The Effect of Habitat Structure Boulder Spacing on Near-Bed Shear Stress and Turbulent Events in a Gravel Bed Channel
Authors: Golpira, Amir; Huang, Fengbin; Baki, Abul B. M.
This study experimentally investigated the effect of boulder spacing and boulder submergence ratio on the near-bed shear stress in a single array of boulders in a gravel bed open channel flume. An acoustic Doppler velocimeter (ADV) was used to measure the instantaneous three-dimensional velocity components. Four methods of estimating near-bed shear stress were compared. The results suggested a significant effect of boulder spacing and boulder submergence ratio on the near-bed shear stress estimations and their spatial distributions. It was found that at unsubmerged condition, the turbulent kinetic energy (TKE) and modified TKE methods can be used interchangeably to estimate the near-bed shear stress. At both submerged and unsubmerged conditions, the Reynolds method performed differently from the other point-methods. Moreover, a quadrant analysis was performed to examine the turbulent events and their contribution to the near-bed Reynolds shear stress with the effect of boulder spacing. Generally, the burst events (ejections and sweeps) were reduced in the presence of boulders. This study may improve the understanding of the effect of the boulder spacing and boulder submergence ratio on the near-bed shear stress estimations of stream restoration practices.
Epidemiology and Outcomes of Early-Onset and Late-Onset Adenovirus Infections in Kidney Transplant Recipients
OPEN FORUM INFECTIOUS DISEASES
Authors: Bruminhent, Jackrapong; Worawichawong, Suchin; Tongsook, Chutatip; Pasomsub, Ekawat; Boongird, Sarinya; Watcharananan, Siriorn P.
Objective. Adenovirus (ADV) infection after kidney transplantation (KT) causes significant morbidity. Patient characteristics and outcomes of ADV infection in KT recipients were investigated. Method. All adult KT recipients with ADV infection between January 2015 and June 2019 were included. ADV infection/disease was defined as detection of ADV DNA in clinical specimens/plus symptoms. Clinical and laboratory findings, treatments, and outcomes were assessed. Results. Adenovirus infection was diagnosed in 24 of 751 (3.2%) KT recipients. Twenty (83%) were male with a median age of 47 years (interquartile range [IQR], 36-58). Fifteen (63%) underwent deceased donor KT, and 13 (54%) received induction therapy. Twenty-one (88%) and 4 (17%) patients developed hemorrhagic cystitis and disseminated disease, respectively. There were equal distributions of early-onset (EOI) (<= 3 months) and late-onset (LOI) (>3 months) infections. Patients who were diagnosed with EOI had lower median absolute lymphocyte counts compared with those with LOI (735/mm(3) [IQR, 543-1123] vs 1122/mm(3) [IQR, 784-1344], P = .04). All achieved resolution after reduction of their immunosuppression regimen and 13 (54%) received cidofovir therapy. Eighteen (75%) developed allograft dysfunction, of which 67% were transient. One (4%) underwent nephrectomy for allograft failure and 1 (4%) died (non-ADV-related). Patients with EOI were more likely to receive cidofovir therapy (75% vs 33%, P = .04) and develop other opportunistic infections (75% vs 8%, P < .001). Conclusions. Adenovirus infection after KT typically involves a genitourinary system and transiently impairs an allograft function. Those who developed early infection tend to have more lymphopenia, coinfection, and receive antiviral therapy.