1,053 research outputs found
Super-resolution electron ptychography of low dimensional materials at 30 keV: beyond the detector limit
Get PDFWe demonstrate that electron ptychographic phase reconstruction can recover spatial frequencies higher than those directly recorded in the experimental electron diffraction patterns. This ability to recover high angle information from the oversampled low angle information allows an annular detector to be inserted which partially shadows a lower pixelated detector to simultaneously record a conventional annular dark field image and a ptychographic dataset. We apply this approach to 30 keV imaging of monolayer molybdenum disulfide and achieve an Abbe limited resolution of 1.2 ± 0.1Å in our reconstructions
Recommended from our members
Structural basis for 2 '-deoxyguanosine recognition by the 2 '-dG-II class of riboswitches
Get PDFA recent bioinformatic analysis of well-characterized classes of riboswitches uncovered subgroups unable to bind to the regulatory molecule of the parental class. Within the guanine/adenine class, seven groups of RNAs were identified that deviate from the consensus sequence at one or more of three positions directly involved purine nucleobase recognition, one of which was validated as a second class of 2′-deoxyguanosine riboswitch (called 2′-dG-II). To understand how 2′-dG-II riboswitches recognize their cognate ligand and how they differ from a previously identified class of 2′-deoxyguanosine binding riboswitches, we have solved the crystal structure of a 2′-dG-II aptamer domain bound to 2′-deoxyguanosine. This structure reveals a global architecture similar to other members of the purine riboswitch family, but contains key differences within the ligand binding core. Defining the 2′-dG-II riboswitches is a two-nucleotide insertion in the three-way junction that promotes novel base-base interactions. Unlike 2′-dG-I riboswitches, the 2′-dG-II class only requires local changes to the ligand binding pocket of the guanine/adenine class to achieve a change in ligand preference. Notably, members of the 2′-dG-II family have variable ability to discriminate between 2′-deoxyguanosine and riboguanosine, suggesting that a subset of 2′-dG-II riboswitches may bind either molecule to regulate gene expression.</p
Solar Absorption in Cloudy Atmospheres
Get PDFThe theoretical computations used to compute spectral absorption of solar radiation are discussed. Radiative properties relevant to the cloud absorption problem are presented and placed in the context of radiative forcing. Implications for future measuring programs and the effect of horizontal inhomogeneities are discussed
Biliary sludge and recurrent ketoacidosis: a case report
Get PDFA five year old boy, weighing 14 kg with no family history of diabetes, presented in frank diabetic ketoacidosis. He recovered, but continued to have episodes of ketoacidosis. He was diagnosed to have biliary sludge, which recovered with insulin treatment
Mobility and connection among the Early Bronze Age Syrian elite
Get PDFThe archaeological site of Umm el-Marra (in the Jabbul plain, western Syria), is a large, fortified urban center. Excavations have uncovered ten tomb structures built during the Early Bronze Age (ca. 2600–2150 BCE) that possibly contain royalty as evidenced by lavish grave goods and paleopathological evidence suggesting sociocultural buffering from the harsh social and physical environments of agricultural urban centers in the Bronze Age Near East. Inside adjacent brick installations are animal (primarily equid) skeletons interpreted as interments, possibly sacrifices in some instances, as part of ceremonies honoring the entombed. The burial site was eventually re-used as evidenced by a monumental platform above the tombs, interpreted as use for ritual activities of ancestor veneration. This study analyzed 87Sr/86Sr and δ18O values from enamel of 13 individuals interred in these tombs, along with enamel and bone samples from animals found in and around the tomb structures. Six of 13 (43 %) individuals analyzed in these tombs are identified as non-locals. Although contemporaneous data in the northern Levant is scarce, we see much higher evidence of human movement at Umm el-Marra compared to others. Only elites are included in this study, but their relative mobility might imply that the ancient city established its position as a secondary center along major trade routes through intermarriage and connectivity. The concept of ‘social memory’ is evident, as the lives and deaths of these elites are integrated into this site where ancestor veneration is evidenced in centuries following interment
Factors associated with severity of hepatic fibrosis in people with chronic hepatitis C infection
Get PDFThe document attached has been archived with permission from the editor of the Medical Journal of Australia. An external link to the publisher’s copy is included.OBJECTIVE: To determine factors associated with hepatic fibrosis development in people with chronic hepatitis C virus (HCV) infection. METHODS: As a requirement for access to interferon therapy through the S100 scheme in Australia, individual pretreatment demographic and clinical information was collected on 2986 patients from 61 hospital-based liver clinics from 1 October 1994 through 31 December 1996. Patients with both a hepatic fibrosis score and an estimated duration of HCV infection (910) were divided into 540 with no or minimal hepatic fibrosis (stage 0–1) and 370 with moderate to severe hepatic fibrosis (stage 2–3). Seven factors were examined: age at HCV infection, sex, ethnicity, source of infection, duration of infection, alcohol intake, and mean ALT level. A further analysis was performed for all 1135 patients with a hepatic fibrosis score disregarding age at and duration of HCV infection. RESULTS: In multivariate analysis, four factors were significantly associated with moderate to severe hepatic fibrosis: age at infection (OR, 2.33 for age 31–40 years, 5.27 for age > 40 years, and 0.20 for age 30 years, compared with 3 times, compared with 1.5–2 times the upper limit of normal). In the analysis disregarding age at HCV infection and duration of HCV infection, older age was strongly associated with moderate to severe hepatic fibrosis (OR, 2.32 for age 36–40 years, 2.46 for age 41–50 years, 7.87 for age 51–60 years, and 7.15 for age > 60 years, compared with 16–30 years). There was no association in either analysis with sex or source of HCV infection. CONCLUSION: These factors may assist in targeting patients for both liver biopsy-based investigation and therapeutic intervention.Mark Danta, Gregory J Dore, Lisa Hennessy, Yueming Li, Chris R Vickers, Hugh Harley, Meng Ngu, William Reed, Paul V Desmond, William Sievert, Geoff C Farrell, John M Kaldor and Robert G Bate
Operando and High-throughput multicscale-tomography
Get PDFWe report about multiscale tomography with high throughput at the Diamond beamline I13L. The beamline has the purpose of multi-scale and operando imaging and consists of two independent branchlines operating in real and reciprocal space. The imaging branch -called Diamond-Manchester branchline- hosts micro-tomography, grating interferometry and a full-field microscope. For rapid recording a broad spectrum of the undulator radiation is used either with band-passing the light with a combination of a filter and a deflecting mirror or using a multilayer monochromator. For all the methods similar recording times can be achieved, with typical scanning times of some minutes and covering the resolution range from microns to the 100nm range. Most recently a robot arm has been installed to increase the throughput to 300 samples per day. The system is now implemented for user operation in remote operation mode for the micro-tomography setup and can be expanded to the two other experiments. The instrumental capabilities are applied on various topics such as the study of biodiversity of insects or the structural variations of electrode materials in batteries. Fast recording with dedicated sample environments (not using the sample changing robot) enables operando studies in many areas, the charging/discharging cycles on batteries, the degradation of teeth enamel under various conditions or loading brine sandstone mixtures with CO2, to name some examples. For imaging with highest spatial resolution we managed to improve significantly the recording speed of ptycho-tomography, which is now in the order of hours and will be reduced further. We demonstrated in the past 2-D recording with 10kHz and expand the instrumental capability with specific hardware dependent triggering and scanning schemes. We expand the research program for multi-scale imaging across both branchlines (imaging and coherence branchlines) with first studies such as batteries, brain research, concrete
- …
