The Dimorphos ejecta plume properties revealed by LICIACube.

The Double Asteroid Redirection Test (DART) had an impact with Dimorphos (a satellite of the asteroid Didymos) on 26 September 20221. Ground-based observations showed that the Didymos system brightened by a factor of 8.3 after the impact because of ejecta, returning to the pre-impact brightness 23.7 days afterwards2. Hubble Space Telescope observations made from 15 minutes after impact to 18.5 days after, with a spatial resolution of 2.1 kilometres per pixel, showed a complex evolution of the ejecta3, consistent with other asteroid impact events. The momentum enhancement factor, determined using the measured binary period change4, ranges between 2.2 and 4.9, depending on the assumptions about the mass and density of Dimorphos5. Here we report observations from the LUKE and LEIA instruments on the LICIACube cube satellite, which was deployed 15 days in advance of the impact of DART. Data were taken from 71 seconds before the impact until 320 seconds afterwards. The ejecta plume was a cone with an aperture angle of 140 ± 4 degrees. The inner region of the plume was blue, becoming redder with increasing distance from Dimorphos. The ejecta plume exhibited a complex and inhomogeneous structure, characterized by filaments, dust grains and single or clustered boulders. The ejecta velocities ranged from a few tens of metres per second to about 500 metres per second.

A long-period radio transient active for three decades.

Several long-period radio transients have recently been discovered, with strongly polarized coherent radio pulses appearing on timescales between tens to thousands of seconds1,2. In some cases, the radio pulses have been interpreted as coming from rotating neutron stars with extremely strong magnetic fields, known as magnetars; the origin of other, occasionally periodic and less-well-sampled radio transients is still debated3. Coherent periodic radio emission is usually explained by rotating dipolar magnetic fields and pair-production mechanisms, but such models do not easily predict radio emission from such slowly rotating neutron stars and maintain it for extended times. On the other hand, highly magnetic isolated white dwarfs would be expected to have long spin periodicities, but periodic coherent radio emission has not yet been directly detected from these sources. Here we report observations of a long-period (21 min) radio transient, which we have labelled GPM J1839-10. The pulses vary in brightness by two orders of magnitude, last between 30 and 300 s and have quasiperiodic substructure. The observations prompted a search of radio archives and we found that the source has been repeating since at least 1988. The archival data enabled constraint of the period derivative to <3.6 × 10-13 s s-1, which is at the very limit of any classical theoretical model that predicts dipolar radio emission from an isolated neutron star.

Unpacking the CNS Manifestations of Epstein-Barr Virus: An Imaging Perspective.

Epstein-Barr virus is a ubiquitous herpesvirus that may cause both infective (encephalitis, meningitis, and so forth) and postinfection inflammatory (such as Guillain-Barré syndrome, acute disseminated encephalomyelitis) manifestations in the CNS. Diagnosis of Epstein-Barr virus-related CNS pathologies is often complicated due to a nonspecific clinical presentation and overlap with other infectious and noninfectious causes, both clinically and on imaging. The Epstein-Barr virus is also implicated in several lymphoproliferative disorders in both immunocompromised and immunocompetent hosts. MR imaging is preferred for evaluating the extent of involvement and monitoring therapy response, given its high sensitivity and specificity, though imaging findings may be nonspecific. Herein, we review the imaging spectrum of Epstein-Barr virus-associated CNS disorders.

Amino Acid Tracer PET MRI in Glioma Management: What a Neuroradiologist Needs to Know.

PET with amino acid tracers provides additional insight beyond MR imaging into the biology of gliomas that can be used for initial diagnosis, delineation of tumor margins, planning of surgical and radiation therapy, assessment of residual tumor, and evaluation of posttreatment response. Hybrid PET MR imaging allows the simultaneous acquisition of various PET and MR imaging parameters in a single investigation with reduced scanning time and improved anatomic localization. This review aimed to provide neuroradiologists with a concise overview of the various amino acid tracers and a practical understanding of the clinical applications of amino acid PET MR imaging in glioma management. Future perspectives in newer advances, novel radiotracers, radiomics, and cost-effectiveness are also outlined.

Diagnostic Performance of PET and Perfusion-Weighted Imaging in Differentiating Tumor Recurrence or Progression from Radiation Necrosis in Posttreatment Gliomas: A Review of Literature.

Tumor resection followed by chemoradiation remains the current criterion standard treatment for high-grade gliomas. Regardless of aggressive treatment, tumor recurrence and radiation necrosis are 2 different outcomes. Differentiation of tumor recurrence from radiation necrosis remains a critical problem in these patients because of considerable overlap in clinical and imaging presentations. Contrast-enhanced MR imaging is the universal imaging technique for diagnosis, treatment evaluation, and detection of recurrence of high-grade gliomas. PWI and PET with novel radiotracers have an evolving role for monitoring treatment response in high-grade gliomas. In the literature, there is no clear consensus on the superiority of either technique or their complementary information. This review aims to elucidate the diagnostic performance of individual and combined use of functional (PWI) and metabolic (PET) imaging modalities to distinguish recurrence from posttreatment changes in gliomas.

The tracking control system of the VLT Survey Telescope.

The VLT survey telescope is the latest telescope installed at European Southern Observatory's Paranal observatory that is considered one of the best sites for optical astronomy for the excellent seeing conditions. The exceptional quality of the site imposes tight requirements for the telescope tracking system that shall perform very well to fully exploit the extreme sharpness of the Chilean sky. We describe the specific solutions adopted for pointing, servo and guiding systems and the results obtained during the commissioning of the telescope. The hardware implementation relies on industry components and the control solutions privilege both the performance and the future maintainability of the system.

Comparison of glomerular filtration rate estimated by plasma clearance method with modification of diet in renal disease prediction equation and Gates method.

Glomerular filtration rate (GFR) prediction equations are widely used in clinical practice for quick assessment of kidney function. Gates method using radionuclide technique is an alternative to prediction equations for quick assessment of GFR. Aim of the study was to compare Gates method and modification of diet in renal disease (MDRD) equation in a sizeable patient population with wide range of renal function to evaluate their clinical utility. GFR was estimated in 897 subjects with wide range of renal function by gates method, and MDRD equation and results were compared against measured GFR. Subjects were divided in to 4 groups (0-30 ml, 31-60 ml, 61-90 ml, >90 ml) on the basis of measured GFR and comparison between two methods done through linear regression analysis. Analysis of R(2) indicated that 56% of the interindividual variability for Gates GFR was in accordance to variation in measured GFR, in the GFR range of (0-30 ml), this value dropped to 39% in the GFR range of 31-60 ml, 40% in the GFR range of 61-90 ml, 26.4% in the GFR range of >90 ml, the corresponding figure for MDRD GFR were 47.9%, 31.1%, 17.6% and 16.1%, respectively. Gates method is more precise for GFR estimation at all levels of renal function.

Evaluation of intracranial space-occupying lesion with Tc99m-glucoheptonate brain single photon emission computed tomography in treatment-naïve patients.

BACKGROUND: Glucoheptonate is a glucose analog with strong affinity for neoplastic brain tissues. Though extensively used as a tracer for detection of brain tumor recurrence, it's utility for characterization of intracranial lesions as neoplastic or otherwise has not been evaluated in treatment-naïve patients. AIM: The study was conducted to determine if glucoheptonate has sufficient specificity for neoplastic lesions of brain so that it can be utilized as a single photon emission computed tomography (SPECT)-tracer for differentiating neoplastic intracranial lesions from non-neoplastic ones in treatment-naïve patients. SETTINGS AND DESIGN: A cross-sectional analysis of treatment-naïve patients with intracranial space-occupying lesion done in a tertiary care hospital. MATERIALS AND METHODS: Fifty-four consecutive patients with clinical and radiological features of space-occupying lesion were included in this study. Glucoheptonate brain SPECT was performed before any definitive therapeutic intervention. Histopathological verification of diagnosis was obtained in all cases. STATISTICAL ANALYSIS USED: Descriptive statistics and student's 't' test. RESULT: Increased glucoheptonate uptake over the site of radiological lesion was noted in 41 patients and no uptake was noticed in 13 patients. Histopathology of 12 out of the 13 glucoheptonate non-avid lesions turned out to be non-neoplastic lesion; however, one lesion was reported as a Grade-2 astrocytoma. Histology from all the glucoheptonate concentrating lesions was of mitotic pathology. The sensitivity, specificity and accuracy of glucoheptonate for neoplastic lesion was 97.6%, 100% and 98.1%. CONCLUSIONS: Glucoheptonate has high degree of specificity for neoplastic tissues of brain and may be used as a tracer for SPECT study to differentiate neoplastic intracranial lesions from non-neoplastic ones.

Serum levels of calcium and albumin in survivors versus nonsurvivors after critical injury.

PURPOSE: Injured patients who require aggressive resuscitation with intravenous (IV) fluids and blood products will frequently acquire low levels of serum calcium (CA) and albumin (ALB) in the intensive care unit (ICU) as result of this therapy. The purpose of this longitudinal study was to determine the time course of CA and ALB during ICU admission in survivors (S) compared to nonsurvivors (N) after major trauma. The study design is to verify if CA, ALB, or albumin-corrected CA can be used as indicators of patient survivability after critical injury. MATERIALS AND METHODS: CA and ALB values were retrospectively recorded in 64 random subjects (S= 32 and N= 32) admitted to the Trauma ICU for 3 or more days. CA and ALB data points were partitioned into 6 time frames of ICU care. Mean values and standard error of the mean for each frame were obtained to depict parametric differences in the time profiles for S versus N. Subgroup analysis was used to determine the impact of blood transfusions on CA and ALB levels. Albumin-corrected CA was computed for every patient at each measurement point and then partitioned into the 6 time frames of ICU care. Parametric t-test and nonparametric rank sum analysis were used to evaluate the ability of CA, ALB, and ALB-corrected CA at discriminating S from N. Each predictive covariate was ranked, divided into quartiles (grades = normal, mild, moderate, severe), and correlated with patient survival likelihood (viz., ratio of S to N in each quartile). RESULTS: Parametric and non-parametric analysis of collected data indicates that the response patterns of CA were significantly different ( P<.00005 ) in S versus N. Time profiles of CA and ALB exhibited similar reductions in both S and N during the resuscitation phase (ie, "hypocalcemia of trauma"). But from these nadir points, CA response patterns in S tended to steadily elevate toward normal levels (ie, "responders"), while N exhibited no such increase in CA values (ie, "nonresponders"). Data revealed that survival likelihood in trauma patients after 3 ICU days is proportional to the upward response of CA from depressed values present after the initial resuscitation. Decreased CA levels after 3 ICU days were associated with decreased survival (Table 1). Rank sum testing showed that values of CA corrected for ALB creates less obvious difference in S and N than uncorrected CA. Subgroup analysis showed a linear decrease in CA and ALB levels with increasing units of blood transfused during treatment for trauma. CONCLUSIONS: CA changes during ICU care demonstrate distinct response patterns (P <.00005) for survivors versus nonsurvivors. The magnitude of upward response in CA after the fluid resuscitation phase is a marker that correlates with a patient's ability to withstand the physiologic stresses encountered during ICU treatment after major trauma. Our findings indicate that uncorrected CA values are a better guide for calcium replacement therapy in trauma patients than albumin-adjusted CA. This study suggests that response patterns of CA can be a useful reference to aid in monitoring the progress of critically injured patients.

Hydrolytic reactions of the phosphorodithioate analogue of uridylyl(3',5')uridine: kinetics and mechanisms for the cleavage, desulfurization, and isomerization of the internucleosidic linkage

The hydrolytic reactions of the phosphorodithioate analogue of uridylyl(3',5')uridine [3',5'-Up(s)2U] were followed by HPLC over a wide pH range at 363.2 K. Under acidic and neutral conditions, three reactions compete: (i) desulfurization to a mixture of the (Rp)- and (Sp)-diastereomers of the corresponding 3',5'- and 2',5'-phosphoromonothioates [3',5'- and 2',5'-Up(s)U], which are subsequently desulfurized to a mixture of uridylyl(3',5')- and -(2',5')uridine [3',5'- and 2',5'-UpU], (ii) isomerization to 2',5'-Up(s)2U, and (iii) cleavage to uridine, in all likelihood via a 2',3'-cyclic phosphorodithioate (2',3'-cUMPS2). Under alkaline conditions (pH > 8), only a hydroxide ion catalyzed hydrolysis to uridine via 2',3'-cUMPS2 takes place. At pH 3-7, all three reactions are pH-independent, the desulfurization being approximately 1 order of magnitude faster than the cleavage and isomerization. At pH < 3, all the reactions are hydronium ion catalyzed. On going to very acidic solutions, the cleavage gradually takes over the desulfurization and isomerization. Accordingly, the cleavage overwhelmingly predominates at pH < 0. The overall hydrolytic stability of 3',5'-Up(s)2U is comparable to that of (Sp)- and (Rp)-3',5'-Up(s)U (and to that of 3',5'-UpU, except at pH < 2). The rate of the hydroxide ion catalyzed hydrolysis of 3',5'-Up(s)2U is 37% and 53% of that of (Sp)- and (Rp)-3',5'-Up(s)U, respectively. The reactions, however, differ with the respect of the product accumulation. While the phosphoromonothioates produce a mixture of 2'- and 3'-thiophosphates as stable products, 3',5'-Up(s)2U is hydrolyzed to uridine without accumulation of the corresponding dithiophosphates. At pH < 3, where the hydrolysis is hydronium ion catalyzed, the kinetic thio-effect of the second thio substitution is small: under very acidic conditions (Ho -0.69), (Sp)-3',5'-Up(s)U reacts 1.6 times as fast as 3',5'-Up(s)2U, but the reactivity difference decreases on going to less acidic solutions. In summary, the hydrolytic stability of 3',5'-Up(s)2U closely resembles that of the corresponding phosphoromonothioate. While replacing one of the nonbridging phosphate oxygens of 3',5'-UpU with sulfur stabilizes the phosphodiester bond under acidic conditions by more than 1 order of magnitude, the replacement of the remaining nonbridging oxygen has only a minor influence on the overall hydrolytic stability.