The purpose of this study was to determine the factors that influence physician preference for type of hysterotomy incisions in gravidas with a singleton or twin pregnancy undergoing cesarean section ...under 28 weeks, and to assess factors that result in delivery complications, defined as either intraoperative dystocia or hysterotomy extension. We hypothesized that compared to those with non-cephalic presentations, gravidas with a presenting fetus in cephalic presentation would have higher rates of low-transverse cesarean section, and reduced rates of delivery complications with low-transverse hysterotomy.OBJECTIVEThe purpose of this study was to determine the factors that influence physician preference for type of hysterotomy incisions in gravidas with a singleton or twin pregnancy undergoing cesarean section under 28 weeks, and to assess factors that result in delivery complications, defined as either intraoperative dystocia or hysterotomy extension. We hypothesized that compared to those with non-cephalic presentations, gravidas with a presenting fetus in cephalic presentation would have higher rates of low-transverse cesarean section, and reduced rates of delivery complications with low-transverse hysterotomy.This was a retrospective cohort chart analysis of 128 gravidas between 23 0/7 and 27 6/7 weeks undergoing cesarean section at a single academic institution between August 2010 and December 2022. Data was abstracted for factors that might influence the decision for hysterotomy incision type, as well as for documentation of difficulty with delivery of the fetus or need for hysterotomy extension to affect delivery.METHODSThis was a retrospective cohort chart analysis of 128 gravidas between 23 0/7 and 27 6/7 weeks undergoing cesarean section at a single academic institution between August 2010 and December 2022. Data was abstracted for factors that might influence the decision for hysterotomy incision type, as well as for documentation of difficulty with delivery of the fetus or need for hysterotomy extension to affect delivery.There was a total of 128 subjects, 113 with a singleton gestation and 15 with twins. The presenting fetus was in cephalic presentation in 43 (33.6%), breech presentation in 71 (55.5%), transverse/oblique lie in 13 (10.2%), and not documented in 1 (0.8%). Sixty-eight (53.1%) had a low-transverse cesarean section (LTCS), 53 (41.4%) had a Classical, 5 (3.9%) had a low-vertical hysterotomy and 2 (1.6%) had a mid-transverse incision. There was a significantly higher rate of LTCS among gravidas with the presenting fetus in cephalic presentation (30/43, 69.8%) compared to those with breech (31/71, 43.7%) or transverse/oblique presentations (7/13, 53.8%), p = .03. No other significant associations were related to hysterotomy incision, including nulliparity, racially or ethnically minoritized status, plurality, indication for cesarean delivery, or pre-cesarean labor. Twenty (15.6%) subjects experienced either an intraoperative dystocia or hysterotomy extension. For the entire cohort, there was a greater median cervical dilatation in those with delivery complications (4.0 cm, IQR .5 - 10 cm) compared to those without complications (1.5, IQR 0 - 4.0), p = .03, but no significant association between delivery complications and fetal presentation, hysterotomy type, plurality, or other demographic/obstetrical factors. However, among gravidas undergoing low-transverse cesarean section, only 2/30 (6.7%) with cephalic presentations had a delivery complication, compared to 9/31 (29.0%) with breech presentations and 3/7 (42.9%) with a transverse/oblique lie, p = .03.RESULTSThere was a total of 128 subjects, 113 with a singleton gestation and 15 with twins. The presenting fetus was in cephalic presentation in 43 (33.6%), breech presentation in 71 (55.5%), transverse/oblique lie in 13 (10.2%), and not documented in 1 (0.8%). Sixty-eight (53.1%) had a low-transverse cesarean section (LTCS), 53 (41.4%) had a Classical, 5 (3.9%) had a low-vertical hysterotomy and 2 (1.6%) had a mid-transverse incision. There was a significantly higher rate of LTCS among gravidas with the presenting fetus in cephalic presentation (30/43, 69.8%) compared to those with breech (31/71, 43.7%) or transverse/oblique presentations (7/13, 53.8%), p = .03. No other significant associations were related to hysterotomy incision, including nulliparity, racially or ethnically minoritized status, plurality, indication for cesarean delivery, or pre-cesarean labor. Twenty (15.6%) subjects experienced either an intraoperative dystocia or hysterotomy extension. For the entire cohort, there was a greater median cervical dilatation in those with delivery complications (4.0 cm, IQR .5 - 10 cm) compared to those without complications (1.5, IQR 0 - 4.0), p = .03, but no significant association between delivery complications and fetal presentation, hysterotomy type, plurality, or other demographic/obstetrical factors. However, among gravidas undergoing low-transverse cesarean section, only 2/30 (6.7%) with cephalic presentations had a delivery complication, compared to 9/31 (29.0%) with breech presentations and 3/7 (42.9%) with a transverse/oblique lie, p = .03.In pregnancies under 28 weeks, the performance of a low-transverse cesarean section was significantly associated only with presentation of the presenting fetus. Among those with cephalic presentations, the rate of intrapartum dystocia or hysterotomy extension was low after a low-transverse hysterotomy, suggesting that in this subgroup, a low-transverse cesarean section should be considered.CONCLUSIONIn pregnancies under 28 weeks, the performance of a low-transverse cesarean section was significantly associated only with presentation of the presenting fetus. Among those with cephalic presentations, the rate of intrapartum dystocia or hysterotomy extension was low after a low-transverse hysterotomy, suggesting that in this subgroup, a low-transverse cesarean section should be considered.
Precursors and particles captured in a net: Porous coordination polymers such as MOF‐5 are efficient gas storage devices and are also able to absorb metal organic chemical vapor deposition (MOCVD) ...precursors (see picture, red: (η5‐C5H5)Pd(η3‐C3H5)). These incorporated compounds are easily reduced to give the corresponding metal nanoparticles. Applications in heterogeneous catalysis, for instance, methanol synthesis or hydrogenation, are described.
Addition of small amounts of promoters to solid catalysts can cause pronounced improvement in the catalytic properties. For the complex catalysts employed in industrial processes, the fate and mode ...of operation of promoters is often not well understood, which hinders a more rational optimization of these important materials. Herein we show for the example of the industrial Cu/ZnO/Al2O3 catalyst for methanol synthesis how structure–performance relationships can deliver such insights and shed light on the role of the Al promoter in this system. We were able to discriminate a structural effect and an electronic promoting effect, identify the relevant Al species as a dopant in ZnO, and determine the optimal Al content of improved Cu/ZnO:Al catalysts. By analogy to Ga- and Cr-promoted samples, we conclude that there is a general effect of promoter-induced defects in ZnO on the metal–support interactions and propose the relevance of this promotion mechanism for other metal/oxide catalysts also.
One of the main stumbling blocks in developing rational design strategies for heterogeneous catalysis is that the complexity of the catalysts impairs efforts to characterize their active sites. We ...show how to identify the crucial atomic structure motif for the industrial Cu/ZnO/Al(2)O(3) methanol synthesis catalyst by using a combination of experimental evidence from bulk, surface-sensitive, and imaging methods collected on real high-performance catalytic systems in combination with density functional theory calculations. The active site consists of Cu steps decorated with Zn atoms, all stabilized by a series of well-defined bulk defects and surface species that need to be present jointly for the system to work.
OBJECTIVE:To report and compare the clinical and radiographic outcomes of patients treated with reverse shoulder arthroplasty (RSA) or hemiarthroplasty for acute complex proximal humeral fractures.
...DATA SOURCES:A systematic review of PubMed, Cumulative Index to Nursing and Allied Health Literature, SportDiscus, and Cochrane Central Register of Controlled Trials was conducted. All published English language studies before January 2014 were reviewed for possible inclusion. Search terms included the followingproximal humerus, fracture, arthroplasty, hemiarthroplasty, RSA, and reverse total shoulder arthroplasty.
STUDY SELECTION:Studies reporting outcomes in human subjects after either RSA or hemiarthroplasty for acute proximal humeral fractures were assessed for inclusion. Additional inclusion criteria included a minimum clinical follow-up of 1 year. Level V evidence, basic science/cadaveric studies, and those studies reporting outcomes after revision arthroplasty were excluded.
DATA EXTRACTION:Patient demographics, clinical/radiographic outcomes, and complications were recorded. Posttreatment weighted means were calculated and reported. Homogenous outcome measures were analyzed, and a direct comparison of outcomes between treatment groups was performed.
CONCLUSIONS:Patients treated with RSA possess improved forward flexion (RSA118 degrees, Hemi108 degrees) but decreased external rotation (RSA20 degrees, Hemi30 degrees) compared with patients undergoing hemiarthroplasty after acute proximal humeral fracture. No significant clinical difference in either American Shoulder and Elbow Surgeons Shoulder Score (RSA64.7, Hemi63.0) or Constant score (RSA54.6, Hemi58.0) was identified. RSA was associated with an increased rate of clinical complications (9.6%) and a lower revision rate (0.93%) at short-term to midterm follow-up compared with hemiarthroplasty. RSA offers an acceptable surgical option for patients after complex acute proximal humeral fractures.
LEVEL OF EVIDENCE:Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.
Movement patterns during songbird migration remain poorly understood despite their expected fitness consequences in terms of survival, energetic condition and timing of migration that will carry over ...to subsequent phases of the annual cycle. We took an experimental approach to test hypotheses regarding the influence of habitat, energetic condition, time of season and sex on the hour-by-hour, local movement decisions of a songbird during spring stopover. To simulate arrival of nocturnal migrants at unfamiliar stopover sites, we translocated and continuously tracked migratory red-eyed vireos (Vireo olivaceus) throughout spring stopover with and without energetic reserves that were released in two replicates of three forested habitat types. Migrants moved the most upon release, during which time they selected habitat characterized by greater food abundance and higher foraging attack rates. Presumably under pressure to replenish fuel stores necessary to continue migration in a timely fashion, migrants released in poorer energetic condition moved faster and further than migrants in better condition and the same pattern was true for migrants released late in spring relative to those released earlier. However, a migrant's energetic condition had less influence on their behavior when they were in poor quality habitat. Movement did not differ between sexes. Our study illustrates the importance of quickly finding suitable habitat at each stopover site, especially for energetically constrained migrants later in the season. If an initial period prior to foraging were necessary at each stop along a migrant's journey, non-foraging periods would cumulatively result in a significant energetic and time cost to migration. However, we suggest behavior during stopover is not solely a function of underlying resource distributions but is a complex response to a combination of endogenous and exogenous factors.
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