We explore the properties of elastic and inelastic scattering in a thick organic specimen, together with the mechanisms that provide contrast in a transmission electron microscope (TEM) and ...scanning-transmission electron microscope (STEM). Experimental data recorded from amorphous carbon are used to predict the bright-field image intensity, mass-thickness contrast and dose-limited resolution as a function of thickness, objective-aperture size, and primary-electron energy E0. Combining this information with estimates of chromatic aberration, objective-aperture diffraction and beam broadening in the specimen, we calculate the achievable TEM and STEM resolution to be around 4 nm at E0 = 300 keV (or below 3 nm at MeV energies) for a 10 µm-diameter objective aperture and 1 – 2 µm thickness of hydrated biological tissue. The 3 MeV resolution for a 10-μm tissue sample is probably closer to 10 nm. We also comment on the error involved in quadrature addition of resolution factors, when one or more of the point-spread functions are non-Gaussian.
•Electron scattering in a thick TEM specimen is reviewed, including the effect of a collection aperture.•Experimental data are used to predict image intensity, contrast and dose-limited resolution.•Including instrumental effects, bright-field resolution is estimated for accelerating voltages a up to 3 MV.•Linear and quadratic addition of resolution components are discussed and compared.
Substrate expansion/shrinkage makes it difficult to measure accurately the thermal expansion coefficient (TEC) of thin films. Furthermore, even very thin contamination layers can affect TEC ...measurements. We excluded the effects of contamination, quantified the effect of substrate, and succeeded in measuring the TEC of suspended single-layer graphene (SLG) at temperatures ranging from room temperature to 900 °C. The SLG was supported by Quantifoil, an amorphous-carbon film with prefabricated holes. The TEC was measured at both the suspended and supported areas of the SLG using electron diffraction in a transmission electron microscope. It was found that the TEC of suspended SLG is positive, and the values are related to a lattice spacing of SLG, which may indicate a tensile/compressive stress of the suspended SLG. The TEC values of suspended SLG ranged from 1.2×10−6 to 2.4×10−5 K−1, and were inversely proportional to the measured values of SLG lattice spacing, which ranged from 0.2088 to 0.2110 nm at 400 °C. The TEC values of the supported area were smaller than those of the suspended area, indicating that the support film suppressed SLG expansion. This report also shows how the support film and contamination affect graphene TEC using three different samples, including double-layer graphene.
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ABSTRACT We report the first hard X-ray observations with NuSTAR of the BL Lac-type blazar PKS 2155-304, augmented with soft X-ray data from XMM-Newton and γ-ray data from the Fermi Large Area ...Telescope, obtained in 2013 April when the source was in a very low flux state. A joint NuSTAR and XMM spectrum, covering the energy range 0.5-60 keV, is best described by a model consisting of a log-parabola component with curvature and a (local) photon index 3.04 0.15 at photon energy of 2 keV, and a hard power-law tail with photon index 2.2 0.4. The hard X-ray tail can be smoothly joined to the quasi-simultaneous γ-ray spectrum by a synchrotron self-Compton component produced by an electron distribution with index p = 2.2. Assuming that the power-law electron distribution extends down to γmin = 1 and that there is one proton per electron, an unrealistically high total jet power of Lp ∼ 1047 erg s−1 is inferred. This can be reduced by two orders of magnitude either by considering a significant presence of electron-positron pairs with lepton-to-proton ratio , or by introducing an additional, low-energy break in the electron energy distribution at the electron Lorentz factor γbr1 ∼ 100. In either case, the jet composition is expected to be strongly matter-dominated.
ABSTRACT We report the results of a multiband observing campaign on the famous blazar 3C 279 conducted during a phase of increased activity from 2013 December to 2014 April, including first ...observations of it with NuSTAR. The γ-ray emission of the source measured by Fermi-LAT showed multiple distinct flares reaching the highest flux level measured in this object since the beginning of the Fermi mission, with of 10−5 photons cm−2 s−1, and with a flux-doubling time scale as short as 2 hr. The γ-ray spectrum during one of the flares was very hard, with an index of , which is rarely seen in flat-spectrum radio quasars. The lack of concurrent optical variability implies a very high Compton dominance parameter . Two 1 day NuSTAR observations with accompanying Swift pointings were separated by 2 weeks, probing different levels of source activity. While the 0.5−70 keV X-ray spectrum obtained during the first pointing, and fitted jointly with Swift-XRT is well-described by a simple power law, the second joint observation showed an unusual spectral structure: the spectrum softens by at ∼4 keV. Modeling the broadband spectral energy distribution during this flare with the standard synchrotron plus inverse-Compton model requires: (1) the location of the γ-ray emitting region is comparable with the broad-line region radius, (2) a very hard electron energy distribution index , (3) total jet power significantly exceeding the accretion-disk luminosity , and (4) extremely low jet magnetization with . We also find that single-zone models that match the observed γ-ray and optical spectra cannot satisfactorily explain the production of X-ray emission.
Archaeological studies of alcohol have tended to focus on consumption while production, particularly of beer, has been more difficult to recognize and interpret. The ethnoarchaeological study of ...modern maize beer or
chicha production on Peru’s north coast provides information on (1) production steps and their material correlates, (2) labor and raw material inputs at different scales and possible labor bottlenecks, and (3) variation in technology and organization that is linked to contexts of consumption and cultural differences through time across the Andes. Because of this variation, the ethnoarchaeological observations reported here should not be directly projected onto the past, but rather should serve as points of comparison with the archaeological record.
We present time-resolved broadband observations of the quasar 3C 279 obtained from multi-wavelength campaigns conducted during the first two years of the Fermi Gamma-ray Space Telescope mission. ...While investigating the previously reported gamma -ray/optical flare accompanied by a change in optical polarization, we found that the optical emission appears to be delayed with respect to the gamma -ray emission by about 10 days. X-ray observations reveal a pair of "isolated" flares separated by ~90 days, with only weak gamma -ray/optical counterparts. The spectral structure measured by Spitzer reveals a synchrotron component peaking in the mid-infrared band with a sharp break at the far-infrared band during the gamma -ray flare, while the peak appears in the millimeter (mm)/submillimeter (sub-mm) band in the low state. Selected spectral energy distributions are fitted with leptonic models including Comptonization of external radiation produced in a dusty torus or the broad-line region. Adopting the interpretation of the polarization swing involving propagation of the emitting region along a curved trajectory, we can explain the evolution of the broadband spectra during the gamma -ray flaring event by a shift of its location from ~1 pc to ~4 pc from the central black hole. On the other hand, if the gamma -ray flare is generated instead at sub-pc distance from the central black hole, the far-infrared break can be explained by synchrotron self-absorption. We also model the low spectral state, dominated by the mm/sub-mm peaking synchrotron component, and suggest that the corresponding inverse-Compton component explains the steady X-ray emission.
Opioids, such as morphine and fentanyl, are widely used as effective analgesics for the treatment of acute and chronic pain. In addition, the opioid system has a key role in the rewarding effects of ...morphine, ethanol, cocaine and various other drugs. Although opioid sensitivity is well known to vary widely among individual subjects, several candidate genetic polymorphisms reported so far are not sufficient for fully understanding the wide range of interindividual differences in human opioid sensitivity. By conducting a multistage genome-wide association study (GWAS) in healthy subjects, we found that genetic polymorphisms within a linkage disequilibrium block that spans 2q33.3-2q34 were strongly associated with the requirements for postoperative opioid analgesics after painful cosmetic surgery. The C allele of the best candidate single-nucleotide polymorphism (SNP), rs2952768, was associated with more analgesic requirements, and consistent results were obtained in patients who underwent abdominal surgery. In addition, carriers of the C allele in this SNP exhibited less vulnerability to severe drug dependence in patients with methamphetamine dependence, alcohol dependence, and eating disorders and a lower 'Reward Dependence' score on a personality questionnaire in healthy subjects. Furthermore, the C/C genotype of this SNP was significantly associated with the elevated expression of a neighboring gene, CREB1. These results show that SNPs in this locus are the most potent genetic factors associated with human opioid sensitivity known to date, affecting both the efficacy of opioid analgesics and liability to severe substance dependence. Our findings provide valuable information for the personalized treatment of pain and drug dependence.
•Omega-3 polyunsaturated fatty acids and psychoeducation may improve depression.•Severity of depression was lower in placebo and treated group compared to baseline.•Omega-3 polyunsaturated fatty ...acids and psychoeducation improved symptoms.•Psychoeducation alone also ameliorated symptoms.
This study assessed whether a combined intervention of omega-3 polyunsaturated fatty acids (PUFAs) and psychoeducation better improved mild to moderate depression in workers compared to psychoeducation alone.
This study was a double-blinded, parallel group, randomized controlled trial that compared the intervention group, receiving omega-3 fatty acids, with a control group, receiving a placebo supplement. Participants receiving omega-3 fatty acids took 15 × 300 mg capsules per day for 12 weeks. The total daily dose of omega-3 PUFAs was 500 mg docosahexaenoic acid and 1000 mg eicosapentaenoic acid (EPA). The Beck Depression Inventory®-II (BDI-II) was used to assess the severity of depression after treatment.
After 12 weeks of treatment, BDI-II scores were significantly lower in the placebo and omega-3 group, when compared to their respective baseline scores (Placebo: t = − 4.6, p < 0.01; Omega-3: t = − 7.3, p < 0.01). However, after 12 weeks of treatment, we found no significant difference between both groups with respect to changes in the BDI-II scores (0.7; 95% CI, − 0.7 to 2.1; p = 0.30).
This study did not measure blood omega-3 fatty acid concentration and presented a high-dropout rate. Moreover, our results may not be generalizable to other regions.
The results show that a combination of omega-3 fatty acids and psychoeducation and psychoeducation alone can contribute to an improvement in symptoms in people with mild to moderate depression. However, there is no difference between the interventions in ameliorating symptoms of depression.
ABSTRACT Powerful blazars are flat-spectrum radio quasars whose emission is dominated by a Compton component peaking between a few hundred keV and a few hundred MeV. We observed two bright blazars, ...PKS 2149-306 at redshift z = 2.345 and S5 0836+710 at z = 2.172, in the hard X-ray band with the Nuclear Spectroscopic Telescope Array satellite. Simultaneous soft-X-rays and UV-optical observations were performed with the Swift satellite, while near-infrared (near-IR) data were obtained with the Rapid Eye Mount telescope. To study their variability, we repeated these observations for both sources on a timescale of a few months. While no fast variability was detected during a single observation, both sources were variable in the X-ray band, up to 50%, between the two observations, with larger variability at higher energies. No variability was detected in the optical/NIR band. These data, together with Fermi-Large Area Telescope, Wide-field Infrared Survey Explorer, and other literature data, are then used to study the overall spectral energy distributions (SEDs) of these blazars. Although the jet nonthermal emission dominates the SED, it leaves the UV band unhidden, allowing us to detect the thermal emission of the disk and to estimate the black hole mass. The nonthermal emission is well reproduced by a one-zone leptonic model by the synchrotron, self-Compton, and external Compton processes. Our data are better reproduced if we assume that the location of the dissipation region of the jet, Rdiss, is in between the torus and the broad-line region. The observed variability is explained by changing a minimum number of model parameters by a very small amount.
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