The pulsar wind model is updated by considering the effect of particle density and pulsar death. It can describe both the short-term and long-term rotational evolution of pulsars consistently. It is ...applied to model the rotational evolution of the Crab pulsar. The pulsar is spun down by a combination of magnetic dipole radiation and particle wind. The parameters of the Crab pulsar, including magnetic field, inclination angle, and particle density are calculated. The primary particle density in acceleration region is about 103 times the Goldreich–Julian charge density. The lower braking index between glitches is due to a larger outflowing particle density. This may be glitch induced magnetospheric activities in normal pulsars. Evolution of braking index and the Crab pulsar in
$P-\dot{P}$
diagram are calculated. The Crab pulsar will evolve from magnetic dipole radiation dominated case towards particle wind-dominated case. Considering the effect of pulsar ‘death’, the Crab pulsar (and other normal pulsars) will not evolve to the cluster of magnetars but downwards to the death valley. Different acceleration models are also considered. Applications to other sources are also discussed, including pulsars with braking index measured, and the magnetar population.
The annual nitrogen (N) budget and groundwater nitrate-N concentrations were studied in the field in three major intensive cropping systems in Shandong province, north China. In the greenhouse ...vegetable systems the annual N inputs from fertilizers, manures and irrigation water were 1358, 1881 and 402
kg
N
ha
−1 on average, representing 2.5, 37.5 and 83.8 times the corresponding values in wheat (
Triticum aestivum L.)–maize (
Zea mays L.) rotations and 2.1, 10.4 and 68.2 times the values in apple (
Malus pumila Mill.) orchards. The N surplus values were 349, 3327 and 746
kg
N
ha
−1, with residual soil nitrate-N after harvest amounting to 221–275, 1173 and 613
kg
N
ha
−1 in the top 90
cm of the soil profile and 213–242, 1032 and 976
kg
N
ha
−1 at 90–180
cm depth in wheat–maize, greenhouse vegetable and orchard systems, respectively. Nitrate leaching was evident in all three cropping systems and the groundwater in shallow wells (<15
m depth) was heavily contaminated in the greenhouse vegetable production area, where total N inputs were much higher than crop requirements and the excessive fertilizer N inputs were only about 40% of total N inputs.
Intensive greenhouse vegetable production systems may pose a greater nitrogen pollution threat than apple orchards or cereal rotations to soil and water quality in north China.
Dwarf Pulses of 10 Pulsars Detected by FAST Yan, Yi; Han, J. L.; Zhou, D. J. ...
Astrophysical journal/The Astrophysical journal,
04/2024, Letnik:
965, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Abstract How pulsars radiate is a long-standing problem. Detailed polarization measurements of individual pulses shed light on currently unknown emission processes. Recently, based on supersensitive ...observations, dwarf pulses have been recognized as weak narrow pulses often appearing during the nulling state. In this study, we report the detection of dwarf pulses from 10 pulsars, PSRs B0525+21, B1237+25, J1538+2345, J1824−0127, J1851−0053, B1901+10, J1939+10, B1944+17, B2000+40, and J2112+4058, based on observations conducted with the Five-hundred-meter Aperture Spherical radio Telescope. Dwarf pulses of five pulsars are clearly discernible in the two-dimensional distribution of pulse intensity and pulse width. For the other five pulsars, PSRs J1538+2345, J1824−0127, J1939+10, B2000+40, and J2112+4058, only a few dwarf pulses are detected from pulse stacks. The dwarf pulses can emerge in both cone and core emission components for PSR B1237+25, and the polarization angles of these dwarf pulses are mostly in the orthogonal polarization mode of normal pulses for PSR B1944+17. In general, pulsars with detected dwarf pulses tend to be located within the “death valley” region of the distribution of pulsar periods and period derivatives.
The coupled evolution of pulsar rotation and inclination angle in the wind braking model is calculated. The oblique pulsar tends to align. The pulsar alignment affects its spin-down behavior. As a ...pulsar evolves from the magneto-dipole radiation dominated case to the particle wind dominated case, the braking index first increases and then decreases. In the early time, the braking index may be larger than three. During the following long time, the braking index is always smaller than three. The minimum braking index is about one. This can explain the existence of a high braking index larger than three and a low braking index simultaneously. The pulsar braking index is expected to evolve from larger than three to about one. The general trend is for the pulsar braking index to evolve from the Crab-like case to the Vela-like case.
Objectives/Hypothesis
To estimate the number, demographics, and outcomes of pediatric patients who underwent tracheostomy in 2012 and to contrast those outcomes by age, race, and gender.
Study Design
...Cross‐sectional study.
Methods
The 2012 Kids Inpatient Database was queried to identify tracheostomy patients using the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD‐9‐CM) procedural codes 311, 3121, and 3129. All patients ≤18 years of age at the time of admission were included and categorized as neonates (≤28 days), infants (>28 days ≤1 year), toddler (1 to 3 years), children (4 to 12 years), adolescents (13 to 17 years), and adults (=18 years). We recorded age, gender, race, insurance status, and zip code of primary residence. We used these variables to contrast the following outcomes: length of stay, total charges, complications of care, and mortality using multiple regression analysis.
Results
An estimated 4,424 pediatric tracheostomies occurred during 2012. Fifty‐one percent of the patients were ≤3 years old, and 62% were male. Forty‐eight percentwere white followed by black (21%), Hispanic (20%), and Asian (3%). The median length of stay was 42 days, and the median total charges were $472,738. The complication rate was 29% and the mortality rate was 8.0%. The length of stay and total charges was predicted by age, with neonates having significantly longer hospitalizations. The complication rate was not associated with age, gender, or ethnicity. However, the mortality rate was associated with younger age.
Conclusions
Pediatric tracheostomies are associated with significant hospital utilizations, complications, and mortality. Increased risk of mortality is observed among neonates and infants. Continued study of tracheostomy outcomes among these subsets of the pediatric population are warranted.
Level of Evidence
4
Laryngoscope, 129:1706–1711, 2019
Objectives
To determine how initial postoperative airway endoscopy findings after stent removal predict successful decannulation in children undergoing double‐staged laryngotracheoplasty (dsLTP). ...Secondary objectives assessed timing of decannulation and number of endoscopic interventions needed after dsLTP.
Methods
A case series with chart review included children who underwent dsLTP at a tertiary children's hospital between 2008 and 2021. Rates of decannulation, time to decannulation, and number of interventions after dsLTP were recorded for children with high‐ or low‐grade stenosis at the first bronchoscopy after stent removal.
Results
Of the 65 children who were included, 88% had high‐grade stenosis and 98% had a preoperative tracheostomy. Successful decannulation happened in 74% of the children, and 44% of the children were decannulated within 12 months of surgery. For children with low‐grade stenosis at the first endoscopy after stent removal, 84% were successfully decannulated compared with 36% of the children with high‐grade stenosis (p = 0.001). After dsLTP, children with high‐grade stenosis required 7.5 interventions (SD: 3.3) compared with 4.0 interventions (SD: 3.0) for children with low‐grade stenosis (p < 0.001). Decannulated children with high‐grade stenosis necessitated more endoscopic procedures (7.0 vs. 3.7, p = 0.02). Time to decannulation was similar between children with high‐ and low‐grade early postoperative stenosis (21.9 vs. 17.8 months, p = 0.63).
Conclusions
Higher grade stenosis identified on the first airway endoscopy after suprastomal stent removal is correlated with lower decannulation rates and more postoperative endoscopic interventions. Although time to decannulation was not impacted by early stenosis grade, surgeons might utilize these early airway findings to counsel families and prognosticate possible surgical success.
Level of Evidence
4 Laryngoscope, 134:963–967, 2024
Double‐Staged laryngotracheoplasty (dsLTP) is a procedure used to treat subglottic stenosis in the pediatric population, with decannulation being the ultimate goal of surgery. This study aims to determine how often initial postoperative airway endoscopy after stent removal predicts the likelihood of decannulation, time to decannulation, and number of endoscopic procedures needed after dsLTP. The study found that early airway findings correlate with likelihood of decannulation, and number of endoscopic procedures.
Mortality Among Children with a Tracheostomy Teplitzky, Taylor B.; Brown, Ashley F.; Brooks, Rebecca L. ...
The Laryngoscope,
February 2023, 2023-02-00, 20230201, Letnik:
133, Številka:
2
Journal Article
Recenzirano
Objectives
To characterize the cause of death among children with a tracheostomy.
Study Design
Prospective cohort.
Methods
All pediatric patients (<18 years) who had a tracheostomy placed at a ...tertiary care institution between 2015 and 2020 were included. The location and cause of death were recorded along with patient demographics and age.
Results
A total of 271 tracheostomies were placed with 46 mortalities reviewed for a mortality rate of 16.8%. Mean age at placement was 1.7 years (SD: 3.4) and mean age at death was 2.9 years (SD: 3.5). Most tracheostomies were placed for respiratory failure (N = 33, 72%). The mean time to death after tracheostomy was 1.2 years (SD: 1.2) and 28% (N = 13) occurred during the same admission as placement. Mean time to death after hospital discharge was 1.3 years (SD: 1.3). Etiology of death was respiratory failure (33%, N = 15), cardiopulmonary arrest (15%, N = 7), unknown (43%, N = 20), or secondary to a tracheostomy‐related complication for 9% (N = 4). Location of death was in intensive care units for 41% (N = 19) and 30% died at home (N = 14). Comfort care measures were taken for 37% (N = 17). Severe neurological disability (HR: 4.06, p = 0.003, 95% CI: 1.59–10.34) and congenital heart disease (HR: 2.36, p = 0.009, 95% CI: 1.24–4.48) correlated with time to death on Cox proportional hazard modeling.
Conclusions
Nearly one‐third of children with a tracheostomy who expire will do so during the same admission as tracheostomy placement. Although progression of underlying disease will lead to most deaths, 9% will be a result of a tracheostomy‐related complication, which represents a meaningful target for quality improvement initiatives.
Level of Evidence
3 Laryngoscope, 133:403–409, 2023
Objective
To evaluate for differences in time to decannulation and survival rates for pediatric tracheotomy patients based on ventilator status upon discharge.
Study Design
Retrospective longitudinal ...cohort study.
Methods
A single‐institution longitudinal study of pediatric tracheostomy patients was conducted. Patients were categorized based on mechanical ventilation status on discharge and principal reason for tracheostomy. Survival rates were determined using the Kaplan‐Meier method. The Wilcoxon's Rank Sum test and Cox regression analysis evaluated differences in survival times and time to decannulation based on primary indication for tracheotomy and ventilation status.
Results
Chart review identified 305 patients who required a tracheostomy under the age of 3. The median age at the time of tracheotomy was 5.2 months. The indications for tracheotomy in these patients were airway obstruction in 145 (48%), respiratory failure in 214 (70%), and pulmonary toilet in 10 (3.3%). Seventy‐nine percent of patients were ventilator dependent at discharge. At the conclusion of the study period, 55% of patients were alive with tracheostomy in place, 30% patients were decannulated, and 15% patients were deceased. Patients with ventilator dependence at initial discharge, bronchopulmonary dysplasia, or airway obstruction were more likely to be decannulated. Hispanic patients were less likely to be decannulated. Patients had an equal probability of death regardless of ventilator status at discharge.
Conclusions
This study demonstrated that the time to decannulation and likelihood of decannulation varies based on the indication for the tracheostomy. The majority of patients with a tracheostomy were not decannulated at the conclusion of this study. Median time to decannulation was 2.5 years for patients with a median death time of 6 months.
Level of Evidence
2b Laryngoscope, 130:2319–2324, 2020
Objectives/Hypothesis
Bronchopulmonary dysplasia (BPD) and invasive respiratory support is increasing among extremely preterm neonates. Yet, it is unclear if there is a corresponding increase in ...tracheostomies. We hypothesize that in extremely preterm neonates with BPD, the incidence of tracheostomy has increased.
Study Design
Retrospective cross‐sectional analysis.
Methods
We analyzed the 2006 to 2012 Kids’ Inpatient Databases (KID) for hospital discharges of nonextremely preterm neonates (gestational age >28 weeks and <37 weeks or birth weight >1,500 g) and extremely preterm neonates (gestational age ≤28 weeks or birth weight ≤1,500 g). We studied tracheostomy placement trends in these two populations to see if they are increasing among extremely preterm neonates, especially those with BPD.
Results
The study included 1,418,681 preterm neonates (52% male, 50% white, 19% black, 20% Hispanic, 4.2% Asian), of whom 118,676 (8.4%) were extremely preterm. A total of 2,029 tracheostomies were performed, of which 803 (0.68%) were in extremely preterm neonates. The estimated percent change of occurrence of extremely preterm neonates with BPD increased 17% between 2006 and 2012, and tracheostomy placement increased 31%. Amongst all who received tracheostomies, mortality rate was higher in extremely preterm neonates compared to nonextremely preterm neonates (18% vs. 14%, P = .05). However, in extremely preterm neonates, those with tracheostomies had a lower mortality rate compared to those without (18% vs. 24%, P = .002).
Conclusions
Extremely preterm neonates, compared to nonextremely preterm neonates, experienced a marked increase in tracheostomies placed from 2006 to 2012 as well as an increased incidence of BPD, confirming our primary study hypothesis.
Level of Evidence
4 Laryngoscope, 130: 2056–2062, 2020
Hydrogen sulfide (H2S), a gasotransmitter, has been recently linked to mesenchymal stem cell (MSC) function and bone homeostasis. Periodontal ligament stem cells (PDLSCs) are the main MSCs in PDL, ...which respond to mechanical force to induce physiological activities during orthodontic tooth movement (OTM). However, it is unknown whether mechanical force might induce endogenous H2S production by PDLSCs to regulate alveolar bone homeostasis. Here, we used a mouse OTM model to demonstrate that orthodontic force-induced endogenous H2S production in PDL tissue was associated with macrophage accumulation and osteoclastic activity in alveolar bone. Then, we showed that mechanical force application induced cystathionine β-synthase (CBS) expression and endogenous H2S production by PDLSCs. Moreover, blocking endogenous H2S or systemically increasing H2S levels could decrease or enhance force-induced osteoclastic activities to control tooth movement. We further revealed how force-induced H2S production by PDLSCs contributed to the secretion of monocyte chemoattractant protein-1 (MCP-1) and the expression of receptor activator of nuclear factor–κB ligand/osteoprotegerin (RANKL/OPG) system by PDLSCs. The secretion and expression of these factors controlled macrophage migration and osteoclast differentiation. This study demonstrated that PDLSCs produced H2S to respond to and transduce force signals. Force-induced gasotransmitter H2S production in PDLSCs therefore regulated osteoclastic activities in alveolar bone and controlled the OTM process through the MCP-1 secretion and RANKL/OPG system.
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