We report the discovery of the unusually bright long-duration gamma-ray burst (GRB), GRB 221009A, as observed by the Neil Gehrels Swift Observatory (Swift), Monitor of All-sky X-ray Image (MAXI), and ...Neutron Star Interior Composition Explorer Mission (NICER). This energetic GRB was located relatively nearby (z = 0.151), allowing for sustained observations of the afterglow. The large X-ray luminosity and low Galactic latitude (b = 4.3 degrees) make GRB 221009A a powerful probe of dust in the Milky Way. Using echo tomography we map the line-of-sight dust distribution and find evidence for significant column densities at large distances (~> 10kpc). We present analysis of the light curves and spectra at X-ray and UV/optical wavelengths, and find that the X-ray afterglow of GRB 221009A is more than an order of magnitude brighter at T0 + 4.5 ks than any previous GRB observed by Swift. In its rest frame GRB 221009A is at the high end of the afterglow luminosity distribution, but not uniquely so. In a simulation of randomly generated bursts, only 1 in 10^4 long GRBs were as energetic as GRB 221009A; such a large E_gamma,iso implies a narrow jet structure, but the afterglow light curve is inconsistent with simple top-hat jet models. Using the sample of Swift GRBs with redshifts, we estimate that GRBs as energetic and nearby as GRB 221009A occur at a rate of ~<1 per 1000 yr - making this a truly remarkable opportunity unlikely to be repeated in our lifetime.
A black hole can launch a powerful relativistic jet after it tidally disrupts a star. If this jet fortuitously aligns with our line of sight, the overall brightness is Doppler boosted by several ...orders of magnitude. Consequently, such on-axis relativistic tidal disruption events (TDEs) have the potential to unveil cosmological (redshift \(z>\)1) quiescent black holes and are ideal test beds to understand the radiative mechanisms operating in super-Eddington jets. Here, we present multi-wavelength (X-ray, UV, optical, and radio) observations of the optically discovered transient \target at \(z=1.193\). Its unusual X-ray properties, including a peak observed luminosity of \(\gtrsim\)10\(^{48}\) erg s\(^{-1}\), systematic variability on timescales as short as 1000 seconds, and overall duration lasting more than 30 days in the rest-frame are traits associated with relativistic TDEs. The X-ray to radio spectral energy distributions spanning 5-50 days after discovery can be explained as synchrotron emission from a relativistic jet (radio), synchrotron self-Compton (X-rays), and thermal emission similar to that seen in low-redshift TDEs (UV/optical). Our modeling implies a beamed, highly relativistic jet akin to blazars but requires extreme matter-domination, i.e, high ratio of electron-to-magnetic field energy densities in the jet, and challenges our theoretical understanding of jets.
Making prenatal and birthing services accessible in rural communities no longer able to support a local full-service hospital and the introduction of managed care cost control has led to ...consideration of alternative models. One such model, the freestanding birth center located in an isolated rural community, challenges the guidelines of several state and professional organizations directed at assuring adequate emergency response, including cesarean sections. An extensive review of freestanding birth centers and their effect on birth outcomes revealed little outcomes data about birth centers distant from full-service hospitals. Most states have modeled their birth center regulations on recommendations from the National Association of Childbearing Centers, but others, such as New York, have more rigidly defined transport parameters that exclude many rural locations. A consensus panel convened by the New York State Rural Health Council concluded that demonstrations projects featuring a rural birthing center farther than 20 minutes from a full-service hospital and operated within a networked rural health system should be developed. Consumers would need to be fully informed about the implications of their choice of birth services and all qualified providers, including midwives, should be included in a team approach to care giving.
It has been unclear for more than a decade whether companies have a duty to update information that was true when made, but which subsequently becomes stale and because of changed circumstances is ...now incorrect. It is likely that there is a duty to correct statements that are later found to have been untrue at the time they were made, but courts have disagreed about whether there is a duty to update statements that when made were accurate. Some circuits acknowledge that antifraud concepts may create a duty to update in certain circumstances. However, antifraud statutes lack any explicit instruction to update, and silence absent a duty to disclose is not misleading. Furthermore, even if a separate duty to update did exist at one time, it may have been largely subsumed by the Sarbanes-Oxley Act of 2002. Rule 10b-5 of the Securities Exchange Act of 1934 states that with regard to purchasing or selling securities, companies must disclose "material facts . . . necessary in order to make the statements made, in the light of the circumstances under which they were made, not misleading." The First, Second, and Third Circuits suggest that there is a duty to update when subsequent events render a previous statement misleading. try to create a shield of protection against fraud claims, company directors and officers should consider implementing regular reviews of all qualitative statements, including estimates, projections, and other forward-looking statements. During reviews, directors and officers could consider, for instance, whether the SEC tends to require prompt disclosure of similar statements and whether the statements have affected market indicators.
The insonation of circulating microbubbles (MBs) by low frequency (1 MHz) ultrasound (US) pulses has previously been associated with changes in vascular permeability and local changes in blood flow. ...Here, using a clinical scanner, 5 MHz insonation of bound, targeted MBs is demonstrated to locally alter blood flow in murine tumors. Peptide-targeted MBs were administrated into murine Met-1 and NDL tumor models via tail vein injection (5×10 7 MBs). Thirty frames of CPS contrast images (Siemens Sequoia 512, 0.09 MI, 10 Hz frame rate) were recorded to assess tumor blood flow. Seven minutes after injection, freely-circulating MBs had cleared from the blood stream leaving bound MBs that had accumulated in the tumor vasculature. At this time, 5 MHz pulses with a peak negative pressure (PNP) of 2 or 4 MPa, a pulse length of 5 cycles and a pulse repetition period of 8.1 ms were transmitted for 0.9 second. Five minutes after the high-pressure pulse sequence, a second dose of MBs was injected and 30 frames of CPS images were acquired. Optical images of systemically-injected FITC-dextran (MW=150,000), pre-administration of an anti-CD41 antibody, and histology were used to investigate the possible mechanism for the vascular changes. After the insonation of bound MBs with a 4 MPa PNP, additional regions of reduced blood flow were observed in 71% of Met-1 tumors (n=28) and 40% of NDL tumors (n = 10). In Met-1 tumors insonified with 4 MPa pulses, the area over which reduced blood flow was observed increased from 22±13% to 63±17% (pμ0.01) of the tumor region of interest. Decreasing the PNP to 2 MPa decreased the percentage of Met-1 tumors with additional regions of reduced blood flow from 71% to 28%. Histological analysis of Met-1 tumors after 4 MPa insonation demonstrated that the mean microvascular diameter in insonified tumors was approximately 17±8 μm, compared to 7±4 μm in control tumors (pμ0.01). Extravasation of FITC-dextran was observed in 4 MPa insonified, but not control, Met-1 tumors. The results suggest that high-pressure insonation of targeted MBs which had accumulated at high concentration, may result in changes in blood flow.
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