Determining If Two Solid Ellipsoids Intersect

An analytical method is presented for determining if two ellipsoids share the same volume. The formulation involves adding an extra dimension to the solutions space and examining eignevalues that are associated with degenerate quadric surfaces. The eigenvalue behavior is characterized and then demonstrated with an example. The same method is also used to determine if two ellipsoids appear to share the same projected area based on an observer\u27s viewing angle. The following approach yields direct results without approximation, iteration, or any form of numerical search. It is computationally efficient in the sense that no dimensional distortions, coordinate rotations, transformations, or eigenvector computations are needed

Determining If Two Ellipsoids Share the Same Volume

An analytical method is presented for determining if two ellipsoids share the same volume. The formulation involves adding an extra dimension to the solution space and examining eigenvalues that are associated with degenerate quadric surfaces. The eigenvalue behavior is characterized and then demonstrated with an example. The same method is also used to determine if two ellipsoids appear to share the same projected area based on an oberver\u27s viewing angle. The following approach yields direct results without approximation, iteration, or any form of numerical search. It is computationally efficient in the sense that no dimensional distortions, coordinate rotations, transformations, or eigenvector computations are needed

Type 3 Deiodinase and Consumptive Hypothyroidism: A Common Mechanism for a Rare Disease

The major product secreted by the thyroid is thyroxine (T4), whereas most of the biologically active triiodothyronine (T3) derives from the peripheral conversion of T4 into T3. The deiodinase enzymes are involved in activation and inactivation of thyroid hormones (THs). Type 1 and type 2 deiodinase (D1 and D2) convert T4 into T3 whereas D3 degrades T4 and T3 into inactive metabolites and is thus the major physiological TH inactivator. The hypothalamic-pituitary-thyroid axis maintains circulating TH levels constant, while the deiodinases tissue-specifically regulate intracellular thyroid status by controlling TH action in a precise spatio-temporal fashion. Here we review the data related to the recent identification of a paraneoplastic syndrome called “consumptive hypothyroidism,” which exemplifies how deiodinases alter substantially the concentration of TH in blood. This syndrome results from the aberrant uncontrolled expression of D3 that can induce a severe form of hypothyroidism by inactivating T4 and T3 in defined tumor tissue. This rare TH insufficiency generally affects patients in the first years of life, and has distinct features in terms of diagnosis, treatment, and prognosis with respect to other forms of hypothyroidism

Dark energy-matter equivalence by the evolution of cosmic equation of state

We consider a model-independent approach to constrain the equivalence redshift, $z_{eq}$, at which dark energy and the total matter (cold dark matter and baryonic) equate their magnitudes. To this aim, in the context of a homogeneous and isotropic universe, we first consider a generic model where the dark energy contribution is provided by an unknown function of barotropic fluids. Afterwards, we compute the deceleration and jerk parameters, evaluating at our epoch, namely $z=0$, and at $z=z_{eq}$. Thus, by Taylor expanding around current time the Hubble rate, luminosity and angular distances, we substitute the theoretical expressions obtained from the aforementioned generic dark energy model, defining a correspondence between quantities evaluated at $z=0$ and $z=z_{eq}$. In so doing, we directly fit these quantities by means of current data sets, involving the most recent Pantheon type Ia supernovae, baryonic acoustic oscillation and Hubble rate points. We consider two hierarchies in our fitting procedures and compare our findings in the spatially-flat universe first and including spatial curvature, later. We assess constraints on the overall equation of state of the universe and its first derivative. We compare our results with those predicted by the standard $\Lambda$CDM paradigm. Specifically, our findings are in agreement at the 2$\sigma$ confidence level, assuming a constant dark energy term. However, our analysis does not rule out the possibility of a slight evolution of dark energy, indicating a small deviation from the scenario of a pure cosmological constant. In particular, the possible departures appear consistent with a phenomenological $\omega$CDM model, rather than more complicated dark energy parameterizations.Comment: 28 pages, 8 figures, 3 table

Flogosi post-trapianto di cornea

Il Trapianto di Cornea, o Cheratoplastica, che prevede la sostituzione sub-totale della cornea mediante un innesto circolare di tessuto omologo (lembo), rappresenta la procedura d’elezione per il trattamento di diverse patologie corneali congenite o acquisite. Se ne discutono tutti i determinanti e le prospettive

Design of Spacecraft Missions to Remove Multiple Orbital Debris Objects

The amount of hazardous debris in Earth orbit has been increasing, posing an evergreater danger to space assets and human missions. In January of 2007, a Chinese ASAT test produced approximately 2600 pieces of orbital debris. In February of 2009, Iridium 33 collided with an inactive Russian satellite, yielding approximately 1300 pieces of debris. These recent disastrous events and the sheer size of the Earth orbiting population make clear the necessity of removing orbital debris. In fact, experts from both NASA and ESA have stated that 10 to 20 pieces of orbital debris need to be removed per year to stabilize the orbital debris environment. However, no spacecraft trajectories have yet been designed for removing multiple debris objects and the size of the debris population makes the design of such trajectories a daunting task. Designing an efficient spacecraft trajectory to rendezvous with each of a large number of orbital debris pieces is akin to the famous Traveling Salesman problem, an NP-complete combinatorial optimization problem in which a number of cities are to be visited in turn. The goal is to choose the order in which the cities are visited so as to minimize the total path distance traveled. In the case of orbital debris, the pieces of debris to be visited must be selected and ordered such that spacecraft propellant consumption is minimized or at least kept low enough to be feasible. Emergent Space Technologies, Inc. has developed specialized algorithms for designing efficient tour missions for near-Earth asteroids that may be applied to the design of efficient spacecraft missions capable of visiting large numbers of orbital debris pieces. The first step is to identify a list of high priority debris targets using the Analytical Graphics, Inc. SOCRATES website and then obtain their state information from Celestrak. The tour trajectory design algorithms will then be used to determine the itinerary of objects and v requirements. These results will shed light on how many debris pieces can be visited for various amounts of propellant, which launch vehicles can accommodate such missions, and how much margin is available for debris removal system payloads

How public ambulance arrivals impact on Emergency Department workload and resource use

Objectives: To examine patient's characteristics associated with ED arrival mode, and to determine EMS impact on ED clinical resource use, workload and crowding. Methods: This is a retrospective study of patients seen at Sant'Andrea Hospital ED. Comparison focused on visit characteristics, and on resource use. Results: The use of EMS ambulance confirms association to older age, higher rate of hospital admission, longer length of stay, and severity of injury. Moreover our data show that ambulance referred patients are triaged into a higher acuity category and have a greater intensive care unit admission. Conclusion: Ambulance arrivals have a significant impact on ED resource use, workload and crowding

Endovascular aortic graft infection resulting in retroperitoneal abscess: report of a case

Infection is a rare complication of aortoiliac endovascular procedures, with an incidence inferior to 0.5%, and it may result in a retroperitoneal abscess potentially evolving to sepsis and gastrointestinal bleeding. In more than 50% of cases endovascular aortoiliac prosthetic grafts infection occur months or years after the procedure. The growing number of endovascular procedures, and as the actually midterm follow up in most cases, septic sequelae will no doubt continue to occur with increased frequency and may represent an emerging problem in the ED for the emergency physician. Endovascular graft infection begins with unspecific clinical manifestations. An high index of suspicion in any patient with an aortic stent graft presenting prolonged or recurrent fever and or abdominal or back pain and a low threshold for obtaining CT scan should increase the clinician's ability to make a timely diagnosis in the ED setting

Frequency encoding for simultaneous display of multimodality images.

An original method for simultaneous display of functional and anatomic images, based on frequency encoding (FE), merges color PET with T1-weighted MR brain images, and grayscale PET with multispectral color MR images. A comparison with two other methods reported in the literature for image fusion (averaging and intensity modulation techniques) was performed. Methods: For FE, the Fourier transform of the merged image was obtained summing the low frequencies of the PET image and the high frequencies of the MR image. For image averaging, the merged image was obtained as a weighted average of the intensities of the two images to be merged. For intensity modulation, the red, green and blue components of the color image were multiplied on a pixel- by-pixel basis by the grayscale image. A comparison of the performances of the three techniques was made by three independent observers assessing the conspicuity of specific MRI and PET information in the merged images. For evaluation purposes, images from seven patients and a computer-simulated MRI/PET phantom were used. Data were compared with a chi-square test applied to ranks. Results: For the depiction of MRI and PET information when merging color PET and T1-weighted MR images, FE was rated superior to intensity modulation and averaging techniques in a significant number of comparisons. For merging grayscale PET with multispectral color MR images, FE and intensity modulation were rated superior to image averaging in terms of both MRI and PET information. Conclusion: The data suggest that improved simultaneous evaluation of MRI and PET information can be achieved with a method based on FE

A voxel-based morphometry study of disease severity correlates in relapsing–remitting multiple sclerosis

Previous studies have shown a preferential loss of grey matter in fronto-temporal regions in patients with multiple sclerosis. Studies of correlates of disease severity are more controversial, because some studies have suggested an association between sensorimotor cortex atrophy and Expanded Disability Status Scale score, while others did not find such a correlation. The objective of this study was to assess the correlation of regional loss of grey matter and white matter with indexes of clinical and radiological severity in relapsing–remitting multiple sclerosis, including the Expanded Disability Status Scale and lesion load. Correlations between Expanded Disability Status Scale, lesion load and disease duration were assessed in 128 patients with relapsing–remitting multiple sclerosis (Expanded Disability Status Scale range 1.0–6.0) using optimized voxel-based morphometry. Bilateral loss of grey matter in sensorimotor cortices was correlated with Expanded Disability Status Scale, and tissue loss also involved adjacent white matter, extending along pyramidal tracts to the brainstem. Increasing lesion load was correlated with loss of deep grey matter and white matter. No specific region of grey matter or white matter showed a significant correlation with disease duration. These findings support the hypothesis that motor neuron involvement plays a major role in the progression of physical disability. Lesion load accrual affects mainly highly interconnected subcortical structures, while disease duration has a less significant impact on brain atrophy, probably owing to the inter-subject heterogeneity of the clinical course of the disease