgroup 7% versus 16%). A trend toward improved time to deterioration of global health status, pain, and swallowing with afatinib was observed in both subgroups.ConclusionsAdvancing age (â„65 years) did not adversely affect clinical outcomes or safety with afatinib versus methotrexate in second-line R/M HNSCC patients.Clinical trial registrationNCT01345682 (ClinicalTrials.gov)