102 research outputs found
High-speed scanless entire bandwidth mid-infrared chemical imaging
Mid-infrared spectroscopy probes molecular vibrations to identify chemical
species and functional groups. Therefore, mid-infrared hyperspectral imaging is
one of the most powerful and promising candidates for chemical imaging using
optical methods. Yet high-speed and entire bandwidth mid-infrared hyperspectral
imaging has not been realized. Here we report a mid-infrared hyperspectral
chemical imaging technique that uses chirped pulse upconversion of sub-cycle
pulses at the image plane. This technique offers a lateral resolution of 15
m, and the field of view is adjustable between 800 m 600
m to 12 mm 9 mm. The hyperspectral imaging produces a 640
480 pixel image in 8 s, which covers a spectral range of 640-3015
cm, comprising 1069 wavelength points and offering a wavenumber
resolution of 2.6-3.7 cm. For discrete frequency mid-infrared imaging,
the measurement speed reaches a frame rate of 5 kHz, the repetition rate of the
laser. As a demonstration, we effectively identified and mapped different
components in a microfluidic device, plant cell, and mouse embryo section. The
great capacity and latent force of this technique in chemical imaging promise
to be applied to many fields such as chemical analysis, biology, and medicine.Comment: 22 pages, 10 figure
Magnetar Broadband X-ray Spectra Correlated with Magnetic Fields: Suzaku Archive of SGRs and AXPs Combined with NuSTAR, Swift, and RXTE
The 1–70 keV persistent spectra of 15 magnetars, observed with Suzaku from 2006 to 2013, were studied as a complete sample. Combined with early NuSTAR observations of four hard X-ray emitters, nine objects showed a hard power-law emission dominating at ≳ 10 keV with the 15–60 keV flux of ~1–11 x 10^(-11) erg s^(−1) cm^(−2). The hard X-ray luminosity L_h, relative to that of a soft-thermal surface radiation L_s, tends to become higher toward younger and strongly magnetized objects. Their hardness ratio, updated from a previous study and defined as ξ = L_h/L_s, is correlated with the measured spin-down rate P as ξ = 0.62 x (P/10^(-11)s s^(-1))^(0.72), corresponding to positive and negative correlations with the dipole field strength B_d (ξ ∝ B^(1.41)_d) and the characteristic age τ_c (ξ ∝ τ_c^(-0.68)), respectively. Among our sample, five transients were observed during X-ray outbursts, and the results are compared with their long-term 1–10 keV flux decays monitored with Swift/XRT and RXTE/PCA. Fading curves of three bright outbursts are approximated by an empirical formula used in the seismology, showing a ~10–40 day plateau phase. Transients show the maximum luminosities of L_s ~ 10^(35) erg s^(−1), which are comparable to those of persistently bright ones, and fade back to ≾10^(32) erg s^(−1). Spectral properties are discussed in the framework of the magnetar hypothesis
Photoemission Angular Distribution Beyond the Single Wavevector Description of Photoelectron Final States
We develop a novel simulation procedure for angle-resolved photoemission
spectroscopy (ARPES), where a photoelectron wave function is set to be an
outgoing plane wave in a vacuum associated with the emitted photoelectron wave
packet. ARPES measurements on the transition metal dichalcogenide
- are performed, and our simulations exhibit good
agreement with experiments. Analysis of our calculated final state wave
functions quantitatively visualizes that they include various waves due to the
boundary condition and the uneven crystal potential. These results show that a
more detailed investigation of the photoelectron final states is necessary to
fully explain the photon-energy- and light-polarization-dependent ARPES
spectra.Comment: 6+14 pages, 4+15 figure
PRRX1 promotes malignant properties in human osteosarcoma
Paired related homeobox 1 (PRRX1) is a marker of limb bud mesenchymal cells, and deficiency of p53 or Rb in Prrx1-positive cells induces osteosarcoma in several mouse models. However, the regulatory roles of PRRX1 in human osteosarcoma have not been defined. In this study, we performed PRRX1 immunostaining on 35 human osteosarcoma specimens to assess the correlation between PRRX1 level and overall survival. In patients with osteosarcoma, the expression level of PRRX1 positively correlated with poor prognosis or the ratio of lung metastasis. Additionally, we found PRRX1 expression on in 143B cells, a human osteosarcoma line with a high metastatic capacity. Downregulation of PRRX1 not only suppressed proliferation and invasion but also increased the sensitivity to cisplatin and doxorubicin. When 143B cells were subcutaneously transplanted into nude mice, PRRX1 knockdown decreased tumor sizes and rates of lung metastasis. Interestingly, forskolin, a chemical compound identified by Connectivity Map analysis using RNA expression signatures during PRRX1 knockdown, decreased tumor proliferation and cell migration to the same degree as PRRX1 knockdown. These results demonstrate that PRRX1 promotes tumor malignancy in human osteosarcoma
Broken Screw Rotational Symmetry in the Near-Surface Electronic Structure of -Stacked Crystals
We investigate the electronic structure of - and
by angle-resolved photoemission spectroscopy (ARPES) and
photoemission intensity calculations. Although in bulk form, these materials
are expected to exhibit band degeneracy in the plane due to screw
rotation and time-reversal symmetries, we observe gapped band dispersion near
the surface. We extract from first-principles calculations the near-surface
electronic structure probed by ARPES and find that the calculated photoemission
spectra from the near-surface region reproduce the gapped ARPES spectra. Our
results show that the near-surface electronic structure can be qualitatively
different from the bulk one due to partially broken nonsymmorphic symmetries.Comment: 6+11 pages, 4+13 figure
Support for UNRWA's survival
The United Nations Relief and Works Agency for Palestine Refugees in the Near East (UNRWA) provides life-saving humanitarian aid for 5·4 million Palestine refugees now entering their eighth decade of statelessness and conflict. About a third of Palestine refugees still live in 58 recognised camps. UNRWA operates 702 schools and 144 health centres, some of which are affected by the ongoing humanitarian disasters in Syria and the Gaza Strip. It has dramatically reduced the prevalence of infectious diseases, mortality, and illiteracy. Its social services include rebuilding infrastructure and homes that have been destroyed by conflict and providing cash assistance and micro-finance loans for Palestinians whose rights are curtailed and who are denied the right of return to their homeland
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