A model‐based investigation of the transport, distribution and deposition of mineral dust in the Southern Hemisphere (SH) is performed by using the GFDL Atmospheric Model (AM2). The study represents an attempt to quantify the contribution of the major sources by tagging dust based on its origin. We evaluate the contribution of each source to the emission, distribution, mass burden and deposition of dust in the Southern Ocean and Antarctica, and show that each source produces distinctive meridional transport, vertical distribution, and deposition patterns. The dust in SH originates primarily from Australia (120 Tg a−1), Patagonia (38 Tg a−1) and the inter‐hemispheric transport from Northern Hemisphere (31 Tg a−1). A small fraction of it (7 Tg a−1) is transported and deposited in the Southern Ocean and Antarctica, where dust from South America, Australia, and Northern Hemisphere are essentially located in the boundary layer, mid‐troposphere, and upper‐troposphere, respectively. These three sources contribute to nearly all the dust burden in the Southern Ocean and Antarctica. South America and Australia are the main sources of the dust deposition, but they differ zonally, with each one dominating half of a hemisphere along 120°E–60°W: the half comprising the Atlantic and Indian oceans in the case of the South American dust and the Pacific half in the case of the Australian dust. Our study also indicates a potentially important role of Northern Hemisphere dust, as it appears to be a significant part of the dust burden but contributing little to the dust deposition in Antarctica.

We present an analysis of version 5.1 of the Community Atmospheric Model (CAM5.1) at a high horizontal resolution. Intercomparison of this global model at approximately 0.25 , 1 , and 2 is presented for extreme daily precipitation as well as for a suite of seasonal mean fields. In general, extreme precipitation amounts are larger in high resolution than in lower-resolution configurations. In many but not all locations and/or seasons, extreme daily precipitation rates in the high-resolution configuration are higher and more realistic. The high-resolution configuration produces tropical cyclones up to category 5 on the SaffirSimpson scale and a comparison to observations reveals both realistic and unrealistic model behavior. In the absence of extensive model tuning at high resolution, simulation of many of the mean fields analyzed in this study is degraded compared to the tuned lower-resolution public released version of the model.

Colonic lipoma is an uncommon tumor of the gastrointestinal tract. Most cases are asymptomatic, with a small tumor size, and do not need any special treatment. However, we encountered one patient with a giant submucosal lipoma, with a maximum diameter of 8.5 cm, which exhibited symptoms such as intermittent lower abdominal pain, changes in bowel habits with passage of fresh blood and mucus per rectum, abdominal distension, anorexia and weight loss. Unfortunately, the possibility of colonic malignancy could not be precluded and left hemicolectomy was planned. The exact diagnosis of this special case was accomplished by intraoperative pathology. In the end, local resection was performed instead of left hemicolectomy. To the best of our knowledge, colonic lipoma exceeding 8 cm in diameter has not been previously reported. We, therefore, present this case and discuss age and sex factors, clinical and histopathological findings, diagnostic methods and treatment by reviewing the available literature, to serve as a reminder that colonic lipoma can also exist in patients with significant symptoms. In addition, intraoperative pathology should be investigated in those doubtful cases, so as to guide the exact diagnosis and treatment plan.

One key question regarding current climate models is whether the projection of climate extremes converges to a realistic representation as the spatial and temporal resolutions of the model are increased. Ideally the model extreme statistics should approach a fixed distribution once the resolutions are commensurate with the characteristic length and time scales of the processes governing the formation of the extreme phenomena of interest. In this study, a series of AGCM runs with idealized ‘aquaplanet‐steady‐state’ boundary conditions have been performed with the Community Atmosphere Model CAM3 to investigate the effect of horizontal resolution on climate extreme simulations. The use of the aquaplanet framework highlights the roles of model physics and dynamics and removes any apparent convergence in extreme statistics due to better resolution of surface boundary conditions and other external inputs. Assessed at a same large spatial scale, the results show that the horizontal resolution and time step have strong effects on the simulations of precipitation extremes. The horizontal resolution has a much stronger impact on precipitation extremes than on mean precipitation. Updrafts are strongly correlated with extreme precipitation at tropics at all the resolutions, while positive low‐tropospheric temperature anomalies are associated with extreme precipitation at mid‐latitudes.

DNA molecules are highly compacted in the eukaryotic nucleus where distal regulatory elements reach their targets through three-dimensional chromosomal interactions. G-quadruplexes, stable four-stranded non-canonical DNA structures, can change local chromatin organization through the exclusion of nucleosomes. However, the relationship between G-quadruplexes and higher-order genome organization remains unknown. Here, we found that G-quadruplexes are significantly enriched at boundaries of topological associated domains (TADs). Architectural protein occupancy, which plays critical roles in the formation of TADs, was highly correlated with the content of G-quadruplexes at TAD boundaries. Moreover, adjacent boundaries containing G-quadruplexes frequently interacted with each other because of the high enrichment of architectural protein binding sites. Similar to CCCTC-binding factor (CTCF) binding sites, G-quadruplexes also showed strong insulation ability in the separation of adjacent regions. Additionally, the insulation ability of CTCF binding sites and TAD boundaries was significantly reinforced by G-quadruplexes. Furthermore, G-quadruplex motifs on different strands were associated with the orientation of CTCF binding sites. These findings suggest a potential role for G-quadruplexes in loop extrusion. The enrichment of transcription factor binding sites (TFBSs) around regulatory elements containing G-quadruplexes led to frequent interactions between regulatory elements containing G-quadruplexes. Intriguingly, more than 99% of G-quadruplexes overlapped with TFBSs. The binding sites of CTCF and cohesin proteins were preferentially located surrounding G-quadruplexes. Accordingly, we proposed a new mechanism of long-distance gene regulation in which G-quadruplexes are involved in distal interactions between enhancers and promoters.