Aim
After extended left colectomy, traditional colorectal anastomosis is often not feasible because of insufficient length of the remaining colon to perform a tension‐free anastomosis. Total ...colectomy with ileorectal anastomosis could be an alternative but this can lead to unsatisfactory quality of life. Trans‐mesenteric colorectal anastomosis or inverted right colonic transposition (the so‐called Deloyers procedure) are two possible solutions for creating a tension‐free colorectal anastomosis after extended left colectomy. Few studies have reported their results of these two techniques and mostly via laparotomy. The aim of this study was to describe the trans‐mesenteric colorectal anastomosis and the inverted right colonic transposition procedure via a laparoscopic approach and report the outcome in a series of 13 consecutive patients.
Method
This was retrospective chart review of laparoscopic colorectal surgery with trans‐mesenteric colorectal anastomosis or the inverted right colonic transposition procedure from January 2015 up to 2019. An accompanying video demonstrates these two techniques.
Results
Thirteen consecutive patients underwent either a laparoscopic trans‐mesenteric colorectal anastomosis (n = 9) or an inverted right colonic transposition procedure (n = 4). One patient had intra‐operative presacral bleeding that was stopped successfully without conversion. Two patients had a postoperative intra‐abdominal abscess, but no anastomotic complications were recorded. The median number of bowel movements per day after 6 months was 2 (range 2–5).
Conclusions
Trans‐mesenteric colorectal anastomosis or the inverted right colonic transposition procedure is feasible laparoscopically. The now well‐established classical advantages of the laparoscopic approach are associated with good functional outcome after these procedures.
The Asteroid Terrestrial impact Last Alert System (ATLAS) system consists of two 0.5 m Schmidt telescopes with cameras covering 29 square degrees at plate scale of 1.86 arcsec per pixel. Working in ...tandem, the telescopes routinely survey the whole sky visible from Hawaii (above δ > − 50 ° ) every two nights, exposing four times per night, typically reaching o < 19 magnitude per exposure when the moon is illuminated and c < 19.5 magnitude per exposure in dark skies. Construction is underway of two further units to be sited in Chile and South Africa which will result in an all-sky daily cadence from 2021. Initially designed for detecting potentially hazardous near earth objects, the ATLAS data enable a range of astrophysical time domain science. To extract transients from the data stream requires a computing system to process the data, assimilate detections in time and space and associate them with known astrophysical sources. Here we describe the hardware and software infrastructure to produce a stream of clean, real, astrophysical transients in real time. This involves machine learning and boosted decision tree algorithms to identify extragalactic and Galactic transients. Typically we detect 10-15 supernova candidates per night which we immediately announce publicly. The ATLAS discoveries not only enable rapid follow-up of interesting sources but will provide complete statistical samples within the local volume of 100 Mpc. A simple comparison of the detected supernova rate within 100 Mpc, with no corrections for completeness, is already significantly higher (factor 1.5 to 2) than the current accepted rates.
Abstract
We present analysis of the light curves (LCs) of 77 hydrogen-poor superluminous supernovae (SLSNe I) discovered during the Zwicky Transient Facility Phase I operation. We find that the ...majority (67%) of the sample can be fit equally well by both magnetar and ejecta–circumstellar medium (CSM) interaction plus
56
Ni decay models. This implies that LCs alone cannot unambiguously constrain the physical power sources for an SLSN I. However, 23% of the sample show inverted V-shape, steep-declining LCs or features of long rise and fast post-peak decay, which are better described by the CSM+Ni model. The remaining 10% of the sample favors the magnetar model. Moreover, our analysis shows that the LC undulations are quite common, with a fraction of 18%–44% in our gold sample. Among those strongly undulating events, about 62% of them are found to be CSM-favored, implying that the undulations tend to occur in the CSM-favored events. Undulations show a wide range in energy and duration, with median values (and 1
σ
errors) being as
1.7
%
−
0.7
%
+
1.5
%
E
rad
,
total
and
28.8
−
9.1
+
14.4
days, respectively. Our analysis of the undulation timescales suggests that intrinsic temporal variations of the central engine can explain half of the undulating events, while CSM interaction (CSI) can account for the majority of the sample. Finally, all of the well-observed He-rich SLSNe Ib either have strongly undulating LCs or the LCs are much better fit by the CSM+Ni model. These observations imply that their progenitor stars have not had enough time to lose all of the He-envelopes before supernova explosions, and H-poor CSM are likely to present in these events.
As a promising energy converter, the requirement for miniaturization and high-accuracy of triboelectric nanogenerators always remains urgent. In this work, a micro triboelectric ultrasonic device was ...developed by integrating a triboelectric nanogenerator and micro-electro-mechanical systems technology. To date, it sets a world record for the smallest triboelectric device, with a 50 µm-sized diaphragm, and enables the working frequency to be brought to megahertz. This dramatically improves the miniaturization and chip integration of the triboelectric nanogenerator. With 63 kPa@1 MHz ultrasound input, the micro triboelectric ultrasonic device can generate the voltage signal of 16.8 mV and 12.7 mV through oil and sound-attenuation medium, respectively. It also achieved the signal-to-ratio of 20.54 dB and exhibited the practical potential for signal communication by modulating the incident ultrasound. Finally, detailed optimization approaches have also been proposed to further improve the output power of the micro triboelectric ultrasonic device.
We present the ATLAS discovery and initial analysis of the first 18 days of the unusual transient event, ATLAS18qqn/AT2018cow. It is characterized by a high peak luminosity (∼1.7 × 1044 erg s−1), ...rapidly evolving light curves (>5 mag rise to peak in ∼3.5 days), and hot blackbody spectra, peaking at ∼27,000 K that are relatively featureless and unchanging over the first two weeks. The bolometric light curve cannot be powered by radioactive decay under realistic assumptions. The detection of high-energy emission may suggest a central engine as the powering source. Using a magnetar model, we estimated an ejected mass of 0.1-0.4 M , which lies between that of low-energy core-collapse events and the kilonova, AT2017gfo. The spectra cooled rapidly from 27,000 to 15,000 K in just over two weeks but remained smooth and featureless. Broad and shallow emission lines appear after about 20 days, and we tentatively identify them as He i although they would be redshifted from their rest wavelengths. We rule out that there are any features in the spectra due to intermediate mass elements up to and including the Fe group. The presence of r-process elements cannot be ruled out. If these lines are due to He, then we suggest a low-mass star with residual He as a potential progenitor. Alternatively, models of magnetars formed in neutron star mergers, or accretion onto a central compact object, give plausible matches to the data.
In this Letter, we demonstrate highly efficient, polarization-insensitive planar lenses (metalenses) at red, green, and blue wavelengths (λ = 660, 532, and 405 nm). Metalenses with numerical ...apertures (NA) of 0.85 and 0.6 and corresponding efficiencies as high as 60% and 90% are achieved. These metalenses are less than 600 nm-thick and can focus incident light down to diffraction-limited spots as small as ∼0.64λ and provide high-resolution imaging. In addition, the focal spots are very symmetric with high Strehl ratios. The single step lithography and compatibility with large-scale fabrication processes make metalenses highly promising for widespread applications in imaging and spectroscopy.
ABSTRACT Nebular-phase observations and spectral models of Type Ic superluminous supernovae (SLSNe) are presented. LSQ14an and SN 2015bn both display late-time spectra similar to galaxy-subtracted ...spectra of SN 2007bi, and the class shows strong similarity with broad-lined SNe Ic such as SN 1998bw. Near-infrared observations of SN 2015bn show a strong Ca ii triplet, O i 9263, O i 1.13 m, and Mg i 1.50 m, but no distinct He, Si, or S emission. The high Ca ii NIR/Ca ii 7291, 7323 ratio of ∼2 indicates a high electron density of cm−3. Spectral models of oxygen-zone emission are investigated to put constraints on the emitting region. Models require M to produce enough O i 6300, 6364 luminosity, irrespective of the powering situation and the density. The high oxygen-zone mass, supported by high estimated magnesium masses, points to explosions of massive CO cores, requiring . Collisions of pair-instability pulsations do not provide enough mass to account for the emission. O ii and O iii lines emerge naturally in many models, which strengthens the identification of broad O ii 7320, 7330, O iii 4363, and O iii 4959, 5007 in some spectra. A small filling factor for the O/Mg zone is needed to produce enough luminosity in Mg i 4571, Mg i 1.504 m, and O i recombination lines, which shows that the ejecta is clumped. We review the constraints from the nebular spectral modeling in the context of the various scenarios proposed for SLSNe.
We perform an observationally based evaluation of the cloud ice water content (CIWC) and path (CIWP) of present‐day GCMs, notably 20th century CMIP5 simulations, and compare these results to CMIP3 ...and two recent reanalyses. We use three different CloudSat + CALIPSO ice water products and two methods to remove the contribution from the convective core ice mass and/or precipitating cloud hydrometeors with variable sizes and falling speeds so that a robust observational estimate can be obtained for model evaluations. The results show that for annual mean CIWP, there are factors of 2–10 in the differences between observations and models for a majority of the GCMs and for a number of regions. However, there are a number of CMIP5 models, including CNRM‐CM5, MRI, CCSM4 and CanESM2, as well as the UCLA CGCM, that perform well compared to our past evaluations. Systematic biases in CIWC vertical structure occur below the mid‐troposphere where the models overestimate CIWC, with this bias arising mostly from the extratropics. The tropics are marked by model differences in the level of maximum CIWC (∼250–550 hPa). Based on a number of metrics, the ensemble behavior of CMIP5 has improved considerably relative to CMIP3, although neither the CMIP5 ensemble mean nor any individual model performs particularly well, and there are still a number of models that exhibit very large biases despite the availability of relevant observations. The implications of these results on model representations of the Earth radiation balance are discussed, along with caveats and uncertainties associated with the observational estimates, model and observation representations of the precipitating and cloudy ice components, relevant physical processes and parameterizations.
Key Points
A robust evaluation of the cloud ice water content for GCMs
Implications of this study on model representations of the Earth radiation
Aims.
We investigate electron temperature (
T
e
) and gas-phase oxygen abundance (
Z
Te
) measurements for galaxies in the local Universe (
z
< 0.25). Our sample comprises spectra from a total of ...264 emission-line systems, ranging from individual H
II
regions to whole galaxies, including 23 composite H
II
regions from star-forming main sequence galaxies in the MaNGA survey.
Methods.
We utilise 130 of these systems with directly measurable
T
e
(O
II
) to calibrate a new metallicity-dependent
T
e
(O
III
)–
T
e
(O
II
) relation that provides a better representation of our varied dataset than existing relations from the literature. We also provide an alternative
T
e
(O
III
)–
T
e
(N
II
) calibration. This new
T
e
method is then used to obtain accurate
Z
Te
estimates and form the mass – metallicity relation (MZR) for a sample of 118 local galaxies.
Results.
We find that all the
T
e
(O
III
)–
T
e
(O
II
) relations considered here systematically under-estimate
Z
Te
for low-ionisation systems by up to 0.6 dex. We determine that this is due to such systems having an intrinsically higher O
+
abundance than O
++
abundance, rendering
Z
Te
estimates based only on O
III
lines inaccurate. We therefore provide an empirical correction based on strong emission lines to account for this bias when using our new
T
e
(O
III
)–
T
e
(O
III
) and
T
e
(O
III
)–
T
e
(N
II
) relations. This allows for accurate metallicities (1
σ
= 0.08 dex) to be derived for any low-redshift system with an O
III
λ
4363 detection, regardless of its physical size or ionisation state. The MZR formed from our dataset is in very good agreement with those formed from direct measurements of metal recombination lines and blue supergiant absorption lines, in contrast to most other
T
e
-based and strong-line-based MZRs. Our new
T
e
method therefore provides an accurate and precise way of obtaining
Z
Te
for a large and diverse range of star-forming systems in the local Universe.
In this Letter, we experimentally report an achromatic metalens (AML) operating over a continuous bandwidth in the visible. This is accomplished via dispersion engineering of dielectric phase ...shifters: titanium dioxide nanopillars tiled on a dielectric spacer layer above a metallic mirror. The AML works in reflection mode with a focal length independent of wavelength from λ = 490 to 550 nm. We also design a metalens with reverse chromatic dispersion, where the focal length increases as the wavelength increases, contrary to conventional diffractive lenses. The ability to engineer the chromatic dispersion of metalenses at will enables a wide variety of applications that were not previously possible. In particular, for the AML design, we envision applications such as imaging under LED illumination, fluorescence, and photoluminescence spectroscopy.
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