Particle tunneling through a polarizable insulator

The tunneling probability between two leads connected by a molecule, a chain, a film, or a bulk polarizable insulator is investigated within a model of an electron tunneling from lead A to a state higher in energy, describing the barrier, and from there to lead B. To describe the possibility of energy exchange with excitations of the molecule or the insulator we couple the intermediate state to a single oscillator or to a spectrum of these, respectively. In the single-oscillator case we find for weak coupling that the tunneling is weakly suppressed by a Debye-Waller-type factor. For stronger coupling the oscillator gets 'stiff' and we observe a suppression of tunneling since the effective barrier is increased. The probability for the electron to excite the oscillator increases with the coupling. In the case of a film, or a bulk barrier the behavior is qualitatively the same as in the single oscillator case. An insulating chain, as opposed to a film or a bulk connecting the two leads,shows an 'orthogonality catastrophe' similar to that of an electronic transition in a Fermi gas.Comment: 4 pages, 1 figur

Constraints on the average magnetic field strength of relic radio sources 0917+75 and 1401-33 from XMM-Newton observations

We observed two relic radio sources, 0917+75 and 1401-33, with the XMM-Newton X-ray observatory. We did not detect any X-ray emission, thermal or non-thermal, in excess of the local background level from either target. This imposes new upper limits on the X-ray flux due to inverse Compton scattering of photons from the cosmic microwave background by relativistic electrons in the relic sources, and new lower limits on the magnetic field strength from the relative strength of the radio and X-ray emission. The combination of radio and X-ray observations provides a measure of the magnetic field independent of equipartition or minimum energy assumptions. Due to increasing sensitivity of radio observations, the known population of cluster relics has been growing; however, studies of non-thermal X-ray emission from relics remain scarce. Our study adds to the small sample of relics studied in X-rays. In both relics, our field strength lower limits are slightly larger than estimates of the equipartition magnetic field.Comment: 11 pages, 5 figures. Accepted by MNRA

A pilot study examining garment severance damage caused by a trained sharp-weapon user

The pilot study summarized in this paper aimed to raise awareness of a gap that exists in the forensic textile science literature about damage caused to clothing by trained sharp-weapon users. A male trained in the Filipino martial arts discipline of Eskrima performed attack techniques on a physical model of a male torso covered with a 97% cotton/3% elastane knitted T-shirt, that is, a garment commonly worn by males. Fabric severance appearance created by three different, but commonly available, knives was evaluated. High-speed video was used to capture each attack. After each attack the resulting damage to the garment was assessed. This pilot study highlighted differences in severances associated with weapon selection, that is, not all knives resulted in similar patterns of textile damage. In addition, a mixture of stab and slash severances were observed. The findings demonstrated the possible misinterpretation of textile damage under these circumstances compared to damage patterns reported in the existing forensic textile science literature for more commonly occurring knife attacks (i.e. stabbings)

The embodiment of emotional feelings in the brain

Central to Walter Cannon's challenge to peripheral theories of emotion was that bodily arousal responses are too undifferentiated to account for the wealth of emotional feelings. Despite considerable evidence to the contrary, this remains widely accepted and for nearly a century has left the issue of whether visceral afferent signals are essential for emotional experience unresolved. Here we combine functional magnetic resonance imaging and multiorgan physiological recording to dissect experience of two distinct disgust forms and their relationship to peripheral and central physiological activity. We show that experience of core and body–boundary–violation disgust are dissociable in both peripheral autonomic and central neural responses and also that emotional experience specific to anterior insular activity encodes these different underlying patterns of peripheral physiological responses. These findings demonstrate that organ-specific physiological responses differentiate emotional feeling states and support the hypothesis that central representations of organism physiological homeostasis constitute a critical aspect of the neural basis of feelings

Visualization of diffusion limited antimicrobial peptide attack on supported lipid membranes

Understanding the mechanism of action of antimicrobial peptides (AMP) is fundamental to the development and design of peptide based antimicrobials. Utilizing fast-scan atomic force microscopy (AFM) we detail the attack of an AMP on both prototypical prokaryotic (DOPC:DOPG) and eukaryotic (DOPC:DOPE) model lipid membranes on the nanoscale and in real time. Previously shown to have a favourable therapeutic index, we study Smp43, an AMP with a helical-hinge-helical topology isolated from the venom of the North African scorpion Scorpio maurus palmatus. We observe the dynamic formation of highly branched defects being supported by 2D diffusion models and further experimental data from liposome leakage assays and quartz crystal microbalance-dissipation (QCM-D) analysis, we propose that Smp43 disrupts these membranes via a common mechanism, which we have termed ‘diffusion limited disruption’ that encompasses elements of both the carpet model and the expanding pore mechanism

Image analysis of palm oil crystallisation as observed by hot stage microscopy

An image processing algorithm previously used to analyse the crystallisation of a pure fat (tripalmitin) has been applied to the crystallisation of a multicomponent natural fat (palm oil). In contrast to tripalmitin, which produced circular crystals with a constant growth rate, palm oil produced speckled crystals caused by the inclusion of entrapped liquid, and growth rates gradually decreased with time. This can be explained by the depletion of crystallisable material in the liquid phase, whereas direct impingement of crystals (the basis of the Avrami equation) was less common. A theoretical analysis combining this depletion with assuming that the growth rate is proportional to the supersaturation of a crystallisable pseudo-component predicted a tanh function variation of radius with time. This was generally able to provide good fits to the growth curves. It was found that growth rate was a relatively mild function of temperature but also varied from crystal to crystal and even between different sides of the same crystal, which may be due to variations in composition within the liquid phase. Nucleation rates were confirmed to vary approximately exponentially with decreasing temperature, resulting in much greater numbers of crystals and a smaller final average crystal size at lower temperatures

Automated analysis of lymphocytic infiltration, tumor budding, and their spatial relationship improves prognostic accuracy in colorectal cancer

Funding: Medical Research Scotland, and Indica Labs, Inc. provided in-kind resource.Both immune profiling and tumor budding significantly correlate with colorectal cancer (CRC) patient outcome, but are traditionally reported independently. This study evaluated the association and interaction between lymphocytic infiltration and tumor budding, coregistered on a single slide, in order to determine a more precise prognostic algorithm for patients with stage II CRC. Multiplexed immunofluorescence and automated image analysis were used for the quantification of CD3+CD8+ T cells, and tumor buds (TBs), across whole slide images of three independent cohorts (training cohort: n = 114, validation cohort 1: n = 56, validation cohort 2: n = 62). Machine learning algorithms were used for feature selection and prognostic risk model development. High numbers of TBs (HR = 5.899, 95% CI, 1.875 - 18.55), low CD3+ 11 T cell density (HR = 9.964, 95% CI 3.156 - 31.46), and low mean number of CD3+CD8+ T cells within 50 μm of TBs (HR = 8.907, 95% CI 2.834 - 28.0) were associated with reduced disease-specific survival. A prognostic signature, derived from integrating TBs, lymphocyte infiltration, and their spatial relationship, reported a more significant cohort stratification (HR = 18.75, 95% CI 6.46–54.43), than TBs, Immunoscore, or pT stage. This was confirmed in two independent validation cohorts (HR = 12.27, 95% CI 3.524–42.73, HR = 15.61, 95% CI 4.692-51.91). The investigation of the spatial relationship between lymphocytes and TBs within the tumor microenvironment improves accuracy of prognosis of patients with stage II CRC through an automated image analysis and machine learning workflow.PostprintPeer reviewe

The Rich Mid-Infrared Environments of Two Highly-Obscured X-ray Binaries: Spitzer Observations of IGR J16318-4848 and GX 301-2

We present the results of Spitzer mid-infrared spectroscopic observations of two highly-obscured massive X-ray binaries: IGR J16318-4848 and GX301-2. Our observations reveal for the first time the extremely rich mid-infrared environments of this type of source, including multiple continuum emission components (a hot component with T > 700 K and a warm component with T ~ 180 K) with apparent silicate absorption features, numerous HI recombination lines, many forbidden ionic lines of low ionization potentials, and pure rotational H2 lines. This indicates that both sources have hot and warm circumstellar dust, ionized stellar winds, extended low-density ionized regions, and photo-dissociated regions. It appears difficult to attribute the total optical extinction of both sources to the hot and warm dust components, which suggests that there could be an otherwise observable colder dust component responsible for the most of the optical extinction and silicate absorption features. The observed mid-infrared spectra are similar to those from Luminous Blue Variables, indicating that the highly-obscured massive X-ray binaries may represent a previously unknown evolutionary phase of X-ray binaries with early-type optical companions. Our results highlight the importance and utility of mid-infrared spectroscopy to investigate highly-obscured X-ray binaries.Comment: To appear in ApJ Letter