Short Plateau Phase Research Articles

SN 2021wvw: A Core-collapse Supernova at the Subluminous, Slower, and Shorter End of Type IIPs

We present detailed multiband photometric and spectroscopic observations and analysis of a rare core-collapse supernova, SN 2021wvw, that includes photometric evolution up to 250 days and spectroscopic coverage up to 100 days postexplosion. A unique event that does not fit well within the general trends observed for Type IIP supernovae, SN 2021wvw shows an intermediate luminosity with a short plateau phase of just about 75 days, followed by a very sharp (∼10 days) transition to the tail phase. Even in the velocity space, it lies at a lower velocity compared to a larger Type II sample. The observed peak absolute magnitude is −16.1 mag in r-band, and the nickel mass is well constrained to 0.020 ± 0.006 M ⊙. Detailed hydrodynamical modeling using MESA+STELLA suggests a radially compact, low-metallicity, high-mass red supergiant progenitor (M ZAMS = 18 M ⊙), which exploded with ∼0.2 × 1051 erg s−1 leaving an ejecta mass of M ej ≈ 5 M ⊙. Significant late-time fallback during the shock propagation phase is also seen in progenitor+explosion models consistent with the light-curve properties. As the faintest short-plateau supernova characterized to date, this event adds to the growing diversity of transitional events between the canonical ∼100 days plateau Type IIP and stripped-envelope events.

Fast and not-so-furious: Case study of the fast and faint Type IIb SN 2021bxu

ABSTRACT We present photometric and spectroscopic observations and analysis of SN 2021bxu (ATLAS21dov), a low-luminosity, fast-evolving Type IIb supernova (SN). SN 2021bxu is unique, showing a large initial decline in brightness followed by a short plateau phase. With $M_r = -15.93 \pm 0.16\, \mathrm{mag}$ during the plateau, it is at the lower end of the luminosity distribution of stripped-envelope supernovae (SE-SNe) and shows a distinct ∼10 d plateau not caused by H- or He-recombination. SN 2021bxu shows line velocities which are at least $\sim 1500\, \mathrm{km\, s^{-1}}$ slower than typical SE-SNe. It is photometrically and spectroscopically similar to Type IIb SNe during the photospheric phases of evolution, with similarities to Ca-rich IIb SNe. We find that the bolometric light curve is best described by a composite model of shock interaction between the ejecta and an envelope of extended material, combined with a typical SN IIb powered by the radioactive decay of 56Ni. The best-fitting parameters for SN 2021bxu include a 56Ni mass of $M_{\mathrm{Ni}} = 0.029^{+0.004}_{-0.005}\, \mathrm{{\rm M}_{\odot }}$, an ejecta mass of $M_{\mathrm{ej}} = 0.61^{+0.06}_{-0.05}\, \mathrm{{\rm M}_{\odot }}$, and an ejecta kinetic energy of $K_{\mathrm{ej}} = 8.8^{+1.1}_{-1.0} \times 10^{49}\, \mathrm{erg}$. From the fits to the properties of the extended material of Ca-rich IIb SNe we find a trend of decreasing envelope radius with increasing envelope mass. SN 2021bxu has MNi on the low end compared to SE-SNe and Ca-rich SNe in the literature, demonstrating that SN 2021bxu-like events are rare explosions in extreme areas of parameter space. The progenitor of SN 2021bxu is likely a low-mass He star with an extended envelope.

Intraoperative hypothermia in the neonate population: risk factors, outcomes, and typical patterns

The risk factors, outcomes, and typical patterns of intraoperative hypothermia were studied in neonates to better guide the application of insulation measures in the operating room. This retrospective study enrolled 401 neonates undergoing surgery under general anaesthesia with tracheal intubation, including abdominal surgery, thoracic surgery, brain surgery, and others. The study collected basic characteristics, such as age, sex, weight, birth weight, gestational week, primary diagnosis and American Society of Anaesthesiologists (ASA) grade. Perioperative data included preoperative body temperature, length of hospital stay, length of intensive care unit (ICU) stay, intubation time, postoperative bleeding, postoperative pneumonia, postoperative death, and total cost of hospitalization. Intraoperative data included surgical procedures, anaesthesia duration, operation duration, blood transfusion, fluid or albumin infusion, and application of vasoactive drugs. The incidence of intraoperative hypothermia (< 36 °C) was 81.05%. Compared to normothermic patients, gestational week (OR 0.717; 95% CI 0.577–0.890; P = 0.003), preoperative temperature (OR 0.228; 95% CI 0.091–0.571; P = 0.002), duration of anaesthesia (OR 1.052; 95% CI 1.027–1.077; P < 0.001), and type of surgery (OR 2.725; 95% CI 1.292–5.747; P = 0.008) were associated with the risk of intraoperative hypothermia. Patients with hypothermia had longer length of ICU stay (P = 0.001), longer length of hospital stay (P < 0.001), and higher hospital costs (P < 0.001). But there were no association between clinical outcomes and intraoperative hypothermia in the multivariable regression adjusted analysis. The lowest point of intraoperative body temperature was approximately 1 h 30 min. Then, the body temperature of patients successively entered a short plateau phase and a period of slow ascent. The greatest decrease in body temperatures occurred in preterm babies and neonates with preoperative hypothermia. The lowest core temperatures that occurred in neonates with preoperative hypothermia was lower than 35 °C. This study shows that there is a high incidence of intraoperative hypothermia in the neonate population. The intraoperative body temperature of neonates dropped to the lowest point in 1–1.5 h. The greatest decrease in core temperatures occurred in preterm babies and neonates with lower preoperative temperature.

SN 2019edo: A Type II-P Supernova with a Fast Brightness Rise and a Short Plateau Phase

SN 2019edo: A Type II-P Supernova with a Fast Brightness Rise and a Short Plateau Phase

SN 2017czd: A Rapidly Evolving Supernova from a Weak Explosion of a Type IIb Supernova Progenitor

Abstract We present optical and near-infrared observations of the rapidly evolving supernova (SN) 2017czd that shows hydrogen features. The optical light curves exhibit a short plateau phase (∼13 days in the R-band) followed by a rapid decline by 4.5 mag ∼20 days after the plateau. The decline rate is larger than those of any standard SNe, and close to those of rapidly evolving transients. The peak absolute magnitude is −16.8 mag in the V band, which is within the observed range for SNe IIP and rapidly evolving transients. The spectra of SN 2017czd clearly show the hydrogen features and resemble those of SNe IIP at first. The Hα line, however, does not evolve much with time, and it becomes similar to those in SNe IIb at the decline phase. We calculate the synthetic light curves using a SN IIb progenitor that has 16 at the zero-age main sequence and evolves into a binary system. The model with a low explosion energy (5 × 1050 erg) and a low 56Ni mass ( ) can reproduce the short plateau phase, as well as the sudden drop of the light curve, as observed in SN 2017czd. We conclude that SN 2017czd might be the first weak explosion identified from a SN IIb progenitor. We suggest that some rapidly evolving transients can be explained by such a weak progenitor explosion with a barely hydrogen-rich envelope.

The Early Detection and Follow-up of the Highly Obscured Type II Supernova 2016ija/DLT16am∗

Abstract We present our analysis of the Type II supernova DLT16am (SN 2016ija). The object was discovered during the ongoing (DLT40) one-day cadence supernova search at in the “edge-on” nearby ( ) galaxy NGC 1532. The subsequent prompt and high-cadenced spectroscopic and photometric follow-up revealed a highly extinguished transient, with , consistent with a standard extinction law with R V = 3.1 and a bright ( ) absolute peak magnitude. A comparison of the photometric features with those of large samples of SNe II reveals a fast rise for the derived luminosity and a relatively short plateau phase, with a slope of , consistent with the photometric properties typical of those of fast-declining SNe II. Despite the large uncertainties on the distance and the extinction in the direction of DLT16am, the measured photospheric expansion velocity and the derived absolute V-band magnitude at after the explosion match the existing luminosity–velocity relation for SNe II.

Supernova 2013fc in a circumnuclear ring of a luminous infrared galaxy: the big brother of SN 1998S

We present photometric and spectroscopic observations of SN 2013fc, a bright type II supernova (SN) in a circumnuclear star-forming ring in the luminous infrared galaxy ESO 154-G010, observed as part of the Public ESO Spectroscopic Survey of Transient Objects (PESSTO). SN 2013fc is both photometrically and spectroscopically similar to the well-studied type IIn SN 1998S and to the bright type II-L SN 1979C. It exhibits an initial linear decline, followed by a short plateau phase and a tail phase with a decline too fast for $^{56}$Co decay with full gamma-ray trapping. Initially the spectrum was blue and featureless. Later on, a strong broad ($\sim 8000$ km s$^{-1}$) H $\alpha$ emission profile became prominent. We apply a Starlight stellar population model fit to the SN location (observed when the SN had faded) to estimate a high extinction of $A_V = 2.9 \pm 0.2$ mag and an age of $10_{-2}^{+3}$ Myr for the underlying cluster. We compare the SN to SNe 1998S and 1979C and discuss its possible progenitor star considering the similarities to these events. With a peak brightness of $B = -20.46 \pm 0.21$ mag, SN 2013fc is 0.9 mag brighter than SN 1998S and of comparable brightness to SN 1979C. We suggest that SN 2013fc was consistent with a massive red supergiant (RSG) progenitor. Recent mass loss probably due to a strong RSG wind created the circumstellar matter illuminated through its interaction with the SN ejecta. We also observe a near-infrared excess, possibly due to newly condensed dust.

Bachmann’s Bundle

Bachmann’s bundle (BB), also known as the interatrial bundle, is well recognized as a muscular bundle comprising of parallel aligned myocardial strands connecting the right and left atrial walls and is considered to be the main pathway of interatrial conduction.1 Disruption of the bundle’s structure causes interatrial conduction block (IAB),2 which is associated with development of various atrial tachyarrhythmias3,4 and with electromechanical dysfunction of the left atrium.5 Technological progress providing sophisticated mapping and imaging techniques in the past decade has increased our knowledge of specific anatomic structures and their role in development of both atrial brady- and tachyarrhythmias. This review outlines the current knowledge of the relation between anatomic and electrophysiological properties of BB and its possible role in initiation and perpetuation of atrial fibrillation (AF). In 1963, Thomas N. James described 3 pathways connecting the sinus node to the atrioventricular node (AVN), namely the anterior, medial, and posterior internodal pathways.6 Whether these conduction pathways were because of the presence of specialized conduction tissue or because of the anisotropic orientation of the muscle fibers remains controversial. Nevertheless, James described the anterior pathway as leaving the sinus node in anterior direction and giving off a secondary branch at the level of the superior vena cava to form BB.1 BB stretches subepicardially across the interatrial groove (septal raphe). It is at the interatrial groove that the BB can be identified as a discrete bundle (Figures 1 and 2) separated by fatty tissues from the infolded right atrial wall that is the limbus of the oval fossa. Notably, the bundle is not surrounded by a fibrous tissue sheath. Instead, the bundle is comprised of strands of atrial myocardium that are similarly aligned in parallel fashion. Its rightward and leftward extensions bifurcate to pass to either …

Magnesium Chloride Concentration-Dependent Formation of Tofu-Like Precipitates with Different Physicochemical Properties

A wet precipitate is generated in the process of making tofu by adding a coagulant to the basic soymilk ingredient. We investigated the magnesium chloride concentration-dependent change in the precipitate weight. The wet precipitate weight dramatically increased following a short plateau phase at a low concentration of magnesium chloride. It is interesting that this weight slightly decreased following a long plateau phase at a high concentration. These low and high concentrations respectively induced precipitates with a smooth surface and rough surface. The precipitate with a smooth surface had a higher water content than that with a rough surface. These precipitates also had obviously different solubility in various chemical reagents. The different properties indicate that these precipitates were formed by different intermolecular interactions. These results can be utilized to more clearly understand the mechanisms involved in tofu formation.

Discovery of a Short Plateau Phase in the Early Evolution of a Gamma-Ray Burst Afterglow

Abstract We report on optical observations during the first hour of the gamma-ray burst (GRB) afterglow of GRB 021004. Our observations revealed the existence of a short plateau phase, in which the afterglow remained at almost constant brightness, before an ordinary rapid-fading phase. This plateau phase lasted for about 2 hours from 0.024 to 0.10 d after the burst, which corresponds to a missing blank of the early afterglow light curve of GRB 990123. We propose that the plateau phase can be interpreted as being the natural evolution of synchrotron emission from the forward shock region of a blast wave. The time when the typical frequency of the synchrotron emission passes through the optical range has been predicted to be about 0.1 d after the burst, which is consistent with the observed light curve. Our scenario hence implies that the observed feature in GRB 021004 is a common nature of GRB afterglows.

Brain tissue oxygen response in severe traumatic brain injury

To investigate clinical relevance and prognostic value of brain tissue oxygen response (TOR: response of brain tissue pO(2) to changes in arterial pO(2)) in traumatic brain injury (TBI). In a prospective cohort study TOR was investigated in 41 patients with severe TBI (Glasgow Coma Score < or =8) in whom continuous monitoring of brain tissue oxygen pressure (PbrO(2)) was performed.TOR was investigated each day over a five day period for 15 minutes by increasing FiO(2) on the ventilator setting. FiO(2) was increased directly from baseline to 1.0 for a period of 15 minutes under stable conditions (145 tests). In 34 patients the effect of decreasing PaCO(2) was evaluated on TOR by performing the same test after increasing inspiratory minute volume on the ventilator setting to 20% above baseline. Arterial blood gas analysis was performed before and after changing ventilator settings. Multimodality monitoring, including PbrO(2) was performed in all patients. Outcome at six months was evaluated according to the Glasgow Outcome Scale. For statistical analysis the Mann-whitney U-test was used for ordinally distributed variables, and the Chi-square test for categorical variables. Predictive value of TOR was analyzed in a multivariable model. 145 tests were available for analysis. Baseline PbrO(2) varied from 4.0 to 50 mmHg at PaO(2) values of 73-237 mmHg. At FiO(2) settings of 1.0, PbrO(2) varied from 9.1-200 mmHg and PaO(2) from 196-499 mmHg. Three distinct patterns of response were noted: response type A is characterized by a sharp increase in PbrO(2), reaching a plateau within several minutes; type B by the absence of a plateau, and type C by a short plateau phase followed by a subsequent further increase in PbrO(2). Patterns characterized by a stable plateau (type A), considered indicative of intact regulatory mechanisms, were seen more frequently from 48 hours after injury on. If present within the first 24 hours after injury such a response was related to more favorable outcome (p = 0.06). Mean TOR of all tests was 0.73 +/- 0.59 with an median TOR of 0.58. Patients with an unfavourable outcome had a higher TOR (1.03 +/- 0.60) during the first 24 hours, compared to patients with a favorable outcome (0.61 +/- 0.51; p = 0.02). Multiple logistic regression analysis supported the independent predictive value of tissue oxygen response for unfavorable outcome (odds ratio 4.8). During increased hyperventilation, mean TOR decreased substantially from 0.75 +/- 0.54 to 0.65 +/- 0.45 (p = 0.06; Wilcoxon test). Within the first 24 hours after injury a decrease in TOR following hyperventilation was significantly related to poorer outcome (p = 0.01). Evaluation of TOR affords insight in (disturbances in) oxygen regulation after traumatic brain injury, is of prognostic value and may aid in identifying patients at (increased) risk for ischemia.

Dwarf Nova-Like Outburst of Short-Period Intermediate Polar HT Camelopardalis

We report on the first time-series observations of a short outburst of the proposed intermediate polar HT Cam ($=$ RX J0757.0$+$6306). On 2001 December 29, we detected that the object was undergoing a bright outburst at a magnitude of $m_\mathrm{vis}=12.2$. Following this detection, we started international joint observations through VSNET. The light curve showed a gradual decline for the first 0.5 d. Following this short plateau phase, the rate of decline dramatically increased to more than $4 \,\mathrm{mag} \,\mathrm{d}^{-1}$. Within 1.5 d from the outburst detection, the object almost declined to the quiescent level. During the rapidly declining phase, long-term modulations with a period of 86min and strong pulses with a period of 8.6 min were observed. We concluded that 86 min and 8.6 min are the orbital period and the spin period of HT Cam, respectively. By detecting the spin period, we confirmed the IP classification of HT Cam. However, its outburst behavior rather resembles that of dwarf novae. The discrepancy between the declining rates of the total flux and the pulse flux strongly suggests that disk instabilities took place during the outburst.

The Subluminous Type Ia Supernova 1998de in NGC 252

ABSTRACTWe present spectroscopic and extensive photometric observations of supernova (SN) 1998de in the S0 galaxy NGC 252, discovered during the course of the Lick Observatory Supernova Search. These data, which span a time period of 8 days before to 76 days after B‐band maximum, unambiguously establish SN 1998de as a peculiar and subluminous Type Ia supernova (SN Ia) with strong similarities to SN 1991bg, the prototype of these intrinsically dim SNe Ia. We find that SN 1998de, which has Δm15(B) = 1.95 ± 0.09 mag, rises and declines much faster than normal SNe Ia and does not exhibit the usual plateau in the R band. In the I band it shows a short plateau phase or possibly a secondary maximum, soon after the first maximum. We find that subluminous SNe Ia with the same value of Δm15(B) can have slightly different light curves at longer wavelengths. The notable spectroscopic similarities between SN 1998de and SN 1991bg are the wide Ti ii trough at 4100–4500 Å, the strong Ca ii features, and the early onset of the nebular phase. We observe that spectroscopic deviations of SN 1998de from SN 1991bg increase toward redder wavelengths. These deviations include the absence of the conspicuous Na i D absorption found in SN 1991bg at 5700 Å and the evolution of a region (6800–7600 Å) from featureless to feature‐rich. Several lines of evidence suggest that SN 1998de was a slightly more powerful explosion than SN 1991bg. We discuss the implications of our observations for progenitor models and the explosion mechanism of peculiar, subluminous SNe Ia. The extensive photometric data make SN 1998de a better template than SN 1991bg for calibrating the low‐luminosity end of the luminosity versus decline rate relationship.

Separation of ionic currents in the somatic membrane of frog sensory neurons.

Electrical properties of isolated frog primary afferent neurons were examined by suction pipette technique, which combines internal perfusion with current or voltage clamp using a switching circuit with a single electrode. When K+ in the external and internal solutions was totally replaced with Cs+, extremely prolonged Ca spikes, lasting for 5 to 10 sec, and Na spikes, having a short plateau phase of 10 to 15 msec, were observed in Na+-free and Ca2+-free solutions, respectively. Under voltage clamp, Ca2+ current (ICa) appeared at around -30 mV and maximum peak current was elicited at about 0 mV. With increasing test pulses to the positive side, ICa became smaller and flattened but did not reverse. Increases of [Ca]o induced a hyperbolic increase of ICa and also shifted its I-V curve along the voltage axis to the more positive direction. Internal perfusion of F- blocked ICa time-dependently. The Ca channel was permeable to foreign divalent cations in the sequence of ICa greater than IBa greater than ISr much greater than IMn greater than IZn. Organic Ca-blockers equally depressed the divalent cation currents dose- and time-dependently without shifting the I-V relationships, while inorganic blockers suppressed these currents dose-dependently and the inhibition appeared much stronger in the order of IBa = ISr greater than ICa greater than IMn = IZn.

Clinical pharmacology of tiamulin in ruminants.

Median values for the minimum inhibitory concentrations (MIC) of tiamulin for Mycoplasma and Acholeplasma isolated from ruminants were 0.05 micrograms/ml and 0.025 micrograms/ml, respectively. These values were close to the MIC values of tylosin and considerably lower than the respective values for spectinomycin, Spiramycin and oxytetracycline. The serum concentration--time profile of tiamulin after intramuscular (i.m.) injection to goats, ewes, cows and calves, and after oral administration to preruminant calves was characterized by a rapid absorption phase (absorption t1/2 of less than 30 min.), a short plateau phase, an elimination t1/2 ranging between 3 and 6 h, and low peak serum drug levels. The serum elimination t1/2 of the drug after intravenous (i.v.) injection was 25 min. It appears that tiamulin is extensively metabolized in ruminants and is well distributed throughout the body. Drug concentrations in the lungs, liver, and the kidneys 1 h after i.v. injection were four to seven times higher than in blood. The drug penetrated very rapidly into the milk after i.m. administration; mean peak drug concentrations in normal milk and in milk secreted from inflamed glands of cows were 7.5 times and 1.2 times higher respectively, than the mean peak serum drug concentrations. Concentrations of tiamulin of potential therapeutic value in the treatment of mycoplasmal infections can be maintained in the lungs for at least 12 h after i.m. injection at 10 mg/kg, and in preruminant calves after an oral dose of 20 mg/kg. However, tiamulin possesses several very serious side-effects and the i.v. route of administration is definitely contraindicated.