[Idiopathic orbital inflammatory syndrome: Report of 24 cases].

PubMed

Khochtali, S; Zayani, M; Ksiaa, I; Ben Meriem, I; Zaouali, S; Jelliti, B; Khairallah, M

2018-04-01

Idiopathic orbital inflammatory syndrome (IOIS) is an inflammatory condition of unknown etiology. The inflammation may affect all the structures within the orbit (anterior, diffuse, apical, myositic, dacryoadenitis) and corresponds to uniquely orbital inflammation without an identifiable local cause or systemic disease. The goal of this study is to describe the clinical and radiographic characteristics of IOIS and discuss the role of orbital biopsy in this condition. This is a retrospective review of the charts of 24 patients diagnosed with IOIS at Fattouma Bourguiba hospital, Monastir, Tunisia, from January 2007 to December 2015. This study included all patients with IOIS and a minimum follow-up of six months. All patients had a complete ophthalmological examination and orbital and head CT scan and/or MRI. A work-up was performed in all cases to rule out local causes and systemic disease. Only 11 patients underwent biopsy. The diagnosis of the clinical entity IOIS was made according to the Rootman criteria. Oral steroids were the first line therapy. A bolus of intravenous methylprednisolone was administered first in vision-threatening cases. Response to treatment was defined as disappearance of signs and symptoms of IOIS. Orbital pain was the most common symptom (62.5%), followed by proptosis and decreased vision (37.5% each). Best-corrected visual acuity (BCVA) was greater than 5/10 in 70.7% of patients. Lacrimal gland enlargement was observed in 3 patients. Oculomotor disorders were present in 70% of cases and 20.8% of patients had compressive optic neuropathy. Orbital imaging showed, in most cases, oculomotor muscle inflammation (87.5%) involving particularly the superior rectus muscle (54.2%) and inflammation of orbital fat (66.7%). Fifty percent had myositic inflammation. Biopsy was performed in 11 patients, showing nonspecific inflammation (n=10) and the sclerosing form (n=1). A total of 83.3% of patients received oral corticosteroids for a mean duration of 5.5 months. IOIS is a diagnosis of exclusion, based on history, clinical course, response to steroid therapy, laboratory tests, or even biopsy in selected cases. Orbital imaging provides valuable clues for diagnosis of IOIS and for identification of affected structures. Prolonged steroid therapy is necessary as IOIS classically responds to steroids; nevertheless, partial recovery or relapses often occur. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

The Poynting-Robertson effect in the Newtonian potential with a Yukawa correction

NASA Astrophysics Data System (ADS)

Haranas, Ioannis; Ragos, Omiros; Gkigkitzis, Ioannis; Kotsireas, Ilias; Martz, Connor; Van Middekoop, Sheldon

2018-01-01

We consider a Yukawa-type gravitational potential combined with the Poynting-Robertson effect. Dust particles originating within the asteroid belt and moving on circular and elliptic trajectories are studied and expressions for the time rate of change of their orbital radii and semimajor axes, respectively, are obtained. These expressions are written in terms of basic particle parameters, namely their density and diameter. Then, they are applied to produce expressions for the time required by the dust particles to reach the orbit of Earth. For the Yukawa gravitational potential, dust particles of diameter 10^{ - 3} m in circular orbits require times of the order of 8.557 × 106 yr and for elliptic orbits of eccentricities e =0.1, 0.5 require times of 9.396 × 106 and 2.129 × 106 yr respectively to reach Earth's orbit. Finally, various cases of the Yukawa potential are studied and the corresponding particle times to reach Earth's are derived per case along with numerical results for circular and various elliptical orbits.

Expanding MIRAgel scleral buckle simulating an orbital tumor in four cases.

PubMed

Shields, Carol L; Demirci, Hakan; Marr, Brian P; Mashayekhi, Arman; Materin, Miguel A; Shields, Jerry A

2005-01-01

To describe four patients with an enlarging orbital mass from a swollen MIRAgel scleral buckle that simulated an orbital neoplasm. In a retrospective, single-center case series at the Ocular Oncology Service at Wills Eye Hospital of Thomas Jefferson University, 4 eyes of 4 patients were referred for evaluation and treatment of a suspected orbital tumor. The initial presenting features were orbital mass (case 1), strabismus (case 2), and conjunctival mass with orbital extension (cases 3 and 4). Each patient vaguely recalled previous uncomplicated retinal detachment surgery 12 to 20 years earlier. Confirmation of the buckling implant material was made with the retina surgeon in 3 cases. A nontender, forniceal conjunctival mass, deep to the Tenon fascia and appearing as a translucent firm elevation was seen in all 4 cases. Axial CT (case 1) revealed a circumscribed anterior temporal orbital mass, believed to be a large inclusion cyst, 4 times thicker than the nasal scleral buckle. Ocular ultrasonography depicted an echolucent mass in the episcleral region (cases 3 and 4) that was 2 times thicker than the nasal scleral buckle (case 3). Excision was attempted in case 1, but only piecemeal removal was achieved, leading to extensive postoperative inflammation and decreased vision. The other 3 cases were followed conservatively without excision because they were each recognized to be a swollen MIRAgel implant and not an orbital tumor. MIRAgel scleral buckle material can greatly enlarge over a period of 10 years and simulate an orbital tumor or orbital cyst. Patients often do not recall details of the retinal surgery. Caution is advised regarding excision of this material because it is friable and can lead to extensive postoperative inflammation.

Titanium Mesh Reconstruction of Orbital Roof Fracture with Traumatic Encephalocele: A Case Report and Review of Literature

PubMed Central

Mokal, Nitin J.; Desai, Mahinoor F.

2012-01-01

Orbital roof fractures are rare. Traumatic encephaloceles in the orbital cavity are even rarer, with only 21 cases published to date. Orbital roof fractures are generally encountered in males between 20 and 40 years of age following automobile collision. We report a case of an orbital roof fracture with traumatic encephalocele into the left orbit. Early diagnosis and treatment are very important because the raised intraorbital pressure may irreversibly damage the optic nerve. Computed tomography with 3-D reconstruction, the imaging modality of choice, showed the displaced fracture fragment deep into the orbit. Reconstruction of the orbital roof should be performed in every case. We used an extracranial approach to elevate the fracture with titanium mesh to stabilize the fragment. The cosmetic results were excellent but delay in treatment was responsible for delayed recovery of vision. The case report is followed by a brief overview of orbital roof fractures including pertinent review of literature. PMID:23450105

Cranio-orbital primary intraosseous haemangioma

PubMed Central

Gupta, T; Rose, G E; Manisali, M; Minhas, P; Uddin, J M; Verity, D H

2013-01-01

Purpose Primary intraosseous haemangioma (IOH) is a rare benign neoplasm presenting in the fourth and fifth decades of life. The spine and skull are the most commonly involved, orbital involvement is extremely rare. We describe six patients with cranio-orbital IOH, the largest case series to date. Patients and methods Retrospective review of six patients with histologically confirmed primary IOH involving the orbit. Clinical characteristics, imaging features, approach to management, and histopathological findings are described. Results Five patients were male with a median age of 56. Pain and diplopia were the most common presenting features. A characteristic ‘honeycomb' pattern on CT imaging was demonstrated in three of the cases. Complete surgical excision was performed in all cases with presurgical embolisation carried out in one case. In all the cases, histological studies identified cavernous vascular spaces within the bony tissue. These channels were lined by single layer of cytologically normal endothelial cells. Discussion IOCH of the cranio-orbital region is rare; in the absence of typical imaging features, the differential diagnosis includes chondroma, chondrosarcoma, bony metastasis, and lymphoma. Surgical excision may be necessary to exclude more sinister pathology. Intraoperative haemorrhage can be severe and may be reduced by preoperative embolisation. PMID:23989119

Single-stage soft tissue reconstruction and orbital fracture repair for complex facial injuries.

PubMed

Wu, Peng Sen; Matoo, Reshvin; Sun, Hong; Song, Li Yuan; Kikkawa, Don O; Lu, Wei

2017-02-01

Orbital fractures with open periorbital wounds cause significant morbidity. Timing of debridement with fracture repair and soft tissue reconstruction is controversial. This study focuses on the efficacy of early single-stage repair in combined bony and soft tissue injuries. Retrospective review. Twenty-three patients with combined open soft tissue wounds and orbital fractures were studied for single-stage orbital reconstruction and periorbital soft tissue repair. Inclusion criteria were open soft tissue wounds with clinical and radiographic evidence of orbital fractures and repair performed within 48 h after injury. Surgical complications and reconstructive outcomes were assessed over 6 months. The main outcome measures were enophthalmos, pre- and post-CT imaging of orbits, scar evaluation, presence of diplopia, and eyelid position. Enophthalmos was corrected in 16/19 cases and improved in 3/19 cases. 3D reconstruction of CT images showed markedly improved orbital alignment with objective measurements of the optic foramen to cornea distance (mm) in reconstructed orbits relative to intact orbits of 0.66, 95% confidence interval [CI] (lower 0.33, upper 0.99) mm. The mean baseline of Stony Brook Scar Evaluation Scale was 0.6, 95%CI (0.30-0.92), and for 6 months, the mean score was 3.4, 95%CI (3.05-3.73). Residual diplopia in secondary gazes was present in two patients; one patient had ectropion. Complications included one case of local wound infection. An early single-stage repair of combined soft tissue and orbital fractures yields satisfactory functional and aesthetic outcomes. Complications are low and likely related to trauma severity. Copyright © 2016 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

[Diagnosis and treatment of strabismus caused by nasal endoscopic surgery].

PubMed

Ai, L K; Wu, X; Wang, J N; Li, J; Wu, Y; Zhou, J; Song, W X; Guo, R L

2017-12-11

Objective: Strabismus with diplopia is the main orbital complication of functional endoscopic sinus surgery (FESS). This study was to analyze clinical findings, treatment and outcomes of such cases. Methods: Retrospective case series. Twenty-three cases were divided into 3 groups based on the disease severity: group A, partial transection of the medial rectus muscle, group B, complete transection of the medical rectus, group C, transection of the medial rectus combined with the other orbital injuries. Complete ophthalmology examinations, including eye alignment, eye motility, force duction test, force generation test, general eye exam, and medical imaging (orbital CT or MRI), were performed for each case. The treatment included botulinum toxin (Botox) injection to the lateral rectus muscle, transposition of the vertical rectus muscle, and orbital surgery if needed. Results: In group A with Botox injection, all the cases achieved single vision in primary position, but still remained some adduction weakness. In group B treated by vertical transposition surgery combined with Botox, 22% of the cases got single vision in primary gaze. In group C, even with more efforts of treatment, the cases with orbital injury can only get cosmetic improvement, and diplopia and adduction dysfunction were found in most cases. Conclusions: Due to the variety of the complications of FESS, force duction test is a crucial exam to detect the direction and severity of synechia in the orbit, which will give solid information to surgery approach as well as prognosis. Botox injection at early stage will minimize the contraction of antagonist lateral rectus, helping to postpone the transposition surgery which may cause anterior segment ischemia when performed right after the medial rectus transection injury. Botox may even reduce the synechia by minimizing the scarring process. Partial vertical rectus transposition combined with muscle resection may effectively correct the eye misalignment in primary gaze and improve eye motility. The prognosis of FESS induced orbital complications is quite related with the severity of the injury. Botox combined with surgery may help medial rectus transection cases to achieve single vision in primary gaze, but when there is any other orbital injury, treatment may only improve cosmetic appearance. (Chin J Ophthalmol, 2017, 53: 917-923) .

Collision Index and Stability of Elliptic Relative Equilibria in Planar {n}-body Problem

NASA Astrophysics Data System (ADS)

Hu, Xijun; Ou, Yuwei

2016-12-01

It is well known that a planar central configuration of the {n}-body problem gives rise to solutions where each particle moves on a specific Keplerian orbit while the totality of the particles move on a homographic motion. When the eccentricity {e} of the Keplerian orbit belongs in {[0,1)}, following Meyer and Schmidt, we call such solutions elliptic relative equilibria (shortly, ERE). In order to study the linear stability of ERE in the near-collision case, namely when {1-e} is small enough, we introduce the collision index for planar central configurations. The collision index is a Maslov-type index for heteroclinic orbits and orbits parametrised by half-lines that, according to the definition given by Hu and Portaluri (An index theory for unbounded motions of Hamiltonian systems, Hu and Portaluri (2015, preprint)), we shall refer to as half-clinic orbits and whose definition in this context, is essentially based on a blow up technique in the case {e=1}. We get the fundamental properties of collision index and approximation theorems. As applications, we give some new hyperbolic criteria and prove that, generically, the ERE of minimal central configurations are hyperbolic in the near-collision case, and we give a detailed analysis of Euler collinear orbits in the near-collision case.

Advanced interferometric synthetic aperture radar (InSAR) time series analysis using interferograms of multiple-orbit tracks: A case study on Miyake-jima

NASA Astrophysics Data System (ADS)

Ozawa, Taku; Ueda, Hideki

2011-12-01

InSAR time series analysis is an effective tool for detecting spatially and temporally complicated volcanic deformation. To obtain details of such deformation, we developed an advanced InSAR time series analysis using interferograms of multiple-orbit tracks. Considering only right- (or only left-) looking SAR observations, incidence directions for different orbit tracks are mostly included in a common plane. Therefore, slant-range changes in their interferograms can be expressed by two components in the plane. This approach estimates the time series of their components from interferograms of multiple-orbit tracks by the least squares analysis, and higher accuracy is obtained if many interferograms of different orbit tracks are available. Additionally, this analysis can combine interferograms for different incidence angles. In a case study on Miyake-jima, we obtained a deformation time series corresponding to GPS observations from PALSAR interferograms of six orbit tracks. The obtained accuracy was better than that with the SBAS approach, demonstrating its effectiveness. Furthermore, it is expected that higher accuracy would be obtained if SAR observations were carried out more frequently in all orbit tracks. The deformation obtained in the case study indicates uplift along the west coast and subsidence with contraction around the caldera. The speed of the uplift was almost constant, but the subsidence around the caldera decelerated from 2009. A flat deformation source was estimated near sea level under the caldera, implying that deceleration of subsidence was related to interaction between volcanic thermal activity and the aquifer.

To study the effect of orbital sling on post operative vision in cases of maxillary carcinoma undergoing total maxillectomy.

PubMed

Shukla, Anirudh; Dudeja, Vivek

2014-06-01

To study effect of orbital sling on post operative vision in cases of maxillary carcinoma undergoing total maxillectomy. All patients with the principal procedure of "total maxillectomy" for histopathologically proven cases of carcinoma maxilla in department of otorhinolaryngology and head-neck surgery, N.S.C.B. medical college, Jabalapur, Madhya Pradesh, India from July 2011 to October 2013 were included. Out of the 20 patients irrespective of whether orbital sling was created or not, maximum number of patients 8 (40 %) showed a 3 step improvement, and maximum improvement seen was up to five steps. Out of the 14 patients in which orbital sling was created maximum number of patients 7 (50 %) showed a 3 step improvement, and maximum improvement seen was up to five steps. Out of the 6 patients in whom orbital sling was not created maximum number of patients 3 (50 %) showed a 2 step improvement, and maximum improvement seen was up to three steps. Infraorbital repair with the help of sling results in better improvement of vision as compared to those in whom sling was not or could not be made with no significant difference on eye movements.

Satellite Orbit Under Influence of a Drag - Analytical Approach

NASA Astrophysics Data System (ADS)

Martinović, M. M.; Šegan, S. D.

2017-12-01

The report studies some changes in orbital elements of the artificial satellites of Earth under influence of atmospheric drag. In order to develop possibilities of applying the results in many future cases, an analytical interpretation of the orbital element perturbations is given via useful, but very long expressions. The development is based on the TD88 air density model, recently upgraded with some additional terms. Some expressions and formulae were developed by the computer algebra system Mathematica and tested in some hypothetical cases. The results have good agreement with iterative (numerical) approach.

Tuberculous Orbital Abscess Associated with Thyroid Tuberculosis

PubMed Central

Sharma, Kumudini; Kanaujia, Vikas; Jain, Anu; Bains, Sukhdeep; Suman, Suvarna

2011-01-01

Purpose To report an unusual presentation of tuberculosis. Case Report A six-year old boy presented with left upper lid swelling of 15 days’ duration and an asymptomatic midline neck mass from 2 months ago. Imaging studies, and microbiologic tests which demonstrated acid-fast bacilli in the fine needle aspirate of the thyroid mass, both confirmed a diagnosis of cold tuberculous thyroid abscess with presumed hematogenous spread to the orbit. The patient demonstrated marked improvement of both lesions with antitubercular drugs. Conclusion This case illustrates a very rare association of orbital and thyroid tuberculosis. PMID:22454737

[Rationale for a diagnostic approach in non-Graves' orbital inflammation--Report of 61 patients].

PubMed

Gavard-Perret, A; Lagier, J; Delmas, J; Delas, J; Adenis, J-P; Robert, P-Y

2015-12-01

Orbital inflammatory syndromes include a wide variety of inflammatory intraorbital processes which are very different in terms of clinical presentation and prognosis. We currently prefer to differentiate so-called "specific" inflammations, for which an etiology is able to be identified, from idiopathic orbital inflammatory syndromes (IOIS), for which the etiology remains unknown and the histology is nonspecific. To propose an efficient diagnostic approach for clinicians managing patients with non-Graves' orbital inflammations. This is a retrospective and prospective study concerning 61 patients managed by the medical team for non-Graves' orbital inflammations between May, 1999 and May, 2013 in the ophthalmology departments of Nice and Limoges university hospitals in France. Seventeen specific inflammations, 19 orbital lymphomas and 25 idiopathic orbital inflammatory syndromes were included. Patients were divided into two groups. Thirty-six patients (group 1) underwent primary biopsy, while for the other 25 (group 2), therapy was begun empirically without biopsy. We could therefore compare both approaches in terms of diagnostic efficiency and time until identification of a specific etiology. Our statistical results show that an approach without primary biopsy leads to a number of specific diagnoses statistically much lower than that obtained by the approach with primary biopsy. Also, the risk of missing a specific inflammation (with as a consequence an inappropriate treatment and a risk of functional sequelae as well as a fatal risk of missing a lymphoproliferative pathology) is very clearly higher in the case of not performing primary biopsy. Finally, the average time elapsed between the initial consultation with the ophthalmologist and a specific diagnosis was one month in the case of the first approach, while this delay was almost three times higher with the second approach, with a mean of 2.91 months (P<0.01). Our study shows that biopsy should be the mainstay of diagnostic management. A trial of empiric treatment is only performed first in myositis or in locations where biopsy could jeopardize functional prognosis. It should only be done after biopsy in all other cases. Of course, in all cases of relapse or recurrence after treatment, biopsy should be performed or repeated. The diagnostic work-up of a patient with an orbital inflammatory process must of course include blood testing and orbital imaging, but also a systematic primary biopsy for histological examination in the vast majority of cases. It must be repeated at least in the case of any doubt about the diagnosis or in the case of any recurrence or resistance to treatment. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Accelerated orbits in black hole fields: the static case

NASA Astrophysics Data System (ADS)

Bini, Donato; de Felice, Fernando; Geralico, Andrea

2011-11-01

We study non-geodesic orbits of test particles endowed with a structure, assuming the Schwarzschild spacetime as background. We develop a formalism which allows one to recognize the geometrical characterization of those orbits in terms of their Frenet-Serret parameters and apply it to explicit cases as those of spatially circular orbits which witness the equilibrium under conflicting types of interactions. In our general analysis, we solve the equations of motion offering a detailed picture of the dynamics having in mind a check with a possible astronomical setup. We focus on certain ambiguities which plague the interpretation of the measurements preventing one from identifying the particular structure carried by the particle.

The management of orbital cysts associated with congenital microphthalmos and anophthalmos

PubMed Central

McLean, C J; Ragge, N K; Jones, R B; Collin, J R O

2003-01-01

Aims: To study the management of the orbital cysts present in a group of patients with anophthalmos and microphthalmos. Methods: A retrospective study of 34 patients (40 orbits) treated for orbital cyst associated with microphthalmos and anophthalmos. Results: The two largest treatment groups comprised 17 orbits (42.5%) where the cyst was removed surgically and 17 orbits (42.5%) where the cyst was retained and conformers were used. The remaining cases comprised two orbits (5%) where the cyst was aspirated initially; two orbits (5%) with large cysts which will need to be excised after further orbital growth; one orbit (2.5%) in which a silicone expander was used initially, and one orbit (2.5%) in which a mildly microphthalmic eye had some vision and was monitored but required no surgery. Conclusion: In this study 33 out of 34 patients had a good cosmetic result which illustrates that the orbital cyst in microphthalmos or anophthalmos performs a useful role in socket expansion and that the majority of patients with this condition can expect a good cosmetic outcome. PMID:12812886

A Hamiltonian approach to the planar optimization of mid-course corrections

NASA Astrophysics Data System (ADS)

Iorfida, E.; Palmer, P. L.; Roberts, M.

2016-04-01

Lawden's primer vector theory gives a set of necessary conditions that characterize the optimality of a transfer orbit, defined accordingly to the possibility of adding mid-course corrections. In this paper a novel approach is proposed where, through a polar coordinates transformation, the primer vector components decouple. Furthermore, the case when transfer, departure and arrival orbits are coplanar is analyzed using a Hamiltonian approach. This procedure leads to approximate analytic solutions for the in-plane components of the primer vector. Moreover, the solution for the circular transfer case is proven to be the Hill's solution. The novel procedure reduces the mathematical and computational complexity of the original case study. It is shown that the primer vector is independent of the semi-major axis of the transfer orbit. The case with a fixed transfer trajectory and variable initial and final thrust impulses is studied. The acquired related optimality maps are presented and analyzed and they express the likelihood of a set of trajectories to be optimal. Furthermore, it is presented which kind of requirements have to be fulfilled by a set of departure and arrival orbits to have the same profile of primer vector.

GOATS - Orbitology Component

NASA Technical Reports Server (NTRS)

Haber, Benjamin M.; Green, Joseph J.

2010-01-01

The GOATS Orbitology Component software was developed to specifically address the concerns presented by orbit analysis tools that are often written as stand-alone applications. These applications do not easily interface with standard JPL first-principles analysis tools, and have a steep learning curve due to their complicated nature. This toolset is written as a series of MATLAB functions, allowing seamless integration into existing JPL optical systems engineering modeling and analysis modules. The functions are completely open, and allow for advanced users to delve into and modify the underlying physics being modeled. Additionally, this software module fills an analysis gap, allowing for quick, high-level mission analysis trades without the need for detailed and complicated orbit analysis using commercial stand-alone tools. This software consists of a series of MATLAB functions to provide for geometric orbit-related analysis. This includes propagation of orbits to varying levels of generalization. In the simplest case, geosynchronous orbits can be modeled by specifying a subset of three orbit elements. The next case is a circular orbit, which can be specified by a subset of four orbit elements. The most general case is an arbitrary elliptical orbit specified by all six orbit elements. These orbits are all solved geometrically, under the basic problem of an object in circular (or elliptical) orbit around a rotating spheroid. The orbit functions output time series ground tracks, which serve as the basis for more detailed orbit analysis. This software module also includes functions to track the positions of the Sun, Moon, and arbitrary celestial bodies specified by right ascension and declination. Also included are functions to calculate line-of-sight geometries to ground-based targets, angular rotations and decompositions, and other line-of-site calculations. The toolset allows for the rapid execution of orbit trade studies at the level of detail required for the early stage of mission concept development.

A Method for Calculating the Mean Orbits of Meteor Streams

NASA Astrophysics Data System (ADS)

Voloshchuk, Yu. I.; Kashcheev, B. L.

An examination of the published catalogs of orbits of meteor streams and of a large number of works devoted to the selection of streams, their analysis and interpretation, showed that elements of stream orbits are calculated, as a rule, as arithmetical (sometimes, weighed) sample means. On the basis of these means, a search for parent bodies, a study of the evolution of swarms generating these streams, an analysis of one-dimensional and multidimensional distributions of these elements, etc., are performed. We show that systematic errors in the estimates of elements of the mean orbits are present in each of the catalogs. These errors are caused by the formal averaging of orbital elements over the sample, while ignoring the fact that they represent not only correlated, but dependent quantities, with nonlinear, in most cases, interrelations between them. Numerous examples are given of such inaccuracies, in particular, the cases where the "mean orbit of the stream" recorded by ground-based techniques does not cross the Earth's orbit. We suggest the computation algorithm, in which the averaging over the sample is carried out at the initial stage of the calculation of the mean orbit, and only for the variables required for subsequent calculations. After this, the known astrometric formulas are used to sequentially calculate all other parameters of the stream, considered now as a standard orbit. Variance analysis is used to estimate the errors in orbital elements of the streams, in the case that their orbits are obtained by averaging the orbital elements of meteoroids forming the stream, without taking into account their interdependence. The results obtained in this analysis indicate the behavior of systematic errors in the elements of orbits of meteor streams. As an example, the effect of the incorrect computation method on the distribution of elements of the stream orbits close to the orbits of asteroids of the Apollo, Aten, and Amor groups (AAA asteroids) is examined.

The plastic surgeon and Graves disease.

PubMed

Chiarelli, A

2004-01-01

Thyroid-associated ophthalmopathy is a disease caused by autoimmune processes that also affects the thyroid gland and the lower limbs; at orbital level, it involves the muscle and adipose tissue. When medical treatment fails to achieve appreciable results, surgery aims to decompress the orbital cavity. In recent years, the treatment has been considerably improved by the introduction of transpalpebral lipectomy, which has produced valid results especially in cases when extrinsic muscle hypertrophy is limited; if it is severe, however, lipectomy can be combined with expansion of the orbital cavity, thus enabling the latter to be restricted to one or two walls instead of three. Studying 52 patients who underwent orbital decompression involving lipectomy and/or orbital expansion, affecting a total of 96 orbits, enabled an assessment of the pros and cons of the single techniques in an attempt to identify a rational approach to this pathology. It emerged that lipectomy alone may suffice and obtain valid results in cases of mild-to-moderate proptosis (up to 24 mm) with limited extrinsic muscle hypertrophy, whereas orbital expansion--with or without lipectomy--is likely to be necessary in moderate-to-severe cases (proptosis greater than 24 mm). Additional procedures to correct the elevator and retractor muscles of the eyelids were almost always necessary.

Orbital blowout fracture location in Japanese and Chinese patients.

PubMed

Sun, Michelle T; Wu, Wencan; Watanabe, Akihide; Kakizaki, Hirohiko; Chen, Ben; Ueda, Kosuke; Katori, Nobutada; Takahashi, Yasuhiro; Selva, Dinesh

2015-01-01

To characterize the location of orbital blowout fractures in Asian individuals. This was a retrospective review of 470 consecutive Asian patients with orbital blowout fractures who presented to four tertiary care hospitals in Japan and China. Computed tomography (CT) characterized the location and severity of fractures involving the medial wall, the orbital floor, and/or the maxilloethmoidal strut. A total of 475 orbital blowout fractures were identified. More than one fracture location was involved in 19% of all cases. The medial orbital wall was the most commonly involved location, presenting in 29 cases (61%), of which 204 (43%) were isolated medial blowout fractures. The orbital floor was the second most common location involved, present in 226 cases (48%) with 150 isolated orbital floor fractures (32%), while the maxilloethmoidal strut was involved in 45 cases (9%) with 30 of those being isolated strut fractures (6%). The majority of fractures (62%) were classified as moderately severe, whilst 14% were mild, and 24% were severe. Associated nasal fractures were present in 16% of the cases. Orbital blowout fractures in Japanese and Chinese individuals occur most commonly in the medial wall. This is in contrast to previous reports on white individuals, who tend to sustain fractures involving the orbital floor rather than the medial wall.

Low-Cost 3D Printing Orbital Implant Templates in Secondary Orbital Reconstructions.

PubMed

Callahan, Alison B; Campbell, Ashley A; Petris, Carisa; Kazim, Michael

Despite its increasing use in craniofacial reconstructions, three-dimensional (3D) printing of customized orbital implants has not been widely adopted. Limitations include the cost of 3D printers able to print in a biocompatible material suitable for implantation in the orbit and the breadth of available implant materials. The authors report the technique of low-cost 3D printing of orbital implant templates used in complex, often secondary, orbital reconstructions. A retrospective case series of 5 orbital reconstructions utilizing a technique of 3D printed orbital implant templates is presented. Each patient's Digital Imaging and Communications in Medicine data were uploaded and processed to create 3D renderings upon which a customized implant was designed and sent electronically to printers open for student use at our affiliated institutions. The mock implants were sterilized and used intraoperatively as a stencil and mold. The final implant material was chosen by the surgeons based on the requirements of the case. Five orbital reconstructions were performed with this technique: 3 tumor reconstructions and 2 orbital fractures. Four of the 5 cases were secondary reconstructions. Molded Medpor Titan (Stryker, Kalamazoo, MI) implants were used in 4 cases and titanium mesh in 1 case. The stenciled and molded implants were adjusted no more than 2 times before anchored in place (mean 1). No case underwent further revision. The technique and cases presented demonstrate 1) the feasibility and accessibility of low-cost, independent use of 3D printing technology to fashion patient-specific implants in orbital reconstructions, 2) the ability to apply this technology to the surgeon's preference of any routinely implantable material, and 3) the utility of this technique in complex, secondary reconstructions.

Automating Initial Guess Generation for High Fidelity Trajectory Optimization Tools

NASA Technical Reports Server (NTRS)

Villa, Benjamin; Lantoine, Gregory; Sims, Jon; Whiffen, Gregory

2013-01-01

Many academic studies in spaceflight dynamics rely on simplified dynamical models, such as restricted three-body models or averaged forms of the equations of motion of an orbiter. In practice, the end result of these preliminary orbit studies needs to be transformed into more realistic models, in particular to generate good initial guesses for high-fidelity trajectory optimization tools like Mystic. This paper reviews and extends some of the approaches used in the literature to perform such a task, and explores the inherent trade-offs of such a transformation with a view toward automating it for the case of ballistic arcs. Sample test cases in the libration point regimes and small body orbiter transfers are presented.

On orbital stability of planar oscillations of a satellite in a circular orbit on the boundary of the parametric resonance

NASA Astrophysics Data System (ADS)

Bardin, B. S.; Chekina, E. A.

2018-05-01

We consider the motion of a satellite about its center of mass in a circular orbit. We study the problem of orbital stability for planar pendulum-like oscillations of the satellite. It is supposed that the satellite is a rigid body whose mass geometry is that of a plate. For the unperturbed motion the plane of the satellite-plate is perpendicular to the plane of the orbit. We perform a nonlinear analysis of the orbital stability of planar pendulum-like oscillations for previously unexplored parameter values corresponding to the combination resonance. It appears that in this case both formal orbital stability and instability can take place. The results of stability study are shown in stability diagrams.

Three-dimensional printing of orbital and peri-orbital masses in three dogs and its potential applications in veterinary ophthalmology.

PubMed

Dorbandt, Daniel M; Joslyn, Stephen K; Hamor, Ralph E

2017-01-01

To describe the technique and utility of three-dimensional (3D) printing for orbital and peri-orbital masses and discuss other potential applications for 3D printing. Three dogs with a chronic history of nonpainful exophthalmos. Computed tomography (CT) and subsequent 3D printing of the head was performed on each case. CT confirmed a confined mass, and an ultrasound-guided biopsy was obtained in each circumstance. An orbitotomy was tentatively planned for each case, and a 3D print of each head with the associated globe and mass was created to assist in surgical planning. In case 1, the mass was located in the cranioventral aspect of the right orbit, and the histopathologic diagnosis was adenoma. In case 2, the mass was located within the lateral masseter muscle, ventral to the right orbit between the zygomatic arch and the ramus of the mandible. The histopathologic diagnosis in case 2 was consistent with a lipoma. In case 3, the mass was located in the ventral orbit, and the histopathologic diagnosis was histiocytic cellular infiltrate. Three-dimensional printing in cases with orbital and peri-orbital masses has exceptional potential for improved surgical planning and provides another modality for visualization to help veterinarians, students, and owners understand distribution of disease. Additionally, as the techniques of 3D printing continue to evolve, the potential exists to revolutionize ocular surgery and drug delivery. © 2016 American College of Veterinary Ophthalmologists.

Geocenter motion estimated from GRACE orbits: The impact of F10.7 solar flux

NASA Astrophysics Data System (ADS)

Tseng, Tzu-Pang; Hwang, Cheinway; Sośnica, Krzysztof; Kuo, Chung-Yen; Liu, Ya-Chi; Yeh, Wen-Hao

2017-06-01

We assess the impact of orbit modeling on the origin offsets between GRACE kinematic and reduced-dynamic orbits. The origin of the kinematic orbit is the center of IGS network (CN), whereas the origin of the reduced-dynamic orbit is assumed to be the center of mass of the Earth (CM). Theoretically, the origin offset between these two orbits is associated with the geocenter motion. However, the dynamic property of the reduced-dynamic orbit is highly related to orbit parameterizations. The assessment of the F10.7 impact on the geocenter motion is implemented by using different orbit parameterization setups in the reduced-dynamic method. We generate two types of reduced-dynamic orbits using 15 and 240 empirical parameters per day from 2005 to 2012. The empirical parameter used in Bernese GNSS Software is called piece-wise constant empirical acceleration (PCA) and is mainly to absorb the non-gravitational forces mostly related to the atmospheric drag and solar radiation pressure. The differences between kinematic and dynamic orbits can serve as a measurement for geocenter. The RMS value of the geocenter measurement in the 15-PCA case is approximately 3.5 cm and approximately 2 cm in the 240-PCA case. The correlation between the orbit difference and F10.7 is about 0.90 in the 15-PCA case and -0.10 to 0 in the 240-PCA case. This implies that the reduced-dynamic orbit modeled with 240 PCAs absorbs the F10.7 variation, which aliases to the 15-PCA orbit solution. The annual amplitudes of the geocenter motion are 3.1, 3.1 and 2.5 mm in the 15-PCA case, compared to 0.9, 2.0 and 1.3 mm in the 240-PCA case in the X, Y and Z components, respectively. The 15-PCA solution is thus closer to the geocenter motions derived from other space-geodetic techniques. The proposed method is limited to the parameterizations in the reduced-dynamic approach.

Safety of silastic sheet for orbital wall reconstruction.

PubMed

Moon, Seong June; Suh, Hyun Suk; Park, Bo Young; Kang, So Ra

2014-07-01

Many implants are being used for the reconstruction of orbital wall fractures. The effect of the choice of implant for the reconstruction of an orbital wall fracture on the surgical outcome is under debate. The purpose of this article is to compare the outcomes of orbital wall reconstruction of small orbital wall fractures on the basis of the implants used. The authors conducted a retrospective study using electronic databases. Between March 2001 and December 2012, 461 patients with orbital wall fractures were included in this study. Among them, 431 patients in whom the fracture size was less than 300 mm(2) were analyzed. The fracture size was calculated using computed tomography scans of the orbit in the sagittal and coronal images. Cases in which the fracture size was less than 300 mm(2) were included in this study. One hundred and twenty-nine patients were treated with silastic sheets; 238 patients were treated with titanium meshes; and absorbable meshes were used in the case of 64 patients. Overall, 13 patients required revision, and the revision rate was 3.0%. The revision rate of the silastic sheet group was 5.4%. In the multivariable analysis, the revision rate of the group reconstructed with silastic sheets was highly statistically significant (P=0.043, odds ratio=3.65). However, other factors such as age, sex, fracture type, and fracture size were not significant. Reconstruction of orbital wall fractures with silastic sheets may cause more complications than that with other materials such as titanium meshes and absorbable meshes.

Classifying orbits in galaxy models with a prolate or an oblate dark matter halo component

NASA Astrophysics Data System (ADS)

Zotos, Euaggelos E.

2014-03-01

Aims: The distinction between regular and chaotic motion in galaxies is undoubtedly an issue of paramount importance. We explore the nature of orbits of stars moving in the meridional plane (R,z) of an axially symmetric galactic model with a disk, a spherical nucleus, and a flat biaxial dark matter halo component. In particular, we study the influence of all the involved parameters of the dynamical system by computing both the percentage of chaotic orbits and the percentages of orbits of the main regular resonant families in each case. Methods: To distinguish between ordered and chaotic motion, we use the smaller alignment index (SALI) method to extensive samples of orbits by numerically integrating the equations of motion as well as the variational equations. Moreover, a method based on the concept of spectral dynamics that utilizes the Fourier transform of the time series of each coordinate is used to identify the various families of regular orbits and also to recognize the secondary resonances that bifurcate from them. Two cases are studied for every parameter: (i) the case where the halo component is prolate and (ii) the case where an oblate dark halo is present. Results: Our numerical investigation indicates that all the dynamical quantities affect, more or less, the overall orbital structure. It was observed that the mass of the nucleus, the halo flattening parameter, the scale length of the halo, the angular momentum, and the orbital energy are the most influential quantities, while the effect of all the other parameters is much weaker. It was also found that all the parameters corresponding to the disk only have a minor influence on the nature of orbits. Furthermore, some other quantities, such as the minimum distance to the origin, the horizontal, and the vertical force, were tested as potential chaos detectors. Our analysis revealed that only general information can be obtained from these quantities. We also compared our results with early related work. Appendix A is available in electronic form at http://www.aanda.org

Orbital cellulitis: clinical course and management challenges. the Lagos State University Teaching Hospital experience.

PubMed

Balogun, Bolanle G; Balogun, Modupe M; Adekoya, Bola J

2012-01-01

Orbital cellulitis is a devastating acute infection of orbital soft tissues located posterior to the orbital septum. It is both vision and life-threatening. It is an ocular emergency which most often present in childhood. This article reviewed cases presenting during the study period with the view of examining the pattern of presentation, clinical course and management challenges. A retrospective study was conducted on patients presenting with orbital cellulitis between January 2008 and June 2011. Socio-demographic data, entry and discharge visual acuity, presenting complaints, predisposing factors, duration of complaints, admission period and complications were extracted from clinical records and analyzed. Seventeen (17) patients presented with orbital cellulitis constituting 6.2% of ocular emergency admissions during the study period. Twelve (70.6%) were males. Thirteen (76.5%) were children. The major predisposing factors were upper respiratory tract infections, and facial and globe injuries in five (22.7%) cases respectively. Only five (29.4%), presented within three days of disease onset. Average duration of admission was 10.6 days. Complications during the course of disease were category 4 and 5 blindness in five (23.5%), orbital abscess four (23.5%), cavernous sinus thrombosis two (11.8%), contralateral preseptal cellulitis two (11.8%) and exposure keratopathy in one (5.9%). Orbital cellulitis has remained a disease with high ocular morbidity. The major management challenges were poor financial status of patients precluding necessary diagnostic laboratory and imaging studies. Early recognition, diagnosis and treatment are crucial to the preservation of vision and reduced occurrence of complications. The importance of record keeping is also highlighted.

February Hydrids (FHY-1032)

NASA Astrophysics Data System (ADS)

Roggemans, Paul; Cambell-Burns, Peter

2018-03-01

CAMS reported an outburst of an unknown minor stream on 14 February 2018, listed in the IAU working list of meteor showers as #1032 FCM (α = 124°, δ = +2°, λʘ = 324°, vg = 16.5 km/s). This analysis shows that many similar orbits can be found in the time span and region in space around the reference orbit. The term 'outburst' is rather misleading as only few orbits were detected during several nights. A search through all public available orbit catalogues resulted in a significant number of similar orbits, but the region proves to be rich in unrelated similar sporadic meteors that fulfill low and medium low D-criteria. This case study on the possible February Hydrids did not result in a convincing evidence for the existence of this minor shower. Both the distribution of the number of similar orbits and the spreading in space indicate the possible presence of a diffuse minor shower without any distinct peak activity. This is a case of a barely detectable minor stream.

Ventral transpalpebral anterior orbitotomy: surgical description and report of 3 cases.

PubMed

McDonald, Jessica E; Knollinger, Amy M; Dees, Darryl D

2016-01-01

To describe a surgical approach to allow access to the ventral anterior canine orbit and report outcomes of three cases. After induction of general anesthesia and aseptic preparation of the surgical site, a 2.5- to 3-cm curvilinear skin incision was created through the inferior eyelid at the level of the ventral orbital rim. A combination of sharp and blunt dissection facilitated entrance into the ventral anterior orbital space for the removal of diseased tissues or allows for drainage of purulent debris. Two-layer closure was performed, and postoperative lateral temporary tarsorrhaphy sutures were retained to provide globe protection. Three dogs underwent unilateral ventral transpalpebral anterior orbitotomy. Prior to surgery, apart from a complete ophthalmic examination, ocular ultrasound was used to diagnose orbital disease in two cases, and MRI was utilized in the third case. Exploratory orbitotomy revealed a large mucocele in case 1, orbital bacterial abscessation in case 2, and necrotizing zygomatic sialoadenitis in case 3. Clinical exophthalmos resolved immediately after surgery. The surgical site in all cases healed within 2 weeks. One patient had a superficial corneal ulceration 2 weeks after surgery which healed uneventfully. Recurrence of orbital disease was not noted in any case. Ventral transpalpebral anterior orbitotomy is a simple procedure that allows easy access to the ventral anterior orbit to allow for removal of diseased tissues or to facilitate drainage of abscessation. Recurrence of orbital disease was not seen in any patient, with one patient experiencing blindness as a long-term complication following the procedure. © 2015 American College of Veterinary Ophthalmologists.

Orbital fat decompression for thyroid eye disease: retrospective case review and criteria for optimal case selection.

PubMed

Prat, Marta Calsina; Braunstein, Alexandra L; Dagi Glass, Lora R; Kazim, Michael

2015-01-01

The purpose of this study is to identify the subgroups of thyroid eye disease (TED) patients most likely to benefit from orbital fat decompression. This retrospective study reviews 217 orbits of 109 patients who underwent orbital fat decompression for proptosis secondary to thyroid eye disease. Charts were reviewed for demographic, radiographic, clinical, and surgical data. Three groups of patients were defined for the purposes of statistical analysis: those with proptosis secondary to expansion of the fat compartment (group I), those with proptosis secondary to enlargement of the extraocular muscles (group II), and those with proptosis secondary to enlargement of both fat and muscle (group III). Groups I and II, and those patients with greater preoperative proptosis and those with a history of radiation therapy were most likely to benefit from orbital fat decompression. However, even those in group III or with lesser proptosis appreciated significant benefit. While orbital fat decompression can and, at times, should be combined with bone decompression to treat proptosis resulting from thyroid eye disease, orbital fat decompression alone is associated with lower rates of surgical morbidity, and is especially effective for group I and II patients, those with greater preoperative proptosis, and those with a history of radiation.

Detection of symmetric homoclinic orbits to saddle-centres in reversible systems

NASA Astrophysics Data System (ADS)

Yagasaki, Kazuyuki; Wagenknecht, Thomas

2006-02-01

We present a perturbation technique for the detection of symmetric homoclinic orbits to saddle-centre equilibria in reversible systems of ordinary differential equations. We assume that the unperturbed system has primary, symmetric homoclinic orbits, which may be either isolated or appear in a family, and use an idea similar to that of Melnikov’s method to detect homoclinic orbits in their neighbourhood. This technique also allows us to identify bifurcations of unperturbed or perturbed, symmetric homoclinic orbits. Our technique is of importance in applications such as nonlinear optics and water waves since homoclinic orbits to saddle-centre equilibria describe embedded solitons (ESs) in systems of partial differential equations representing physical models, and except for special cases their existence has been previously studied only numerically using shooting methods and continuation techniques. We apply the general theory to two examples, a four-dimensional system describing ESs in nonlinear optical media and a six-dimensional system which can possess a one-parameter family of symmetric homoclinic orbits in the unperturbed case. For these examples, the analysis is compared with numerical computations and an excellent agreement between both results is found.

Improved solution accuracy for Landsat-4 (TDRSS-user) orbit determination

NASA Technical Reports Server (NTRS)

Oza, D. H.; Niklewski, D. J.; Doll, C. E.; Mistretta, G. D.; Hart, R. C.

1994-01-01

This paper presents the results of a study to compare the orbit determination accuracy for a Tracking and Data Relay Satellite System (TDRSS) user spacecraft, Landsat-4, obtained using a Prototype Filter Smoother (PFS), with the accuracy of an established batch-least-squares system, the Goddard Trajectory Determination System (GTDS). The results of Landsat-4 orbit determination will provide useful experience for the Earth Observing System (EOS) series of satellites. The Landsat-4 ephemerides were estimated for the January 17-23, 1991, timeframe, during which intensive TDRSS tracking data for Landsat-4 were available. Independent assessments were made of the consistencies (overlap comparisons for the batch case and convariances for the sequential case) of solutions produced by the batch and sequential methods. The filtered and smoothed PFS orbit solutions were compared with the definitive GTDS orbit solutions for Landsat-4; the solution differences were generally less than 15 meters.

Hydrostar Thermal and Structural Deformation Analyses of Antenna Array Concept

NASA Technical Reports Server (NTRS)

Amundsen, Ruth M.; Hope, Drew J.

1998-01-01

The proposed Hydrostar mission used a large orbiting antenna array to demonstrate synthetic aperture technology in space while obtaining global soil moisture data. In order to produce accurate data, the array was required to remain as close as possible to its perfectly aligned placement while undergoing the mechanical and thermal stresses induced by orbital changes. Thermal and structural analyses for a design concept of this antenna array were performed. The thermal analysis included orbital radiation calculations, as well as parametric studies of orbit altitude, material properties and coating types. The thermal results included predicted thermal distributions over the array for several cases. The structural analysis provided thermally-driven deflections based on these cases, as well as based on a 1-g inertial load. In order to minimize the deflections of the array in orbit, the use of XN70, a carbon-reinforced polycyanate composite, was recommended.

Infective Endocarditis Presenting as Bilateral Orbital Cellulitis: An Unusual Case

PubMed Central

Hasan, Badar; Ukani, Rehman; Pauly, Rebecca R

2017-01-01

Orbital cellulitis is a severe and sight-threatening infection of orbital tissues posterior to the orbital septum. The most common causes of orbital cellulitis are rhinosinusitis, orbital trauma, and surgery. Infective endocarditis (IE) is a systemic infection that begins on cardiac valves and spreads by means of the bloodstream to peripheral organs. Septic emboli can spread to any organ including the eyes and can cause focal or diffuse ophthalmic infection. Ocular complications of IE classically include Roth’s spots, subconjunctival hemorrhages, chorioretinitis, and endophthalmitis. IE as a cause of orbital cellulitis has been described by only one author in the literature. Here, we present a very rare case of bilateral orbital cellulitis caused by IE. Through this case, we aim to create awareness of the potential for serious ocular complications in IE and provide an overview of the management. PMID:28721318

Glial heterotopia in an adult: A rare orbital mass.

PubMed

Sundaresh, Divya Dabir; Mangala Gouri, S R

2016-11-01

Heterotopic glial tissue is very rare in the orbit. Our case was an adult, which is unique since most cases reported in literature involve children. We describe a case of a 60-year-old man who presented with an orbital mass, which histopathologically revealed heterotopic glial tissue.

Neonatal orbital abscess

PubMed Central

Al-Salem, Khalil M; Alsarayra, Fawaz A; Somkawar, Areej R

2014-01-01

Orbital complications due to ethmoiditis are rare in neonates. A case of orbital abscess due to acute ethmoiditis in a 28-day-old girl is presented. A Successful outcome was achieved following antimicrobial therapy alone; spontaneous drainage of the abscess occurred from the lower lid without the need for surgery. From this case report, we intend to emphasize on eyelid retraction as a sign of neonatal orbital abscess, and to review all the available literature of similar cases. PMID:24008806

Growing skull fracture of the posterior cranial fossa and of the orbital roof.

PubMed

Caffo, M; Germanò, A; Caruso, G; Meli, F; Calisto, A; Tomasello, F

2003-03-01

Growing Skull Fractures (GSF) are rare complications of head trauma, primarily reported in infancy and early childhood. GSF are commonly located on calvaria, and rarely in other locations, including the skull base. In this study, we report two cases of GSF occurring in unusual locations. The first, a 8-month old girl, with a GSF of the suboccipital posterior fossa region, and the second, a 4-year old boy with a GSF of the right orbital roof. Both cases underwent operative treatment of the GSF, with microsurgical dissection and excision of the protruding gliotic brain tissue, watertight duraplasty and autologous bone cranial repair. The authors conducted a Medline search of the relevant English literature from 1966 to 2002. From the search, three cases of suboccipital posterior fossa region GSF and twelve series of orbital GSF, describing a total of 22 cases, have been found. A survey of the pathogenic mechanisms underlying this entity in these locations is reported. A review of suboccipital posterior fossa and orbital roof GSF cases, of nosological, ophthalmological and neurological data, neuroradiological and operative findings, and results of different treatment strategies are described.

Regions of stability of asteroids

NASA Technical Reports Server (NTRS)

Szebehely, V.; Lundberg, J.; Vicente, R.

1983-01-01

Using Hill's modified stability criterion, regions of orbital elements are established for conditions of stability. The model of the three-dimensional restricted problem of three bodies is used with the sun and Jupiter as the primaries. Four different cases are studied: direct and retrograde, outside and inside asteroidal orbits. The directions of the asteroidal orbits refer to the synodical reference frame and the positions refer to Jupiter's orbit. The orbital parameters of the asteroids are the semi-major axis (a), the eccentricity (e), and the inclination from Jupiter's orbital plane (i). The argument of the perihelion and the longitude of the ascending node are fixed at Omega = omega = 90 deg and the time of perihelion passage is T = 0 for all orbits.

Analytical slave-spin mean-field approach to orbital selective Mott insulators

NASA Astrophysics Data System (ADS)

Komijani, Yashar; Kotliar, Gabriel

2017-09-01

We use the slave-spin mean-field approach to study particle-hole symmetric one- and two-band Hubbard models in the presence of Hund's coupling interaction. By analytical analysis of the Hamiltonian, we show that the locking of the two orbitals vs orbital selective Mott transition can be formulated within a Landau-Ginzburg framework. By applying the slave-spin mean field to impurity problems, we are able to make a correspondence between impurity and lattice. We also consider the stability of the orbital selective Mott phase to the hybridization between the orbitals and study the limitations of the slave-spin method for treating interorbital tunnelings in the case of multiorbital Bethe lattices with particle-hole symmetry.

Orbital involvement in extranodal natural killer T cell lymphoma: an atypical case presentation and review of the literature.

PubMed

Ely, A; Evans, J; Sundstrom, J M; Malysz, J; Specht, C S; Wilkinson, M

2012-08-01

To report a rare case of extranodal NK/T cell lymphoma (NKTL) and to compare its features with those cases previously reported. Case report, observational and literature review. Complete ophthalmologic examinations followed by excisional biopsy, histopathologic examination and therapy with radiation and chemotherapy. Evaluation of clinical presenting features and histopathologic diagnosis along with patient outcome. A 22 year old female presented as a referral with right orbital swelling, decreased vision and eye pain for 5 weeks. Subsequent orbital CT and multiple biopsies resulted in a diagnosis of extranodal natural killer (NK)/T cell lymphoma (NKTL). Despite continued chemotherapy and orbital radiation the patient expired within 3 months of diagnosis. To our knowledge, only 8 cases of orbital involvement without nasal mucosal involvement are reported in the literature, the majority in patients of male gender around the fifth decade. Here we present an atypical and aggressive case of extranodal NK/T cell lymphoma presenting in a 22 year old Caucasian female as orbital swelling without evidence of nasal mucosal involvement. It is important to distinguish NKTL from the more common benign lymphoproliferative lesions of the orbital adnexa as prognosis of these two clinical entities varies and timely diagnosis is key. The present case demonstrates that extranodal NKTL can occur in the orbit without evidence of the more common nasal mucosal presentations and should be included in the differential diagnosis of ocular adnexal lesions suspicious for a lymphoproliferative disorder and/or an inflammatory process.

The periodic dynamics of the irregular heterogeneous celestial bodies

NASA Astrophysics Data System (ADS)

Lan, Lei; Yang, Mo; Baoyin, Hexi; Li, Junfeng

2017-02-01

In this paper, we develop a methodology to study the periodic dynamics of irregular heterogeneous celestial bodies. Heterogeneous bodies are not scarce in space. It has been found that bodies, such as 4 Vesta, 624 Hektor, 87 Sylvia, 16 Psyche and 25143 Itokawa, may all have varied internal structures. They can be divided into large-scale and small-scale cases. The varied internal structures of large-scale bodies always result from gradient pressure inside, which leads to compactness differences of the inner material. However, the heterogeneity of a small-scale body is always reflected by the different densities of different areas, which may originate from collision formation from multiple objects. We propose a modeling procedure for the heterogeneous bodies derived from the conventional polyhedral method and then compare its dynamical characteristics with those of the homogeneous case. It is found that zero-velocity curves, positions of equilibrium points, types of bifurcations in the continuation of the orbital family and the stabilities of periodic orbits near the heterogeneous body are different from those in the homogeneous case. The suborbicular orbits near the equatorial plane are potential parking orbits for a future mission, so we discuss the switching of the orbital stability of the family because it has fundamental significance to orbit maintenance and operations around actual asteroids.

A case of non-lacrimal immunoglobulin G4 (IgG4)-related orbital disease with mastitis.

PubMed

Farooq, Tahir Ali; Mudhar, Hardeep; Sandramouli, S

2016-01-01

IgG4-related orbital disease is a recognised cause for orbital inflammation. As its awareness increases and diagnostic accuracy improves there will be an increased number of cases being identified. This unique case demonstrates for the first time, with histological evidence, a case of a non-lacrimal IgG4-related orbital disease with concurrent IgG4-related mastitis. We describe a 47 year old who presented with a supraorbital swelling and mass. This was initially successfully treated with oral steroids and was later excised on recurrence. Immunohistochemical and blood serum analysis confirmed IgG4-related orbital disease. On systemic enquiry she was found to have a mass of the breast, which was shown to be IgG4-related mastitis. She is currently asymptomatic with no sign of recurrence and is under long-term surveillance. This case highlights the importance of systemic work up in patients presenting with orbital foci of IgG4 disease.

[Medpor plus titanic mesh implant in the repair of orbital blowout fractures].

PubMed

Han, Xiao-hui; Zhang, Jia-yu; Cai, Jian-qiu; Shi, Ming-guang

2011-05-10

To study the efficacy of porous polyethylene (Medpor) plus titanic mesh sheets in the repair of orbital blowout fractures. A total of 20 patients underwent open surgical reduction with the combined usage of Medpor and titanic mesh. And they were followed up for average period of 14.5 months (range: 9 - 18). There is no infection or extrusion of medpor and titanic mesh in follow-up periods. There was no instance of decreased visual acuity at post-operation. And all cases of enophthalmos were corrected. The post-operative protrusion degree of both eyes was almost identical at less than 2 mm. The movement of eye balls was satisfactory in all directions. Diplopia disappeared in 18 cases with a cure rate of 90%, 1 case improved and 1 case persisted. Medpor plus titanic mesh implant is a safe and effective treatment in the repair of orbital blow out fractures.

Determination of ASPS performance for large payloads in the shuttle orbiter disturbance environment. [digital simulation

NASA Technical Reports Server (NTRS)

Keckler, C. R.; Kibler, K. S.; Powell, L. F.

1979-01-01

A high fidelity simulation of the annular suspension and pointing system (ASPS), its payload, and the shuttle orbiter was used to define the worst case orientations of the ASPS and its payload for the various vehicle disturbances, and to determine the performance capability of the ASPS under these conditions. The most demanding and largest proposed payload, the Solar Optical Telescope was selected for study. It was found that, in all cases, the ASPS more than satisfied the payload's requirements. It is concluded that, to satisfy facility class payload requirements, the ASPS or a shuttle orbiter free-drift mode (control system off) should be utilized.

Effects of structural spin-orbit coupling in two dimensional electron and hole liquids

NASA Astrophysics Data System (ADS)

Chesi, Stefano

The recent interest in spin-dependent phenomena in semiconductor heterostructures motivates our detailed study of the structural spin-orbit coupling present in clean two-dimensional electron and hole liquids. Interesting polarization effects are produced in a system out of equilibrium, as when a finite current flows in the sample. In particular, the consequences of a lateral confinement creating a quasi one-dimensional wire are studied in detail, partially motivated by a recent experimental investigation of the point-contact transmission for two-dimensional holes. We also address the role of the electron-electron interaction in the presence of spin-orbit coupling, which has received little attention in the literature. We discuss the formulation of the Hartree-Fock approximation in the particular case of linear Rashba spin-orbit. We establish the form of the mean-field phase diagram in the homogeneous case, which shows a complex interplay between paramagnetic and ferromagnetic states. The latter can be polarized in the plane or in a transverse direction, and are characterized by a complex spin structure and nontrivial occupation. The generality of the Hartree-Fock method allows a simple treatment of the Pauli spin susceptibility, and the application to different forms of spin-orbit coupling. Correlation corrections can be obtained in an analytic form for particular asymptotic regimes. For linear Rashba spin-orbit we identified the relevance of the large spin-orbit limit, dominated by many-body effects, and explicitly treated the high density limit, in which the system is asymptotically noninteracting. As a special case, we derive a new exact formula for the polarization dependence of the ring-diagram correlation energy.

Sinus opacification associated with exacerbation of thyroid eye disease.

PubMed

Abazari, Azin; Chak, Garrick; Feldon, Steven E

2010-01-01

To describe the association of sinus opacification with exacerbation of thyroid eye disease. Three cases followed orbital decompression performed when disease was quiescent and one case occurred without prior orbital or sinus surgery. Retrospective observational case series. Four patients' charts were retrospectively reviewed. Three patients with thyroid eye disease (TED), whose ophthalmopathy was stable after orbital decompression surgery, experienced recurrence of TED signs and symptoms after development of sinus inflammation. The fourth patient with TED did not have orbital surgery but presented with unilateral ophthalmopathy and ipsilateral sinus opacification. Paranasal sinus disease can exacerbate TED, possibly through a nonspecific inflammatory response. Minimizing inflammation proximal to the orbit may afford some protection against progression of the orbital process occurring in TED.

[Simultaneous repairing defects of orbital floor and palate with the modified temporalis muscle flap after the maxillectomy].

PubMed

Zhong, Q; Huang, Z G; Fang, J G; Chen, X J; Chen, X H; Hou, L Z; Li, P D; Ma, H Z; He, S Z

2016-09-07

Objective: To evaluate the outcome of one-stage reconstruction of maxillary and orbital defects with modified temporalis muscle flap (TMF) following the removal of malignant neoplasms. Methods: In this retrospective study, 15 patients underwent the reconstruction of defects of orbital floor and palate after maxillectomy for malignant tumor were included from June 2008 to June 2014. The modified temporalis muscle flap was used to repair the defects after surgery, and functional outcomes were analyzed. Results: All the patients were followed up for 12-81 months. Three cases of them received preoperative radiotherapy and 12 cases underwent postoperative radiotherapy. All flaps were survived. Epithelization of the tissues in oral and nasal cavity was completed in 4-6 weeks. Good functional reconstruction on swallowing and speaking functional results were achieved with maxillary and orbital reconstruction and no secondary deformity of external nose was observed. The eye positions in all cases were normal. Diplopia, diminution and loss of vision were not found. Conclusion: The modified TMF can be used for simultaneous reconstruction for the defects of orbital floor and palate after maxillectomy in patients whom free tissue flap can not be applied to, showing better cosmetic and functional results.

[Treatment of orbital abscesses and phlegmon in dogs and cats].

PubMed

Rühli, M B; Spiess, B M

1995-08-01

A diagnosis of orbital cellulitis or abscess was made in 13 dogs and four cats over the past five years. A foreign body was found in three of these cases. In five cases pasteurella spp. was isolated. In 15 of these cases the abscess was drained surgically. One dog was permanently blind due to inadequate surgical drainage of the abscess. In the remaining cases healing was uneventful. The surgical and medical therapy of orbital abscesses is illustrated by an exemplary case.

The Innisfree meteorite: Dynamical history of the orbit - Possible family of meteor bodies

NASA Astrophysics Data System (ADS)

Galibina, I. V.; Terent'eva, A. K.

1987-09-01

Evolution of the Innisfree meteorite orbit caused by secular perturbations is studied over the time interval of 500000 yrs (from the current epoch backwards). Calculations are made by the Gauss-Halphen-Gorjatschew method taking into account perturbations from the four outer planets - Jupiter, Saturn, Uranus and Neptune. In the above mentioned time interval the meteorite orbit has undergone no essential transformations. The Innisfree orbit intersected in 91 cases the Earth orbit and in 94 - the Mars orbit. A system of small and large meteor bodies (producing ordinary meteors and fireballs) which may be genetically related to the Innisfree meteorite has been found, i.e. there probably exists an Innisfree family of meteor bodies.

Orbital debris issues

NASA Technical Reports Server (NTRS)

Kessler, D. J.

1985-01-01

Man-made orbital debris, identified as a potential hazard to future space activities, is grouped into size categories. At least 79 satellites have broken up in orbit to date and, in combination with exploded rocket casings and antisatellite debris, threaten 10 km/sec collisions with other orbiting platforms. Only 5 percent of the debris is connected to payloads. The total population of orbiting objects over 4 cm in diameter could number as high as 15,000, and at 1 cm in diameter could be 32,000, based on NASA and NORAD studies. NASA has initiated the 10 yr Space Debris Assessment Program to characterize the hazards of orbiting debris, the potential damage to typical spacecraft components, and to identify means of controlling the damage.

F-18 FDG PET/CT findings in a patient with bilateral orbital and gastric mucosa-associated lymphoid tissue lymphomas.

PubMed

Suga, Kazuyoshi; Yasuhiko, Kawakami; Hiyama, Atsuto; Takeda, Koumei; Matsunaga, Naofumi

2009-09-01

Orbital mucosa-associated lymphoid tissue (MALT) lymphoma is an uncommon disease, while the incidence is recently increasing. We describe the F-18 fluorodeoxyglucose positron emission tomography computerized tomography (FDG PET/CT) findings in a case of bilateral orbital MALT lymphomas with a coexisting gastric lesion. Although only the lesion in the left orbit was initially identified on MR imaging, FDG PET/CT scan unexpectedly and additionally could identify the tiny lesion of the contralateral orbit and the gastric lesion. This patient received radiotherapy to all these lesions, with a combination of rituximab monoclonal antibody therapy. The follow-up PET/CT studies at 3, 6, and 9 months and 1.5 years after treatment showed regression or disappearance of all these FDG-avid lesions. Accurate localization and staging are crucial to select an adequate treatment in MALT lymphoma at any location. This case indicates the feasibility of FDG PET/CT scan for accurate localization and staging and also for monitoring treatment in patients with orbital MALT lymphoma.

Minimum fuel coplanar aeroassisted orbital transfer using collocation and nonlinear programming

NASA Technical Reports Server (NTRS)

Shi, Yun Yuan; Young, D. H.

1991-01-01

The fuel optimal control problem arising in coplanar orbital transfer employing aeroassisted technology is addressed. The mission involves the transfer from high energy orbit (HEO) to low energy orbit (LEO) without plane change. The basic approach here is to employ a combination of propulsive maneuvers in space and aerodynamic maneuvers in the atmosphere. The basic sequence of events for the coplanar aeroassisted HEO to LEO orbit transfer consists of three phases. In the first phase, the transfer begins with a deorbit impulse at HEO which injects the vehicle into a elliptic transfer orbit with perigee inside the atmosphere. In the second phase, the vehicle is optimally controlled by lift and drag modulation to satisfy heating constraints and to exit the atmosphere with the desired flight path angle and velocity so that the apogee of the exit orbit is the altitude of the desired LEO. Finally, the second impulse is required to circularize the orbit at LEO. The performance index is maximum final mass. Simulation results show that the coplanar aerocapture is quite different from the case where orbital plane changes are made inside the atmosphere. In the latter case, the vehicle has to penetrate deeper into the atmosphere to perform the desired orbital plane change. For the coplanar case, the vehicle needs only to penetrate the atmosphere deep enough to reduce the exit velocity so the vehicle can be captured at the desired LEO. The peak heating rates are lower and the entry corridor is wider. From the thermal protection point of view, the coplanar transfer may be desirable. Parametric studies also show the maximum peak heating rates and the entry corridor width are functions of maximum lift coefficient. The problem is solved using a direct optimization technique which uses piecewise polynomial representation for the states and controls and collocation to represent the differential equations. This converts the optimal control problem into a nonlinear programming problem which is solved numerically by using a modified version of NPSOL. Solutions were obtained for the described problem for cases with and without heating constraints. The method appears to be more robust than other optimization methods. In addition, the method can handle complex dynamical constraints.

Similarity in Bilateral Isolated Internal Orbital Fractures.

PubMed

Chen, Hung-Chang; Cox, Jacob T; Sanyal, Abanti; Mahoney, Nicholas R

2018-04-13

In evaluating patients sustaining bilateral isolated internal orbital fractures, the authors have observed both similar fracture locations and also similar expansion of orbital volumes. In this study, we aim to investigate if there is a propensity for the 2 orbits to fracture in symmetrically similar patterns when sustaining similar trauma. A retrospective chart review was performed studying all cases at our institution of bilateral isolated internal orbital fractures involving the medial wall and/or the floor at the time of presentation. The similarity of the bilateral fracture locations was evaluated using the Fisher's exact test. The bilateral expanded orbital volumes were analyzed using the Wilcoxon signed-rank test to assess for orbital volume similarity. Twenty-four patients with bilateral internal orbital fractures were analyzed for fracture location similarity. Seventeen patients (70.8%) had 100% concordance in the orbital subregion fractured, and the association between the right and the left orbital fracture subregion locations was statistically significant (P < 0.0001). Fifteen patients were analyzed for orbital volume similarity. The average orbital cavity volume was 31.2 ± 3.8 cm on the right and 32.0 ± 3.7 cm on the left. There was a statistically significant difference between right and left orbital cavity volumes (P = 0.0026). The data from this study suggest that an individual who suffers isolated bilateral internal orbital fractures has a statistically significant similarity in the location of their orbital fractures. However, there does not appear to be statistically significant similarity in the expansion of the orbital volumes in these patients.

3D Computational Mechanics Elucidate the Evolutionary Implications of Orbit Position and Size Diversity of Early Amphibians

PubMed Central

Marcé-Nogué, Jordi; Fortuny, Josep; De Esteban-Trivigno, Soledad; Sánchez, Montserrat; Gil, Lluís; Galobart, Àngel

2015-01-01

For the first time in vertebrate palaeontology, the potential of joining Finite Element Analysis (FEA) and Parametrical Analysis (PA) is used to shed new light on two different cranial parameters from the orbits to evaluate their biomechanical role and evolutionary patterns. The early tetrapod group of Stereospondyls, one of the largest groups of Temnospondyls is used as a case study because its orbits position and size vary hugely within the members of this group. An adult skull of Edingerella madagascariensis was analysed using two different cases of boundary and loading conditions in order to quantify stress and deformation response under a bilateral bite and during skull raising. Firstly, the variation of the original geometry of its orbits was introduced in the models producing new FEA results, allowing the exploration of the ecomorphology, feeding strategy and evolutionary patterns of these top predators. Secondly, the quantitative results were analysed in order to check if the orbit size and position were correlated with different stress patterns. These results revealed that in most of the cases the stress distribution is not affected by changes in the size and position of the orbit. This finding supports the high mechanical plasticity of this group during the Triassic period. The absence of mechanical constraints regarding the orbit probably promoted the ecomorphological diversity acknowledged for this group, as well as its ecological niche differentiation in the terrestrial Triassic ecosystems in clades as lydekkerinids, trematosaurs, capitosaurs or metoposaurs. PMID:26107295

Primary sporadic Burkitt lymphoma of the orbit, clinical characteristics, management, and outcomes: a case study.

PubMed

Bouali, Sofiene; Said, Imed Ben; Yedeas, Mohamed Dahmani; Abderrahmen, Khansa; Maatar, Nidhal; Boubaker, Adnen; Kallel, Jalel; Jemel, Hafedh

2016-03-01

Involvement of the orbit with Burkitt's lymphoma is a very rare presentation of extra-nodal lymphoma. We report a case of a 2-year-old female presented an unusual location of sporadic Burkitt's lymphoma arising in the orbital region. Diagnostic magnetic resonance imagining identified an oval-shaped mass on the lateral rectus of the right orbit that caused dislocation of eyeball, for which she underwent a biopsy from the periorbital swellings. The mass was histologically confirmed as Burkitt's lymphoma, and postoperative aggressive chemotherapy was initiated. We describe clinical diagnosis, histological aspects, radiological features, and current management of this rapidly growing malignant tumor. Because of the rapid progression of Burkitt lymphoma, and considering that it responds well to treatment, early recognition and appropriate management are important factors for survival and to preserve visual function.

Effects on biological systems of reflected light from a satellite power system

NASA Technical Reports Server (NTRS)

White, M.

1981-01-01

Light reflection produced by the satellite power system and the possible effects of that light on the human eye, plants, and animals were studied. For the human eye, two cases of reflected light, might cause eye damage if viewed for too long. These cases are: (1) if, while in low Earth orbit, the orbital transfer vehicle is misaligned to reflect the Sun to Earth there exists a maximum safe fixation time for the naked eye of 42.4 secs; (2) reflection from the aluminum paint on the back of the orbital transfer vehicle, while in or near low Earth orbit, can be safely viewed by the naked eye for 129 sec. For plants and animals the intensity and timing of light are not a major problem. Ways for reducing and/or eliminating the irradiances are proposed.

The evolution of a binary in a retrograde circular orbit embedded in an accretion disk

NASA Astrophysics Data System (ADS)

Ivanov, P. B.; Papaloizou, J. C. B.; Paardekooper, S.-J.; Polnarev, A. G.

2015-04-01

Aims: Supermassive black hole binaries may form as a consequence of galaxy mergers. Both prograde and retrograde orbits have been proposed. We study a binary with a small mass ratio, q, in a retrograde orbit immersed in and interacting with a gaseous accretion disk in order to estimate the time scales for inward migration that leads to coalescence and the accretion rate to the secondary component. Methods: We employed both semi-analytic methods and two-dimensional numerical simulations, focusing on the case where the binary mass ratio is small but large enough to significantly perturb the disk. Results: We develop the theory of type I migration in this case and go on to determine the conditions for gap formation. We find that when this happens inward migration occurs on a time scale equal to the time required for one half of the secondary mass to be accreted through the unperturbed accretion disk. The accretion rate onto the secondary itself is found to only play a minor role in the orbital evolution as it is of the order of q1/3 of that to the primary. We obtain good general agreement between the semi-analytic and fully numerical approaches and note that the former can be applied to disks with a wide dynamic range on long time scales. Conclusions: We conclude that inward migration induced by interaction with the disk can enable the binary to migrate inwards, alleviating the so-called final parsec problem. When q is sufficiently small, there is no well-pronounced cavity inside the binary orbit, unlike the prograde case. The accretion rate to the secondary does not influence the binary orbital evolution much, but can lead to some interesting observational consequences, provided the accretion efficiency is sufficiently large. In this case the binary may be detected as, for example, two sources of radiation rotating around each other. However, the study should be extended to consider orbits with significant eccentricity and the effects of gravitational radiation at small length scales. Also, torques acting between a circumbinary accretion disk, which has a non-zero inclination with respect to a retrograde binary orbit at large distances, may cause the inclination to increase on a time scale that can be similar to, or smaller than, the time scale of orbital evolution, depending on the disk parameters and binary mass ratio. This is also an aspect for future study. The movies are available in electronic form at http://www.aanda.org

[Orbital decompression in Grave's disease: comparison of techniques].

PubMed

Sellari-Franceschini, S; Berrettini, S; Forli, F; Bartalena, L; Marcocci, C; Tanda, M L; Nardi, M; Lepri, A; Pinchera, A

1999-12-01

Grave's ophthalmopathy is an inflammatory, autoimmune disorder often associated with Grave's disease. The inflammatory infiltration involves the retrobulbar fatty tissue and the extrinsic eye muscles, causing proptosis, extraocular muscle dysfunction and often diplopia. Orbital decompression is an effective treatment in such cases, particularly when resistant to drugs and external radiation therapy. This work compares the results of orbital decompression performed by removing: a) the medial and lateral walls (Mourits technique) in 10 patients (19 orbits) and b) the medial and lower walls (Walsh-Ogura technique) in 17 patients (31 orbits). The results show that removing the floor of the orbit enables better reduction of proptosis but more easily leads to post-operative diplopia. Thus it proves necessary to combine the two techniques, modifying the surgical approach on a case-by-case basis.

On the Coplanar Integrable Case of the Twice-Averaged Hill Problem with Central Body Oblateness

NASA Astrophysics Data System (ADS)

Vashkov'yak, M. A.

2018-01-01

The twice-averaged Hill problem with the oblateness of the central planet is considered in the case where its equatorial plane coincides with the plane of its orbital motion relative to the perturbing body. A qualitative study of this so-called coplanar integrable case was begun by Y. Kozai in 1963 and continued by M.L. Lidov and M.V. Yarskaya in 1974. However, no rigorous analytical solution of the problem can be obtained due to the complexity of the integrals. In this paper we obtain some quantitative evolution characteristics and propose an approximate constructive-analytical solution of the evolution system in the form of explicit time dependences of satellite orbit elements. The methodical accuracy has been estimated for several orbits of artificial lunar satellites by comparison with the numerical solution of the evolution system.

Primary desmoplastic small round cell tumor in the left orbit: a case report and literature review.

PubMed

He, Xue-Rui; Liu, Zheng; Wei, Jing; Li, Wan-Jun; Liu, Tao

2018-01-30

Desmoplastic small round cell tumor is a rare malignant neoplasm that most often occurs in the abdomen or pelvis of young men. We herein describe a rare case of desmoplastic small round cell tumor arising from the left orbit in a 16-year-old male. A biopsy was performed and the histology showed the nests of tumor cells with small round cell morphology. The tumor cells showed immunopositivity for desmin, CD99, CD56, SMA, NSE, CgA, SYN, Ki67 and vimentin. Fluorescence in situ hybridization study using EWSR1 break-apart probe was positive for EWSR1 gene rearrangement. After complete surgical resection of the tumor, we did not find tumor recurrence or metastasis with one-year follow-up. Furthermore, a review of the relevant English literature has been discussed. In the present study, for the first time, we report a case of desmoplastic small round cell tumor which is located in the orbital region.

[Orbital extension of sinus plasmacytoma secondarily transforming into multiple myeloma: a case study].

PubMed

Balayre, S; Gicquel, J-J; Mercie, M; Dighiero, P

2004-01-01

We report the case of a 39-year-old man who consulted for severe exophthalmia with diplopia associated with chronic sinusitis evolving over 6 months. A cervicofacial CT scan showed a tumoral mass invading the maxillary and ethmoidal left sinus and orbital cavity. A biopsy of the mass and general evaluation confirmed the diagnosis of extramedullary plasmocytoma. Secondarily it transformed into multiple myeloma. In light of this case of extramedullary plasmocytoma in a young subject, we discuss the clinical characteristics, ophthalmologic manifestations, and the various therapeutic modalities according to the stage of the disease and the ocular repercussions.

Minimum impulse transfers to rotate the line of apsides

NASA Technical Reports Server (NTRS)

Phong, Connie; Sweetser, Theodore H.

2005-01-01

Transfer between two coplanar orbits can be accomplished via a single impulse if the two orbits intersect. Optimization of a single-impulse transfer, however, is not possible since the transfer orbit is completely constrained by the initial and final orbits. On the other hand, two-impulse transfers are possible between any two terminal orbits. While optimal scenarios are not known for the general two-impulse case, there are various approximate solutions to many special cases. We consider the problem of an inplane rotation of the line of apsides, leaving the size and shape of the orbit unaffected.

Contingency study for the third international Sun-Earth Explorer (ISEE-3) satellite

NASA Technical Reports Server (NTRS)

Dunham, D. W.

1979-01-01

The third satellite of the international Sun-Earth Explorer program was inserted into a periodic halo orbit about L sub 1, the collinear libration point between the Sun and the Earth-Moon barycenter. A plan is presented that was developed to enable insertion into the halo orbit in case there was a large underperformance of the Delta second or third stage during the maneuver to insert the spacecraft into the transfer trajectory. After one orbit of the Earth, a maneuver would be performed near perigee to increase the energy of the orbit. A relatively small second maneuver would put the spacecraft in a transfer trajectory to the halo orbit, into which it could be inserted for a total cost within the fuel budget. Overburns (hot transfer trajectory insertions) were also studied.

Analysis of Parallel Burn Without Crossfeed TSTO RLV Architectures and Comparison to Parallel Burn With Crossfeed and Series Burn Architectures

NASA Technical Reports Server (NTRS)

Smith, Garrett; Phillips, Alan

2002-01-01

There are currently three dominant TSTO class architectures. These are Series Burn (SB), Parallel Burn with crossfeed (PBw/cf), and Parallel Burn without crossfeed (PBncf). The goal of this study was to determine what factors uniquely affect PBncf architectures, how each of these factors interact, and to determine from a performance perspective whether a PBncf vehicle could be competitive with a PBw/cf or SB vehicle using equivalent technology and assumptions. In all cases, performance was evaluated on a relative basis for a fixed payload and mission by comparing gross and dry vehicle masses of a closed vehicle. Propellant combinations studied were LOX: LH2 propelled orbiter and booster (HH) and LOX: Kerosene booster with LOX: LH2 orbiter (KH). The study conclusions were: 1) a PBncf orbiter should be throttled as deeply as possible after launch until the staging point. 2) a detailed structural model is essential to accurate architecture analysis and evaluation. 3) a PBncf TSTO architecture is feasible for systems that stage at mach 7. 3a) HH architectures can achieve a mass growth relative to PBw/cf of < 20%. 3b) KH architectures can achieve a mass growth relative to Series Burn of < 20%. 4) center of gravity (CG) control will be a major issue for a PBncf vehicle, due to the low orbiter specific thrust to weight ratio and to the position of the orbiter required to align the nozzle heights at liftoff. 5 ) thrust to weight ratios of 1.3 at liftoff and between 1.0 and 0.9 when staging at mach 7 appear to be close to ideal for PBncf vehicles. 6) performance for all vehicles studied is better when staged at mach 7 instead of mach 5. The study showed that a Series Burn architecture has the lowest gross mass for HH cases, and has the lowest dry mass for KH cases. The potential disadvantages of SB are the required use of an air-start for the orbiter engines and potential CG control issues. A Parallel Burn with crossfeed architecture solves both these problems, but the mechanics of a large bipropellant crossfeed system pose significant technical difficulties. Parallel Burn without crossfeed vehicles start both booster and orbiter engines on the ground and thus avoid both the risk of orbiter air-start and the complexity of a crossfeed system. The drawback is that the orbiter must use 20% to 35% of its propellant before reaching the staging point. This induces a weight penalty in the orbiter in order to carry additional propellant, which causes a further weight penalty in the booster to achieve the same staging point. One way to reduce the orbiter propellant consumption during the first stage is to throttle down the orbiter engines as much as possible. Another possibility is to use smaller or fewer engines. Throttling the orbiter engines soon after liftoff minimizes CG control problems due to a low orbiter liftoff thrust, but may result in an unnecessarily high orbiter thrust after staging. Reducing the number or size of engines size may cause CG control problems and drift at launch. The study suggested possible methods to maximize performance of PBncf vehicle architectures in order to meet mission design requirements.

Suppression of the overlap between Majorana fermions by orbital magnetic effects in semiconducting-superconducting nanowires

NASA Astrophysics Data System (ADS)

Dmytruk, Olesia; Klinovaja, Jelena

2018-04-01

We study both analytically and numerically the role of orbital effects caused by a magnetic field applied along the axis of a semiconducting Rashba nanowire in the topological regime hosting Majorana fermions. We demonstrate that the orbital effects can be effectively taken into account in a one-dimensional model by shifting the chemical potential and thus modifying the topological criterion. We focus on the energy splitting between two Majorana fermions in a finite nanowire and find a striking interplay between orbital and Zeeman effects on this splitting. In the limit of strong spin-orbit interaction, we find regimes where the amplitude of the oscillating splitting stays constant or even decays with increasing the magnetic field, in stark contrast to the commonly studied case where orbital effects of the magnetic field are neglected. The period of these oscillations is found to be almost constant in many parameter regimes.

Canine orbital meningiomas: a review of 22 cases.

PubMed

Mauldin, E.A.; Deehr, A.J.; Hertzke, D.; Dubielzig, R.R.

2000-01-01

Clinical and pathologic features of primary orbital meningiomas in the dog were reviewed. Twenty-two meningiomas, confined to the orbit, were identified from the Comparative Ophthalmic Pathology Laboratory of Wisconsin from 1981 to 1997. The dogs ranged in age from 3 to 17 years (mean = 9.2 years). The clinical presentation, reported in 20 cases, was indicative of a retrobulbar mass and included exophthalmos and orbital swelling (18/20), and papilledema or abnormalities of the posterior segment (7/20). Visual acuity was reported in 15 cases; of those, 12 dogs were blind in the affected eye. Follow-up information was obtained on 17 cases; six dogs developed local recurrence of the neoplasm. Two dogs with recurrent neoplasms simultaneously developed blindness in the opposite eye. Extension along the optic nerve to the optic chiasm was suspected. No metastasis was found at the time of the study. Enucleation with excisional biopsy was effective therapy to date in 11 cases (0.2-4.5 years follow-up time). All neoplasms were located within the vicinity of the optic nerve and, when sectioned through the optic nerve head, appeared to completely envelope the nerve. The neoplastic cells were arranged in tight whorls and bundles characteristic of meningiomas. Most tumors had islands of chondroid and osseous metaplasia (17/22). Ocular invasion was limited to small foci in the posterior choroid or optic nerve head of six dogs. Immunoperoxidase stains on 10 cases were positive for vimentin and S-100, but negative for cytokeratin. Electron microscopy revealed complex interdigitations between cell membranes and few desmosomal intercellular attachments. Primary orbital meningiomas have a characteristic histologic appearance and may recur locally after surgical excision.

Successful application of endoscopic modified medial maxillectomy to orbital floor trapdoor fracture in a pediatric patient.

PubMed

Matsuda, Yasunori; Sakaida, Hiroshi; Kobayashi, Masayoshi; Takeuchi, Kazuhiko

2016-10-01

Although surgical treatment of orbital floor fractures can be performed by many different approaches, the application of endoscopic modified medial maxillectomy (EMMM) for this condition has rarely been described in the literature. We report on a case of a 7-year-old boy with a trapdoor orbital floor fracture successfully treated with the application of EMMM. The patient suffered trauma to the right orbit floor and the inferior rectus was entrapped at the orbital floor. Initially, surgical repair via endoscopic endonasal approach was attempted. However, we were unable to adequately access the orbital floor through the maxillary ostium. Therefore, an alternative route of access to the orbital floor was established by EMMM. With sufficient visualization and operating space, the involved orbital content was completely released from the entrapment site and reduced into the orbit. To facilitate wound healing, the orbital floor was supported with a water-inflated urethral balloon catheter for 8 days. At follow-up 8 months later, there was no gaze restriction or complications associated with the EMMM. This case illustrates the efficacy and safety of EMMM in endoscopic endonasal repair of orbital floor fracture, particularly for cases with a narrow nasal cavity such as in pediatric patients. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Respiratory epithelial ingrowth and hemorrhage as late complications of orbital floor fracture repair with silicone sheet implant.

PubMed

Jones, David F; Wilson, Matthew W

2008-01-01

The authors present a unique case of rapidly progressive proptosis in a woman 23 years after repair of an orbital floor fracture. Clinical studies, surgical exploration, and pathology revealed a hemorrhagic cyst lined with respiratory epithelium surrounding her previously placed silicone implant.

The Hydraulic Mechanism in the Orbital Blowout Fracture Because of a High-Pressure Air Gun Injury.

PubMed

Kang, Seok Joo; Chung, Eui Han

2015-10-01

There are 2 predominant mechanisms that are used to explain the pathogenesis of orbital blowout fracture; these include hydraulic and buckling mechanisms. Still, however, its pathophysiology remains uncertain. To date, studies in this series have been conducted using dry skulls, cadavers, or animals. But few clinical studies have been conducted to examine whether the hydraulic mechanism is involved in the occurrence of pure orbital blowout fracture. The authors experienced a case of a 52-year-old man who had a pure medial blowout fracture after sustaining an eye injury because of a high-pressure air gun. Our case suggests that surgeons should be aware of the possibility that the hydraulic mechanism might be involved in the blowout fracture in patients presenting with complications, such as limitation of eye movement, diplopia, and enophthalmos.

[Pediatric orbital emphysema caused by a compressed-air pistol shot: a case report].

PubMed

Navarro-Mingorance, A; Reyes-Dominguez, S B; León-León, M C

2014-09-01

We report the case of a 2 year-old child with orbital emphysema secondary to a compressed-air gun shot in the malar region, with no evidence of orbital wall fracture. Conservative treatment was applied, and no complications were observed. Orbital emphysema in the absence of an orbital wall fracture is a rare situation. Orbital emphysema is usually seen in facial trauma associated with damage to the adjacent paranasal sinuses or facial bones. To our knowledge there have been very few reports of orbital emphysema caused by a compressed-air injury. Copyright © 2012 Sociedad Española de Oftalmología. Published by Elsevier Espana. All rights reserved.

Valley-orbit splitting in doped nanocrystalline silicon: k•p calculations

NASA Astrophysics Data System (ADS)

Belyakov, Vladimir A.; Burdov, Vladimir A.

2007-07-01

The valley-orbit splitting in silicon quantum dots with shallow donors has been theoretically studied. In particular, the chemical-shift calculation was carried out within the frames of k•p approximation for single- and many-donor cases. For both cases, the great value of the chemical shift has been obtained compared to its bulk value. Such increase of the chemical shift becomes possible due to the quantum confinement effect in a dot. It is shown for the single-donor case that the level splitting and chemical shift strongly depend on the dot radius and donor position inside the nanocrystal. In the many-donor case, the chemical shift is almost proportional to the number of donors.

Computed tomography in the management of orbital infections associated with dental disease.

PubMed Central

Flood, T. P.; Braude, L. S.; Jampol, L. M.; Herzog, S.

1982-01-01

Two patients developed orbital infection secondary to dental infections. In one patient the infection spread from maxillary premolar and molar teeth to the infratemporal and pterygopalatine fossa and then through the inferior orbital fissure to the subperiosteal space. A subperiosteal abscess in the posterior orbital wall developed, which subsequently spread within the muscle cone. In the second patient infection of an anterior maxillary tooth caused a pansinusitis and unilateral orbital cellulitis. In both patients computed tomographic scanning of the orbit proved valuable in localising the infection and, in one case, planning a surgical approach to the orbit. The infection in both patients responded to treatment, with no permanent visual impairment. Appropriate antibiotics and prompt identification and surgical drainage of orbital abscesses are essential for the preservation of vision in cases of orbital infection. Images PMID:7066283

TDRSS-user orbit determination using batch least-squares and sequential methods

NASA Astrophysics Data System (ADS)

Oza, D. H.; Jones, T. L.; Hakimi, M.; Samii, Mina V.; Doll, C. E.; Mistretta, G. D.; Hart, R. C.

1993-02-01

The Goddard Space Flight Center (GSFC) Flight Dynamics Division (FDD) commissioned Applied Technology Associates, Incorporated, to develop the Real-Time Orbit Determination/Enhanced (RTOD/E) system on a Disk Operating System (DOS)-based personal computer (PC) as a prototype system for sequential orbit determination of spacecraft. This paper presents the results of a study to compare the orbit determination accuracy for a Tracking and Data Relay Satellite System (TDRSS) user spacecraft, Landsat-4, obtained using RTOD/E, operating on a PC, with the accuracy of an established batch least-squares system, the Goddard Trajectory Determination System (GTDS), and operating on a mainframe computer. The results of Landsat-4 orbit determination will provide useful experience for the Earth Observing System (EOS) series of satellites. The Landsat-4 ephemerides were estimated for the January 17-23, 1991, timeframe, during which intensive TDRSS tracking data for Landsat-4 were available. Independent assessments were made of the consistencies (overlap comparisons for the batch case and covariances and the first measurement residuals for the sequential case) of solutions produced by the batch and sequential methods. The forward-filtered RTOD/E orbit solutions were compared with the definitive GTDS orbit solutions for Landsat-4; the solution differences were less than 40 meters after the filter had reached steady state.

TDRSS-user orbit determination using batch least-squares and sequential methods

NASA Technical Reports Server (NTRS)

Oza, D. H.; Jones, T. L.; Hakimi, M.; Samii, Mina V.; Doll, C. E.; Mistretta, G. D.; Hart, R. C.

1993-01-01

The Goddard Space Flight Center (GSFC) Flight Dynamics Division (FDD) commissioned Applied Technology Associates, Incorporated, to develop the Real-Time Orbit Determination/Enhanced (RTOD/E) system on a Disk Operating System (DOS)-based personal computer (PC) as a prototype system for sequential orbit determination of spacecraft. This paper presents the results of a study to compare the orbit determination accuracy for a Tracking and Data Relay Satellite System (TDRSS) user spacecraft, Landsat-4, obtained using RTOD/E, operating on a PC, with the accuracy of an established batch least-squares system, the Goddard Trajectory Determination System (GTDS), and operating on a mainframe computer. The results of Landsat-4 orbit determination will provide useful experience for the Earth Observing System (EOS) series of satellites. The Landsat-4 ephemerides were estimated for the January 17-23, 1991, timeframe, during which intensive TDRSS tracking data for Landsat-4 were available. Independent assessments were made of the consistencies (overlap comparisons for the batch case and covariances and the first measurement residuals for the sequential case) of solutions produced by the batch and sequential methods. The forward-filtered RTOD/E orbit solutions were compared with the definitive GTDS orbit solutions for Landsat-4; the solution differences were less than 40 meters after the filter had reached steady state.

Earth Orbiting Support Systems for commercial low Earth orbit data relay: Assessing architectures through tradespace exploration

NASA Astrophysics Data System (ADS)

Palermo, Gianluca; Golkar, Alessandro; Gaudenzi, Paolo

2015-06-01

As small satellites and Sun Synchronous Earth Observation systems are assuming an increased role in nowadays space activities, including commercial investments, it is of interest to assess how infrastructures could be developed to support the development of such systems and other spacecraft that could benefit from having a data relay service in Low Earth Orbit (LEO), as opposed to traditional Geostationary relays. This paper presents a tradespace exploration study of the architecture of such LEO commercial satellite data relay systems, here defined as Earth Orbiting Support Systems (EOSS). The paper proposes a methodology to formulate architectural decisions for EOSS constellations, and enumerate the corresponding tradespace of feasible architectures. Evaluation metrics are proposed to measure benefits and costs of architectures; lastly, a multicriteria Pareto criterion is used to downselect optimal architectures for subsequent analysis. The methodology is applied to two case studies for a set of 30 and 100 customer-spacecraft respectively, representing potential markets for LEO services in Exploration, Earth Observation, Science, and CubeSats. Pareto analysis shows how increased performance of the constellation is always achieved by an increased node size, as measured by the gain of the communications antenna mounted on EOSS spacecraft. On the other hand, nonlinear trends in optimal orbital altitude, number of satellites per plane, and number of orbital planes, are found in both cases. An upward trend in individual node memory capacity is found, although never exceeding 256 Gbits of onboard memory for both cases that have been considered, assuming the availability of a polar ground station for EOSS data downlink. System architects can use the proposed methodology to identify optimal EOSS constellations for a given service pricing strategy and customer target, thus identifying alternatives for selection by decision makers.

Evaluation of Landsat-4 orbit determination accuracy using batch least-squares and sequential methods

NASA Astrophysics Data System (ADS)

Oza, D. H.; Jones, T. L.; Feiertag, R.; Samii, M. V.; Doll, C. E.; Mistretta, G. D.; Hart, R. C.

The Goddard Space Flight Center (GSFC) Flight Dynamics Division (FDD) commissioned Applied Technology Associates, Incorporated, to develop the Real-Time Orbit Determination/Enhanced (RTOD/E) system on a Disk Operating System (DOS)-based personal computer (PC) as a prototype system for sequential orbit determination of spacecraft. This paper presents the results of a study to compare the orbit determination accuracy for a Tracking and Data Relay Satellite (TDRS) System (TDRSS) user spacecraft, Landsat-4, obtained using RTOD/E, operating on a PC, with the accuracy of an established batch least-squares system, the Goddard Trajectory Determination System (GTDS), operating on a mainframe computer. The results of Landsat-4 orbit determination will provide useful experience for the Earth Observing System (EOS) series of satellites. The Landsat-4 ephemerides were estimated for the May 18-24, 1992, timeframe, during which intensive TDRSS tracking data for Landsat-4 were available. During this period, there were two separate orbit-adjust maneuvers on one of the TDRSS spacecraft (TDRS-East) and one small orbit-adjust maneuver for Landsat-4. Independent assessments were made of the consistencies (overlap comparisons for the batch case and covariances and the first measurement residuals for the sequential case) of solutions produced by the batch and sequential methods. The forward-filtered RTOD/E orbit solutions were compared with the definitive GTDS orbit solutions for Landsat-4; the solution differences were generally less than 30 meters after the filter had reached steady state.

Evaluation of Landsat-4 orbit determination accuracy using batch least-squares and sequential methods

NASA Technical Reports Server (NTRS)

Oza, D. H.; Jones, T. L.; Feiertag, R.; Samii, M. V.; Doll, C. E.; Mistretta, G. D.; Hart, R. C.

1993-01-01

The Goddard Space Flight Center (GSFC) Flight Dynamics Division (FDD) commissioned Applied Technology Associates, Incorporated, to develop the Real-Time Orbit Determination/Enhanced (RTOD/E) system on a Disk Operating System (DOS)-based personal computer (PC) as a prototype system for sequential orbit determination of spacecraft. This paper presents the results of a study to compare the orbit determination accuracy for a Tracking and Data Relay Satellite (TDRS) System (TDRSS) user spacecraft, Landsat-4, obtained using RTOD/E, operating on a PC, with the accuracy of an established batch least-squares system, the Goddard Trajectory Determination System (GTDS), operating on a mainframe computer. The results of Landsat-4 orbit determination will provide useful experience for the Earth Observing System (EOS) series of satellites. The Landsat-4 ephemerides were estimated for the May 18-24, 1992, timeframe, during which intensive TDRSS tracking data for Landsat-4 were available. During this period, there were two separate orbit-adjust maneuvers on one of the TDRSS spacecraft (TDRS-East) and one small orbit-adjust maneuver for Landsat-4. Independent assessments were made of the consistencies (overlap comparisons for the batch case and covariances and the first measurement residuals for the sequential case) of solutions produced by the batch and sequential methods. The forward-filtered RTOD/E orbit solutions were compared with the definitive GTDS orbit solutions for Landsat-4; the solution differences were generally less than 30 meters after the filter had reached steady state.

Orbiter/Space lab momentum management for POP orientations

NASA Technical Reports Server (NTRS)

Cox, J. W.

1974-01-01

An angular momentum management scheme applicable to the orbiter/spacelab is described. The basis of the scheme is to periodically maneuver the vehicle through a small angle thereby using the gravity gradient torque to dump momentum from the control moment gyro (CMG) control system. The orbiter is operated with its principal vehicle axis perpendicular to the orbital plane. Numerous case runs were conducted on the hybrid simulation and representative cases are included.

An analytical procedure for evaluating shuttle abort staging aerodynamic characteristics

NASA Technical Reports Server (NTRS)

Meyer, R.

1973-01-01

An engineering analysis and computer code (AERSEP) for predicting Space Shuttle Orbiter - HO Tank longitudinal aerodynamic characteristics during abort separation has been developed. Computed results are applicable at Mach numbers above 2 for angle-of-attack between plus or minus 10 degrees. No practical restrictions on orbiter-tank relative positioning are indicated for tank-under-orbiter configurations. Input data requirements and computer running times are minimal facilitating program use for parametric studies, test planning, and trajectory analysis. In a majority of cases AERSEP Orbiter-Tank interference predictions are as accurate as state-of-the-art estimates for interference-free or isolated-vehicle configurations. AERSEP isolated-orbiter predictions also show excellent correlation with data.

Exact formulas for multipole moments using Slater-type molecular orbitals

NASA Technical Reports Server (NTRS)

Jones, H. W.

1986-01-01

A triple infinite sum of formulas expressed as an expansion in Legendre polynomials is generated by use of computer algebra to represent the potential from the midpoint of two Slater-type orbitals; the charge density that determines the potential is given as the product of the two orbitals. An example using 1s orbitals shows that only a few terms are needed to obtain four-figure accuracy. Exact formulas are obtained for multipole moments by means of a careful study of expanded formulas, allowing an 'extrapolation to infinity'. This Loewdin alpha-function approach augmented by using a C matrix to characterize Slater-type orbitals can be readily generalized to all cases.

Legal liability in iatrogenic orbital injury.

PubMed

Svider, Peter F; Kovalerchik, Olga; Mauro, Andrew C; Baredes, Soly; Eloy, Jean Anderson

2013-09-01

In this study, we detailed factors governing legal outcomes in iatrogenic orbital injury, with the purpose of discussing strategies to minimize liability and enhance patient safety. Retrospective analysis. Jury verdict and settlement reports were searched from publically available federal and state court records using the Westlaw database (Thomson Reuters, New York, NY). After exclusion of nonrelevant cases, 20 cases of iatrogenic orbital injuries were examined for factors such as legal outcome, damages awarded, defendant specialty, alleged causes of malpractice, and patient demographic information. The majority (60.0%) of cases were resolved in the defendant's favor. Payment was considerable for the cases decided in support of the plaintiff, averaging $1.13 million. Out-of-court settlements averaged $1.78 million (range, $487,500-$3.9 million), whereas jury-awarded damages averaged $472,661 (range, $75,000-$763,214). Complications stemming from endoscopic sinus surgery were most common (50.0%). Diplopia was the most common medical complaint (50.0%), whereas permanent deficits and having to undergo additional surgery were each present in 65.0% of cases. The potential for permanent sequelae of iatrogenic orbital injury makes this complication susceptible to malpractice litigation. Otolaryngologists were the most common defendants. Although cases were resolved in the defendant's favor 60% of the time, payments made were considerable, averaging $1.13 million. Steps to minimize liability and improve patient safety include an informed consent process explicitly listing risks, including diplopia and blindness, and obtaining timely ophthalmology consultation when a complication is recognized. Copyright © 2013 The American Laryngological, Rhinological and Otological Society, Inc.

Human Exploration Missions Study Launch Window from Earth Orbit

NASA Technical Reports Server (NTRS)

Young, Archie

2001-01-01

The determination of orbital launch window characteristics is of major importance in the analysis of human interplanetary missions and systems. The orbital launch window characteristics are directly involved in the selection of mission trajectories, the development of orbit operational concepts, and the design of orbital launch systems. The orbital launch window problem arises because of the dynamic nature of the relative geometry between outgoing (departure) asymptote of the hyperbolic escape trajectory and the earth parking orbit. The orientation of the escape hyperbola asymptotic relative to earth is a function of time. The required hyperbola energy level also varies with time. In addition, the inertial orientation of the parking orbit is a function of time because of the perturbations caused by the Earth's oblateness. Thus, a coplanar injection onto the escape hyperbola can be made only at a point in time when the outgoing escape asymptote is contained by the plane of parking orbit. Even though this condition may be planned as a nominal situation, it will not generally represent the more probable injection geometry. The general case of an escape injection maneuver performed at a time other than the coplanar time will involve both a path angle and plane change and, therefore, a Delta(V) penalty. Usually, because of the Delta(V) penalty the actual departure injection window is smaller in duration than that determined by energy requirement alone. This report contains the formulation, characteristics, and test cases for five different launch window modes for Earth orbit. These modes are: (1) One impulsive maneuver from a Low Earth Orbit (LEO), (2) Two impulsive maneuvers from LEO, (3) Three impulsive maneuvers from LEO, (4) One impulsive maneuvers from a Highly Elliptical Orbit (HEO), (5) Two impulsive maneuvers from a Highly Elliptical Orbit (HEO) The formulation of these five different launch window modes provides a rapid means of generating realistic parametric data for space exploration studies. Also the formulation provides vector and geometrical data sufficient for use as a good starting point in detail trajectory analysis based on calculus of variations, steepest descent, or parameter optimization program techniques.

Infected orbital cyst following exenteration.

PubMed

Barak, A; Hirsh, A; Rosner, M; Rosen, N

1996-09-01

An orbital cyst is a rare complication of orbital trauma and exenteration. Infections of such cysts have not been described, and are potentially dangerous unless treated immediately. The authors describe a case of delayed treatment of such an infected cyst, which resolved following surgical drainage. The potentially hazardous outcome makes knowledge of such cases important.

Large-size space debris flyby in low earth orbits

NASA Astrophysics Data System (ADS)

Baranov, A. A.; Grishko, D. A.; Razoumny, Y. N.

2017-09-01

the analysis of NORAD catalogue of space objects executed with respect to the overall sizes of upper-stages and last stages of carrier rockets allows the classification of 5 groups of large-size space debris (LSSD). These groups are defined according to the proximity of orbital inclinations of the involved objects. The orbits within a group have various values of deviations in the Right Ascension of the Ascending Node (RAAN). It is proposed to use the RAANs deviations' evolution portrait to clarify the orbital planes' relative spatial distribution in a group so that the RAAN deviations should be calculated with respect to the concrete precessing orbital plane of the concrete object. In case of the first three groups (inclinations i = 71°, i = 74°, i = 81°) the straight lines of the RAAN relative deviations almost do not intersect each other. So the simple, successive flyby of group's elements is effective, but the significant value of total Δ V is required to form drift orbits. In case of the fifth group (Sun-synchronous orbits) these straight lines chaotically intersect each other for many times due to the noticeable differences in values of semi-major axes and orbital inclinations. The intersections' existence makes it possible to create such a flyby sequence for LSSD group when the orbit of one LSSD object simultaneously serves as the drift orbit to attain another LSSD object. This flyby scheme requiring less Δ V was called "diagonal." The RAANs deviations' evolution portrait built for the fourth group (to be studied in the paper) contains both types of lines, so the simultaneous combination of diagonal and successive flyby schemes is possible. The value of total Δ V and temporal costs were calculated to cover all the elements of the 4th group. The article is also enriched by the results obtained for the flyby problem solution in case of all the five mentioned LSSD groups. The general recommendations are given concerned with the required reserve of total Δ V and with amount of detachable de-orbiting units onboard the maneuvering platform and onboard the refueling vehicle.

Posttraumatic subperiosteal hematomas of the orbit in children.

PubMed

Yazici, Bülent; Gönen, Tansu

2011-01-01

To describe 5 pediatric patients with traumatic orbital subperiosteal hematoma and review the relevant literature. Retrospective chart analysis of 5 children with posttraumatic subperiosteal hematoma and a systematic review of the English language literature. Five new pediatric cases of orbital subperiosteal hematoma are presented with varying clinical and radiologic manifestations and treatments. Literature review (including the current 5 cases) yielded 23 cases in total. Eighteen (78%) of the patients were boys, and 5 (22%) were girls. The children ranged in age from 5 to 17 years, with the mean and median ages being 12 years. The leading cause was blunt trauma related to falls or direct impact. Two patients (9%) had an inherited coagulopathy, predisposing them to orbital hemorrhage. The hematomas developed in the superior orbit in all cases except one. In 3 patients (13%), orbital hematomas were bilateral. In 9 patients (39%), the hematomas extended in subgaleal or frontal subdural spaces. In 7 patients (30%), subperiosteal hematoma was associated with compressive optic neuropathy. Four patients (17%) had a nondisplaced orbital roof fracture. Seventeen patients were treated with surgical evacuation of hematoma (52%) or with needle aspiration (22%), and 5 patients (22%) were observed for spontaneous resolution. Three patients (13%) experienced a recurrence of hemorrhage. In children, traumatic subperiosteal hematomas of the orbit typically occur after blunt trauma in the superior orbit. The risk of compressive optic neuropathy may be higher in patients with bilateral hematoma and massive subgaleal hematoma. Most patients are treated with evacuation of the hematoma.

Logarithmic spiral trajectories generated by Solar sails

NASA Astrophysics Data System (ADS)

Bassetto, Marco; Niccolai, Lorenzo; Quarta, Alessandro A.; Mengali, Giovanni

2018-02-01

Analytic solutions to continuous thrust-propelled trajectories are available in a few cases only. An interesting case is offered by the logarithmic spiral, that is, a trajectory characterized by a constant flight path angle and a fixed thrust vector direction in an orbital reference frame. The logarithmic spiral is important from a practical point of view, because it may be passively maintained by a Solar sail-based spacecraft. The aim of this paper is to provide a systematic study concerning the possibility of inserting a Solar sail-based spacecraft into a heliocentric logarithmic spiral trajectory without using any impulsive maneuver. The required conditions to be met by the sail in terms of attitude angle, propulsive performance, parking orbit characteristics, and initial position are thoroughly investigated. The closed-form variations of the osculating orbital parameters are analyzed, and the obtained analytical results are used for investigating the phasing maneuver of a Solar sail along an elliptic heliocentric orbit. In this mission scenario, the phasing orbit is composed of two symmetric logarithmic spiral trajectories connected with a coasting arc.

Complications of orbital floor repair with silastic sheet: the skin fistula.

PubMed

Aboh, Ikenna Valentine; Chisci, Glauco; Gennaro, Paolo; Giovannetti, Filippo; Bartoli, Davina; Priore, Paolo; Anelli, Andrea; Iannetti, Giorgio

2013-07-01

Treatment of orbital floor fracture is a subject of great interest in maxillofacial surgery. Many materials have been described for its reconstruction.In this article, the authors report a case of a patient who, 7 years from a previous orbital floor fracture and treatment with silastic sheet, presented herself to their clinic for the failure of the material used for its reconstruction and a skin fistula.Orbital floor repair with silastic sheet is an old method that no one uses anymore, but we still observe cases of late complications with this material. So a fine knowledge of silastic sheet complications is needed for young surgeons.The authors report the case and perform a literature review about the use of more modern biomaterials for orbital floor reconstruction.

Motion of the moonlet in the binary system 243 Ida

NASA Astrophysics Data System (ADS)

Lan, L.; Ni, Y.; Jiang, Y.; Li, J.

2018-02-01

The motion of the moonlet Dactyl in the binary system 243 Ida is investigated in this paper. First, periodic orbits in the vicinity of the primary are calculated, including the orbits around the equilibrium points and large-scale orbits. The Floquet multipliers' topological cases of periodic orbits are calculated to study the orbits' stabilities. During the continuation of the retrograde near-circular orbits near the equatorial plane, two period-doubling bifurcations and one Neimark-Sacker bifurcation occur one by one, leading to two stable regions and two unstable regions. Bifurcations occur at the boundaries of these regions. Periodic orbits in the stable regions are all stable, but in the unstable regions are all unstable. Moreover, many quasi-periodic orbits exist near the equatorial plane. Long-term integration indicates that a particle in a quasi-periodic orbit runs in a space like a tire. Quasi-periodic orbits in different regions have different styles of motion indicated by the Poincare sections. There is the possibility that moonlet Dactyl is in a quasi-periodic orbit near the stable region I, which is enlightening for the stability of the binary system.

Dimension of subperiosteal orbital abscess as an indication for surgical management in children.

PubMed

Gavriel, Haim; Yeheskeli, Eyal; Aviram, Eliad; Yehoshua, Lior; Eviatar, Ephraim

2011-11-01

Eyelid edema in children is one of the signs of orbital complications secondary to acute rhinosinusitis, and identifying abscess formation is crucial for management decision. The objective of this study is to determine whether there are different computed tomography scan abscess dimensions and volumes in children requiring medical versus surgical management for subperiosteal orbital abscess (SPOA). Case series with chart review. The study was conducted at Assaf Harofeh Medical Center. Clinical and radiological parameters of 95 children admitted with eyelid edema between January 2005 and December 2007 were studied. Of 95 cases of orbital cellulitis, a total of 48 children with sinogenic orbital complications with a mean (SD) age of 4.03 (3.46) years were included. No significant difference was found between the surgically and medically treated SPOA groups regarding the use of preadmission antibiotic and clinical presentation. Statistically significant larger abscesses in the surgically treated group were noted (mean volume 1.389 vs 0.486 mL in the conservatively treated group; P = .013) and a longer mean anterior-posterior and medial-lateral dimension (P = .001 and .017, respectively). Children presenting with significant or progressing ocular findings or failure to improve after 48 hours of medical therapy, together with an abscess volume of more than 0.5 mL, a length greater than 17 mm, and a width greater than 4.5 mm, should be strongly considered to have surgical drainage.

Bilateral sclerosing orbital pseudotumour in an adult

PubMed Central

Sripathi, Smiti; Shenoy, Poonam Mohan; Ayachit, Anurag; Kadavigere, Rajagopal

2014-01-01

Sclerosing pseudotumour of the orbit is a rare idiopathic chronic inflammatory process, which greatly mimics neoplasms both clinically and on imaging studies. It is therefore important to differentiate this entity from true neoplasms and to rule out any systemic associations. We present a rare case of sclerosing orbital pseudotumour in an adult man with no systemic illnesses who presented with painless progressive proptosis of both eyes and showed a gradual initial response to steroid therapy but relapsed after a 2-year interval. PMID:24876210

Bilateral sclerosing orbital pseudotumour in an adult.

PubMed

Sripathi, Smiti; Shenoy, Poonam Mohan; Ayachit, Anurag; Kadavigere, Rajagopal

2014-05-29

Sclerosing pseudotumour of the orbit is a rare idiopathic chronic inflammatory process, which greatly mimics neoplasms both clinically and on imaging studies. It is therefore important to differentiate this entity from true neoplasms and to rule out any systemic associations. We present a rare case of sclerosing orbital pseudotumour in an adult man with no systemic illnesses who presented with painless progressive proptosis of both eyes and showed a gradual initial response to steroid therapy but relapsed after a 2-year interval. 2014 BMJ Publishing Group Ltd.

GEODYN system description, volume 1. [computer program for estimation of orbit and geodetic parameters

NASA Technical Reports Server (NTRS)

Chin, M. M.; Goad, C. C.; Martin, T. V.

1972-01-01

A computer program for the estimation of orbit and geodetic parameters is presented. The areas in which the program is operational are defined. The specific uses of the program are given as: (1) determination of definitive orbits, (2) tracking instrument calibration, (3) satellite operational predictions, and (4) geodetic parameter estimation. The relationship between the various elements in the solution of the orbit and geodetic parameter estimation problem is analyzed. The solution of the problems corresponds to the orbit generation mode in the first case and to the data reduction mode in the second case.

Orbital stability close to asteroid 624 Hektor using the polyhedral model

NASA Astrophysics Data System (ADS)

Jiang, Yu; Baoyin, Hexi; Li, Hengnian

2018-03-01

We investigate the orbital stability close to the unique L4-point Jupiter binary Trojan asteroid 624 Hektor. The gravitational potential of 624 Hektor is calculated using the polyhedron model with observational data of 2038 faces and 1021 vertexes. Previous studies have presented three different density values for 624 Hektor. The equilibrium points in the gravitational potential of 624 Hektor with different density values have been studied in detail. There are five equilibrium points in the gravitational potential of 624 Hektor no matter the density value. The positions, Jacobian, eigenvalues, topological cases, stability, as well as the Hessian matrix of the equilibrium points are investigated. For the three different density values the number, topological cases, and the stability of the equilibrium points with different density values are the same. However, the positions of the equilibrium points vary with the density value of the asteroid 624 Hektor. The outer equilibrium points move away from the asteroid's mass center when the density increases, and the inner equilibrium point moves close to the asteroid's mass center when the density increases. There exist unstable periodic orbits near the surface of 624 Hektor. We calculated an orbit near the primary's equatorial plane of this binary Trojan asteroid; the results indicate that the orbit remains stable after 28.8375 d.

The Columbia Thyroid Eye Disease-Compressive Optic Neuropathy Formula.

PubMed

Callahan, Alison B; Campbell, Ashley A; Oropesa, Susel; Baraban, Aryeh; Kazim, Michael

2018-06-13

Diagnosing thyroid eye disease-compressive optic neuropathy (TED-CON) is challenging, particularly in cases lacking a relative afferent pupillary defect. Large case series of TED-CON patients and accessible diagnostic tools are lacking in the current literature. This study aims to create a mathematical formula that accurately predicts the presence or absence of CON based on the most salient clinical measures of optic neuropathy. A retrospective case series compares 108 patients (216 orbits) with either unilateral or bilateral TED-CON and 41 age-matched patients (82 orbits) with noncompressive TED. Utilizing clinical variables assessing optic nerve function and/or risk of compressive disease, and with the aid of generalized linear regression modeling, the authors create a mathematical formula that weighs the relative contribution of each clinical variable in the overall prediction of CON. Data from 213 orbits in 110 patients derived the formula: y = -0.69 + 2.58 × (afferent pupillary defect) - 0.31 × (summed limitation of ductions) - 0.2 × (mean deviation on Humphrey visual field testing) - 0.02 × (% color plates). This accurately predicted the presence of CON (y > 0) versus non-CON (y < 0) in 82% of cases with 83% sensitivity and 81% specificity. When there was no relative afferent pupillary defect, which was the case in 63% of CON orbits, the formula correctly predicted CON in 78% of orbits with 73% sensitivity and 83% specificity. The authors developed a mathematical formula, the Columbia TED-CON Formula (CTD Formula), that can help guide clinicians in accurately diagnosing TED-CON, particularly in the presence of bilateral disease and when no relative afferent pupillary defect is present.

Periodic orbits around areostationary points in the Martian gravity field

NASA Astrophysics Data System (ADS)

Liu, Xiao-Dong; Baoyin, Hexi; Ma, Xing-Rui

2012-05-01

This study investigates the problem of areostationary orbits around Mars in three-dimensional space. Areostationary orbits are expected to be used to establish a future telecommunication network for the exploration of Mars. However, no artificial satellites have been placed in these orbits thus far. The characteristics of the Martian gravity field are presented, and areostationary points and their linear stability are calculated. By taking linearized solutions in the planar case as the initial guesses and utilizing the Levenberg-Marquardt method, families of periodic orbits around areostationary points are shown to exist. Short-period orbits and long-period orbits are found around linearly stable areostationary points, but only short-period orbits are found around unstable areostationary points. Vertical periodic orbits around both linearly stable and unstable areostationary points are also examined. Satellites in these periodic orbits could depart from areostationary points by a few degrees in longitude, which would facilitate observation of the Martian topography. Based on the eigenvalues of the monodromy matrix, the evolution of the stability index of periodic orbits is determined. Finally, heteroclinic orbits connecting the two unstable areostationary points are found, providing the possibility for orbital transfer with minimal energy consumption.

Solar Array and Auroral Charging Studies of DMSP Spacecraft

NASA Technical Reports Server (NTRS)

Matias, Kelwin

2013-01-01

The SSJ electrostatic analyzers and the SSIES plasma instruments on the DMSP spacecraft in low Earth polar orbit can be used to conduct case studies of auroral and solar array charging. We will use a program written in the Interactive Data Language (IDL) to evaluate questionable charging events in the SSJ records by comparing charging signatures in SSJ and SSIES data. In addition, we will assemble a number of case studies of solar array charging showing the signatures from the SSJ data and compare to the SSIES charging signatures. In addition we will use Satellite Tool Kit (STK) to propagate orbits, obtain solar intensity, and use to verify onset of charging with sunrise.

Orbitals in Chemical Education. An Analysis through Their Graphical Representations

ERIC Educational Resources Information Center

Barradas-Solas, Francisco; Gomez, Pedro J. Sanchez

2014-01-01

Students' understanding of the orbital concept has been subject to considerable research and debate and often found at variance with a quantum mechanical ideal. Could it be the case that orbitals as actually used by practising chemists in teaching and research also differ from that ideal? Our experience shows that this might often be the case.…

[One-stage reconstruction of zygomatico-orbital complex with the use of implants of different origin].

PubMed

Menabde, G T; Gvenetadze, Z V; Atskvereli, L Sh

2009-03-01

Reconstruction of zygomatico-orbital complex remains as one of the troublesome and topical problems at steady posttraumatic deformations and fresh traumas of the mentioned region. The present work provides analysis of our own experience of surgical treatment of patients suffering from posttraumatic deformations and defects of zygomatico-orbital complex. The work was based on the results of examination and treatment of 33 patients who underwent an operation during the period from 2003 to 2008 years. Of 33, 21 patients were operated due to fresh traumas of the zygomatico-orbital region, and 12 - due to steady posttraumatic deformations of the mentioned region. Of 33 clinical cases, 19 patients underwent reconstruction of zygomatico-orbital complex with the use of implant. In 11 cases implants were perforated titanic plates, in 6 cases - bone cement (Surgical Simplex P), and in 2 cases - combination of titanic plates with bone cement. The results of our investigations have shown that one-stage reconstruction of zygomatico-orbital complex with the use of titanic plates and bone cement liquidates functional and cosmetic disorders. It has been suggested that the use of elaborated complex approaches in treatment of posttraumatic deformations and fresh traumas of zygomatico-orbital region is reasonable and acceptable.

Distant retrograde orbits for the Moon's exploration

NASA Astrophysics Data System (ADS)

Sidorenko, Vladislav

We discuss the properties of the distant retrograde orbits (which are called quasi-satellite orbits also) around Moon. For the first time the distant retrograde orbits were described by J.Jackson in studies on restricted three body problem at the beginning of 20th century [1]. In the synodic (rotating) reference frame distant retrograde orbit looks like an ellipse whose center is slowly drifting in the vicinity of minor primary body while in the inertial reference frame the third body is orbiting the major primary body. Although being away the Hill sphere the third body permanently stays close enough to the minor primary. Due to this reason the distant retrograde orbits are called “quasi-satellite” orbits (QS-orbits) too. Several asteroids in solar system are in a QS-orbit with respect to one of the planet. As an example we can mention the asteroid 2002VE68 which circumnavigates Venus [2]. Attention of specialists in space flight mechanics was attracted to QS-orbits after the publications of NASA technical reports devoted to periodic moon orbits [3,4]. Moving in QS-orbit the SC remains permanently (or at least for long enough time) in the vicinity of small celestial body even in the case when the Hill sphere lies beneath the surface of the body. The properties of the QS-orbit can be studied using the averaging of the motion equations [5,6,7]. From the theoretical point of view it is a specific case of 1:1 mean motion resonance. The integrals of the averaged equations become the parameters defining the secular evolution of the QS-orbit. If the trajectory is robust enough to small perturbations in the simplified problem (i.e., restricted three body problem) it may correspond to long-term stability of the real-world orbit. Our investigations demonstrate that under the proper choice of the initial conditions the QS-orbits don’t escape from Moon or don’t impact Moon for long enough time. These orbits can be recommended as a convenient technique for the large scale browsing of the Moon’s environment. [1] Jackson, J. (1913) MNRAS, 74, 62-82. [2] Mikkola, S., Brasser, R., Wiegert, P., Innanen, K. (2004) MNRAS, 351, L63-L65. [3] Broucke, R.A. (1968) NASA Technical Report 32-1168, JPL. [4] Broucke, R.A. (1969) NASA Technical Report 32-1360, JPL. [5] Kogan, A.I. (1989) Cosmic Research, 26, 705-710. [6] Namouni, F. (1999) Icarus, 6, 293-314. [7] Sidorenko, V.V., Neishtadt, A.I., Artemyev, A.V., Zelenyi, L.M. (2013) Doklady Physics, 58, 207-211.

A Case of Orbital Abscess following Porous Orbital Implant Infection

PubMed Central

Hong, Seung Woo; Paik, Ji-Sun; Kim, So-Youl

2006-01-01

Purpose We present a case of orbital abscess following porous orbital implant infection in a 73-year-old woman with rheumatoid arthritis. Methods Just one month after a seemingly uncomplicated enucleation and porous polyethylene (Medpor®) orbital implant surgery, implant exposure developed with profuse pus discharge. The patient was unresponsive to implant removal and MRI confirmed the presence of an orbital pus pocket. Despite extirpation of the four rectus muscles, inflammatory granulation debridement and abscess drainage, another new pus pocket developed. Results After partial orbital exenteration, the wound finally healed well without any additional abscess formation. Conclusions A patient who has risk factors for delayed wound healing must be examined thoroughly and extreme care such as exenteration must be taken if there is persistent infection. PMID:17302210

Orbital metastases in Italy

PubMed Central

Magliozzi, Patrizio; Strianese, Diego; Bonavolontà, Paola; Ferrara, Mariantonia; Ruggiero, Pasquale; Carandente, Raffaella; Bonavolontà, Giulio; Tranfa, Fausto

2015-01-01

AIM To describe a series of Italian patients with orbital metastasis focusing on the outcomes in relation to the different primary site of malignancy. METHODS Retrospective chart review of 93 patients with orbital metastasis collected in a tertiary referral centre in a period of 38y and review of literature. RESULTS Out of 93 patients, 52 were females and 41 were males. Median age at diagnosis was 51y (range 1 to 88y). The patients have been divided into four groups on the basis of the year of diagnosis. The frequency of recorded cases had decreased significantly (P<0.05) during the last 9.5y. Primary tumor site was breast in 36 cases (39%), kidney in 10 (11%), lung in 8 (9%), skin in 6 (6%); other sites were less frequent. In 16 case (17%) the primary tumor remained unknown. The most frequent clinical findings were proptosis (73%), limited ocular motility (55%), blepharoptosis (46%) and blurred vision (43%). The diagnosis were established by history, ocular and systemic evaluation, orbital imaging studies and open biopsy or fine needle aspiration biopsy (FNAB). Treatment included surgical excision, irradiation, chemotherapy, hormone therapy, or observation. Ninety-one percent of patients died of metastasis with an overall mean survival time (OMST) after the orbital diagnosis of 13.5mo. CONCLUSION Breast, kidney and lung are the most frequent primary sites of cancer leading to an orbital metastasis. When the primary site is unknown, gastrointestinal tract should be carefully investigated. In the last decade a decrease in the frequency of orbital metastasis has been observed. Surgery provides a local palliation. Prognosis remains poor with a OMST of 13.5mo ranging from the 3mo in the lung cancer to 24mo in the kidney tumor. PMID:26558220

Management of missiles injuries of the facial skeleton: primary, intermediate, and secondary phases.

PubMed

Kummoona, Raja

2010-07-01

This study included 235 patients with missile injuries of the facial skeleton, who were treated in the Maxillofacial Unit of the Hospital of Specialized Surgery in Medical City, Baghdad, Iraq, during a period of 4 years of war, since Iraq became the international battlefield for terrorism. There were 195 men and 40 women, with ages ranging from 1 to 70 years (mean, 39.5 years); all patients had severe facial injuries and posttraumatic missile deformities, including 27 patients with orbital injuries. This study also evaluates the management of the immediate, intermediate, and secondary phases.Deformities of the facial skeleton as a complication of missile injuries were classified into the following cases: 95 patients (40.43%) had bone loss, 72 patients (30.64%) had soft-tissue loss, 33 patients (14.05%) had orbital injuries, and 35 patients (14.90%) had other deformities of scar contracture, fistula, and sinus formation.The bony defects of the mandible were reconstructed by both bone chips carried by osteomesh tray harvested from the iliac crest in 24 patients and by block of corticocancellous bone graft from the iliac crest in 38 patients for reconstruction of the mandible, 4 cases for maxillary reconstruction, and 4 cases of orbital floor defect. K-wire was used in 23 cases for holding missing segments of the mandible. Soft-tissue reconstruction of the face was done in 72 cases, local flaps were used in 30 cases, regional flaps including lateral cervical flap in 10 cases, and cervicofacial flaps in 11 cases. The orbit was reconstructed by bone graft, lyophilized dura, and silastic implant. Low-velocity bullet injury to the frontal part of the head was treated by coronal flap, as an access in 6 cases required craniotomy and dura was reconstructed by galea or temporalis muscle. Scar contracture was treated by scar revision, and sinus tract was excised at the same time of scar revision. Primary phase required an urgent airway management, controlling an active bleeding by surgical intervention; most entrance and exit wounds as well as retained missile were located in the cheek, chin, and mandibular body. Few cases were reported of mortality due to complication related to head injuries.

Surgical decompression in endocrine orbitopathy. Visual evoked potential evaluation and effect on the optic nerve.

PubMed

Clauser, Luigi C; Tieghi, Riccardo; Galie', Manlio; Franco, Filippo; Carinci, Francesco

2012-10-01

Endocrine orbitopathy (EO) represents the most frequent and important extrathyroidal stigma of Graves disease. This chronic autoimmune condition involves the orbital contents, including extraocular muscles, periorbital connective-fatty tissue and lacrimal gland. The increase of fat tissue and the enlargement of extraocular muscles within the bony confines of the orbit leads to proptosis, and in the most severe cases optic neuropathy, caused by compression and stretching of the optic nerve. The congestion and the pressure of the enlarged muscles, constrict the nerve and can lead to reduced sight or loss of vision with the so called "orbital apex syndrome". Generally surgical treatment of EO, based on fat and/or orbital wall expansion, is possible and effective in improving exophthalmos and diplopia. Since there are limited reports focussing on optic neuropathy recovery after fat and/or orbital walls decompression the Authors decided to perform a retrospective analysis on a series of patients affected by EO. The study population was composed of 10 patients affected by EO and presenting to the Unit of Cranio Maxillofacial Surgery, Center for Craniofacial Deformities & Orbital Surgery St. Anna Hospital and University, Ferrara, Italy, for evaluation and treatment. A complete Visual Evoked Potentials (VEP) evaluation was performed. There were seven women and three men with a median age of 55 years. Optic nerve VEP amplitude and latency were recorded as normal or pathological. Abnormal results were scored as moderate, mild and severe. Differences in VEP pre and post-operatively were recorded as present or absent (i.e. VEP Delta). Pearson chi square test was applied. There were 20 operated orbits. The first VEP evaluation was performed 3.2 months before surgery and post-operative VEP control was done after a mean of 18.7 months. Fat decompression was performed in all cases and eight patients had also bony decompression. VEP amplitude and latency were affected in 10 and 15 cases before operation and six and nine after surgery, respectively. VEP amplitude and latency significantly improved after orbital decompression. Fat and orbital wall decompression are of paramount importance not only to improve exophthalmos and diplopia in patients affected by EO but also as rescue surgery for severe cases where optic neuropathy caused by stretching of the optical nerve is detected by VEP. Imaging and functional nerve evaluation are mandatory in all cases of EO. Copyright © 2012 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Orbital schwannomatosis in the absence of neurofibromatosis.

PubMed

Koktekir, Bengu Ekinci; Kim, H Jane; Geske, Mike; Bloomer, Michelle; Vagefi, Reza; Kersten, Robert C

2014-11-01

The aim of this study was to describe 3 cases of primary orbital schwannomatosis without associated systemic neurofibromatosis. This is a retrospective interventional study of 3 patients who presented with multiple, distinct masses in the orbit (n = 3) as well as in the hemiface (n = 1). The clinical presentation, imaging features, surgical procedures, and outcomes were defined. Two women and a man presented with of exophthalmos and diplopia. Pain was the most prominent complaint in 2 patients. None of the patients had associated systemic neurofibromatosis by history or examination. Radiologic evaluation with computed tomography or magnetic resonance imaging of orbit revealed multiple well-demarcated intraconal and extraconal masses. Masses were excised, and histopathology confirmed all masses to be schwannomas. Postoperative follow-up was uneventful with alleviation of primary complaints in all patients. Multiple orbital schwannomas (primary orbital schwannomatosis) may be observed in patients without systemic association of neurofibromatosis. Management includes surgical excision of the tumors to achieve relief from their mass effects.

Effective bond orders from two-step spin–orbit coupling approaches: The I{sub 2}, At{sub 2}, IO{sup +}, and AtO{sup +} case studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maurice, Rémi, E-mail: remi.maurice@subatech.in2p3.fr; Montavon, Gilles; Réal, Florent

2015-03-07

The nature of chemical bonds in heavy main-group diatomics is discussed from the viewpoint of effective bond orders, which are computed from spin–orbit wave functions resulting from spin–orbit configuration interaction calculations. The reliability of the relativistic correlated wave functions obtained in such two-step spin–orbit coupling frameworks is assessed by benchmark studies of the spectroscopic constants with respect to either experimental data, or state-of-the-art fully relativistic correlated calculations. The I{sub 2}, At{sub 2}, IO{sup +}, and AtO{sup +} species are considered, and differences and similarities between the astatine and iodine elements are highlighted. In particular, we demonstrate that spin–orbit coupling weakensmore » the covalent character of the bond in At{sub 2} even more than electron correlation, making the consideration of spin–orbit coupling compulsory for discussing chemical bonding in heavy (6p) main group element systems.« less

Orbital necrotizing fasciitis and osteomyelitis caused by arcanobacterium haemolyticum: a case report.

PubMed

Stone, Lindsay A; Harshbarger, Raymond J

2015-01-01

The facial region is infrequently affected by necrotizing infections. Orbital necrotizing infections are even rarer, seen following trauma, local skin infection, and sinusitis. The authors report a unique case of orbital necrotizing fasciitis and osteomyelitis resulting from Arcanobacterium Haemolyticum ethmoid sinusitis. No prior occurrences of Arcanobacterial species orbital necrotizing fasciitis/osteomyelitis have been reported.A 16-year-old boy presented to the ER with a 3-day history of fever, chills, headache, and sinus pressure. CT scan revealed soft tissue swelling of the right orbit, forehead, and ethmoid sinusitis. Within 24 hours of admission, he suffered rapidly progressive swelling and erythema of the right orbit and forehead with diminished visual acuity, despite broad-spectrum antibiotics. Orbital exploration revealed frankly necrotic fascia and periosteum along the superior aspect. Lateral canthotomy, cantholysis, decompression of the optic nerve, and soft tissue debridement with bone biopsy was performed. Operative specimens isolated Arcanobacterium Haemolyticum. Pathologic examination revealed right orbital osteomyelitis.

[Retrobulbar space-occupying lesions in dogs and cats: symptoms and diagnosis].

PubMed

Rühli, M B; Spiess, B M

1995-06-01

In the last five years 55 cases of orbital space-occupying lesions in dogs and cats were treated at the Veterinary Surgical Clinic of the University of Zurich. The most frequent diagnosis was orbital neoplasia (n = 29), followed by orbital abscesses or cellulitis (n = 17). Orbital hematoma (n = 5), salivary mucocele (n = 3), A/V-fistulas (n = 1), and eosinophilic myositis (n = 1) appear to be less frequent entities. The 55 cases comprised 42 dogs and only 13 cats, which seem to be less likely to suffer from orbital disease. This difference was particularly obvious in orbital inflammatory disease. The most important clinical sign is exophthalmos. Other symptoms are listed in tables. Special emphasis is put on the diagnostic work-up of orbital space-occupying lesions. An algorithm shall guide the practitioner to the correct diagnosis. The management of orbital disease is only briefly mentioned but will be the topic of a future article.

Equine orbital neoplasia: a review of 10 cases (1983-1998).

PubMed Central

Baptiste, K E; Grahn, B H

2000-01-01

The clinical manifestations, laboratory findings, and survival times of 10 horses with orbital neoplasms are reported. In all cases, orbital neoplasms were malignant and locally invasive with no defined surgical circumscribed edges. It was often difficult to identify the primary cell type of the neoplasia in histologic specimens due to the poorly differentiated, anaplastic nature of the majority of cases. All except one horse were eventually euthanized 2 mo to 5 y after diagnosis due to poor response to treatment, metastasis, or unrelenting orbital neoplasia. Mean survival time increased with surgical treatment, but no significant difference was found among no treatment, chemotherapy, surgical mass removal, or exenteration/enucleation. Equine practitioners should be aware of the marked difference in prognosis of orbital neoplasms compared with ocular or localized eyelid neoplasia. Images Figure 1. Figure 2. Figure 3. PMID:10769765

Impact of End-of-Life manoeuvres on the collision risk in protected regions

NASA Astrophysics Data System (ADS)

Frey, Stefan; Lemmens, Stijn; Bastida Virgili, Benjamin; Flohrer, Tim; Gass, Volker

2017-09-01

The Inter-Agency Space Debris Coordination Committee (IADC) Space Debris Mitigation Guidelines, issued in 2002 and revised in 2007, address the post mission disposal of objects in orbit. After their mission, objects crossing the Low Earth Orbit (LEO) should have a remaining lifetime in orbit not exceeding 25 years. Objects near the Geostationary Orbit (GEO) region should be placed in an orbit that remains outside of the GEO protected region. In this paper, the impact of satellites and rocket bodies performing End-of-Life (EOL) orbital manoeuvres on the collision risk in the LEO and GEO protected regions is investigated. The cases of full or partial compliance with the IADC post mission disposal guideline are studied. ESA's Meteoroid and Space Debris Terrestrial Environment Reference (MASTER) model is used to compare the space debris flux rate of the object during the remaining lifetime estimated for the pre-EOL-manoeuvre and for the post-EOL-manoeuvre orbit. The study shows that, on average, the probability of collision can be significantly decreased by performing an EOL-manoeuver.

Automated tru-cut imaging-guided core needle biopsy of canine orbital neoplasia. A prospective feasibility study

PubMed Central

Cirla, A.; Rondena, M.; Bertolini, G.

2016-01-01

The purpose of this study was to evaluate the diagnostic value of imaging-guided core needle biopsy for canine orbital mass diagnosis. A second excisional biopsy obtained during surgery or necropsy was used as the reference standard. A prospective feasibility study was conducted in 23 canine orbital masses at a single centre. A complete ophthalmic examination was always followed by orbital ultrasound and computed tomography (CT) examination of the head. All masses were sampled with the patient still on the CT table using ultrasound (US) guided automatic tru-cut device. The most suitable sampling approach to the orbit was chosen each time based on the CT image analysis. One of the following different approaches was used: trans-orbital, trans-conjunctival or trans-masseteric. In all cases, the imaging-guided biopsy provided a sufficient amount of tissue for the histopathological diagnosis, which concurred with the biopsies obtained using the excisional technique. CT examination was essential for morphological diagnosis and provided detailed topographic information that allowed us to choose the safest orbital approach for the biopsy. US guided automatic tru-cut biopsy based on CT images, performed with patient still on the CT table, resulted in a minimally invasive, relatively easy, and accurate diagnostic procedure in dogs with orbital masses. PMID:27540512

Automated tru-cut imaging-guided core needle biopsy of canine orbital neoplasia. A prospective feasibility study.

PubMed

Cirla, A; Rondena, M; Bertolini, G

2016-01-01

The purpose of this study was to evaluate the diagnostic value of imaging-guided core needle biopsy for canine orbital mass diagnosis. A second excisional biopsy obtained during surgery or necropsy was used as the reference standard. A prospective feasibility study was conducted in 23 canine orbital masses at a single centre. A complete ophthalmic examination was always followed by orbital ultrasound and computed tomography (CT) examination of the head. All masses were sampled with the patient still on the CT table using ultrasound (US) guided automatic tru-cut device. The most suitable sampling approach to the orbit was chosen each time based on the CT image analysis. One of the following different approaches was used: trans-orbital, trans-conjunctival or trans-masseteric. In all cases, the imaging-guided biopsy provided a sufficient amount of tissue for the histopathological diagnosis, which concurred with the biopsies obtained using the excisional technique. CT examination was essential for morphological diagnosis and provided detailed topographic information that allowed us to choose the safest orbital approach for the biopsy. US guided automatic tru-cut biopsy based on CT images, performed with patient still on the CT table, resulted in a minimally invasive, relatively easy, and accurate diagnostic procedure in dogs with orbital masses.

Local nature of impurity induced spin-orbit torques

NASA Astrophysics Data System (ADS)

Nikolaev, Sergey; Kalitsov, Alan; Chshiev, Mairbec; Mryasov, Oleg

Spin-orbit torques are of a great interest due to their potential applications for spin electronics. Generally, it originates from strong spin orbit coupling of heavy 4d/5d elements and its mechanism is usually attributed either to the Spin Hall effect or Rashba spin-orbit coupling. We have developed a quantum-mechanical approach based on the non-equilibrium Green's function formalism and tight binding Hamiltonian model to study spin-orbit torques and extended our theory for the case of extrinsic spin-orbit coupling induced by impurities. For the sake of simplicity, we consider a magnetic material on a two dimensional lattice with a single non-magnetic impurity. However, our model can be easily extended for three dimensional layered heterostructures. Based on our calculations, we present the detailed analysis of the origin of local spin-orbit torques and persistent charge currents around the impurity, that give rise to spin-orbit torques even in equilibrium and explain the existence of anisotropy.

Orbital cellulitis following silicone-sponge scleral buckles

PubMed Central

Nemet, Arie Y; Ferencz, Joseph R; Segal, Ori; Meshi, Amit

2013-01-01

Background Acute or chronic infection of the scleral explant is rare. We report seven cases of scleral explant infections that caused orbital cellulitis. Materials and methods This was a retrospective chart review of oculoplastics at oculoplastics and vitreo-retinal units in a secondary referral hospital. All subjects had orbital cellulitis secondary to scleral buckle in the range of January 1990 to March 2010. Demographics, imaging studies, and pathology specimens were reviewed. Results A total of 841 silicone-sponge scleral buckle implants for rhegmatogenous retinal detachment were performed. Forty were extracted (4.75%; annual rate of 1.9 cases). Seven (0.83%) had orbital cellulitis. The mean time from implantation to presentation was 5.7 years. There was bacterial growth in all specimens, with Staphylococcus aureus in four. Conclusions Patients who are operated on with silicone-sponge scleral buckling for rhegmatogenous retinal detachment sometimes require removal of the implant because of infection. However, the infection rate is low. Patients should be followed in the long term for possible complications. PMID:24204118

Mature orbital teratoma with an ectopic tooth and primary anophthalmos.

PubMed

Chawla, Bhavna; Chauhan, Kanchan; Kashyap, Seema

2013-02-01

To describe the clinicopathologic features and management of an unusual case of orbital teratoma. A 7-year-old girl presented with a history of an orbital mass since birth. CT scan showed a large mass lesion involving the right orbit, with absence of the eyeball. An ectopic tooth was identified within the tumor. Lid-sparing exenteration surgery was performed. Histopathologic examination of the excised mass showed presence of elements from all three germ layers, consistent with a diagnosis of mature orbital teratoma. Normal ocular structures were not identified on histopathology. At one year follow-up, there was no tumor recurrence. We report an extremely rare and interesting case of a mature orbital teratoma, which was associated with primary anophthalmos and an ectopic tooth.

Porous and nonporous orbital implants for treating the anophthalmic socket: A meta-analysis of case series studies.

PubMed

Schellini, Silvana; Jorge, Eliane; Sousa, Roberta; Burroughs, John; El-Dib, Regina

2016-01-01

To assess the efficacy and safety of porous and nonporous implants for management of the anophthalmic socket. Case series meta-analysis was conducted with no language restriction, including studies from: PUBMED, EMBASE and LILACS. Study eligibility criteria were case series design with more than 20 cases reported, use of porous and/or nonporous orbital implants, anophthalmic socket and, treatment success defined as no implant exposure or extrusion. Complications rates from each included study were quantified. Proportional meta-analysis was performed on both outcomes with a random-effects model and the 95% confidential intervals were calculated. A total of 35 case series studies with a total of 3,805 patients were included in the meta-analysis. There are no studies comparing porous and nonporous implants in the anophthalmic socket treatment. There was no statistically significant difference between porous polyethylene (PP) and hydroxyapatite (HA) on implant exposure: 0.026 (0.012-0.045) vs 0.054 (0.041-0.070), respectively and, neither on implant extrusion: 0.0042 (0.0008-0.010) vs. 0.018 (0.004-0.042), respectively. However, there was a significant difference supporting the use of PP when compared to bioceramic implant: 0.026 (0.012 -0.045) vs. 0.12 (0.06-0.20), respectively, on implant exposure. PP implants showed lower chance of exposure than bioceramic implant for anophthalmic socket reconstruction, although we cannot rule out the possibility of heterogeneity bias due to the nature and level of evidence of the included studies. Clinical trials are necessary to expand the knowledge of porous and nonporous orbital implants in the anophthalmic socket management.

Canine lobular orbital adenoma: a report of 15 cases with distinctive features.

PubMed

Headrick, Jason F; Bentley, Ellison; Dubielzig, Richard R

2004-01-01

To describe a unique orbital neoplasm in dogs, of lacrimal or salivary gland origin. Fifteen dogs with lesions consistent with a diagnosis of lobular adenomas involving the orbit were identified from the Comparative Ophthalmic Pathology Laboratory of Wisconsin from 1994 to 2001. The neoplasm occurred in nine females and six males. Affected dogs ranged in age from 7 to 17 years (mean = 9.7 years). Follow-up information was available for 13 of the 15 cases. The clinical presentation included swollen/hyperemic eyelids (4/15), third eyelid protrusion (3/15), conjunctival mass (6/15), exophthalmos (4/15), resistance to retropulsion (2/15), or strabismus (1/15). In 13 cases the masses were composed of nodular, friable tissue and they were solid in two cases. Histologically, the tissue was found in encapsulated lobules resembling well differentiated lacrimal or salivary glands but completely lacking ducts. Granular PAS-positive material was found within the cytoplasm. There was recurrence in 10 of the 13 cases available for follow-up. Of those cases in which enucleation or exenteration was performed (3/15), there was recurrence of disease in one case. In three cases the dogs were euthanized before recurrence at 3 months, 5 months and 3 years post surgery. None of the deaths was related to the tumor. In the 15 cases reviewed, lobular adenomas of the orbit presented clinically and histologically as a benign neoplasm of lacrimal or salivary gland origin. Recurrence was likely unless the mass was completely excised, at times requiring orbital exenteration.

The value of color Doppler imaging and intralesional steroid injection in pediatric orbital capillary hemangioma.

PubMed

Ke, Yifeng; Hao, Rui; He, Yanjin; Tam, Eric S; Li, Xiaorong

2014-05-01

To evaluate color Doppler imaging (CDI) as the primary imaging modality in the diagnosis of pediatric orbital capillary hemangioma. This is a retrospective study of 36 consecutive cases of orbital capillary hemangiomas between January 2006 and July 2011. Data on demographic details, clinical findings, gray-scale ultrasonography, CDI characteristics, treatment, and follow-up period were reviewed. The mean age of onset was 7 weeks. Twenty-nine (81%) lesions presented as eyelid masses, whereas seven (19%) presented as exophthalmos. Nineteen (53%) tumors were located on the upper eyelid, seven (19%) on the lower eyelid, six (17%) in the medial canthus, and one on both upper and lower eyelids. Ultrasonography depicted a heterogeneous, well-defined, irregular tumor with a low or moderate echogenicity. All lesions presented with abundant color blood flow on CDI. The intralesional blood flow had a mean peak systolic velocity of 37.5 ± 24.5 cm/second, and a mean resistance index of 0.69 ± 0.16, representing a shift in the pulse Doppler toward high velocity and high resistance. After a single intratumoral injection of betamethasone, 18 cases (50%) resolved. Additionally, 15 (42%) and four (11%) cases resolved after two injections and three injections, respectively. Only three (8%) masses persisted after three injections within the follow-up period. The blood flow characteristics of CDI play a vital role in the differentiation of orbital capillary hemangiomas from other orbital lesions. The availability and lack of adverse effects of CDI enable its utilization in the early clinical diagnosis of pediatric orbital capillary hemangioma. Copyright © 2014. Published by Elsevier B.V.

Libration of arguments of circumbinary-planet orbits at resonance

NASA Astrophysics Data System (ADS)

Schubart, Joachim

2017-06-01

The paper refers to fictitious resonant orbits of planet type that surround both components of a binary system. In case of 16 studied examples a suitable choice of the starting values leads to a process of libration of special angular arguments and to an evolution with an at least temporary stay of the planet in the resonant orbit. The ratio of the periods of revolution of the binary and a planet is equal to 1:5. Eight orbits depend on the ratio 1:5 of the masses of the binary components, but two other ratios appear as well. The basis of this study is the planar, elliptic or circular restricted problem of three bodies, but remarks at the end of the text refer to a four-body problem.

[Applicability of Pedicled Coronoid Process and Temporal Muscle(Fascial)Combined(PCPTM)Flap for Reconstruction of Orbital Floor Defect Following Hemi-Maxillectomy for Advanced Maxillary Cancer - A Report of Two Cases].

PubMed

Karino, Masaaki; Kanno, Takahiro; Kaneko, Ichiro; Ide, Taichi; Yoshino, Aya; Sekine, Joji

2017-11-01

We usually perform surgery for resectable oral and maxillofacial carcinomas. Following complete cancer resection, reconstruction of soft and hard tissues using various types of local flaps and/or vascularized free flaps is usually performed. The maxilla is composed of various anatomical structures. In particular, reconstruction of the orbit is one of the most important and challenging procedures for prevention of functional and esthetic complications. Here we report 2 cases of orbital floor defect reconstruction following advanced maxillary cancer resection using a pedicled coronoid process and temporal muscle (fascial)combined(PCPTM)flap. Case 1: A 69-year-old Japanese man with squamous cell carcinoma of the left maxilla (cT4aN2bM0, Stage IV A). Case 2: An 86-year-old Japanese woman with recurrence of myoepithelial carcinoma of the left maxilla. In both cases, the orbital floor defect was reconstructed following hemi-maxillectomy using a PCPTM flap. Minor infection and/or partial necrosis were observed postoperatively, and a maxillofacial prosthesis was used in one case. A PCPTM flap was feasible for reconstruction of surgical defects of the orbital floor following maxillectomy for cancer.

Kalman filtering applied to real-time monitoring of apogee maneuvers

NASA Technical Reports Server (NTRS)

Deboer, Frederic; Barbier, Christian

1993-01-01

Part of the Space Mathematics Division in CNES, the Flight Dynamics Center provides attitude and orbit determinations and maneuvers during the Launch and Early Operation Phase (LEOP) of geostationary satellites. Orbit determination is based on a Kalman filter method; when the 2 GHz CNES/NASA network is used, Doppler measurements are available and allow orbit determination during the apogee maneuvers. This method was used for TELE-X and TDF 2 LEOP (3-axis controlled satellites) and also for TELECOM 2 and HISPASAT (spun satellites): it enables us to follow the evolution of the maneuver and gives out a quite accurate estimation of the reached orbit. In this paper, we briefly describe the dynamic models of the orbit evolution in both cases, '3-axis' and 'inertial' thrust. Then, we present the results obtained for each case. Afterwards, we present some cases to show the robustness of the filter.

Ethmoidal sinus adenocarcinoma with orbital invasion.

PubMed

Koukoulomatis, P; Charakidas, A; Papakrivopoulos, A; Giotakis, I

2001-01-01

To report a rare case of massive ethmoidal adenocarcinoma with orbital invasion but minimal ophthalmic symptoms on presentation. Case report of a 69-year-old, otherwise healthy, retired carpenter who was referred for treatment of bilateral senile cataract. A relative afferent pupillary defect and sectorial disc atrophy on ophthalmic examination led to further investigation and identification of an extensive ethmoidal neoplasm with orbital invasion. An incisional biopsy was performed and histopathologic examination revealed an adenocarcinoma of low-grade malignancy. Ethmoidal adenocarcinomas with orbital involvement may occasionally be relatively asymptomatic and masked by coexisting ocular disease.

A case of orbital hemangiopericytoma in a dog.

PubMed

Beltran, W A; Colle, M A; Boulouha, L; Daude-Lagrave, A; Moissonnier, P; Clerc, B

2001-12-01

A 7-and-a-half-year-old-dog was presented with progressive unilateral exophthalmos. Computed tomography imaging revealed an orbital mass that was surgically excised by lateral orbitotomy to preserve vision. The tumor was diagnosed histologically as a hemangiopericytoma. Twelve months postoperatively there were no signs of a local recurrence. This is the first case report of a hemangiopericytoma involving the orbit of a dog.

Correction of Posttraumatic Enophthalmos

PubMed Central

Hazani, Ron

2012-01-01

Management of posttraumatic enophthalmos can present as a challenge to the reconstructive surgeon, particularly in cases of late presentation. This article reviews the pertinent anatomy of the orbit, diagnostic modalities, indications for surgery, and surgical approaches as they relate to the treatment of posttraumatic enophthalmos. Internal orbital reconstruction has evolved to an elegant procedure incorporating various biologic or alloplastic implants, including anatomical pre-bent implants. Successful repair of late enophthalmos has been demonstrated in multiple recent studies and is likely related to the precision with which orbital anatomy can be restored. PMID:22783485

Formation flying for electric sails in displaced orbits. Part I: Geometrical analysis

NASA Astrophysics Data System (ADS)

Wang, Wei; Mengali, Giovanni; Quarta, Alessandro A.; Yuan, Jianping

2017-09-01

We present a geometrical methodology for analyzing the formation flying of electric solar wind sail based spacecraft that operate in heliocentric, elliptic, displaced orbits. The spacecraft orbit is maintained by adjusting its propulsive acceleration modulus, whose value is estimated using a thrust model that takes into account a variation of the propulsive performance with the sail attitude. The properties of the relative motion of the spacecraft are studied in detail and a geometrical solution is obtained in terms of relative displaced orbital elements, assumed to be small quantities. In particular, for the small eccentricity case (i.e. for a near-circular displaced orbit), the bounds characterized by the extreme values of relative distances are analytically calculated, thus providing an useful mathematical tool for preliminary design of the spacecraft formation structure.

The end-of-life disposal of satellites in libration-point orbits using solar radiation pressure

NASA Astrophysics Data System (ADS)

Soldini, Stefania; Colombo, Camilla; Walker, Scott

2016-04-01

This paper proposes an end-of-life propellant-free disposal strategy for libration-point orbits which uses solar radiation pressure to restrict the evolution of the spacecraft motion. The spacecraft is initially disposed into the unstable manifold leaving the libration-point orbit, before a reflective sun-pointing surface is deployed to enhance the effect of solar radiation pressure. Therefore, the consequent increase in energy prevents the spacecraft's return to Earth. Three European Space Agency missions are selected as test case scenarios: Herschel, SOHO and Gaia. Guidelines for the end-of-life disposal of future libration-point orbit missions are proposed and a preliminary study on the effect of the Earth's orbital eccentricity on the disposal strategy is shown for the Gaia mission.

Systems Engineering Case Studies: Synopsis of the Learning Principles

DTIC Science & Technology

2010-05-17

Engineering Case Study HST refers to the Hubble Space Telescope Systems Engineering Case Study TBMCS refers to the Theater Battle Management Core System...going to orbit undetected in spite of substantial evidence that could have been used to prevent this occurrence. TBMCS /1 Requirements Definition...baseline was volatile up to system acceptance, which took place after TBMCS passed operational test and evaluation. TBMCS /2 System Architecture The

Elliptical multi-sun-synchronous orbits for Mars exploration

NASA Astrophysics Data System (ADS)

Circi, Christian; Ortore, Emiliano; Bunkheila, Federico; Ulivieri, Carlo

2012-11-01

The multi-sun-synchronous orbits allow cycles of observation of the same area in which solar illumination repetitively changes according to the value of the orbit elements and returns to the initial condition after a temporal interval multiple of the repetition of observation. This paper generalizes the concept of multi-sun-synchronous orbits, whose classical sun-synchronous orbits represent particular solutions, taking into consideration the elliptical case. The feasibility of using this typology of orbits, referred to as elliptical periodic multi-sun-synchronous orbits, has been investigated for the exploration of Mars and particular solutions have been selected. Such solutions considerably reduce the manoeuvre of velocity variation at the end of the interplanetary transfer with respect to the case of a target circular orbit around Mars. They are based on the use of quasi-critical inclinations in order to minimize the apsidal line motion and thus reduce orbit maintenance costs. Moreover, in the case of high eccentricities, the argument of pericentre may be set in order to obtain, around the apocentre, a condition of quasi-synchronism with the planet (the footprint of the probe on the surface presents a small shift with respect to a fixed point on the Martian surface). The low altitude of pericentre allows observation of the planet at a higher spatial resolution, while the orbit arc around the apocentre may be used to observe Mars with a wide spatial coverage in quasi-stationary conditions. This latter characteristic is useful for analysing atmospheric and meteorological phenomena and it allows for most of the orbital period a link between a rover on the surface of Mars and a probe orbiting around the planet.

Multi-sun-synchronous (MSS) orbits for earth observation

NASA Astrophysics Data System (ADS)

Ulivieri, Carlo; Anselmo, Luciano

1992-08-01

A case study is outlined for a remote-sensing mission at low and middle latitudes based on multi-sun-synchronous (MSS) orbits. The scenario involves the use of small payloads in low-earth posigrade orbits that would overfly the Mediterranean region. A 600-kg spacecraft is considered in an orbit that is 571 km in altitude and at an inclination of 42.5 deg. The orbit is analyzed in terms of mission characteristics, and two years of operation is shown to be feasible with a fuel-consumption rate of less than three kg/yr of hydrazine. The mission could be based on the use of a Scout solid-propellant rockets into an MSS orbit, and only a limited number of ground stations are required for good data collection. A remote-sensing mission at low/middle latitudes is shown to be efficient in terms of both revisit frequency, fuel consumption, and data acquisition.

Optimization of constellation jettisoning regards to short term collision risks

NASA Astrophysics Data System (ADS)

Handschuh, D.-DA.-A.; Bourgeois, E.

2018-04-01

The space debris problematic is directly linked to the in-orbit collision risk between artificial satellites. With the increase of the space constellation projects, a multiplication of multi-payload launches should occur. In the specific cases where many satellites are injected into orbit with the same launcher upper stage, all these objects will be placed on similar orbits, very close one from each other, at a specific moment where their control capabilities will be very limited. Under this hypothesis, it is up to the launcher operator to ensure that the simultaneous in-orbit injection is safe enough to guarantee the non-collision risk between all the objects under a ballistic hypothesis eventually considering appropriate uncertainties. The purpose of the present study is to find optimized safe separation conditions to limit the in-orbit collision risk following the injection of many objects on very close orbits in a short-delay mission.

Orbital volume augmentation using expandable hydrogel implants in acquired anophthalmia and phthisis bulbi.

PubMed

Kim, Esther Lee; Bernardino, Carlo Rob; Levin, Flora

2016-01-01

The purpose of this study is to describe our experience using expandable spherical hydrogel implants and injectable hydrogel pellets for orbital volume augmentation in cases of post-enucleation socket syndrome after acquired anophthalmia or phthisis bulbi. We retrospectively reviewed the clinical records of all adult patients who received an expandable hydrogel implant for orbital volume loss following enucleation or phthisis bulbi at the Emory Eye Center between 2004 and January 2007 and the Yale Eye Center between 2009 and 2011. The study included 9 women and 5 men with a mean age of 51.2 years old (range 35-76 years old). Follow-up spanned 6 to 71 months (median of 18.5 months). Four patients received spherical hydrogel implants and 10 patients received hydrogel pellet injections. On average, nine pellets (range 5-16) were placed in each patient over an average of 1.7 injections (range 1-3). Most commonly, five pellets were injected per session, as was the case for 13 of the 17 treatment sessions. Post-operative complications included 2 cases of pellet migration, one subcutaneously and one anteriorly due to insufficiently posterior implant placement, and 1 hospital admission for pain after injection of 10 pellets in one visit. All patients experienced an overall subjective improvement in cosmesis. Self-expandable hydrogel implants appear to offer several advantages over other existing options for orbital volume augmentation, as they are easy to place, generally well-tolerated, volume-titratable, and to the extent that our follow-up shows, may be a safe and durable means of treating orbital volume loss in patients with acquired anophthalmia and phthisis bulbi.

Orbital tuberculosis in childhood with intracranial extension: a case report.

PubMed

Tuli, Navneet

2010-01-28

The common causes of orbital masses in pediatric age group include pseudotumour, lymphomas, hemangioma and dermoid cyst. Orbital tuberculosis is rare especially in children. We report a case of 5 year old child who presented with proptosis and gross diminution of vision due to orbital tuberculoma. Ocular examination of the left eye revealed proptosis with the eyeball displaced downwards and forwards. Vision was counting finger close to face. CT Scan showed an extraconal soft tissue mass along posteromedial side of left orbit with lateral displacement of medial rectus muscle. On antitubercular treatment, proptosis regressed and visual recovery was observed over a period of six month vision, in the left eye at the last followup was 20/30.

Molecular orbital imaging via above-threshold ionization with circularly polarized pulses.

PubMed

Zhu, Xiaosong; Zhang, Qingbin; Hong, Weiyi; Lu, Peixiang; Xu, Zhizhan

2011-07-18

Above-threshold ionization (ATI) for aligned or orientated linear molecules by circularly polarized laser pulsed is investigated. It is found that the all-round structural information of the molecular orbital is extracted with only one shot by the circularly polarized probe pulse rather than with multi-shot detections in a linearly polarized case. The obtained photoelectron momentum spectrum directly depicts the symmetry and electron distribution of the occupied molecular orbital, which results from the strong sensitivity of the ionization probability to these structural features. Our investigation indicates that the circularly polarized probe scheme would present a simple method to study the angle-dependent ionization and image the occupied electronic orbital.

Rigorous Numerics for ill-posed PDEs: Periodic Orbits in the Boussinesq Equation

NASA Astrophysics Data System (ADS)

Castelli, Roberto; Gameiro, Marcio; Lessard, Jean-Philippe

2018-04-01

In this paper, we develop computer-assisted techniques for the analysis of periodic orbits of ill-posed partial differential equations. As a case study, our proposed method is applied to the Boussinesq equation, which has been investigated extensively because of its role in the theory of shallow water waves. The idea is to use the symmetry of the solutions and a Newton-Kantorovich type argument (the radii polynomial approach) to obtain rigorous proofs of existence of the periodic orbits in a weighted ℓ1 Banach space of space-time Fourier coefficients with exponential decay. We present several computer-assisted proofs of the existence of periodic orbits at different parameter values.

Subperiosteal orbital abscess: volumetric criteria for surgical drainage.

PubMed

Tabarino, Florian; Elmaleh-Bergès, Monique; Quesnel, Stéphanie; Lorrot, Mathie; Van Den Abbeele, Thierry; Teissier, Natacha

2015-02-01

To investigate predictive factors of surgical management of subperiosteal orbital abscess in children. A retrospective monocentric study was conducted between 2000 and 2011 with children hospitalized for acute pediatric orbital cellulitis (APOC). Clinical, biological and radiological data as well as medical and surgical management were collected and analyzed. All patients received intravenous antibiotics and underwent a CT-scan. Orbit and subperiosteal intraorbital abscess dimensions were measured on axial and coronal planes and the abscess volume was calculated using a spheroid model. Eighty-three children with APOC (mean age: 4.5 years) were included, 53 were boys (63.9%). Thirty-two children (38.6%) presented with a subperiosteal orbital abscess. Mean abscess volume was 570mm(3) and mean exophthalmos was 4.7mm. Twenty patients were treated surgically, 11 of which by an endoscopic approach. A positive correlation was observed between the volume of the abscess or exophthalmos and surgical drainage: 57.9% of patients underwent surgery when exophthalmos was >4mm, 29.4% between 2 and 4mm, and none when <2mm. All patients with an abscess volume >500mm(3) or >5% of orbital volume were operated on whereas only 30% or 39% of patients, respectively, in case of smaller volumes (P<0.05). Surgery for subperiosteal orbital abscess is usually performed in case of visual complications or unfavorable medical outcome. The importance of the exophthalmos and the volume of the abscess measured on the CT-scan are predictive factors of surgery in children with subperiosteal orbital abscess without visual complications. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Quench of paramagnetic orbital selective Mott phase and appearance of antiferromagnetic orbital selective slater phase in multiorbital correlated systems

NASA Astrophysics Data System (ADS)

Quan, Ya-Min; Liu, Da-Yong; Lin, Hai-Qing; Zou, Liang-Jian

2018-06-01

We present the modulation of magnetic order on the orbital selective Mott phases (OSMP) and the metal-insulator transitions (MIT) of multi-orbital Hubbard models by employing the rotationally invariant slave-boson methods. We show that at half filling, the well-known paramagnetic (PM) OSMP is completely covered by an antiferromagnetic (AFM) Slater insulator, and the PM Mott phase by an AFM Mott insulator when electron correlation strength varies from intermediate to strong both in two- and three-orbitals Hubbard systems. Away from half-filling, we find that a partial-polarized AFM orbital-selective Slater phase appears in the intermediate correlation regime, and an almost full-polarized AFM OSMP fully covers the paramagnetic OSMP. In addition, the ferromagnetic phase in the three-orbital case is more robust than that in the two-orbital case. These results demonstrate that the modulation of magnetic correlation to the quasiparticle spectra leads to much rich and more interesting MIT scenario in multiorbital correlated systems.

Color superfluidity of neutral ultracold fermions in the presence of color-flip and color-orbit fields

NASA Astrophysics Data System (ADS)

Kurkcuoglu, Doga Murat; Sá de Melo, C. A. R.

2018-02-01

We describe how color superfluidity is modified in the presence of color-flip and color-orbit fields in the context of ultracold atoms and discuss connections between this problem and that of color superconductivity in quantum chromodynamics. We study the case of s -wave contact interactions between different colors and we identify several superfluid phases, with five being nodal and one being fully gapped. When our system is described in a mixed-color basis, the superfluid order parameter tensor is characterized by six independent components with explicit momentum dependence induced by color-orbit coupling. The nodal superfluid phases are topological in nature and the low-temperature phase diagram of the color-flip field versus the interaction parameter exhibits a pentacritical point, where all five nodal color superfluid phases converge. These results are in sharp contrast to the case of zero color-flip and color-orbit fields, where the system has perfect U(3) symmetry and possesses a superfluid phase that is characterized by fully gapped quasiparticle excitations with a single complex order parameter with no momentum dependence and by inert unpaired fermions representing a nonsuperfluid component. In the latter case, just a crossover between a Bardeen-Cooper-Schrieffer and a Bose-Einstein-condensation superfluid occurs. Furthermore, we analyze the order parameter tensor in a total pseudospin basis, investigate its momentum dependence in the singlet, triplet, and quintet sectors, and compare the results with the simpler case of spin-1/2 fermions in the presence of spin-flip and spin-orbit fields, where only singlet and triplet channels arise. Finally, we analyze in detail spectroscopic properties of color superfluids in the presence of color-flip and color-orbit fields, such as the quasiparticle excitation spectrum, momentum distribution, and density of states to help characterize all the encountered topological quantum phases, which can be realized in fermionic isotopes of lithium, potassium, and ytterbium atoms with three internal states trapped.

What is the Main Potential Factor Influencing Ocular Protrusion?

PubMed

Li, Yinwei; Su, Yun; Song, Xuefei; Zhou, Huifang; Fan, Xianqun

2017-01-05

BACKGROUND The aim of the present study was to establish the normal-range orbital parameters and to explore the relationships between ocular protrusion and various orbital morphological factors. MATERIAL AND METHODS A retrospective, non-comparative case series was conducted from January 2014 to December 2015. We recruited 56 subjects (112 orbits), including 27 males (21 to 87 years of age) and 29 females (22 to 88 years of age) in this study. Nine length measurements, 2 angle measurements, and 2 volume measurements of various aspects of the orbit were obtained using Mimics v18.0 software. The data were collected manually using a 3D measurement technique. Statistical analyses using t tests and Pearson's correlation analyses were performed to evaluate the differences and relationships between the parameters, respectively. RESULTS Ocular protrusion in both sexes was closely related to the following values: orbital soft tissue volume (OSTV) (males: r=0.61, p<0.001; females: r=0.39, p=0.003), orbital soft tissue volume/bony orbital volume (OSTV/BOV) (males: r=0.90, p<0.001; females: r=0.87, p<0.001), orbital width (males: r=0.40, p=0.003; females: r=0.53, p<0.001), orbital height (males: r=0.29, p=0.038; females: r=0.45, p<0.001), and globe diameter (males: r=0.52, p<0.001; females: r=0.48, p<0.001). No differences were found between the right and left orbits. CONCLUSIONS The study provides insight into the potential factors that influence ocular protrusion, which include the OSTV/BOV ratio, the shape of the orbital aperture, and the ocular axial length. The results of orbital surgery can be made more predictable by accounting for these 3 factors. The database and regression formula might provide support for surgical planning in the future.

Digital evaluation of orbital development after self-inflating hydrogel expansion in Chinese children with congenital microphthalmia.

PubMed

Hou, Zhijia; Xian, Junfang; Chang, Qinglin; Wei, Wenbin; Li, Dongmei

2016-05-01

Assessment of the growth of bony orbit in children with blind microphthalmia is essential to its management. In this study, variables were measured to evaluate the development of the bony microphthalmic orbits after treatment with self-inflating hydrogel expanders. This is a retrospective study with an interventional case series. Thirteen pediatric patients with congenital unilateral blind microphthalmia who had undergone tissue expansion with hydrogel expanders and computed tomography (CT) scanning before and after operation were included in the study. The orbital volume, depth, width, and height and retardation of the orbital rims before and after treatment were measured and analyzed using the iPlan Cranial Software. The mean age at the time of first implantation was 44 months (range, 3-113 months). Of the 13 patients, eleven received orbital expansion, while two received socket expansion. In the orbital expansion group, the mean microphthalmic/contralateral ratio (MCR) of orbital volume was 79.3% before surgery, which increased to 89.8% 3 years post operation (P < 0.001). The mean MCR of orbital width also increased from 88.8% to 91.8% (P = 0.003). The development of inferior and lateral rims showed the greatest retardation before treatment; the retardation of these two rims decreased significantly at the final measurement (P = 0.004). It is also noted that the development of the microphthalmic orbits was limited in the two patients who only underwent socket expansion. The affected orbit enlarged in children with congenital blind microphthalmia following treatment with hydrogel expanders; this suggested that microphthalmia-associated orbital asymmetry can be treated with self-inflating hydrogel expanders. Copyright © 2016 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

The rectilinear three-body problem as a basis for studying highly eccentric systems

NASA Astrophysics Data System (ADS)

Voyatzis, G.; Tsiganis, K.; Gaitanas, M.

2018-01-01

The rectilinear elliptic restricted three-body problem (TBP) is the limiting case of the elliptic restricted TBP when the motion of the primaries is described by a Keplerian ellipse with eccentricity e'=1, but the collision of the primaries is assumed to be a non-singular point. The rectilinear model has been proposed as a starting model for studying the dynamics of motion around highly eccentric binary systems. Broucke (AIAA J 7:1003-1009, 1969) explored the rectilinear problem and obtained isolated periodic orbits for mass parameter μ =0.5 (equal masses of the primaries). We found that all orbits obtained by Broucke are linearly unstable. We extend Broucke's computations by using a finer search for symmetric periodic orbits and computing their linear stability. We found a large number of periodic orbits, but only eight of them were found to be linearly stable and are associated with particular mean motion resonances. These stable orbits are used as generating orbits for continuation with respect to μ and e'<1. Also, continuation of periodic solutions with respect to the mass of the small body can be applied by using the general TBP. FLI maps of dynamical stability show that stable periodic orbits are surrounded in phase space with regions of regular orbits indicating that systems of very highly eccentric orbits can be found in stable resonant configurations. As an application we present a stability study for the planetary system HD7449.

Diagnosis, treatment and outcome of orbital neoplasia in dogs: a retrospective study of 44 cases.

PubMed

Hendrix, D V; Gelatt, K N

2000-03-01

Forty-four dogs with confirmed orbital neoplasia were studied. Eighteen tumour types were represented and 95 per cent of the neoplasms were classified as malignant. The tumour types most commonly diagnosed were osteosarcoma, fibrosarcoma and nasal adenocarcinoma. Thirty-six per cent of the dogs had at least one clinical sign that was compatible with a diagnosis of orbital abscessation or cellulitis. Fifty-six per cent of the dogs, where follow-up information was available, were euthanased or had died within six months of diagnosis, while 19 per cent of the total were still alive after one year post-diagnosis. Cytological examination was diagnostic for orbital neoplasia in 49 per cent of the fine needle aspirates of the retrobulbar space. In contrast, 56 per cent of the non-surgical biopsies were diagnostic for orbital neoplasia. Of those dogs that had died or been euthanased within six months of diagnosis, only 22 per cent had undergone some form of therapy for orbital neoplasia. In comparison, 86 per cent of dogs surviving longer than six months post-diagnosis had undergone such therapy.

Using an Iterative Fourier Series Approach in Determining Orbital Elements of Detached Visual Binary Stars

NASA Astrophysics Data System (ADS)

Tupa, Peter R.; Quirin, S.; DeLeo, G. G.; McCluskey, G. E., Jr.

2007-12-01

We present a modified Fourier transform approach to determine the orbital parameters of detached visual binary stars. Originally inspired by Monet (ApJ 234, 275, 1979), this new method utilizes an iterative routine of refining higher order Fourier terms in a manner consistent with Keplerian motion. In most cases, this approach is not sensitive to the starting orbital parameters in the iterative loop. In many cases we have determined orbital elements even with small fragments of orbits and noisy data, although some systems show computational instabilities. The algorithm was constructed using the MAPLE mathematical software code and tested on artificially created orbits and many real binary systems, including Gliese 22 AC, Tau 51, and BU 738. This work was supported at Lehigh University by NSF-REU grant PHY-9820301.

Orbital Dirofilariasis in Iran: A Case Report

PubMed Central

Mobedi, Iraj

2009-01-01

Dirofilariasis is a common parasitic disease in both domestic and wild animals around the world, with canines as the principal reservoir host and mosquitoes as the vector. Human ophthalmic dirofilariasis is an uncommon condition, but there have been reports from many parts of the world, including Africa, Australia, the Americas, Europe, and Asia. Ophthalmic involvement with Dirofilaria may present itself as periorbital, subconjunctival, orbital, or intraocular infections. In this report, we present a case of orbital dirofilariasis with lateral rectus muscle involvement. To our knowledge, this is the first orbital dirofilariasis case reported in Iran. Although debulking of the tumor usually leads to resolution, our patient showed an episode of recurrence after biopsy. Complete recovery was achieved after a spontaneous discharge, without the need for systemic medication. PMID:19967089

A numerical comparison of discrete Kalman filtering algorithms: An orbit determination case study

NASA Technical Reports Server (NTRS)

Thornton, C. L.; Bierman, G. J.

1976-01-01

The numerical stability and accuracy of various Kalman filter algorithms are thoroughly studied. Numerical results and conclusions are based on a realistic planetary approach orbit determination study. The case study results of this report highlight the numerical instability of the conventional and stabilized Kalman algorithms. Numerical errors associated with these algorithms can be so large as to obscure important mismodeling effects and thus give misleading estimates of filter accuracy. The positive result of this study is that the Bierman-Thornton U-D covariance factorization algorithm is computationally efficient, with CPU costs that differ negligibly from the conventional Kalman costs. In addition, accuracy of the U-D filter using single-precision arithmetic consistently matches the double-precision reference results. Numerical stability of the U-D filter is further demonstrated by its insensitivity of variations in the a priori statistics.

Comparison of Selected Geopotential Models in Terms of the GOCE Orbit Determination Using Simulated GPS Observations

NASA Astrophysics Data System (ADS)

Bobojć, Andrzej

2016-12-01

This work contains a comparative study of the performance of six geopotential models in an orbit estimation process of the satellite of the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) mission. For testing, such models as ULUX_CHAMP2013S, ITG-GRACE 2010S, EIGEN-51C, EIGEN5S, EGM2008, EGM96, were adopted. Different sets of pseudo-range simulations along reference GOCE satellite orbital arcs were obtained using real orbits of the Global Positioning System satellites. These sets were the basic observation data used in the adjustment. The centimeter-accuracy Precise Science Orbit (PSO) for the GOCE satellite provided by the European Space Agency (ESA) was adopted as the GOCE reference orbit. Comparing various variants of the orbital solutions, the relative accuracy of geopotential models in an orbital aspect is determined. Full geopotential models were used in the adjustment process. The solutions were also determined taking into account truncated geopotential models. In such case, an accuracy of the solutions was slightly enhanced. Different arc lengths were taken for the computation.

Projectile metallic foreign bodies in the orbit: a retrospective study of epidemiologic factors, management, and outcomes.

PubMed

Finkelstein, M; Legmann, A; Rubin, P A

1997-01-01

Intraorbital projectile metallic foreign bodies are associated with significant ocular and orbital injuries. The authors sought to evaluate epidemiologic factors, the incidence of associated ocular and orbital injury, and the nature and necessity of surgical intervention in these cases. Charts of all patients with projectile intraorbital metallic foreign bodies seen at our institution (27) over the preceding 7 years were evaluated with respect to age, sex, type of injury, associated ocular and orbital injuries, location of the projectile (anterior, epibulbar, or posterior), postinjury visual acuity, and surgical intervention. The majority of patients were male, between the ages of 11 and 30, and had BB pellet injuries. Thirteen projectiles were lodged anteriorly, 4 were in an epibulbar position, and the remaining 10 were posterior to the equator. Twelve of 13 anterior, and 4 of 4 epibulbar foreign bodies were removed surgically, whereas only 2 of 10 posterior foreign bodies required surgery. No case of surgical intervention resulted in a decrease of visual acuity. Associated ocular injuries were both more common and severe in patients with posteriorly located foreign bodies. Final visual acuity was better at presentation and at discharge in patients with anteriorly located foreign bodies. Intraorbital projectile metallic foreign bodies can be a source of significant ocular morbidity. Management of these cases is dependent on the location of the projectile. Ancillary radiographic studies can be helpful. Surgery to remove the projectile should be considered in each case, but foreign bodies that are not readily accessible often may be left safely in place. Closer regulation of the pellet gun industry, with an emphasis on education and protective eyewear use, would be helpful in reducing these injuries.

Controls Astrophysics and Structures Experiment in Space (CASES) advanced studies and planning

NASA Technical Reports Server (NTRS)

Wu, S. T.

1989-01-01

The CASES (Controls, Astrophysics, and Structures Experiment in Space) program consists of a flight demonstration of CSI (Controls-Structures Interactions) technology on the Space Shuttle. The basis structure consists of a 32 m deployable boom with actuators and sensors distributed along its length. Upon deployment from the Orbiter bay, the CASES structure will be characterized dynamically and its deformations controlled by a series of experimental control laws; and cold gas thrusters at its tip will be used to orient the Orbiter to a fixed celestial reference. The scientific observations will consist of hard x-ray imaging, at high resolution, of the Sun and the Galactic center. The hard x-ray observations require stable (few arc min) pointing at these targets for one or more position-sensitive proportional counters in the Orbiter bay, which view the object to be imaged through an aperture-encoding mask at the boom tip. This report gives the concensus developed at the second CASES Science Working Group meeting, which took place at NASA Marshall Space Flight Center May 16-17, 1990. An earlier paper and scientific summaries are available and form the basis for the present discussion.

Orbital penetration associated with tooth extraction.

PubMed

Smith, Mark M; Smith, Eric M; La Croix, Noelle; Mould, John

2003-03-01

Three cats and 2 dogs were evaluated for ophthalmologic complications associated with tooth extraction procedures. Orbital penetration leading to ocular and, in one case, brain trauma was secondary to iatrogenic injury from a dental elevator. Outcomes included enucleation of the affected eye in 3 cases, and death from brain abscessation in 1 case. Early treatment or, preferably, referral to a veterinary ophthalmology specialist may prevent such outcomes. Awareness of the anatomical proximity of caudal maxillary tooth roots and the orbit, appropriate interpretation of diagnostic intraoral dental radiographs, and technical proficiency in tooth extraction techniques will minimize these complications in veterinary dental practice.

Juvenile nasopharyngeal angiofibroma--a rare case of primary orbital development.

PubMed

Moschos, M; Demetra, A; Kontogeorgos, G

1998-08-01

To present a rare case of juvenile nasopharyngeal angiofibroma invading the ophthalmic orbit. The CT scan examination and the ultrasound tomography revealed the existence of a homogeneous solid mass causing distention and erosion of the nasal wall as well as dislocation of the ocular bulbus. The patient was operated, the mass was carefully liberated from its synechiae and it was totally excised with its capsule. A rare case of juvenile nasopharyngeal angiofibroma invading the orbit is presented. The tumor was totally excized and the patient is five years after the operation in good general health without recurrence of the tumor.

Human Mars Mission: Launch Window from Earth Orbit. Pt. 1

NASA Technical Reports Server (NTRS)

Young, Archie

1999-01-01

The determination of orbital window characteristics is of major importance in the analysis of human interplanetary missions and systems. The orbital launch window characteristics are directly involved in the selection of mission trajectories, the development of orbit operational concepts, and the design of orbital launch systems. The orbital launch window problem arises because of the dynamic nature of the relative geometry between outgoing (departure) asymptote of the hyperbolic escape trajectory and the earth parking orbit. The orientation of the escape hyperbola asymptotic relative to the earth is a function of time. The required hyperbola energy level also varies with time. In addition, the inertial orientation of the parking orbit is a function of time because of the perturbations caused by the Earth's oblateness. Thus, a coplanar injection onto the escape hyperbola can be made only at a point in time when the outgoing escape asymptote is contained by the plane of parking orbit. Even though this condition may be planned as a nominal situation, it will not generally represent the more probable injection geometry. The general case of an escape injection maneuver performed at a time other than the coplanar time will involve both a path angle and plane change and, therefore, a delta V penalty. Usually, because of the delta V penalty the actual departure injection window is smaller in duration than that determined by energy requirement alone. This report contains the formulation, characteristics, and test cases for five different launch window modes for Earth orbit. These modes are: 1) One impulsive maneuver from a Highly Elliptical Orbit (HEO); 2) Two impulsive maneuvers from a Highly Elliptical Orbit (HEO); 3) One impulsive maneuver from a Low Earth Orbit (LEO); 4) Two impulsive maneuvers form LEO; and 5) Three impulsive maneuvers form LEO. The formulation of these five different launch window modes provides a rapid means of generating realistic parametric data for space exploration studies. Also the formulation provides vector and geometrical data sufficient for use as a good starting point in detail trajectory analysis based on calculus of variations, steepest descent, or parameter optimization program techniques.

Exo-Milankovitch Cycles. I. Orbits and Rotation States

NASA Astrophysics Data System (ADS)

Deitrick, Russell; Barnes, Rory; Quinn, Thomas R.; Armstrong, John; Charnay, Benjamin; Wilhelm, Caitlyn

2018-02-01

The obliquity of the Earth, which controls our seasons, varies by only ∼2.°5 over ∼40,000 years, and its eccentricity varies by only ∼0.05 over 100,000 years. Nonetheless, these small variations influence Earth’s ice ages. For exoplanets, however, variations can be significantly larger. Previous studies of the habitability of moonless Earth-like exoplanets have found that high obliquities, high eccentricities, and dynamical variations can extend the outer edge of the habitable zone by preventing runaway glaciation (snowball states). We expand upon these studies by exploring the orbital dynamics with a semianalytic model that allows us to map broad regions of parameter space. We find that, in general, the largest drivers of obliquity variations are secular spin–orbit resonances. We show how the obliquity varies in several test cases, including Kepler-62 f, across a wide range of orbital and spin parameters. These obliquity variations, alongside orbital variations, will have a dramatic impact on the climates of such planets.

Orbit Estimation of Non-Cooperative Maneuvering Spacecraft

DTIC Science & Technology

2015-06-01

only take on values that generate real sigma points; therefore, λ > −n. The additional weighting scheme is outlined in the following equations κ = α2...orbit shapes resulted in a similar model weighting. Additional cases of this orbit type also resulted in heavily weighting smaller η value models. It is...determined using both the symmetric and additional parameters UTs. The best values for the weighting parameters are then compared for each test case

Mercury orbiter transport study

NASA Technical Reports Server (NTRS)

Friedlander, A. L.; Feingold, H.

1977-01-01

A data base and comparative performance analyses of alternative flight mode options for delivering a range of payload masses to Mercury orbit are provided. Launch opportunities over the period 1980-2000 are considered. Extensive data trades are developed for the ballistic flight mode option utilizing one or more swingbys of Venus. Advanced transport options studied include solar electric propulsion and solar sailing. Results show the significant performance tradeoffs among such key parameters as trip time, payload mass, propulsion system mass, orbit size, launch year sensitivity and relative cost-effectiveness. Handbook-type presentation formats, particularly in the case of ballistic mode data, provide planetary program planners with an easily used source of reference information essential in the preliminary steps of mission selection and planning.

Further studies on criteria for the onset of dynamical instability in general three-body systems

NASA Technical Reports Server (NTRS)

Pendleton, Y. J.; Black, D. C.

1983-01-01

Numerical experiments designed for the elucidation of the conditions under which self-gravitating, three-body systems become dynamically unstable are examined of the cases of four orbital configuration types: circular, prograde, and coplanar; circular, retrograde, and coplanar; circular, direct, and inclined; and eccentric, direct, and coplanar. Results indicate that orbital inclination does not significantly affect stability in 'outer planet' configurations, while the stability of 'inner planet' configurations, where the tertiary is in close orbit about one member of the binary, is markedly less affected, once the relative orbital inclination is greater than 50 deg. It is found that the onset of dynamical instability is only weakly dependent on the eccentricity of either the binary or tertiary orbit, as long as the mass of the tertiary is comparable to the reduced mass of the binary.

Alveolar soft-part sarcoma of the orbit: a clinicopathologic analysis of seventeen cases and a review of the literature.

PubMed

Font, R L; Jurco, S; Zimmerman, L E

1982-06-01

This is a clinicopathologic study of 17 cases of alveolar soft-part sarcoma of the orbit. The mean age of patients was 23 and the median was 18 (range, 11 months to 69 years); 13 patients (76.5 per cent) were women and four were men (ratio, 3.25:1). The right and left orbits were equally involved (eight patients each), and in one the laterality was not specified. Histologically, the tumors had a distinctive organoid pattern outlined by thin-walled capillaries and were composed of nests of large polyhedral cells with abundant, finely granular, acidophilic cytoplasm. Approximately two thirds of the tumors had diagnostic PAS-positive diastase-resistant crystalline structures. Histologically, the differential diagnosis included nonchromaffin paraganglioma, granular cell tumor, metastatic renal cell carcinoma, vascular tumor, alveolar rhabdomyosarcoma, and amelanotic malignant melanoma. Electron microscopic studies of one tumor disclosed mitochondria with abnormal cristae, increased amounts of glycogen, and cytoplasmic crystalline structures with a periodicity of 8 to 10 nm. Smaller membrane-bound electron-dense granules appeared to be precursors of the crystals. Follow-up studies showed that eight patients were alive and well (median follow-up period, 11.4 years). Six of the eight patients at the time of diagnosis were 20 years of age or younger. A ninth patient was alive and well 13 years after excision of the orbital mass and four years after bilateral thoracotomy with resection of nine pulmonary nodules. Two patients died as a result of metastatic disease, one 14 years and the other 21 years after initial orbital surgery. Two patients died of other causes, one of whom had pulmonary metastases at autopsy. The follow-up period on two recent cases was less than three years, and two patients were lost to follow-up. The disease pursued an indolent clinical course. Surgery offers the best chance to control the disease.

Burn Delay Analysis of the Lunar Orbit Insertion for Korea Pathfinder Lunar Orbiter

NASA Astrophysics Data System (ADS)

Bae, Jonghee; Song, Young-Joo; Kim, Young-Rok; Kim, Bangyeop

2017-12-01

The first Korea lunar orbiter, Korea Pathfinder Lunar Orbiter (KPLO), has been in development since 2016. After launch, the KPLO will execute several maneuvers to enter into the lunar mission orbit, and will then perform lunar science missions for one year. Among these maneuvers, the lunar orbit insertion (LOI) is the most critical maneuver because the KPLO will experience an extreme velocity change in the presence of the Moon’s gravitational pull. However, the lunar orbiter may have a delayed LOI burn during operation due to hardware limitations and telemetry delays. This delayed burn could occur in different captured lunar orbits; in the worst case, the KPLO could fly away from the Moon. Therefore, in this study, the burn delay for the first LOI maneuver is analyzed to successfully enter the desired lunar orbit. Numerical simulations are performed to evaluate the difference between the desired and delayed lunar orbits due to a burn delay in the LOI maneuver. Based on this analysis, critical factors in the LOI maneuver, the periselene altitude and orbit period, are significantly changed and an additional delta-V in the second LOI maneuver is required as the delay burn interval increases to 10 min from the planned maneuver epoch.

A case of retained wooden foreign body in orbit.

PubMed

Lee, Jin A; Lee, Hae Young

2002-12-01

A 41-year-old man visited our clinic complaining of esodeviation of the right eye. He had been operated on for corneal laceration 3 years before. One month later, exodeviation of the right eye had developed. The result of computed tomography (CT) was reported as orbital abscess and cellulitis. Although antibiotic treatment was administered for 2 weeks, the exodeviation didn't improve. On ocular examinations performed in our hospital in November-2001, his right eye was esotropic and had a relative afferent pupillary defect. Vision of the right eye was decreased to 0.02. Fundus examination showed optic atrophy. A new CT scan disclosed a foreign body introduced into the right medial orbital wall, nasal cavity and ethmoidal sinus. Although foreign body was surgically removed, vision and eye movement were not improved. In the case of a patient who has undergone orbital trauma, complete history taking and physical examinations must be performed. On suspicion of a foreign body, imaging study such as CT or MRI must be performed. However, because CT findings can be variable, careful follow-up is needed.

Preliminary analysis of the benefits derived to US Air Force spacecraft from on-orbit refueling

NASA Astrophysics Data System (ADS)

Smith, Scott

1993-02-01

This analysis was undertaken during FY-91 as a preliminary step to identify potential benefits from refueling Air Force satellites on orbit. Both economic and operational benefits were included. Operational benefits were related in economic terms to allow evaluation. All economic comparisons were made using FY-91 costs. An additional purpose of the effort was to identify the preferred mission parameters, for an on-orbit refueling system. A companion study was being concurrently conducted by SSD/XRP and NASA/JPL to develop a hardware concept for an on-orbit refueling system. The mass estimates for refueling missions obtained from the companion study were used in conducting the economic analyses of this benefits study. For this study, on-orbit refueling was based on the concept developed in the companion JPL study. The concept involves launching an S/C carrying fuel that would be transferred to another 'target' S/C which is already in orbit. The two S/C would then rendezvous, dock, and transfer fuel. Another fluid, such as a cryogenic, might be included if needed by the target S/C. The hardware concept for refueling was intended to minimize costs. The re-fueler S/C was designated to be expendable and would contain only the minimal capabilities. It would be launched into the orbit plane and altitude of the target S/C(s). The re-fueler S/C would rendezvous and dock with the target S/C and the fluid transfer would occur. When the refueling mission was completed, the re-fueler S/C would be ejected from the orbit. In order to optimize launch costs, some missions involved launching two re-fueler S/C on the LV. In this case the second re-fueler S/C would be placed in a storage orbit until needed.

Preliminary analysis of the benefits derived to US Air Force spacecraft from on-orbit refueling

NASA Technical Reports Server (NTRS)

Smith, Scott

1993-01-01

This analysis was undertaken during FY-91 as a preliminary step to identify potential benefits from refueling Air Force satellites on orbit. Both economic and operational benefits were included. Operational benefits were related in economic terms to allow evaluation. All economic comparisons were made using FY-91 costs. An additional purpose of the effort was to identify the preferred mission parameters, for an on-orbit refueling system. A companion study was being concurrently conducted by SSD/XRP and NASA/JPL to develop a hardware concept for an on-orbit refueling system. The mass estimates for refueling missions obtained from the companion study were used in conducting the economic analyses of this benefits study. For this study, on-orbit refueling was based on the concept developed in the companion JPL study. The concept involves launching an S/C carrying fuel that would be transferred to another 'target' S/C which is already in orbit. The two S/C would then rendezvous, dock, and transfer fuel. Another fluid, such as a cryogenic, might be included if needed by the target S/C. The hardware concept for refueling was intended to minimize costs. The re-fueler S/C was designated to be expendable and would contain only the minimal capabilities. It would be launched into the orbit plane and altitude of the target S/C(s). The re-fueler S/C would rendezvous and dock with the target S/C and the fluid transfer would occur. When the refueling mission was completed, the re-fueler S/C would be ejected from the orbit. In order to optimize launch costs, some missions involved launching two re-fueler S/C on the LV. In this case the second re-fueler S/C would be placed in a storage orbit until needed.

NEXT GENERATION OF TELESCOPES OR DYNAMICS REQUIRED TO DETERMINE IF EXO-MOONS HAVE PROGRADE OR RETROGRADE ORBITS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lewis, Karen M.; Fujii, Yuka

2014-08-20

We survey the methods proposed in the literature for detecting moons of extrasolar planets in terms of their ability to distinguish between prograde and retrograde moon orbits, an important tracer of the moon formation channel. We find that most moon detection methods, in particular, sensitive methods for detecting moons of transiting planets, cannot observationally distinguishing prograde and retrograde moon orbits. The prograde and retrograde cases can only be distinguished where the dynamical evolution of the orbit due to, e.g., three body effects is detectable, where one of the two cases is dynamically unstable, or where new observational facilities, which canmore » implement a technique capable of differentiating the two cases, come online. In particular, directly imaged planets are promising targets because repeated spectral and photometric measurements, which are required to determine moon orbit direction, could also be conducted with the primary interest of characterizing the planet itself.« less

Benign orbital apex tumors treated with multisession gamma knife radiosurgery.

PubMed

Goh, Alice Siew Ching; Kim, Yoon-Duck; Woo, Kyung In; Lee, Jung-Il

2013-03-01

The orbital apex is an important anatomic landmark that hosts numerous critical neurovascular structures. Tumor resection performed at this complex region poses a therapeutic challenge to orbital surgeons and often is associated with significant visual morbidity. This article reports the efficacy and safety of multisession gamma knife radiosurgery (GKRS) in benign, well-circumscribed tumors located at the orbital apex. Retrospective interventional case series. Five patients with visual disturbances resulting from a benign, well-circumscribed orbital apex tumor (3 cases of cavernous hemangioma and 2 cases of schwannoma). Each patient treated with GKRS with a total radiation dose of 20 Gy in 4 sessions (5 Gy in each session with an isodose line of 50%) delivered to the tumor margin. Best-corrected visual acuity, visual field changes, orbital imaging, tumor growth control, and side effects of radiation. All patients demonstrated improvement in visual acuity, pupillary responses, color vision, and visual field. Tumor shrinkage was observed in all patients and remained stable until the last follow-up. No adverse events were noted during or after the radiosurgery. None of the patients experienced any radiation-related ocular morbidity. From this experience, multisession GKRS seems to be an effective management strategy to treat solitary, benign, well-circumscribed orbital apex tumors. Copyright © 2013 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

[Exenteration of the Orbit for Basal Cell Carcinoma].

PubMed

Furdová, A; Horkovičová, K; Krčová, I; Krásnik, V

2015-08-01

Primary treatment of basal cell carcinoma of the lower eyelid and the inner corner is essentially surgical, but advanced lesions require extensive surgical interventions. In some cases it is necessary to continue with the mutilating surgery--exenteration of the orbit. In this work we evaluate the indications of radical solutions in patients with basal cell carcinoma invading the orbit and the subsequent possibility for individually made prosthesis to cover the defect of the cavity. Indications to exenteration of the orbit in patients with basal cell carcinoma findings in 2008-2013. Case report of 2 patients. In period 2008-20013 at the Dept. of Ophthalmology, Comenius University in Bratislava totally 221 patients with histologically confirmed basal cell carcinoma of the eyelids and the inner corner were treated. In 5 cases (2.7 %) with infiltration of the orbit the radical surgical procedure, exenteration was necessary. In 3 patients exenteration was indicated as the first surgical procedure in the treatment of basal cell carcinoma, since they had never visited ophthalmologist before only at in the stage of infiltration of the orbit (stage T4). In one case was indicated exenteration after previous surgical interventions and relapses. After healing the cavity patients got individually prepared epithesis. Surgical treatment of basal cell carcinoma involves the radical removal of the neoplasm entire eyelid and stage T1 or T2 can effectively cure virtually all tumors with satisfactory cosmetic and functional results. In advanced stages (T4 stage) by infiltrating the orbit by basal cell carcinoma exenteration of the orbit is necessary. This surgery is a serious situation for the patient and also for his relatives. Individually made prosthesis helps the patient to be enrolled to the social environment.

Optimizing Spacecraft Placement for Liaison Constellations

NASA Technical Reports Server (NTRS)

Chow, C. Channing; Villac, Benjamin F.; Lo, Martin W.

2011-01-01

A navigation and communications network is proposed to support an anticipated need for infrastructure in the Earth-Moon system. Periodic orbits will host the constellations while a novel, autonomous navigation strategy will guide the spacecraft along their path strictly based on satellite-to-satellite telemetry. In particular, this paper investigates the second stage of a larger constellation optimization scheme for multi-spacecraft systems. That is, following an initial orbit down-selection process, this analysis provides insights into the ancillary problem of spacecraft placement. Two case studies are presented that consider configurations of up to four spacecraft for a halo orbit and a cycler trajectory.

Optimization of the rocket mode trajectory in a rocket based combined cycle (RBCC) engine powered SSTO vehicle

NASA Astrophysics Data System (ADS)

Foster, Richard W.

1989-07-01

The application of rocket-based combined cycle (RBCC) engines to booster-stage propulsion, in combination with all-rocket second stages in orbital-ascent missions, has been studied since the mid-1960s; attention is presently given to the case of the 'ejector scramjet' RBCC configuration's application to SSTO vehicles. While total mass delivered to initial orbit is optimized at Mach 20, payload delivery capability to initial orbit optimizes at Mach 17, primarily due to the reduction of hydrogen fuel tankage structure, insulation, and thermal protection system weights.

Wind-accelerated orbital evolution in binary systems with giant stars

NASA Astrophysics Data System (ADS)

Chen, Zhuo; Blackman, Eric G.; Nordhaus, Jason; Frank, Adam; Carroll-Nellenback, Jonathan

2018-01-01

Using 3D radiation-hydrodynamic simulations and analytic theory, we study the orbital evolution of asymptotic giant branch (AGB) binary systems for various initial orbital separations and mass ratios, and thus different initial accretion modes. The time evolution of binary separations and orbital periods are calculated directly from the averaged mass-loss rate, accretion rate and angular momentum loss rate. We separately consider spin-orbit synchronized and zero-spin AGB cases. We find that the angular momentum carried away by the mass loss together with the mass transfer can effectively shrink the orbit when accretion occurs via wind-Roche lobe overflow. In contrast, the larger fraction of mass lost in Bondi-Hoyle-Lyttleton accreting systems acts to enlarge the orbit. Synchronized binaries tend to experience stronger orbital period decay in close binaries. We also find that orbital period decay is faster when we account for the non-linear evolution of the accretion mode as the binary starts to tighten. This can increase the fraction of binaries that result in common envelope, luminous red novae, Type Ia supernovae and planetary nebulae with tight central binaries. The results also imply that planets in the habitable zone around white dwarfs are unlikely to be found.

Endophthalmitis in eyes presenting with orbital signs: a case-control study.

PubMed

Rishi, Pukhraj; Rishi, Ekta; Nandi, Krishnendu; Khan, Balbir

2010-03-01

The purpose of this study was to assess the clinical profile and treatment outcomes in eyes with endophthalmitis presenting with orbital signs. A case-control study of 24 eyes with endophthalmitis and orbital signs at presentation (defined as ocular motility restriction and/or presence of " inverted perpendicular" sign on ultrasonography) was conducted between January 2000 and December 2006. The control group was constituted of 40 age- and sex-matched eyes with endophthalmitis presenting without orbital signs. Optimal structural outcome was defined as resolution of inflammation and infection. Adverse structural outcome was defined as development of phthisis bulbi or need for evisceration or development of retinal detachment. Optimal functional outcome was defined as improvement in postoperative visual acuity to 3/60 or better. The Pearson chi-square test was used with appropriate significance (P < or = 0.05) to compare the mean visual acuity before and after treatment. Twenty-four patients with a mean age of 46.4 years and a mean follow-up of 14.6 months were included. Treatment options included intravitreal antibiotics, vitrectomy, evisceration, and systemic antibiotics. Optimal structural outcome was achieved in 6 (25%) eyes. A total of 70.8% eyes had no light perception, whereas 4 (16.66%) patients regained ambulatory vision (>3/60). There was a statistically significant poor visual (P = 0.05) and structural outcome (P = 0.004), whereas in the control group, 25 patients (62.5%) had vision 3/60 or better (P = 0.001). Orbital signs are independent risk factors for poor structural and visual outcomes in eyes with endophthalmitis.

Interacting Winds in Eclipsing Symbiotic Systems - The Case Study of EG Andromedae

NASA Astrophysics Data System (ADS)

Calabrò, Emanuele

2014-03-01

We report the mathematical representation of the so called eccentric eclipse model, whose numerical solutions can be used to obtain the physical parameters of a quiescent eclipsing symbiotic system. Indeed the nebular region produced by the collision of the stellar winds should be shifted to the orbital axis because of the orbital motion of the system. This mechanism is not negligible, and it led us to modify the classical concept of an eclipse. The orbital elements obtained from spectroscopy and photometry of the symbiotic EG Andromedae were used to test the eccentric eclipse model. Consistent values for the unknown orbital elements of this symbiotic were obtained. The physical parameters are in agreement with those obtained by means of other simulations for this system.

Research on periodic orbits in the three problem

NASA Astrophysics Data System (ADS)

Fernández, S.; Gámez, J.

In order to investigate the possible existence of small planets in extrasolar systems, a restricted, circular and plane three body problem is used. One of the two primaries has a mass similar to the Sun and the other one has a mass greater than Jupiter. Periodic and quasi-periodic orbits for the third body with different values of the Jacobi constant (C) are found by numerical methods. One of the three cases studied is fictitious, the others resemble two real systems of ext rasolar planets. The Everhart method is used and the results show the existence of periodic and quasi-periodic orbits for the lesser value of C. Irregular orbits appear for the other values of C, specially on the exterior zone of the secondary body.

CSM docked DAP/orbital assembly bending interaction-axial case

NASA Technical Reports Server (NTRS)

Turnbull, J. F.; Jones, J. E.

1972-01-01

A digital autopilot which can provide attitude control for the entire Skylab orbital assembly using the service module reaction control jets is described. An important consideration is the potential interaction of the control system with the bending modes of the orbital assembly. Two aspects of this potential interaction were considered. The first was the possibility that bending induced rotations feeding back through the attitude sensor into the control system could produce an instability or self-sustained oscillation. The second was whether the jet activity commanded by the control system could produce excessive loads at any of the critical load points of the orbital assembly. Both aspects were studied by using analytic techniques and by running simulations on the all-digital simulator.

Use of magnetic resonance imaging for the investigation of orbital disease in small animals.

PubMed

Dennis, R

2000-04-01

Twenty-five small animal patients presenting with signs of orbital disease were investigated using magnetic resonance imaging (MRI) in an attempt to assess the value of this imaging technique for diagnosis. All patients were also examined using ultrasonography, and skull radiography was performed in 20 of these animals. The final diagnoses included neoplasia, inflammatory disease and foreign body penetration. MRI produced detailed images of orbital tissues and provided more information about the extent of pathology than the other imaging techniques; a correct diagnosis based solely on the MRI scan was made in 22 cases. Radiography was found to be helpful only in cases in which neoplastic disease extended markedly beyond the confines of the orbit into the nasal chamber and paranasal sinuses. Radiographic changes other than soft tissue swelling were not evident in other orbital disease processes. Ultrasonography gave both false negative and false positive diagnoses for neoplastic masses, although it allowed the correct diagnosis of both cases of foreign bodies and one of the three cases of retrobulbar abscesses in this series. MRI is recommended for patients in which radiography and ultrasonography fall to produce a confident diagnosis or for which surgery is proposed.

Orbital Floor Fracture with Atypical Extraocular Muscle Entrapment Pattern and Intraoperative Asystole in an Adult

PubMed Central

Merali, Farhan I.; Grant, Michael P.; Mahoney, Nicholas R.

2015-01-01

Extraocular muscle entrapment in a nondisplaced orbital fracture, although a well-known entity in pediatric trauma, is atypical in adults. It can present with a triad of bradycardia, nausea, and in rare cases, syncope, and result in severe fibrosis of damaged and incarcerated muscle. We present a case of muscle entrapment in a partially nondisplaced two-wall orbital fracture with accompanying preoperative bradycardia and intraoperative asystole in an adult PMID:26576246

[Clinicopathologic characteristics of hemangiopericytoma/solitary fibrous tumor with giant cells].

PubMed

Wang, Hai-yan; Fan, Qin-he; Gong, Qi-xing; Wang, Zheng

2009-03-01

To study the pathological characteristics, diagnosis and differential diagnoses of hemangiopericytoma-solitary fibrous tumor with giant cells. Pathological characteristics of seven cases of orbital and extraorbital hemangiopericytoma-solitary fibrous tumors with giant cells were evaluated by HE and immunohistochemistry (EnVision method). Two cases were located in the orbit, one of which had recurred. Five cases were located in the extraorbital regions. Histologically, the tumors were well-circumscribed and composed of non-atypical, round to spindle cells with collagen deposition in the stroma. The tumors had prominent vasculatures and in areas, pseudovascular spaces lined by multinucleated giant cells lining which were also present in the stroma. Immunohistochemically, both neoplastic cells and multinucleate giant cells expressed CD34. Seven patients underwent tumor excision and were well and without tumor recurrence upon the clinical follow-up. Hemangiopericytoma-solitary fibrous tumor with giant cells is an intermediate soft tissue tumor. It typically involves the orbital or extraorbital regions. Histologically, the tumor should be distinguished from giant cell fibroblastoma, pleomorphic hyalinzing angiectatic tumor of soft part and angiomatoid fibrous histiocytoma.

RESONANCES REQUIRED: DYNAMICAL ANALYSIS OF THE 24 Sex AND HD 200964 PLANETARY SYSTEMS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wittenmyer, Robert A.; Horner, Jonathan; Tinney, C. G., E-mail: rob@phys.unsw.edu.au

We perform several suites of highly detailed dynamical simulations to investigate the architectures of the 24 Sextantis and HD 200964 planetary systems. The best-fit orbital solution for the two planets in the 24 Sex system places them on orbits with periods that lie very close to 2:1 commensurability, while that for the HD 200964 system places the two planets therein in orbits whose periods lie close to a 4:3 commensurability. In both cases, the proposed best-fit orbits are mutually crossing-a scenario that is only dynamically feasible if the planets are protected from close encounters by the effects of mutual mean-motionmore » resonance (MMR). Our simulations reveal that the best-fit orbits for both systems lie within narrow islands of dynamical stability, and are surrounded by much larger regions of extreme instability. As such, we show that the planets are only feasible if they are currently trapped in mutual MMR-the 2:1 resonance in the case of 24 Sex b and c, and the 4:3 resonance in the case of HD 200964 b and c. In both cases, the region of stability is strongest and most pronounced when the planetary orbits are mutually coplanar. As the inclination of planet c with respect to planet b is increased, the stability of both systems rapidly collapses.« less

Launch Condition Deviations of Reusable Launch Vehicle Simulations in Exo-Atmospheric Zoom Climbs

NASA Technical Reports Server (NTRS)

Urschel, Peter H.; Cox, Timothy H.

2003-01-01

The Defense Advanced Research Projects Agency has proposed a two-stage system to deliver a small payload to orbit. The proposal calls for an airplane to perform an exo-atmospheric zoom climb maneuver, from which a second-stage rocket is launched carrying the payload into orbit. The NASA Dryden Flight Research Center has conducted an in-house generic simulation study to determine how accurately a human-piloted airplane can deliver a second-stage rocket to a desired exo-atmospheric launch condition. A high-performance, fighter-type, fixed-base, real-time, pilot-in-the-loop airplane simulation has been modified to perform exo-atmospheric zoom climb maneuvers. Four research pilots tracked a reference trajectory in the presence of winds, initial offsets, and degraded engine thrust to a second-stage launch condition. These launch conditions have been compared to the reference launch condition to characterize the expected deviation. At each launch condition, a speed change was applied to the second-stage rocket to insert the payload onto a transfer orbit to the desired operational orbit. The most sensitive of the test cases was the degraded thrust case, yielding second-stage launch energies that were too low to achieve the radius of the desired operational orbit. The handling qualities of the airplane, as a first-stage vehicle, have also been investigated.

Treatment of traumatic infra orbital nerve paresthesia

PubMed Central

Lone, Parveen Akhter; Singh, R. K.; Pal, U. S.

2012-01-01

This study was done to find out the role of topiramate therapy in infraorbital nerve paresthesia after miniplate fixation in zygomatic complxex fractures. A total 2 cases of unilateral zygomatic complex fracture, 2-3 weeks old with infra orbital nerve paresthesia were slected. Open reduction and plating was done in frontozygomaticregion. Antiepileptic drug tab topiramate was given in therapeutic doses and dose was increased slowly until functional recovery was noticed. PMID:23833503

Cassini UVIS Observations of Saturn during the Grand Finale Orbits

NASA Astrophysics Data System (ADS)

Pryor, W. R.; Esposito, L. W.; West, R. A.; Jouchoux, A.; Radioti, A.; Grodent, D. C.; Gerard, J. C. M. C.; Gustin, J.; Lamy, L.; Badman, S. V.

2017-12-01

In 2016 and 2017, the Cassini Saturn orbiter executed a final series of high inclination, low-periapsis orbits ideal for studies of Saturn's polar regions. The Cassini Ultraviolet Imaging Spectrograph (UVIS) obtained an extensive set of auroral images, some at the highest spatial resolution obtained during Cassini's long orbital mission (2004-2017). In some cases, two or three spacecraft slews at right angles to the long slit of the spectrograph were required to cover the entire auroral region to form auroral images. We will present selected images from this set showing narrow arcs of emission, more diffuse auroral emissions, multiple auroral arcs in a single image, discrete spots of emission, small scale vortices, large-scale spiral forms, and parallel linear features that appear to cross in places like twisted wires. Some shorter features are transverse to the main auroral arcs, like barbs on a wire. UVIS observations were in some cases simultaneous with auroral observations from the Hubble Space Telescope Space Telescope Imaging Spectrograph (STIS) that will also be presented. UVIS polar images also contain spectral information suitable for studies of the auroral electron energy distribution. The long wavelength part of the UVIS polar images contains a signal from reflected sunlight containing absorption signatures of acetylene and other Saturn hydrocarbons. The hydrocarbon spatial distribution will also be examined.

Particle-in-cell simulations of the plasma interaction with poloidal gaps in the ITER divertor outer vertical target

NASA Astrophysics Data System (ADS)

Komm, M.; Gunn, J. P.; Dejarnac, R.; Pánek, R.; Pitts, R. A.; Podolník, A.

2017-12-01

Predictive modelling of the heat flux distribution on ITER tungsten divertor monoblocks is a critical input to the design choice for component front surface shaping and for the understanding of power loading in the case of small-scale exposed edges. This paper presents results of particle-in-cell (PIC) simulations of plasma interaction in the vicinity of poloidal gaps between monoblocks in the high heat flux areas of the ITER outer vertical target. The main objective of the simulations is to assess the role of local electric fields which are accounted for in a related study using the ion orbit approach including only the Lorentz force (Gunn et al 2017 Nucl. Fusion 57 046025). Results of the PIC simulations demonstrate that even if in some cases the electric field plays a distinct role in determining the precise heat flux distribution, when heat diffusion into the bulk material is taken into account, the thermal responses calculated using the PIC or ion orbit approaches are very similar. This is a consequence of the small spatial scales over which the ion orbits distribute the power. The key result of this study is that the computationally much less intensive ion orbit approximation can be used with confidence in monoblock shaping design studies, thus validating the approach used in Gunn et al (2017 Nucl. Fusion 57 046025).

A case of orbital apex syndrome due to Pseudomonas aeruginosa infection

PubMed Central

Kusunoki, Takeshi; Kase, Kaori; Ikeda, Katsuhisa

2011-01-01

Orbital apex syndrome is commonly been thought to have a poor prognosis. Many cases of this syndrome have been reported to be caused by paranasal sinus mycosis. We encountered a very rare case (60-year-old woman) of sinusitis with orbital apex syndrome due to Pseudomonas aeruginosa infection. She had received insulin and dialysis for diabtes and diabetic nephropathy, moreover anticoagulants after heart by-pass surgery. She underwent endoscopic sinus operation and was treated with antibiotics, but her loss of left vision did not improve. Recently, sinusitis cases due to Pseudomonas aeruginosa were reported to be a increasing. Therefore, we should consider the possibility of Pseudomonas aeruginosa as well as mycosis as infections of the sinus, especially inpatients who are immunocompromised body. PMID:24765368

A case of orbital apex syndrome due to Pseudomonas aeruginosa infection.

PubMed

Kusunoki, Takeshi; Kase, Kaori; Ikeda, Katsuhisa

2011-09-28

Orbital apex syndrome is commonly been thought to have a poor prognosis. Many cases of this syndrome have been reported to be caused by paranasal sinus mycosis. We encountered a very rare case (60-year-old woman) of sinusitis with orbital apex syndrome due to Pseudomonas aeruginosa infection. She had received insulin and dialysis for diabtes and diabetic nephropathy, moreover anticoagulants after heart by-pass surgery. She underwent endoscopic sinus operation and was treated with antibiotics, but her loss of left vision did not improve. Recently, sinusitis cases due to Pseudomonas aeruginosa were reported to be a increasing. Therefore, we should consider the possibility of Pseudomonas aeruginosa as well as mycosis as infections of the sinus, especially inpatients who are immunocompromised body.

A Comparison of Trajectory Optimization Methods for the Impulsive Minimum Fuel Rendezvous Problem

NASA Technical Reports Server (NTRS)

Hughes, Steven P.; Mailhe, Laurie M.; Guzman, Jose J.

2002-01-01

In this paper we present a comparison of optimization approaches to the minimum fuel rendezvous problem. Both indirect and direct methods are compared for a variety of test cases. The indirect approach is based on primer vector theory. The direct approaches are implemented numerically and include Sequential Quadratic Programming (SQP), Quasi-Newton, Simplex, Genetic Algorithms, and Simulated Annealing. Each method is applied to a variety of test cases including, circular to circular coplanar orbits, LEO to GEO, and orbit phasing in highly elliptic orbits. We also compare different constrained optimization routines on complex orbit rendezvous problems with complicated, highly nonlinear constraints.

Orbital invasion routes of non-melanoma skin cancers and survival outcomes.

PubMed

Dundar, Yusuf; Cannon, Richard; Wiggins, Richard; Monroe, Marcus M; Buchmann, Luke O; Hunt, Jason P

2018-02-21

Overall non-melanoma head and neck skin cancer has a good prognosis; however, rarely patients have an aggressive variant which results in orbital invasion via perineural spread or direct extension. Despite these consequences, there are limited published studies defining this clinical entity. The main objectives of the current study are to describe orbital invasion patterns of non-melanoma head and neck skin cancers and their impact on survival. Retrospective case series from a tertiary-care, academic institution performed between 2004 and 2014. Demographic and tumour characteristics are reported as well as patterns of orbital invasion, types of treatments received, and survival outcomes. There were 17 consecutive patients with non-melanoma skin cancer and orbital invasion who met inclusion criteria. Average age at orbital invasion diagnosis was 70.8 years old. 76% were male. Mean follow-up time was 28.5 months. Of these patients, 71% had squamous cell carcinoma and 29% had basal cell carcinoma. Brow (41%) was the most common primary sub-site followed by cheek (23%) and temple (12%). 76% of patients had a history of prior treatment. The lateral orbital wall (41%) was the most common site of invasion, followed by the medial orbital wall (29%) and antero-superior invasion (23%). Age, histology, and location of orbital invasion were associated with disease-specific and overall survival. Orbital invasion for non-melanoma head and neck skin cancers creates a treatment dilemma and the patterns of invasion are described. In addition, the location of orbital invasion is associated with survival outcomes.

In Situ Splitting of a Rib Bone Graft for Reconstruction of Orbital Floor and Medial Wall.

PubMed

Uemura, Tetsuji; Yanai, Tetsu; Yasuta, Masato; Harada, Yoshimi; Morikawa, Aya; Watanabe, Hidetaka; Kurokawa, Masato

2017-06-01

In situ splitting of rib bone graft was conducted in 22 patients for the repair of orbital fracture with no other complicating fractures. A bone graft was harvested from the sixth or seventh rib in the right side. The repair of the orbital floor and medial wall was successful in all the cases. Ten patients had bone grafting to the orbital floor, eight had it done onto medial wall, and 4 onto both floor and wall after reduction. The mean length of in situ rib bone graft was 40.9 mm (range, 20-70 mm), the mean width of these was 14.9 mm (range, 8-20 mm). The bone grafting was done by one leaf for 15 cases and two leafs for 7 cases in size of defects. The technique of in situ splitting of a rib bone graft for the repair of the orbital floor and medial wall is a simple and safe procedure, easily taking out the in situ splitting of a rib, and less pain in donor site. It has proved to be an optimal choice in craniofacial reconstruction, especially the defects of orbital floor and medial wall.

Characteristics of pellet injuries to the orbit.

PubMed

Kükner, A Sahap; Yilmaz, Turgut; Celebi, Serdal; Karslioğlu, Safak; Alagöz, Gürsoy; Serin, Didem; Acar, M Akif; Ozveren, M Faik

2009-01-01

To investigate the features of orbital injuries by pellets fired from the front. Retrospective, 4 cases of pellet injuries. Five orbits of 4 patients who sustained pellet injuries received from the front were reviewed retrospectively. The course of injury and results were assessed. Radiological examinations were reviewed. The patients were evaluated between December 1996 and June 2004. Five orbits of 4 patients sustained injuries caused by pellets fired from an anterior direction. The globe in the injured orbit was intact in 2 cases. Severe loss of vision was also present in these 2 globes due to optic nerve involvement. Final visual acuity was down to no light perception in 4 eyes and limited to light perception in 1 eye. The prognosis of orbital pellet injuries is, unfortunately, poor. A pellet passing through the floor of the orbit often causes double perforation of the globe and, once in the orbital aperture, it travels towards the apex as a result of the conical shape of the orbit and lodges in the optic canal or its entrance, severely damaging the optic nerve. Surgery or other treatments are usually unsuccessful. Even if the globe is intact, vision is usually severely impaired. Copyright 2009 S. Karger AG, Basel.

Expression of Vascular Endothelial Growth Factor Receptors in Benign Vascular Lesions of the Orbit: A Case Series.

PubMed

Atchison, Elizabeth A; Garrity, James A; Castillo, Francisco; Engman, Steven J; Couch, Steven M; Salomão, Diva R

2016-01-01

Vascular lesions of the orbit, although not malignant, can cause morbidity because of their location near critical structures in the orbit. For the same reason, they can be challenging to remove surgically. Anti-vascular endothelial growth factor (VEGF) drugs are increasingly being used to treat diseases with prominent angiogenesis. Our study aimed to determine to what extent VEGF receptors and their subtypes are expressed on selected vascular lesions of the orbit. Retrospective case series of all orbital vascular lesions removed by one of the authors (JAG) at the Mayo Clinic. A total of 52 patients who underwent removal of vascular orbital lesions. The pathology specimens from the patients were retrieved, their pathologic diagnosis was confirmed, demographic and clinical information were gathered, and sections from vascular tumors were stained with vascular endothelial growth factor receptor (VEGFR), vascular endothelial growth factor receptor type 1 (VEGFR1), vascular endothelial growth factor receptor type 2 (VEGFR2), and vascular endothelial growth factor receptor type 3 (VEGFR3). The existence and pattern of staining with VEGF and its subtypes on these lesions. There were 28 specimens of venous malformations, 4 capillary hemangiomas, 7 lymphatic malformations, and 6 lymphaticovenous malformations. All samples stained with VEGF, 55% stained with VEGFR1, 98% stained with VEGFR2, and 96% stained with VEGFR3. Most (94%) of the VEGFR2 staining was diffuse. Most orbital vascular lesions express VEGF receptors, which may suggest a future target for nonsurgical treatment. Copyright © 2016 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

The study of the physics of cometary nuclei

NASA Technical Reports Server (NTRS)

Whipple, F. L.

1985-01-01

The development and utilization of an optimized computer program to analyze orbital stabilization by repeated calculations is presented. The stability of comets in the Opik-Oort Cloud about the Sun against perturbations by the Galactic center involve the same basic type of calculation. The supposed persistence of these bodies in orbits over the life of the solar system, depends upon the stability of bodies of negligible mass in orbits around a body whose mass is small compared to the central mass about which they revolve. The question remains of preferential orientation of extremely eccentric comet orbits, possibly to explain the asymmetry observed among new comet motions. A third application of the computing programs is suited to meteoroids that may exist in orbits about asteroids and that may endanger science spacecraft making flybys too near to asteroids. As in the double-comet case, solar activity and solar gravitational perturbations limit the attendance to an asteroid by small meteroids in their orbits. It is found that the mass distances planned for asteroid fly-bys are adequate.

Comparison of stellar and gasdynamics of a barred galaxy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Contopoulos, G.; Gottesman, S.T.; Hunter, J.H. Jr.

1989-08-01

The stellar and gas dynamics of several models of barred galaxies were studied, and results for some representative cases are reported for galaxies in which the stars and gas respond to the same potentials. Inside corotation there are two main families of periodic orbits, designated x1 and 4/1. Close to the center, the x1 orbits are like elongated ellipses. As the 4/1 resonance is approached, these orbits become like lozenges, with apices along the bar and perpendicular to it. The family 4/1 consists of orbits like parallelograms which produce the boxy component of the bar. The orbits in spirals outsidemore » corotation enhance the spiral between the outer -4/1 resonance and the outer Lindblad resonance. Between corotation and the -4/1 resonance in strong spirals, the orbits are mostly stochastic and fill almost circular rings. A spiral field must be added to gasdynamical models to obtain gaseous arms extending from the end of a bar. 38 refs.« less

Dynamical lifetimes of asteroids in retrograde orbits

NASA Astrophysics Data System (ADS)

Kankiewicz, Paweł; Włodarczyk, Ireneusz

2017-07-01

The population of known minor bodies in retrograde orbits (I > 90°) that are classified as asteroids is still growing. The aim of our study was to estimate the dynamical lifetimes of these bodies using the latest observational data, including astrometry and physical properties. We selected 25 asteroids with the best-determined orbital elements. We studied their dynamical evolution in the past and future for ±100 Myr (±1 Gyr for three particular cases). We first used orbit determination and cloning to produce swarms of test particles. These swarms were then input into long-term numerical integrations, and the orbital elements were averaged. Next, we collected the available thermal properties of our objects and we used them in an enhanced dynamical model with Yarkovsky forces. We also used a gravitational model for comparison. Finally, we estimated the median lifetimes of 25 asteroids. We found three objects whose retrograde orbits were stable with a dynamical lifetime τ ˜ 10-100 Myr. A large portion of the objects studied displayed smaller values of τ (τ ˜ 1 Myr). In addition, we studied the possible influence of the Yarkovsky effect on our results. We found that the Yarkovsky effect can have a significant influence on the lifetimes of asteroids in retrograde orbits. Because of the presence of this effect, it is possible that the median lifetimes of these objects are extended. Additionally, the changes in orbital elements, caused by Yarkovsky forces, appear to depend on the integration direction. To explain this more precisely, the same model based on new physical parameters, determined from future observations, will be required.

The exploration of Titan with an orbiter and a lake probe

NASA Astrophysics Data System (ADS)

Mitri, Giuseppe; Coustenis, Athena; Fanchini, Gilbert; Hayes, Alex G.; Iess, Luciano; Khurana, Krishan; Lebreton, Jean-Pierre; Lopes, Rosaly M.; Lorenz, Ralph D.; Meriggiola, Rachele; Moriconi, Maria Luisa; Orosei, Roberto; Sotin, Christophe; Stofan, Ellen; Tobie, Gabriel; Tokano, Tetsuya; Tosi, Federico

2014-12-01

Fundamental questions involving the origin, evolution, and history of both Titan and the broader Saturnian system can be answered by exploring this satellite from an orbiter and also in situ. We present the science case for an exploration of Titan and one of its lakes from a dedicated orbiter and a lake probe. Observations from an orbit-platform can improve our understanding of Titan's geological processes, surface composition and atmospheric properties. Further, combined measurements of the gravity field, rotational dynamics and electromagnetic field can expand our understanding of the interior and evolution of Titan. An in situ exploration of Titan's lakes provides an unprecedented opportunity to understand the hydrocarbon cycle, investigate a natural laboratory for prebiotic chemistry and habitability potential, and study meteorological and marine processes in an exotic environment. We briefly discuss possible mission scenarios for a future exploration of Titan with an orbiter and a lake probe.

Exospheric perturbations by radiation pressure. II - Solution for orbits in the ecliptic plane

NASA Technical Reports Server (NTRS)

Chamberlain, J. W.

1980-01-01

A previous study (Chamberlain, 1979) gave solutions for the mean time rates of change of orbital elements of satellite atoms in an exosphere influenced by solar radiation pressure; each element was assumed to behave independently. In the present paper, the instantaneous rates of changes for three elements (e, Omega, and phi = omega + Omega) are integrated simultaneously for the case of the inclination i = 0. The results confirm the validity of using mean rates when the orbits are tighly bound to the planet, and serve as examples to be reproduced by the complicated numerical solutions required for arbitrary inclination. Strongly bound hydrogen atoms perturbed in earth orbit by radiation pressure do not seem a likely cause of the geotail extending in the anti-sun direction. Instead, radiation pressure will cause those particles' orbits to form a broad fan-shaped tail and to deteriorate into the earth's atmosphere.

Rotation of a spheroid in a Couette flow at moderate Reynolds numbers.

PubMed

Yu, Zhaosheng; Phan-Thien, Nhan; Tanner, Roger I

2007-08-01

The rotation of a single spheroid in a planar Couette flow as a model for simple shear flow is numerically simulated with the distributed Lagrangian multiplier based fictitious domain method. The study is focused on the effects of inertia on the orbital behavior of prolate and oblate spheroids. The numerical orbits are found to be well described by a simple empirical model, which states that the rate of the spheroid rotation about the vorticity axis is a sinusoidal function of the corresponding projection angle in the flow-gradient plane, and that the exponential growth rate of the orbit function is a constant. The following transitions in the steady state with increasing Reynolds number are identified: Jeffery orbit, tumbling, quasi-Jeffery orbit, log rolling, and inclined rolling for a prolate spheroid; and Jeffery orbit, log rolling, inclined rolling, and motionless state for an oblate spheroid. In addition, it is shown that the orbit behavior is sensitive to the initial orientation in the case of strong inertia and there exist different steady states for certain shear Reynolds number regimes.

A deorbiter CubeSat for active orbital debris removal

NASA Astrophysics Data System (ADS)

Hakima, Houman; Bazzocchi, Michael C. F.; Emami, M. Reza

2018-05-01

This paper introduces a mission concept for active removal of orbital debris based on the utilization of the CubeSat form factor. The CubeSat is deployed from a carrier spacecraft, known as a mothership, and is equipped with orbital and attitude control actuators to attach to the target debris, stabilize its attitude, and subsequently move the debris to a lower orbit where atmospheric drag is high enough for the bodies to burn up. The mass and orbit altitude of debris objects that are within the realms of the CubeSat's propulsion capabilities are identified. The attitude control schemes for the detumbling and deorbiting phases of the mission are specified. The objective of the deorbiting maneuver is to decrease the semi-major axis of the debris orbit, at the fastest rate, from its initial value to a final value of about 6471 km (i.e., 100 km above Earth considering a circular orbit) via a continuous low-thrust orbital transfer. Two case studies are investigated to verify the performance of the deorbiter CubeSat during the detumbling and deorbiting phases of the mission. The baseline target debris used in the study are the decommissioned KOMPSAT-1 satellite and the Pegasus rocket body. The results show that the deorbiting times for the target debris are reduced significantly, from several decades to one or two years.

Ultrahigh field magnetic resonance and colour Doppler real-time fusion imaging of the orbit--a hybrid tool for assessment of choroidal melanoma.

PubMed

Walter, Uwe; Niendorf, Thoralf; Graessl, Andreas; Rieger, Jan; Krüger, Paul-Christian; Langner, Sönke; Guthoff, Rudolf F; Stachs, Oliver

2014-05-01

A combination of magnetic resonance images with real-time high-resolution ultrasound known as fusion imaging may improve ophthalmologic examination. This study was undertaken to evaluate the feasibility of orbital high-field magnetic resonance and real-time colour Doppler ultrasound image fusion and navigation. This case study, performed between April and June 2013, included one healthy man (age, 47 years) and two patients (one woman, 57 years; one man, 67 years) with choroidal melanomas. All cases underwent 7.0-T magnetic resonance imaging using a custom-made ocular imaging surface coil. The Digital Imaging and Communications in Medicine volume data set was then loaded into the ultrasound system for manual registration of the live ultrasound image and fusion imaging examination. Data registration, matching and then volume navigation were feasible in all cases. Fusion imaging provided real-time imaging capabilities and high tissue contrast of choroidal tumour and optic nerve. It also allowed adding a real-time colour Doppler signal on magnetic resonance images for assessment of vasculature of tumour and retrobulbar structures. The combination of orbital high-field magnetic resonance and colour Doppler ultrasound image fusion and navigation is feasible. Multimodal fusion imaging promises to foster assessment and monitoring of choroidal melanoma and optic nerve disorders. • Orbital magnetic resonance and colour Doppler ultrasound real-time fusion imaging is feasible • Fusion imaging combines the spatial and temporal resolution advantages of each modality • Magnetic resonance and ultrasound fusion imaging improves assessment of choroidal melanoma vascularisation.

Derivation of capture probabilities for the corotation eccentric mean motion resonances

NASA Astrophysics Data System (ADS)

El Moutamid, Maryame; Sicardy, Bruno; Renner, Stéfan

2017-08-01

We study in this paper the capture of a massless particle into an isolated, first-order corotation eccentric resonance (CER), in the framework of the planar, eccentric and restricted three-body problem near a m + 1: m mean motion commensurability (m integer). While capture into Lindblad eccentric resonances (where the perturber's orbit is circular) has been investigated years ago, capture into CER (where the perturber's orbit is elliptic) has not yet been investigated in detail. Here, we derive the generic equations of motion near a CER in the general case where both the perturber and the test particle migrate. We derive the probability of capture in that context, and we examine more closely two particular cases: (I) if only the perturber is migrating, capture is possible only if the migration is outward from the primary. Notably, the probability of capture is independent of the way the perturber migrates outward; (II) if only the test particle is migrating, then capture is possible only if the algebraic value of its migration rate is a decreasing function of orbital radius. In this case, the probability of capture is proportional to the radial gradient of migration. These results differ from the capture into Lindblad eccentric resonance (LER), where it is necessary that the orbits of the perturber and the test particle converge for capture to be possible.

Space assembly fixtures and aids

NASA Technical Reports Server (NTRS)

Bloom, K. A.; Lillenas, A. N.

1980-01-01

Concepts and requirements for assembly fixtures and aids necessary for the assembly and maintenance of spare platforms were studied. Emphasis was placed on erectable and deployable type structures with the shuttle orbiter as the assembly base. Both single and multiple orbiter flight cases for the platform assembly were considered. Applicable space platform assembly studies were reviewed to provide a data base for establishing the assembly fixture and aids design requirements, assembly constraints, and the development of representative design concepts. Conclusions indicated that fixture requirements will vary with platform size. Larger platforms will require translation relative to the orbiter RMS working volume. The installation of platform payloads and subsystems (e.g., utility distribution) must also be considered in the specification of assembly fixtures and aids.

Orbital abscess caused by Fusobacterium necrophorum.

PubMed

Pitkäranta, Anne; Lindahl, Päivi; Raade, Merja; Puohiniemi, Ritvaleena

2004-05-01

We report the case of previously healthy boy with orbital abscess secondary to sinusitis. Fusobacterium necrophorum and Streptococcus anginosus was cultured both from the maxillary sinus and the orbital abscess. After surgical drainage and intravenous antibiotic treatment the boy recovered without complications.

Postflight balance control recovery in an elderly astronaut: a case report

NASA Technical Reports Server (NTRS)

Paloski, William H.; Black, F. Owen; Metter, E. Jeffrey

2004-01-01

OBJECTIVE: To examine the sensorimotor adaptive response of a 77-year-old man exposed to the gravito-inertial challenges of orbital space flight. STUDY DESIGN: Prospective case study with retrospective comparisons. SETTING: NASA Neurosciences Laboratory (Johnson Space Center) and Baseline Data Collection Facility (Kennedy Space Center). PRIMARY PARTICIPANT: One 77-year-old male shuttle astronaut. INTERVENTION: Insertion into low Earth orbit was used to remove gravitational stimuli and thereby trigger sensorimotor adaptation to the microgravity environment. Graviceptor stimulation was reintroduced at landing, and sensorimotor readaptation to the terrestrial environment was tracked to completion. MAIN OUTCOME MEASURES: Computerized dynamic posturography tests were administered before and after orbital flight to determine the magnitude and time course of recovery. RESULTS: The elderly astronaut exhibited balance control performance decrements on landing day; however, there were no significant differences between his performance and that of younger astronauts tested on the same shuttle mission or on previous shuttle missions of similar duration. CONCLUSIONS: These results demonstrate that the physiological changes attributed to aging do not necessarily impair adaptive sensorimotor control processes.

Null conformal Killing-Yano tensors and Birkhoff theorem

NASA Astrophysics Data System (ADS)

Ferrando, Joan Josep; Sáez, Juan Antonio

2016-04-01

We study the space-times admitting a null conformal Killing-Yano tensor whose divergence defines a Killing vector. We analyze the similarities and differences with the recently studied non null case (Ferrando and Sáez in Gen Relativ Gravit 47:1911, 2015). The results by Barnes concerning the Birkhoff theorem for the case of null orbits are analyzed and generalized.

A superconducting quenchgun for delivering lunar derived oxygen to lunar orbit

NASA Technical Reports Server (NTRS)

Nottke, Nathan; Bilby, Curt R.

1990-01-01

The development of a parametric model for a superconducting quenchgun for launching lunar derived liquid oxygen to lunar orbit is detailed. An overview is presented of the quenchgun geometry and operating principles, a definition of the required support systems, and the methods used to size the quenchgun launcher and support systems. An analysis assessing the impact of a lunar quenchgun on the OEXP Lunar Evolution Case Study is included.

Full particle orbit effects in regular and stochastic magnetic fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ogawa, Shun; Cambon, Benjamin P.; Leoncini, Xavier

Here we present a numerical study of charged particle motion in a time-independent magnetic field in cylindrical geometry. The magnetic field model consists of an unperturbed reversed-shear (non-monotonic q-profile) helical part and a perturbation consisting of a superposition of modes. Contrary to most of the previous studies, the particle trajectories are computed by directly solving the full Lorentz force equations of motion in a six-dimensional phase space using a sixth-order, implicit, symplectic Gauss-Legendre method. The level of stochasticity in the particle orbits is diagnosed using averaged, effective Poincare sections. It is shown that when only one mode is present, themore » particle orbits can be stochastic even though the magnetic field line orbits are not stochastic (i.e., fully integrable). The lack of integrability of the particle orbits in this case is related to separatrix crossing and the breakdown of the global conservation of the magnetic moment. Some perturbation consisting of two modes creates resonance overlapping, leading to Hamiltonian chaos in magnetic field lines. Then, the particle orbits exhibit a nontrivial dynamics depending on their energy and pitch angle. It is shown that the regions where the particle motion is stochastic decrease as the energy increases. The non-monotonicity of the q-profile implies the existence of magnetic ITBs (internal transport barriers) which correspond to shearless flux surfaces located in the vicinity of the q-profile minimum. It is shown that depending on the energy, these magnetic ITBs might or might not confine particles. That is, magnetic ITBs act as an energy-dependent particle confinement filter. Magnetic field lines in reversed-shear configurations exhibit topological bifurcations (from homoclinic to heteroclinic) due to separatrix reconnection. Finally, we show that a similar but more complex scenario appears in the case of particle orbits that depend in a non-trivial way on the energy and pitch angle of the particles.« less

Full particle orbit effects in regular and stochastic magnetic fields

DOE PAGES

Ogawa, Shun; Cambon, Benjamin P.; Leoncini, Xavier; ...

2016-07-18

Here we present a numerical study of charged particle motion in a time-independent magnetic field in cylindrical geometry. The magnetic field model consists of an unperturbed reversed-shear (non-monotonic q-profile) helical part and a perturbation consisting of a superposition of modes. Contrary to most of the previous studies, the particle trajectories are computed by directly solving the full Lorentz force equations of motion in a six-dimensional phase space using a sixth-order, implicit, symplectic Gauss-Legendre method. The level of stochasticity in the particle orbits is diagnosed using averaged, effective Poincare sections. It is shown that when only one mode is present, themore » particle orbits can be stochastic even though the magnetic field line orbits are not stochastic (i.e., fully integrable). The lack of integrability of the particle orbits in this case is related to separatrix crossing and the breakdown of the global conservation of the magnetic moment. Some perturbation consisting of two modes creates resonance overlapping, leading to Hamiltonian chaos in magnetic field lines. Then, the particle orbits exhibit a nontrivial dynamics depending on their energy and pitch angle. It is shown that the regions where the particle motion is stochastic decrease as the energy increases. The non-monotonicity of the q-profile implies the existence of magnetic ITBs (internal transport barriers) which correspond to shearless flux surfaces located in the vicinity of the q-profile minimum. It is shown that depending on the energy, these magnetic ITBs might or might not confine particles. That is, magnetic ITBs act as an energy-dependent particle confinement filter. Magnetic field lines in reversed-shear configurations exhibit topological bifurcations (from homoclinic to heteroclinic) due to separatrix reconnection. Finally, we show that a similar but more complex scenario appears in the case of particle orbits that depend in a non-trivial way on the energy and pitch angle of the particles.« less

Full particle orbit effects in regular and stochastic magnetic fields

NASA Astrophysics Data System (ADS)

Ogawa, Shun; Cambon, Benjamin; Leoncini, Xavier; Vittot, Michel; del Castillo-Negrete, Diego; Dif-Pradalier, Guilhem; Garbet, Xavier

2016-07-01

We present a numerical study of charged particle motion in a time-independent magnetic field in cylindrical geometry. The magnetic field model consists of an unperturbed reversed-shear (non-monotonic q-profile) helical part and a perturbation consisting of a superposition of modes. Contrary to most of the previous studies, the particle trajectories are computed by directly solving the full Lorentz force equations of motion in a six-dimensional phase space using a sixth-order, implicit, symplectic Gauss-Legendre method. The level of stochasticity in the particle orbits is diagnosed using averaged, effective Poincare sections. It is shown that when only one mode is present, the particle orbits can be stochastic even though the magnetic field line orbits are not stochastic (i.e., fully integrable). The lack of integrability of the particle orbits in this case is related to separatrix crossing and the breakdown of the global conservation of the magnetic moment. Some perturbation consisting of two modes creates resonance overlapping, leading to Hamiltonian chaos in magnetic field lines. Then, the particle orbits exhibit a nontrivial dynamics depending on their energy and pitch angle. It is shown that the regions where the particle motion is stochastic decrease as the energy increases. The non-monotonicity of the q-profile implies the existence of magnetic ITBs (internal transport barriers) which correspond to shearless flux surfaces located in the vicinity of the q-profile minimum. It is shown that depending on the energy, these magnetic ITBs might or might not confine particles. That is, magnetic ITBs act as an energy-dependent particle confinement filter. Magnetic field lines in reversed-shear configurations exhibit topological bifurcations (from homoclinic to heteroclinic) due to separatrix reconnection. We show that a similar but more complex scenario appears in the case of particle orbits that depend in a non-trivial way on the energy and pitch angle of the particles.

Energy transfer, orbital angular momentum, and discrete current in a double-ring fiber array

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alexeyev, C. N.; Volyar, A. V.; Yavorsky, M. A.

We study energy transfer and orbital angular momentum of supermodes in a double-ring array of evanescently coupled monomode optical fibers. The structure of supermodes and the spectra of their propagation constants are obtained. The geometrical parameters of the array, at which the energy is mostly confined within the layers, are determined. The developed method for finding the supermodes of concentric arrays is generalized for the case of multiring arrays. The orbital angular momentum carried by a supermode of a double-ring array is calculated. The discrete lattice current is introduced. It is shown that the sum of discrete currents over themore » array is a conserved quantity. The connection of the total discrete current with orbital angular momentum of discrete optical vortices is made.« less

Contingency plans for the ISEE-3 libration-point mission

NASA Technical Reports Server (NTRS)

Dunham, D. W.

1979-01-01

During the planning stage of the International Sun-Earth Explorer-3 (ISEE-3) mission, a recovery strategy was developed in case the Delta rocket underperformed during the launch phase. If a large underburn had occurred, the ISEE-3 spacecraft would have been allowed to complete one revolution of its highly elliptical earth orbit. The recovery plan called for a maneuver near perigee to increase the energy of the off-nominal orbit; a relatively small second maneuver would then insert the spacecraft into a new transfer trajectory toward the desired halo orbit target, and a third maneuver would place the spacecraft in the halo orbit. Results of the study showed that a large range of underburns could be corrected for a total nominal velocity deviation cost within the ISEE-3 fuel budget.

[Treatment of enophthalmos after severe malar-maxillary complex fracture with titanium mesh and high density polyethylene (Medpor)].

PubMed

Zhao, Yan-feng; Lu, Ping; Zhou, Xiao-nan; Qu, Chang-feng

2010-03-01

To study the surgical management of enophthalmos after severe malar maxillary complex fracture. The X-ray and CT examination were performed before operation to diagnose the orbital fracture and intraorbital tissue displacement. The fractured orbital rim was repositioned intraoperatively, followed by implantation of shaped titanium mesh to rebuild the orbital floor. The Medpor was inserted above the titanium mesh to correct the enophthalmos. From Sept. 2007 to Jan. 2009, 6 cases of enophthalmos after severe malar-maxillary complex fracture were treated. The enophthalmos was corrected or improved obviously in all the patients. The enophthalmos after severe malar-maxillary complex fracture can be corrected or obviously improved. Shaped titanium mesh can be used to rebuild the orbital floor with the Medpor to reconstruct the intraorbital tissue volume.

Development and Execution of End-of-Mission Operations Case Study of the UARS and ERBS End-of-Mission Plans

NASA Technical Reports Server (NTRS)

Hughes, John; Marius, Julio L.; Montoro, Manuel; Patel, Mehul; Bludworth, David

2006-01-01

This Paper is a case study of the development and execution of the End-of-Mission plans for the Earth Radiation Budget Satellite (ERBS) and the Upper Atmosphere Research Satellite (UARS). The goals of the End-of-Mission Plans are to minimize the time the spacecraft remains on orbit and to minimize the risk of creating orbital debris. Both of these Missions predate the NASA Management Instructions (NMI) that directs missions to provide for safe mission termination. Each spacecrafts had their own unique challenges, which required assessing End-of-Mission requirements versus spacecraft limitations. Ultimately the End-of- Mission operations were about risk mitigation. This paper will describe the operational challenges and the lessons learned executing these End-of-Mission Plans

Are Adonis and Hephaistos "Extinct" Comets?

NASA Astrophysics Data System (ADS)

Babadzhanov, P. B.

The investigation of the evolution of Earth-approaching asteroids with the aim of revealing their meteor streams is one of the ways to determine if these asteroids are extinct comets. The orbital evolution of asteroids 2101 Adonis and 2212 Hephaistos studied, respectively, by AlfanGoryachev and Everhart methods shows that these asteroids cross the Earth's orbit four times. Their possible meteoroid swarms may therefore produce four meteor showers each. In this work, the theoretically predicted orbital elements and radiants of these streams are compared to the available observational data. In the cases of both Adonis and Hephaistos, all four meteor showers are shown to be active. Most likely, these asteroids are extinct comets.

[Juvenile nasopharyngeal angiofibroma with orbital extension].

PubMed

Hervás Ontiveros, A; España Gregori, E; Climent Vallano, L; Rivas Rodero, S; Alamar Velázquez, A; Simal Julián, J A

2015-01-01

The case is presented of a 21 year-old male with a history of left proptosis and diplopia of two weeks of onset. The MRI showed an ethmoid-orbital vascular lesion with anterior skull base invasion and orbital extension. Biopsy of the ethmoid confirmed fibrovascular tissue, which supported the diagnosis of angiofibroma. It is a benign neoplasm with local characteristics of malignancy due to its ability to invade adjacent areas. In this case, the debut presented with manifestations of orbital extension. A broad and multidisciplinary approach is needed in order to improve prognosis. Copyright © 2013 Sociedad Española de Oftalmología. Published by Elsevier España, S.L.U. All rights reserved.

Repair of orbital floor fractures with absorbable gelatin film.

PubMed

Mermer, R W; Orban, R E

1995-01-01

Many materials have been utilized for the repair of orbital floor fractures. Absorbable gelatin film is a bioabsorbable sheeting material that is manufactured from denatured collagen. This material is appropriate for the repair of smaller orbital floor defects (5 mm or less) and trapdoor-type fractures; it is used with larger defects as an interpositional graft material between the periorbital tissues and as an orbital floor reconstruction plate or mesh. Sixteen cases consisting of both types of defects were retrospectively examined clinically and radiographically. Satisfactory results were obtained in all of these cases, including no adverse ocular signs or implant rejection, good facial form, good function, and acceptable postoperative radiography results.

Congenital orbital teratoma.

PubMed

Aiyub, Shereen; Chan, Wengonn; Szetu, John; Sullivan, Laurence J; Pater, John; Cooper, Peter; Selva, Dinesh

2013-12-01

We present a case of mature congenital orbital teratoma managed with lid-sparing exenteration and dermis fat graft. This is a case report on the management of congenital orbital teratoma. A full-term baby was born in Fiji with prolapsed right globe which was surrounded by a nonpulsatile, cystic mass. Clinical and imaging features were consistent with congenital orbital teratoma. Due to limited surgical expertise, the patient was transferred to Adelaide, Australia for further management. The patient underwent a lid-sparing exenteration with frozen section control of the apical margin. A dermis fat graft from the groin was placed beneath the lid skin to provide volume. Histopathology revealed mature tissues from each of the three germ cell layers which confirmed the diagnosis of mature teratoma. We describe the successful use of demis fat graft in socket reconstruction following lid-sparing exenteration for congenital orbital teratoma.

Congenital orbital teratoma

PubMed Central

Aiyub, Shereen; Chan, Weng Onn; Szetu, John; Sullivan, Laurence J; Pater, John; Cooper, Peter; Selva, Dinesh

2013-01-01

We present a case of mature congenital orbital teratoma managed with lid-sparing exenteration and dermis fat graft. This is a case report on the management of congenital orbital teratoma. A full-term baby was born in Fiji with prolapsed right globe which was surrounded by a nonpulsatile, cystic mass. Clinical and imaging features were consistent with congenital orbital teratoma. Due to limited surgical expertise, the patient was transferred to Adelaide, Australia for further management. The patient underwent a lid-sparing exenteration with frozen section control of the apical margin. A dermis fat graft from the groin was placed beneath the lid skin to provide volume. Histopathology revealed mature tissues from each of the three germ cell layers which confirmed the diagnosis of mature teratoma. We describe the successful use of demis fat graft in socket reconstruction following lid-sparing exenteration for congenital orbital teratoma. PMID:23619505

Analysis of orbital malignancies presenting in a tertiary care hospital in Pakistan

PubMed Central

Khan, Asad Aslam; Sarwar, Suhail; Sadiq, Mohammad Ali A; Ahmad, Imran; Tariq, Nayab; Sibghat-ul-Noor

2017-01-01

Objective: To determine the frequencies of various orbital malignancies amongst orbital lesions in patients presenting in a tertiary care hospital in Pakistan. Methods: A retrospective analysis of 666 orbital cases with an established histopathological diagnosis of malignant tumors treated in Mayo Hospital Lahore from 1996 to 2015 (20 years). Results: About 66% of the malignant tumors were primary, 25% secondary, 8% haematopoietic and 1% metastatic. Almost 50% of the cases were children. Retinoblastoma is the commonest tumor (43% overall and 87% among children). Squamous cell carcinoma is the second commonest (15.6% overall and 31% among adults). These are then followed by Adenoid cystic carcinoma of Lacrimal Gland (9%), Lymphoma/Leukaemia (8%) and Rhabdomyosarcoma (6.3%). Conclusion: Frequencies of various orbital malignancies show geographical variation in both paediatric and adult population. PMID:28367175

Orbit determination singularities in the Doppler tracking of a planetary orbiter

NASA Technical Reports Server (NTRS)

Wood, L. J.

1985-01-01

On a number of occasions, spacecraft launched by the U.S. have been placed into orbit about the moon, Venus, or Mars. It is pointed out that, in particular, in planetary orbiter missions two-way coherent Doppler data have provided the principal data type for orbit determination applications. The present investigation is concerned with the problem of orbit determination on the basis of Doppler tracking data in the case of a spacecraft in orbit about a natural body other than the earth or the sun. Attention is given to Doppler shift associated with a planetary orbiter, orbit determination using a zeroth-order model for the Doppler shift, and orbit determination using a first-order model for the Doppler shift.

Improving satellite vulnerability assessment to untrackable orbital debris

NASA Astrophysics Data System (ADS)

Welty, Nathan; Schaefer, Frank; Rudolph, Martin; Destefanis, Roberto; Grassi, Lilith

2012-07-01

The projected growth in the untrackable orbital debris population will place an increased emphasis on satellite vulnerability assessments during both design and mission operations. This study presents an enhanced method for assessing satellite vulnerability to untrackable orbital debris that expands on traditional practices. By looking beyond structural penetration of the spacecraft, the method predicts the survivability of individual components and the associated degradation of system functionality resulting from untrackable debris impacts. A new risk assessment tool, the Particle Impact Risk and Vulnerability Assessment Tool (PIRAT), has been developed based on this method and is also presented here. It interfaces with both the NASA ORDEM2000 and ESA MASTER-2009 debris models and has been validated against the benchmark test cases from the Inter-Agency Space Debris Coordination Committee (IADC). This study concludes with an example vulnerability assessment using PIRAT for a generic Earth observation satellite in a Sun-synchronous low-Earth orbit. The results illustrate the additional insight provided by this method that can be used to improve the robustness of future satellite designs and mitigate the overall mission risk posed by untrackable orbital debris.

Design of Quasi-Terminator Orbits near Primitive Bodies

NASA Technical Reports Server (NTRS)

Lantoine, Gregory; Broschart, Stephen B.; Grebow, Daniel J.

2013-01-01

Quasi-terminator orbits are a class of quasi-periodic orbits around a primitive body that exist in the vicinity of the well-known terminator orbits. The inherent stability of quasi-terminator trajectories and their wide variety of viewing geometries make them a very compelling option for primitive body mapping missions. In this paper, we discuss orbit design methodologies for selection of an appropriate quasi-terminator orbit that would meet the needs of a specific mission. Convergence of these orbits in an eccentric, higher-fidelity model is also discussed with an example case at Bennu, the target of the upcoming NASA's OSIRIS-REx mission.

The Solar Poynting-Robertson Effect On Particles Orbiting Solar System Bodies: Circular Orbits

NASA Technical Reports Server (NTRS)

Rubincam, David P.

2013-01-01

The Poynting-Robertson effect from sunlight impinging directly on a particle which orbits a Solar System body (planet, asteroid, comet) is considered from the Sun's rest frame. There appear to be no significant first-order terms in V(sub b)/c for circular orbits, where V(sub b) is the body's speed in its orbit about the Sun and c is the speed of light, when the particle's orbital semimajor axis is much smaller than the body's orbital semimajor axis about the Sun as is mainly the case in the Solar System.

Selection of Thermal Worst-Case Orbits via Modified Efficient Global Optimization

NASA Technical Reports Server (NTRS)

Moeller, Timothy M.; Wilhite, Alan W.; Liles, Kaitlin A.

2014-01-01

Efficient Global Optimization (EGO) was used to select orbits with worst-case hot and cold thermal environments for the Stratospheric Aerosol and Gas Experiment (SAGE) III. The SAGE III system thermal model changed substantially since the previous selection of worst-case orbits (which did not use the EGO method), so the selections were revised to ensure the worst cases are being captured. The EGO method consists of first conducting an initial set of parametric runs, generated with a space-filling Design of Experiments (DoE) method, then fitting a surrogate model to the data and searching for points of maximum Expected Improvement (EI) to conduct additional runs. The general EGO method was modified by using a multi-start optimizer to identify multiple new test points at each iteration. This modification facilitates parallel computing and decreases the burden of user interaction when the optimizer code is not integrated with the model. Thermal worst-case orbits for SAGE III were successfully identified and shown by direct comparison to be more severe than those identified in the previous selection. The EGO method is a useful tool for this application and can result in computational savings if the initial Design of Experiments (DoE) is selected appropriately.

Orbital Metastasis: Rare Initial Presentation of an Occult Gall Bladder Carcinoma.

PubMed

Jain, Tarun Kumar; Parihar, Ashwin Singh; Sood, Ashwani; Basher, Rajender Kumar; Bollampally, Neeraja; Shekhawat, Amit Singh; Mittal, Bhagwant Rai

2018-03-01

Orbital metastases are known to arise from primary breast carcinoma followed by prostate, malignant melanoma, and lung carcinoma. We report a case of orbital metastasis as the initial presentation of an occult primary gall bladder carcinoma. The FDG PET/CT helped in localizing the occult distant primary site, which previously escaped detection, and also enabled the evaluation of orbital metastasis.

Traumatic longitudinal splitting of the inferior rectus muscle

PubMed Central

Laursen, Jessica; Demer, Joseph L.

2011-01-01

Orbital floor fractures and associated injuries can cause strabismus. We present the case of a 34-year-old man with incomitant strabismus following orbital reconstruction after a high-impact baseball injury. Multipositional, high-resolution magnetic resonance imaging (MRI) revealed extensive longitudinal splitting of the inferior rectus muscle by an orbital floor implant that separated its orbital and global layers. PMID:21463958

Behaviour of DFT-based approaches to the spin-orbit term of zero-field splitting tensors: a case study of metallocomplexes, MIII(acac)3 (M = V, Cr, Mn, Fe and Mo).

PubMed

Sugisaki, Kenji; Toyota, Kazuo; Sato, Kazunobu; Shiomi, Daisuke; Takui, Takeji

2017-11-15

Spin-orbit contributions to the zero-field splitting (ZFS) tensor (D SO tensor) of M III (acac) 3 complexes (M = V, Cr, Mn, Fe and Mo; acac = acetylacetonate anion) are evaluated by means of ab initio (a hybrid CASSCF/MRMP2) and DFT (Pederson-Khanna (PK) and natural orbital-based Pederson-Khanna (NOB-PK)) methods, focusing on the behaviour of DFT-based approaches to the D SO tensors against the valence d-electron configurations of the transition metal ions in octahedral coordination. Both the DFT-based approaches reproduce trends in the D tensors. Significantly, the differences between the theoretical and experimental D (D = D ZZ - (D XX + D YY )/2) values are smaller in NOB-PK than in PK, emphasising the usefulness of the natural orbital-based approach to the D tensor calculations of transition metal ion complexes. In the case of d 2 and d 4 electronic configurations, the D SO (NOB-PK) values are considerably underestimated in the absolute magnitude, compared with the experimental ones. The D SO tensor analysis based on the orbital region partitioning technique (ORPT) revealed that the D SO contributions attributed to excitations from the singly occupied region (SOR) to the unoccupied region (UOR) are significantly underestimated in the DFT-based approaches to all the complexes under study. In the case of d 3 and d 5 configurations, the (SOR → UOR) excitations contribute in a nearly isotropic manner, which causes fortuitous error cancellations in the DFT-based D SO values. These results indicate that more efforts to develop DFT frameworks should be directed towards the reproduction of quantitative D SO tensors of transition metal complexes with various electronic configurations and local symmetries around metal ions.

The impact of suction drainage on orbital compartment syndrome after craniofacial surgery.

PubMed

Fenzl, Carlton R; Golio, Dominick

2014-07-01

Postoperative orbital compartment syndrome is a potentially blinding complication of surgery in the orbital region. We describe the technique of orbital drain placement as a method of preventing vision loss resulting from orbital compartment syndrome. We present a retrospective case series of 29 patients who underwent orbital fracture, facial fracture, and orbital implant removal from 7/4/2008 to 5/3/2013 by the same craniofacial surgeon. An orbital drain was placed in each patient. The drainage was recorded daily until drain removal. Criteria for removal included less than or equal to 5 mL of drainage in 24 hours. Of the 29 patients included in this study, 21 were men and 8 were women. Ages ranged from 17 to 67 years. The postoperative drainage ranged from less than 1 mL to 71 mL of serosanguinous fluid. All drains were removed between the first and sixth postoperative days. No postoperative visual loss, infections, or additional antibiotics were recorded with follow-up reaching as far as 40 months. Postoperative orbital compartment syndrome is a dangerous complication of surgery in the orbital region. Its rapid onset necessitates immediate intervention to prevent permanent vision loss. Morphologic changes to the optic nerve as well as reductions in electroretinogram a- and b-wave amplitudes have been demonstrated with as little as 7 mL of fluid accumulation. Intraoperative orbital drain placement should be considered in all patients undergoing surgery in the orbital region as a preventative measure.

[Management of suicidal orbital gunshot wounds to the temple].

PubMed

Schargus, M; Kawa, D; Elling, M; Kunkel, M

2014-10-01

Orbital gunshot wounds are rarely found after suicide. A gunshot fired at point blank range into the temple has devastating effects on all intraorbital and neighboring structures. This article reports on two cases of gunshot wounds to the lateral orbit in attempted suicides with different weapons from 2012 and 2013 and treated at the Ruhr University Eye Hospital in Bochum. In both cases treatment was carried out in cooperation with the department of oral and maxillofacial surgery, Ruhr University Hospital, Bochum. In the first case a 7.65 mm gun was used. The patient presented with a double penetration of both orbits with total destruction of both globes and a reconstruction was not possible. The second patient presented with multiple shots to the head from a small caliber gun (5.6 mm) where one bullet entered the right orbit behind the globe. The bullet could be localized using computed tomography (CT) and surgically removed with preservation of the globe and with a postoperative visual acuity of 20/60. The preservation of visual function after orbital gunshot wounds depends on both the projectile channel and the characteristics of the gun and bullet. Close collaboration in surgical management between ophthalmologists, maxillofacial surgeons and neurosurgeons in specialized centers is necessary because patients often present with multiple trauma and prompt interdisciplinary treatment is needed.

Resonant dynamics of gravitationally bound pair of binaries: the case of 1:1 resonance

NASA Astrophysics Data System (ADS)

Breiter, Slawomir; Vokrouhlický, David

2018-04-01

The work presents a study of the 1:1 resonance case in a hierarchical quadruple stellar system of the 2+2 type. The resonance appears if orbital periods of both binaries are approximately equal. It is assumed that both periods are significantly shorter than the period of principal orbit of one binary with respect to the other. In these circumstances, the problem can be treated as three independent Kepler problems perturbed by mutual gravitational interactions. By means of canonical perturbation methods, the planar problem is reduced to a secular system with 1 degree of freedom involving a resonance angle (the difference of mean longitudes of the binaries) and its conjugate momentum (involving the ratio of orbital period in one binary to the period of principal orbit). The resonant model is supplemented with short periodic perturbations expressions, and verified by the comparison with numerical integration of the original equations of motion. Estimates of the binaries periods variations indicate that the effect is rather weak, but possibly detectible if it occurs in a moderately compact system. However, the analysis of resonance capture scenarios implies that the 1:1 resonance should be exceptional amongst the 2+2 quadruples.

On periodic motions of an orbital dumbbell-shaped body with a cabin-elevator

NASA Astrophysics Data System (ADS)

Burov, A. A.; Kosenko, I. I.; Troger, H.

2012-05-01

The motion of a dumbbell-shaped body (a pair of massive points connected with each other by a weightless rod along which the elevator, i.e., a third point, is moving according to a given law) in an attractive Newtonian central field is considered. In particular, such a mechanical system can be considered as a simplified model of an orbital cable system equipped with an elevator. The practically most interesting case where the cabin performs periodic "shuttle"motions is studied. Under the assumption that the elevator mass is small compared with the dumbbell mass, the Poincaré theory is used to determine the conditions for the existence of families of system periodic motions analytically depending on the arising small parameter and passing into some stable radial steady-state motion of the unperturbed problem as the small parameter tends to zero. It is also proved that, for sufficiently small parameter values, each of the radial relative equilibria generates exactly one family of such periodic motions. The stability of the obtained periodic solutions is studied in the linear approximation, and these solutions themselves are calculated up to terms of the firstorder in the small parameter. The contemporary studies of the motion of orbital dumbbell systems apparently originated in Okunev's papers [1, 2]. These studies were continued in [3], where plane motions of an orbit tether (represented as a dumbbell-shaped satellite) in a circular orbit were considered in the satellite approximation. In [4], in the case of equal masses and in the unbounded statement, the energy-momentum method was used to perform the dynamic reduction of the problem and analyze the stability of relative equilibria. A similar technique was used in [5], where, in contrast to the above-mentioned problems, the massive points were connected by an elastic spring resisting to compression and forming a dumbbell with elastic properties. Under such assumptions, the stability of radial configurations was investigated in that paper. The bifurcations and stability of steady-state configurations of a deformable elastic dumbbell were also studied in [6]. Various obstacles arising in the construction of orbital cable systems, in particular, the strong deformability of known materials, were discussed in [7]. In [8], the problem of orbital motion of a pair of massive points connected by an inextensible weightless cable was considered in the exact statement. In other words, it was assumed that a unilateral constraint is imposed on themassive points. The conditions of stability of vertical positions of the relative equilibria of the cable system, which were obtained in [8], can be used for any ratio of the subsatellite and station masses. In turn, these results agree well with the results obtained earlier in the studies of stability of vertical configurations in the case of equal masses of the system end bodies [3, 4]. One of the basic papers in the dynamics of three-body orbital cable systems is the paper [9]. The steady-state motions and their bifurcations and stability were studied depending on the elevator cabin position in [10].

Periprosthetic bleeding 18 years post-silicone reconstruction of the orbital floor.

PubMed

Ilie, Vlad Ionut; Ilie, Victor George; Quarmby, Craig; Lefter, Mihaela

2011-10-01

Periprosthetic orbital haemorrhage is an uncommon complication of the alloplastic implants used in post-traumatic orbital floor repair. The small case series or individual reports provide no definite causative explanation for this delayed bleeding around silicone implants. It is likely that it is related to the disruption of fine capillaries within the pseudocapsule surrounding the implant, since the material does cause low-grade irritation with evidence of chronic inflammation. We report the case of a patient who developed a spontaneous periprosthetic bleeding 18 years' post-silicone sheet reconstruction of the orbital floor. Urgent removal of the implant insured prompt resolution of all symptoms and no further problem during the 2-year follow-up. This report emphasizes that periprosthetic orbital haemorrhage can occur years after the initial repair. Awareness of this rare complication allows for prompt diagnosis, decreasing the possibility of permanent damage of the orbital content. The removal of implant is necessary to relieve the symptoms and prevent potential infective complications.

Simplified technique for orbital prosthesis fabrication: a clinical report.

PubMed

Veerareddy, Chandrika; Nair, K Chandrasekharan; Reddy, G Ramaswamy

2012-10-01

Loss of orbital content can cause functional impairment, disfigurement of the face, and psychological distress. Rehabilitation of an orbital defect is a complex task, and if reconstruction by plastic surgery is not possible or not desired by the patient, the defect can be rehabilitated by an orbital prosthesis. The prosthetic rehabilitation in such cases depends on the precisely retained, user-friendly removable maxillofacial prosthesis. Many times, making an impression of the orbital area with an accurate record of surface details can be a difficult procedure. The critical areas are making a facial moulage, mold preparation, and attaching the retention device, particularly when eyeglass frames are used. This case focuses on these hindrance factors. A simple basket was used for the impression tray to obtain the facial moulage. A putty mold was used, and attachment of the prosthesis to a retention device was accomplished with positional distance. This method proves to be an economical and simple way of making an orbital prosthesis. © 2012 by the American College of Prosthodontists.

End-of-life disposal of high elliptical orbit missions: The case of INTEGRAL

NASA Astrophysics Data System (ADS)

Armellin, Roberto; San-Juan, Juan F.; Lara, Martin

2015-08-01

Nowadays there is international consensus that space activities must be managed to minimize debris generation and risk. The paper presents a method for the end-of-life (EoL) disposal of spacecraft in high elliptical orbits (HEO). The time evolution of HEO is strongly affected by Earth's oblateness and luni-solar perturbation, and this can cause in the long-term to extended interferences with low Earth orbit (LEO) protected region and uncontrolled Earth re-entry. An EoL disposal concept that exploits the effect of orbital perturbations to reduce the disposal cost is presented. The problem is formulated as a multiobjective optimization problem, which is solved with an evolutionary algorithm. To explore at the best the search space a semi-analytical orbit propagator, which allows the propagation of the orbit motion for 100 years in few seconds, is adopted. The EoL disposal of the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) mission is used as a practical test-case to show the effectiveness of the proposed methodology.

Light control of orbital domains: case of the prototypical manganite La0.5Sr1.5MnO4

NASA Astrophysics Data System (ADS)

Miller, Timothy; Gensch, Michael; Wall, Simon

2016-12-01

Control of electronic and structural ordering in correlated materials on the ultrafast timescale with light is a new and emerging approach to disentangle the complex interplay of the charge, spin, orbital and structural degree of freedom. In this paper we present an overview of how orbital order and orbital domains can be controlled by near IR and THz radiation in the layered manganite La0.5Sr1.5MnO4. We show how near-IR pumping can efficiently and rapidly melt orbital ordering. However, the nanoscale domain structure recovers unchanged demonstrating the importance of structural defects for the orbital domain formation. On the contrary, we show that pulsed THz fields can be used to effectively orientate the domains. In this case the alignment depends on the in-plane electric field polarisation and is induced by an energy penalty that arises from THz field induced hopping of the localised charges.

An aggressive primary orbital natural killer/T-cell lymphoma case: poor response to chemotherapy.

PubMed

Marchino, Tizana; Ibáñez, Núria; Prieto, Sebastián; Novelli, Silvana; Szafranska, Justyna; Mozos, Anna; Graell, Xavier; Buil, José A

2014-01-01

Natural killer/T-cell lymphoma (NKTCL) and its presentation with extranodal orbital involvement as a single lesion are extremely rare. The aim of this article was to describe the presentation, diagnosis, and systemic treatment of a primary orbital NKTCL. A 67-year-old Caucasian woman presented with left exophthalmos, pain, periorbital swelling, and limited extrinsic ocular motility. Orbital cellulitis was suspected, but finally orbital biopsy was performed due to no response to initial antibiotic and anti-inflammatory standard treatment. The pathologic diagnosis was NKTCL. Systemic evaluations were negative. CHOP (cyclophosphamide, doxorubicin, vincristine, prednisone) chemotherapy was initiated, but after 2 cycles of treatment, tumoral progression was observed. SMILE (dexamethasone, methotrexate, ifosfamide, L-asparaginase, etoposide) rescue chemotherapy was then administered. Lymphoma progression was inevitable. She died 10 months later. Although more nasal NKTCL cases have been described, the nonnasal primary orbital NKTCL is an uncommon neoplasm with high mortality rate, despite the recent use of more potent chemotherapy regimens.

The orbit properties of colliding co-orbiting bodies

NASA Technical Reports Server (NTRS)

Freeman, John W.

1987-01-01

It is generally assumed that an ensemble of small bodies located in similar Keplarian orbits will, because of collisions, tend to disperse into more and more dissimilar orbits. This theory was challenged. Alfven maintains that for the case where the time between collisions is longer than the orbit period and the collisions are essentially inelastic the orbits and velocities will become more similar. This gives rise to the concepts of negative diffusion and jet streams. It is proposed that this question might be investigated experimentally using the space station. The proposed experiment is briefly described.

Flyby of large-size space debris objects and their transition to the disposal orbits in LEO

NASA Astrophysics Data System (ADS)

Baranov, Andrey A.; Grishko, Dmitriy A.; Razoumny, Yury N.; Jun, Li

2017-06-01

The article focuses on the flyby issue involving large-size space debris (LSSD) objects in low Earth orbits. The data on overall sizes of the known upper-stages and last stages of launch-vehicles make it possible to emphasize five compact groups of such objects from the Satellite catalogue in 600-2000 km altitude interval. The flyby maneuvers are executed by a single space vehicle (SV) that transfers the current captured LSSD object to the specially selected circular or elliptical disposal orbit (DO) and after a period of time returns to capture a new one. The flight is always realized when a value of the Right Ascension of the Ascending Node (RAAN) is approximately the same for the current DO and for an orbit of the following LSSD object. Distinctive features of changes in mutual distribution of orbital planes of LSSD within a group are shown on the RAAN deviations' evolution portrait. In case of the first three groups (inclinations 71°, 74° and 81°), the lines describing the relative orientation of orbital planes are quasi-parallel. Such configuration allows easy identification of the flyby order within a group, and calculation of the mission duration and the required total ΔV. In case of the 4th and the 5th groups the RAAN deviations' evolution portrait represents a conjunction of lines chaotically intersecting. The article studies changes in mission duration and in the required ΔV depending on the catalogue number of the first object in the flyby order. The article also contains a comparative efficiency analysis of the two world-wide known schemes applicable to LSSD objects' de-orbiting; the analysis is carried out for all 5 distinguished LSSD groups.

Conjunction Assessment for Commercial Satellite Constellations Using Commercial Radar Data Sources

NASA Astrophysics Data System (ADS)

Nicolls, M.; Vittaldev, V.; Ceperley, D.; Creus-Costa, J.; Foster, C.; Griffith, N.; Lu, E.; Mason, J.; Park, I.; Rosner, C.; Stepan, L.

For companies with multiple orbital assets, managing the risk of collision with other low-Earth orbit (LEO) Resident Space Objects (RSOs) can amount to a significant operational burden. LeoLabs and Planet investigate the impact of a workflow that integrates commercial Space Situational Awareness (SSA) data into conjunction assessments for large satellite constellations. Radar measurements from LeoLabs are validated against truth orbits provided by the International Laser Ranging Service (ILRS) and to measurements from Planet’s on-board GPS instrumentation. The radar data is then used as input for orbit fits in order to form the basis of a conjunction assessment. To confirm the reliability of the orbit determination (OD), the generated ephemerides are validated against ILRS and GPS-derived orbits. In addition, a covariance realism assessment is performed in order to check for self-consistency by comparing the propagated orbit and the associated covariance against later measurements. Several cases are investigated to assess the benefits of integrating radar-derived products with Conjunction Data Messages (CDMs) received on Planet spacecraft. Conjunction assessment is refined using onboard GPS measurements from Planet satellites along with tracking measurements of the secondary RSO by LeoLabs. This study demonstrates that commercial data provided by LeoLabs is reliable, accurate, and timely, and that ephemeris generated from LeoLabs data provides solutions and insights which are consistent with those provided in CDMs. For the cases analyzed, the addition of commercial SSA data from LeoLabs has a positive impact on operations due to the additional information on the state of the secondary RSO which can lead to increased confidence in any maneuver-related decisions. Measurements from LeoLabs can also be used to improve conjunction assessment for commercial satellites that do not have any operator OD.

Pediatric ocular trauma caused by recreational drones: two case reports.

PubMed

Spitzer, Nicole; Singh, Jasleen K

2018-03-14

Drones are increasingly being used by children and adults recreationally and commercially. The propeller blades when spinning at high speeds may cause serious harm to the eye and orbital structures. We report 2 cases of injuries to the eye and orbital structures caused by drones. Copyright © 2018. Published by Elsevier Inc.

Forward orbital evolution of the Vesta Family with and without the Yarkovsky effect

NASA Astrophysics Data System (ADS)

Wlodarczyk, Ireneusz; Leliwa-Kopystynski, Jacek

2018-02-01

Vesta family members (VFMs), totally 17164, were selected by means of hierarchical clustering method (HCM) from the data base containing 393347 synthetic proper elements of numbered asteroids from the ASTDyS Catalogue (2015) updated in May 5, 2015. Keplerian elements from the Lowell Catalogue (2015) were used for studying orbital evolution of all 17164 VFMs in the time interval 1 Gy forward. Two cases were considered: evolution pass without the Yarkovsky effect (YN) and evolution pass with it (YY). It has been found that swarm of asteroids disperses about 28 times more efficient for the case YY than in the case YN. Efficiency of dispersion was studied versus semiaxis of asteroids relative to Vesta (smaller or larger than semiaxis of Vesta) as well as versus the sizes of asteroids. Weak relationships between size and efficiency of dispersion on YE have been found for the both cases YN and YY. The loss of number of the asteroids from VF weakly depends on their sizes. The total lost by number as well by mass is about 10% per 1 Gy.

Clostridium septicum gas gangrene in the orbit: a case report.

PubMed

Fejes, I; Dégi, R; Végh, M

2013-02-01

Our report presents a case of Clostridium septicum gas gangrene in an unusual, orbital localization. The predisposing factors are typical: colon tumour and lymphatic malignancy. Most probably bacteria from the intestinal flora entered the bloodstream through the compromised intestinal wall and settled in the orbit resulting in the development of an abscess containing gas. At the site of the gas gangrene, an indolent B cell lymphoma was present. After surgery and antibiotic treatment, the patient healed from the C. septicum infection; but subsequently died as a consequence of the tumour.

Rectal Cancer in the Eye: A Case Report of Orbital Metastasis.

PubMed

Nabeel, Mohammed; Farooqi, Rehan; Mohebtash, Mahsa; Desai, Rupak; Mansuri, Uvesh; Patel, Smit; Patel, Jinal; Khan, Vinshi Naz

2017-08-21

Orbital metastasis from colorectal cancer is extremely rare. In this case report, we describe a 48-year-old woman who presented with recurrent severe headaches and new onset constipation with no known history of cancer. After vigilant workup, imaging, and biopsies, she was diagnosed with orbital metastasis from a primary rectal carcinoma. She was started on chemotherapy and radiation therapy. Her chemotherapy regimen consisted of FLOX (leucovorin + fluorouracil + oxaliplatin), along with panitumumab, which she tolerated well. She received chemotherapy for seven months before she lost her battle with cancer.

Optimal aeroassisted orbital transfer with plane change using collocation and nonlinear programming

NASA Technical Reports Server (NTRS)

Shi, Yun. Y.; Nelson, R. L.; Young, D. H.

1990-01-01

The fuel optimal control problem arising in the non-planar orbital transfer employing aeroassisted technology is addressed. The mission involves the transfer from high energy orbit (HEO) to low energy orbit (LEO) with orbital plane change. The basic strategy here is to employ a combination of propulsive maneuvers in space and aerodynamic maneuvers in the atmosphere. The basic sequence of events for the aeroassisted HEO to LEO transfer consists of three phases. In the first phase, the orbital transfer begins with a deorbit impulse at HEO which injects the vehicle into an elliptic transfer orbit with perigee inside the atmosphere. In the second phase, the vehicle is optimally controlled by lift and bank angle modulations to perform the desired orbital plane change and to satisfy heating constraints. Because of the energy loss during the turn, an impulse is required to initiate the third phase to boost the vehicle back to the desired LEO orbital altitude. The third impulse is then used to circularize the orbit at LEO. The problem is solved by a direct optimization technique which uses piecewise polynomial representation for the state and control variables and collocation to satisfy the differential equations. This technique converts the optimal control problem into a nonlinear programming problem which is solved numerically. Solutions were obtained for cases with and without heat constraints and for cases of different orbital inclination changes. The method appears to be more powerful and robust than other optimization methods. In addition, the method can handle complex dynamical constraints.

Orbital Perturbations of the Galilean Satellites during Planetary Encounters

NASA Astrophysics Data System (ADS)

Deienno, Rogerio; Nesvorný, David; Vokrouhlický, David; Yokoyama, Tadashi

2014-08-01

The Nice model of the dynamical instability and migration of the giant planets can explain many properties of the present solar system, and can be used to constrain its early architecture. In the jumping-Jupiter version of the Nice model, required from the terrestrial planet constraint and dynamical structure of the asteroid belt, Jupiter has encounters with an ice giant. Here, we study the survival of the Galilean satellites in the jumping-Jupiter model. This is an important concern because the ice-giant encounters, if deep enough, could dynamically perturb the orbits of the Galilean satellites and lead to implausible results. We performed numerical integrations where we tracked the effect of planetary encounters on the Galilean moons. We considered three instability cases from Nesvorný & Morbidelli that differed in the number and distribution of encounters. We found that in one case, where the number of close encounters was relatively small, the Galilean satellite orbits were not significantly affected. In the other two, the orbital eccentricities of all moons were excited by encounters, Callisto's semimajor axis changed, and, in a large fraction of trials, the Laplace resonance of the inner three moons was disrupted. The subsequent evolution by tides damps eccentricities and can recapture the moons in the Laplace resonance. A more important constraint is represented by the orbital inclinations of the moons, which can be excited during the encounters and not appreciably damped by tides. We find that one instability case taken from Nesvorný & Morbidelli clearly does not meet this constraint. This shows how the regular satellites of Jupiter can be used to set limits on the properties of encounters in the jumping-Jupiter model, and help us to better understand how the early solar system evolved.

Three-dimensional disc-satellite interaction: torques, migration, and observational signatures

NASA Astrophysics Data System (ADS)

Arzamasskiy, Lev; Zhu, Zhaohuan; Stone, James M.

2018-04-01

The interaction of a satellite with a gaseous disc results in the excitation of spiral density waves, which remove angular momentum from the orbit. In addition, if the orbit is not coplanar with the disc, three-dimensional effects will excite bending and eccentricity waves. We perform three-dimensional hydrodynamic simulations to study nonlinear disc-satellite interaction in inviscid protoplanetary discs for a variety of orbital inclinations from 0° to 180°. It is well known that three-dimensional effects are important even for zero inclination. In this work, we (1) show that for planets with small inclinations (as in the Solar system), effects such as the total torque and migration rate strongly depend on the inclination and are significantly different (about 2.5 times smaller) from the two-dimensional case, (2) give formulae for the migration rate, inclination damping, and precession rate of planets with different inclination angles in disc with different scale heights, and (3) present the observational signatures of a planet on an inclined orbit with respect to the protoplanetary disc. For misaligned planets, we find good agreement with linear theory in the limit of small inclinations, and with dynamical friction estimates for intermediate inclinations. We find that in the latter case, the dynamical friction force is not parallel to the relative planetary velocity. Overall, the derived formulae will be important for studying exoplanets with obliquity.

Systems Engineering Case Studies, Synopsis of the Learning Principles

DTIC Science & Technology

2009-08-24

TBMCS refers to the Theater Battle Management Core System Systems Engineering Case Study Peacekeeper refers to the Peacekeeper Intercontinental...primary mirror defect going to orbit undetected in spite of substantial evidence that could have been used to prevent this occurrence. TBMCS /1...The requirements baseline was volatile up to system acceptance, which took place after TBMCS passed operational test and evaluation. Approved for

Pictorial essay: Orbital tuberculosis

PubMed Central

Narula, Mahender K; Chaudhary, Vikas; Baruah, Dhiraj; Kathuria, Manoj; Anand, Rama

2010-01-01

Tuberculosis of the orbit is rare, even in places where tuberculosis is endemic. The disease may involve soft tissue, the lacrimal gland, or the periosteum or bones of the orbital wall. Intracranial extension, in the form of extradural abscess, and infratemporal fossa extension has been described. This pictorial essay illustrates the imaging findings of nine histopathologically confirmed cases of orbital tuberculosis. All these patients responded to antituberculous treatment. PMID:20351984

An Interesting Case of Tolosa-Hunt Syndrome in a Young Male.

PubMed

Murtaza, Ghulam; Konowitz, Nicholas; Lu, Hannah; Faqah, Anadil; Kuruvilla, Aneesh

2017-01-01

Tolosa-Hunt syndrome is a rare disease with a limited number of cases reported in the literature. It typically presents with orbital pain associated with palsy of the third, fourth, or sixth cranial nerve. We present an interesting case of Tolosa-Hunt syndrome in a young male who responded well to high-dose steroids and in a few days had significant improvement in his retro-orbital pain and ocular movements.

Tidal torques on infrequently colliding particle disks in binary systems and the truncation of the asteroid belt

NASA Technical Reports Server (NTRS)

Franklin, F. A.; Lecar, M.; Lin, D. N. C.; Papaloizou, J.

1980-01-01

Conditions leading to the truncation, at the 2:1 resonance, of a disk of infrequently colliding particles surrounding the primary of a binary system are studied numerically and analytically. Attention is given to the case in which the mass ratio, q, is sufficiently small (less than about 0.1) and the radius of the disk centered on the primary allowably larger, so that first-order orbit-orbit resonances between ring material and the secondary can lie within it. Collisions are found to be less frequent than q to the -2/3 power orbital periods (the period of the forced eccentricity at the 2:1 resonance), and truncation occurs and Kirkwood gaps are produced only if the particle eccentricity is less than some critical value, estimated to be of order q to the 5/9 power, or approximately 0.02 for the sun-Jupiter case having q equal to 10 to the -3rd power.

Orbits: Computer simulation

NASA Technical Reports Server (NTRS)

Muszynska, A.

1985-01-01

In rotating machinery dynamics an orbit (Lissajous curve) represents the dynamic path of the shaft centerline motion during shaft rotation and resulting precession. The orbit can be observed with an oscilloscope connected to XY promixity probes. The orbits can also be simulated by a computer. The software for HP computer simulates orbits for two cases: (1) Symmetric orbit with four frequency components with different radial amplitudes and relative phase angles; and (2) Nonsymmetric orbit with two frequency components with two different vertical/horizontal amplitudes and two different relative phase angles. Each orbit carries a Keyphasor mark (one-per-turn reference). The frequencies, amplitudes, and phase angles, as well as number of time steps for orbit computation, have to be chosen and introduced to the computer by the user. The orbit graphs can be observed on the computer screen.

Endoscopic Assisted Combined Transantral and Subciliary Approach in Treatment of Orbital Floor Fracture: A Case Report.

PubMed

Anehosur, Venkatesh; Harish, K

2018-06-01

Management of orbital floor fracture remains the most debated topic in maxillofacial field. There are many approaches to reconstruct orbital floor fractures and restore orbital position and function, but many have the drawback of incomplete visualization, especially of the posterior part of the orbit. Pain, diplopia and enophthalmos are the most common presenting symptoms in patients who sustained orbital blow out fracture. The main aim in treating orbital fracture is to reduce the prolapsed orbital tissue and reconstruct the floor which will improve diplopia and enophthalmos. As minimally invasive surgical techniques are gaining popularity, it is possible to reconstruct the orbital fracture defects using endoscopes. Endoscopic assisted combined transantral and subciliary technique provides better surgical access and outcome in the treatment of orbital floor fracture.

The Smaller Alignment Index (SALI) applied in a study of stellar orbits in barred galaxies potential models using the LP-VIcode

NASA Astrophysics Data System (ADS)

Caritá, Lucas Antonio; Rodrigues, Irapuan; Puerari, Ivânio; Schiavo, Luiz Eduardo Camargo Aranha

2018-04-01

The Smaller Alignment Index (SALI) is a mathematical tool, not yet conventional, for chaos detection in the phase space of Hamiltonian Dynamical Systems. The SALI values has temporal behaviors very specific to ordered or chaotic motions, what makes the distinction between order and chaos easily observable in these systems. In this paper, this method will be applied to the stability study of stellar orbits immersed in gravitational potential of barred galaxies, since the motion of a test particle in a rotating barred galaxy model is given by a Hamiltonian function. Extracting four parameter sets from the Manos and Athanassoula (2011) work and elaborating a different initial conditions set for each case, we were able to introduce another point of view of their stability study for two degrees of freedom. We have also introduced two new extreme models that corroborates with the conclusions that more axisymmetric bars create an environment with less chaos and that more massive bars create an environment with more chaos. Separate studies were carried out for prograde and retrograde orbits that showed that the retrograde orbits seem more conducive to chaos. To perform all the orbits integrations we used the LP-VIcode program.

Evidence for Reflected Light from the Most Eccentric Known Exoplanet

NASA Astrophysics Data System (ADS)

Kane, Stephen

2015-12-01

Planets in highly eccentric orbits form a class of objects not seen within our Solar System. The most extreme case known amongst these objects is the planet orbiting HD 20782, with an orbital period of 597 days and an eccentricity of 0.96. Here we present new data and analysis for this system as part of the Transit Ephemeris Refinement and Monitoring Survey (TERMS). New radial velocities acquired during periastron provide incredible accuracy for the planetary orbit and astrometric results that show the companion is indeed planetary in nature. We obtained MOST photometry during a predicted periastron passage that shows evidence of phase variations due to reflected light from the planet. The extreme nature of this planet presents an ideal case from which to test theories regarding the formation of eccentric orbits and the response of atmospheres to extreme changes in flux.

Orbital Apex Syndrome Caused by Invasive Aspergillosis as an Adverse Effect of Systemic Chemotherapy for Metastatic Colorectal Cancer: a Case Report.

PubMed

Miyamoto, Yuji; Sakamoto, Yasuo; Ohuchi, Mayuko; Tokunaga, Ryuma; Shigaki, Hironobu; Kurashige, Junji; Iwatsuki, Masaaki; Baba, Yoshifumi; Yoshida, Naoya; Watanabe, Masayuki; Baba, Hideo

2016-02-01

Continuous therapy with cytotoxic drugs suppresses humoral immune function and may result in local infection. We present a case of orbital apex syndrome caused by Aspergillus infection during chemotherapy for metastatic colorectal cancer. A 74-year-old man with colorectal liver metastases under long-term continuous systemic chemotherapy presented with painful, progressive orbital apex syndrome. Magnetic resonance imaging disclosed a small enhancing lesion around the right ethmoid sinus. We initially diagnosed colorectal cancer metastasis and he underwent biopsy via the endoscopic endonasal transethmoid approach. However, pathological examination of the cultured specimen revealed Aspergillus fumigatus. The patient was treated with voriconazole and the orbital apex syndrome resolved after 1 month. Orbital aspergillosis is a life-threatening disease and should be listed as a differential diagnosis of uncommon local infections during continuous chemotherapy. Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

Medical Implications of Space Radiation Exposure Due to Low-Altitude Polar Orbits.

PubMed

Chancellor, Jeffery C; Auñon-Chancellor, Serena M; Charles, John

2018-01-01

Space radiation research has progressed rapidly in recent years, but there remain large uncertainties in predicting and extrapolating biological responses to humans. Exposure to cosmic radiation and solar particle events (SPEs) may pose a critical health risk to future spaceflight crews and can have a serious impact on all biomedical aspects of space exploration. The relatively minimal shielding of the cancelled 1960s Manned Orbiting Laboratory (MOL) program's space vehicle and the high inclination polar orbits would have left the crew susceptible to high exposures of cosmic radiation and high dose-rate SPEs that are mostly unpredictable in frequency and intensity. In this study, we have modeled the nominal and off-nominal radiation environment that a MOL-like spacecraft vehicle would be exposed to during a 30-d mission using high performance, multicore computers. Projected doses from a historically large SPE (e.g., the August 1972 solar event) have been analyzed in the context of the MOL orbit profile, providing an opportunity to study its impact to crew health and subsequent contingencies. It is reasonable to presume that future commercial, government, and military spaceflight missions in low-Earth orbit (LEO) will have vehicles with similar shielding and orbital profiles. Studying the impact of cosmic radiation to the mission's operational integrity and the health of MOL crewmembers provides an excellent surrogate and case-study for future commercial and military spaceflight missions.Chancellor JC, Auñon-Chancellor SM, Charles J. Medical implications of space radiation exposure due to low-altitude polar orbits. Aerosp Med Hum Perform. 2018; 89(1):3-8.

External ophthalmoplegia with orbital myositis in an adult patient after chickenpox infection.

PubMed

Kim, Jung-Hoon; Lee, Seung-Jun; Kim, Moosang

2014-05-16

Herpes zoster and chickenpox are caused by a single virus, varicella-zoster virus. Herpes zoster ophthalmicus-associated ophthalmoplegia is well documented. Very rarely, herpes zoster and chickenpox cause external ophthalmoplegia. A 48-year-old man was diagnosed with chickenpox and treated with intravenous acyclovir. He suddenly reported diplopia and restricted left eye movement. MRI of the orbit revealed thickening and abnormal contrast enhancement of the preseptal space and lateral rectus muscle of the left eye. In this case, external ophthalmoplegia occurred following chickenpox with radiological evidence of orbital myositis. To the best of our knowledge, this is the first case report of external ophthalmoplegia of radiologically confirmed orbital myositis after chickenpox infection. 2014 BMJ Publishing Group Ltd.

Orbito-Masticatory Syndrome

PubMed Central

Mettu, Pradeep; Bhatti, M. Tariq; El-Dairi, Mays; Price, Evan B.; Lin, Amy Y.; Alaraj, Ali; Setabutr, Pete; Moss, Heather E.

2016-01-01

We describe two unique cases of visual symptoms occurring during mastication in patients with lateral orbital wall defects. A 57-year old male reported intermittent double vision and oscillopsia after a right fronto-temporal-orbito-zygomatic craniotomy with osteotomy of the lesser wing of the sphenoid for a complex invasive pituitary adenoma. Proptosis of the right globe was present only during mastication. Computed tomography (CT) revealed a bony defect in the right lateral orbital wall. A 48-year-old man presented with transient diplopia and scotoma in the right eye elicited by chewing. CT and magnetic resonance imaging demonstrated a bilobed lesion connecting the temporal fossa to the orbit through a defect in the right lateral orbital wall. The regional neuroanatomy and pathophysiology as pertaining to the cases are discussed. PMID:26919071

Results after En Bloc Lateral Wall Decompression Surgery with Orbital Fat Resection in 111 Patients with Graves' Orbitopathy

PubMed Central

Fichter, Nicole; Guthoff, Rudolf F.

2015-01-01

Purpose. To evaluate the effect of en bloc lateral wall decompression with additional orbital fat resection in terms of exophthalmos reduction and complications. Methods. A retrospective, noncomparative case series study from 1999 to 2011 (chart review) in Graves' orbitopathy (GO) patients. The standardized surgical technique involved removal of the lateral orbital wall including the orbital rim via a lid crease approach combined with additional orbital fat resection. Exophthalmos, diplopia, retrobulbar pressure sensation, and complications were analyzed pre- and postoperatively. Results. A total of 111 patients (164 orbits) with follow-up >3 months were analysed. Mean exophthalmos reduction was 3.05mm and preoperative orbital pressure sensation resolved or improved in all patients. Visual acuity improved significantly in patients undergoing surgery for rehabilitative or vision threatening purposes. Preoperative diplopia improved in 10 patients (9.0%) but worsened in 5 patients (4.5%), necessitating surgical correction in 3 patients. There were no significant complications; however, one patient had slight hollowing of the temporalis muscle around the scar that did not necessitate revision, and another patient with a circumscribed retraction of the scar itself underwent surgical correction. Conclusions. The study confirms the efficiency of en bloc lateral wall decompression in GO in a large series of patients, highlighting the low risk of disturbance of binocular functions and of cosmetic blemish in the temporal midface region. PMID:26221142

Formation Flying for Distributed InSAR

NASA Technical Reports Server (NTRS)

Scharf, Daniel P.; Murray, Emmanuell A.; Ploen, Scott R.; Gromov, Konstantin G.; Chen, Curtis W.

2006-01-01

We consider two spacecraft flying in formation to create interferometric synthetic aperture radar (InSAR). Several candidate orbits for such in InSar formation have been previously determined based on radar performance and Keplerian orbital dynamics. However, with out active control, disturbance-induced drift can degrade radar performance and (in the worst case) cause a collision. This study evaluates the feasibility of operating the InSAR spacecraft as a formation, that is, with inner-spacecraft sensing and control. We describe the candidate InSAR orbits, design formation guidance and control architectures and algorithms, and report the (Delta)(nu) and control acceleration requirements for the candidate orbits for several tracking performance levels. As part of determining formation requirements, a formation guidance algorithm called Command Virtual Structure is introduced that can reduce the (Delta)(nu) requirements compared to standard Leader/Follower formation approaches.

Orbital fitting of imaged planetary companions with high eccentricities and unbound orbits. Their application to Fomalhaut b and PZ Telecopii B

NASA Astrophysics Data System (ADS)

Beust, H.; Bonnefoy, M.; Maire, A.-L.; Ehrenreich, D.; Lagrange, A.-M.; Chauvin, G.

2016-03-01

Context. Regular follow-up of imaged companions to main-sequence stars often allows a projected orbital motion to be detected. Markov chain Monte Carlo (MCMC) has become very popular recent years for fitting and constraining their orbits. Some of these imaged companions appear to move on very eccentric, possibly unbound orbits. This is, in particular, the case for the exoplanet Fomalhaut b and the brown dwarf companion PZ Tel B on which we focus here. Aims: For these orbits, standard MCMC codes that assume only bound orbits may be inappropriate. Our goal is to develop a new MCMC implementation that is able to handle both bound and unbound orbits in a continuous manner, and to apply this to the cases of Fomalhaut b and PZ Tel B. Methods: We present here this code, based on the use of universal Keplerian variables and Stumpff functions. We present two versions of this code, the second one using a different set of angular variables that were designed to avoid degeneracies arising when the projected orbital motion is quasi-radial, as is the case for PZ Tel B. We also present additional observations of PZ Tel B. Results: The code is applied to Fomalhaut b and PZ Tel B. We confirm previous results in relation to, but we show that on the sole basis of the astrometric data, open orbital solutions are also possible. The eccentricity distribution nevertheless still peaks around ~0.9 in the bound regime. We present a first successful orbital fit of PZ Tel B, which shows in particular that, while both bound and unbound orbital solutions are equally possible, the eccentricity distribution presents a sharp peak very close to e = 1, meaning a quasi-parabolic orbit. Conclusions: It has recently been suggested that the presence of unseen inner companions to imaged ones may lead orbital fitting algorithms to artificially give very high eccentricities. We show that this caveat is unlikely to apply to Fomalhaut b. Concerning PZ Tel B, we derive a possible solution, which involves an inner ~12 MJup companion, that would mimic a e = 1 orbit, despite a real eccentricity of around 0.7, but a dynamical analysis reveals that this type of system would not be stable. We thus conclude that our orbital fit is robust. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile (Program ID: 085.C-0867(B) and 085.C-0277(B)).

Simulation and analyses of the aeroassist flight experiment attitude update method

NASA Technical Reports Server (NTRS)

Carpenter, J. R.

1991-01-01

A method which will be used to update the alignment of the Aeroassist Flight Experiment's Inertial Measuring Unit is simulated and analyzed. This method, the Star Line Maneuver, uses measurements from the Space Shuttle Orbiter star trackers along with an extended Kalman filter to estimate a correction to the attitude quaternion maintained by an Inertial Measuring Unit in the Orbiter's payload bay. This quaternion is corrupted by on-orbit bending of the Orbiter payload bay with respect to the Orbiter navigation base, which is incorporated into the payload quaternion when it is initialized via a direct transfer of the Orbiter attitude state. The method of updating this quaternion is examined through verification of baseline cases and Monte Carlo analysis using a simplified simulation, The simulation uses nominal state dynamics and measurement models from the Kalman filter as its real world models, and is programmed on Microvax minicomputer using Matlab, and interactive matrix analysis tool. Results are presented which confirm and augment previous performance studies, thereby enhancing confidence in the Star Line Maneuver design methodology.

Dynamics of the Triple-Star System Alpha Centauri and its Impact on Habitable Planets

NASA Astrophysics Data System (ADS)

Jayla Jones, Ayanna; Fabrycky, Daniel

2018-01-01

The Alpha Centauri system, our solar system's closest neighbor, has become a target in the search for habitable planets. The system is composed of three stars: Alpha Centauri A and Alpha Centauri B, stars forming an inner binary, and Proxima Centauri, an outer star that orbits around the inner binary. We computed 3-body models to follow the dynamics for the main-sequence lifetimes of the stars that are based on 100 realizations of the observed orbits. In the majority of cases, Proxima only modestly torques the A-B binary orbit, and so previous studies of planet formation and dynamics, which find the habitable zones to be stable, are somewhat justified in ignoring this effect. On the other hand, in ~16% of the observationally allowed orbits, fluctuations in the orbital eccentricity of the A-B orbit destabilize the middle of the habitable zone of both stars. This result calls for further theoretical work to quantify the effect of galactic tides, passing stars, and massive planets in the triple-system dynamics.

Search for and Study of Nearly Periodic Orbits in the Plane Problem of Three Equal-Mass Bodies

NASA Astrophysics Data System (ADS)

Martynova, A. I.; Orlov, V. V.

2005-09-01

We analyze nearly periodic solutions in the plane problem of three equal-mass bodies by numerically simulating the dynamics of triple systems. We identify families of orbits in which all three points are on one straight line (syzygy) at the initial time. In this case, at fixed total energy of a triple system, the set of initial conditions is a bounded region in four-dimensional parameter space. We scan this region and identify sets of trajectories in which the coordinates and velocities of all bodies are close to their initial values at certain times (which are approximately multiples of the period). We classify the nearly periodic orbits by the structure of trajectory loops over one period. We have found the families of orbits generated by von Schubart’s stable periodic orbit revealed in the rectilinear three-body problem. We have also found families of hierarchical, nearly periodic trajectories with prograde and retrograde motions. In the orbits with prograde motions, the trajectory loops of two close bodies form looplike structures. The trajectories with retrograde motions are characterized by leafed structures. Orbits with central and axial symmetries are identified among the families found.

Orbital stability of solitary waves for Kundu equation

NASA Astrophysics Data System (ADS)

Zhang, Weiguo; Qin, Yinghao; Zhao, Yan; Guo, Boling

In this paper, we consider the Kundu equation which is not a standard Hamiltonian system. The abstract orbital stability theory proposed by Grillakis et al. (1987, 1990) cannot be applied directly to study orbital stability of solitary waves for this equation. Motivated by the idea of Guo and Wu (1995), we construct three invariants of motion and use detailed spectral analysis to obtain orbital stability of solitary waves for Kundu equation. Since Kundu equation is more complex than the derivative Schrödinger equation, we utilize some techniques to overcome some difficulties in this paper. It should be pointed out that the results obtained in this paper are more general than those obtained by Guo and Wu (1995). We present a sufficient condition under which solitary waves are orbitally stable for 2c+sυ<0, while Guo and Wu (1995) only considered the case 2c+sυ>0. We obtain the results on orbital stability of solitary waves for the derivative Schrödinger equation given by Colin and Ohta (2006) as a corollary in this paper. Furthermore, we obtain orbital stability of solitary waves for Chen-Lee-Lin equation and Gerdjikov-Ivanov equation, respectively.

Overload control of artificial gravity facility using spinning tether system for high eccentricity transfer orbits

NASA Astrophysics Data System (ADS)

Gou, Xing-wang; Li, Ai-jun; Tian, Hao-chang; Wang, Chang-qing; Lu, Hong-shi

2018-06-01

As the major part of space life supporting systems, artificial gravity requires further study before it becomes mature. Spinning tether system is a good alternative solution to provide artificial gravity for the whole spacecraft other than additional devices, and its longer tether length could significantly reduce spinning velocity and thus enhance comfortability. An approximated overload-based feedback method is proposed to provide estimated spinning velocity signals for controller, so that gravity level could be accurately controlled without complicated GPS modules. System behavior in high eccentricity transfer orbits is also studied to give a complete knowledge of the spinning stabilities. The application range of the proposed method is studied in various orbit cases and spinning velocities, indicating that it is accurate and reliable for most of the mission phases especially for the final constant gravity level phase. In order to provide stable gravity level for transfer orbit missions, a sliding mode controller based on estimated angular signals is designed for closed-loop control. Numerical results indicate that the combination of overload-based feedback and sliding mode controller could satisfy most of the long-term artificial gravity missions. It is capable of forming flexible gravity environment in relatively good accuracy even in the lowest possible orbital radiuses and high eccentricity orbits of crewed space missions. The proposed scheme provides an effective tether solution for the artificial gravity construction in interstellar travel.

Orbital structure in oscillating galactic potentials

NASA Astrophysics Data System (ADS)

Terzić, Balša; Kandrup, Henry E.

2004-01-01

Subjecting a galactic potential to (possibly damped) nearly periodic, time-dependent variations can lead to large numbers of chaotic orbits experiencing systematic changes in energy, and the resulting chaotic phase mixing could play an important role in explaining such phenomena as violent relaxation. This paper focuses on the simplest case of spherically symmetric potentials subjected to strictly periodic driving with the aim of understanding precisely why orbits become chaotic and under what circumstances they will exhibit systematic changes in energy. Four unperturbed potentials V0(r) were considered, each subjected to a time dependence of the form V(r, t) =V0(r)(1 +m0 sinωt). In each case, the orbits divide clearly into regular and chaotic, distinctions which appear absolute. In particular, transitions from regularity to chaos are seemingly impossible. Over finite time intervals, chaotic orbits subdivide into what can be termed `sticky' chaotic orbits, which exhibit no large-scale secular changes in energy and remain trapped in the phase-space region where they started; and `wildly' chaotic orbits, which do exhibit systematic drifts in energy as the orbits diffuse to different phase-space regions. This latter distinction is not absolute, transitions corresponding apparently to orbits penetrating a `leaky' phase-space barrier. The three different orbit types can be identified simply in terms of the frequencies for which their Fourier spectra have the most power. An examination of the statistical properties of orbit ensembles as a function of driving frequency ω allows us to identify the specific resonances that determine orbital structure. Attention focuses also on how, for fixed amplitude m0, such quantities as the mean energy shift, the relative measure of chaotic orbits and the mean value of the largest Lyapunov exponent vary with driving frequency ω and how, for fixed ω, the same quantities depend on m0.

Human Mars Mission: Launch Window from Earth Orbit. Pt. 1

NASA Technical Reports Server (NTRS)

Young, Archie

1999-01-01

The determination of orbital window characteristics is of major importance in the analysis of human interplanetary missions and systems. The orbital launch window characteristics are directly involved in the selection of mission trajectories, the development of orbit operational concepts, and the design of orbital launch systems. The orbital launch window problem arises because of the dynamic nature of the relative geometry between outgoing (departure) asymptote of the hyperbolic escape trajectory and the earth parking orbit. The orientation of the escape hyperbola asymptotic relative to earth is a function of time. The required hyperbola energy level also varies with time. In addition, the inertial orientation of the parking orbit is a function of time because of the perturbations caused by the Earth's oblateness. Thus, a coplanar injection onto the escape hyperbola can be made only at a point in time when the outgoing escape asymptote is contained by the plane of parking orbit. Even though this condition may be planned as a nominal situation, it will not generally represent the more probable injection geometry. The general case of an escape injection maneuver performed at a time other than the coplanar time will involve both a path angle and plane change and, therefore, a DELTA V penalty. Usually, because of the DELTA V penalty the actual departure injection window is smaller in duration than that determined by energy requirement alone. This report contains the formulation, characteristics, and test cases for five different launch window modes for Earth orbit. These modes are: (1) One impulsive maneuver from a Highly Elliptical Orbit (HEO) (2) Two impulsive maneuvers from a Highly Elliptical Orbit (HEO) (3) One impulsive maneuver from a Low Earth Orbit (LEO) (4) Two impulsive maneuvers from LEO (5) Three impulsive maneuvers from LEO.

Orbital dermoid and epidermoid cysts: case study.

PubMed

Veselinović, Dragan; Krasić, Dragan; Stefanović, Ivan; Veselinović, Aleksandar; Radovanović, Zoran; Kostić, Aleksandar; Cvetanović, Marija

2010-01-01

Dermoid and epidermoid cysts of the orbit belong to choristomas, tumours that originate from the aberrant primordial tissue. Clinically, they manifest as cystic movable formations mostly localized in the upper temporal quadrant of the orbit. They are described as both superficial and deep formations with most frequently slow intermittent growth. Apart from aesthetic effects, during their growth, dermoid and epidermoid cysts can cause disturbances in the eye motility, and in rare cases, also an optical nerve compression syndrome. In this paper, we described a child with a congenital orbital dermoid cyst localized in the upper-nasal quadrant that was showing signs of a gradual enlargement and progression. The computerized tomography revealed a cyst of 1.5-2.0 cm in size. At the Maxillofacial Surgery Hospital in Nis, the dermoid cyst was extirpated in toto after orbitotomy performed by superciliary approach. Postoperative course was uneventful, without inflammation signs, and after two weeks excellent functional and aesthetic effects were achieved. Before the decision to treat the dermoid and epidermoid cysts operatively, a detailed diagnostic procedure was necessary to be done in order to locate the cyst precisely and determine its size and possible propagation into the surrounding periorbital structures. Apart from cosmetic indications, operative procedures are recommended in the case of cysts with constant progressions, which cause the pressure to the eye lobe, lead to motility disturbances and indirectly compress the optical nerve and branches of the cranial nerves III, IV and VI.

Extranodal natural killer/T-cell lymphoma presenting as orbital cellulitis

PubMed Central

Zuhaimy, Hanis; Aziz, Hayati Abdul; Vasudevan, Suresh; Hui Hui, Siah

2017-01-01

Objective: To report an aggressive case of extranodal natural killer/T-cell lymphoma (NKTCL) of the ethmoid sinus presenting as orbital cellulitis Method: Case report Results: A 56-year-old male presented with right eye redness, reduced vision, and periorbital swelling for 5 weeks duration associated with a two-month history of blocked nose. The visual acuity of the right eye was 6/18. The eye was proptosed with periorbital oedema and conjunctival chemosis. The pupil was mid-dilated but there was no relative afferent pupillary defect. The fundus was normal. The extraocular movements were restricted in all directions of gaze. Nasal endoscopy revealed pansinusitis that corresponded with CT scan orbit and paranasal sinuses findings. Despite treatment, he showed no clinical improvement. Ethmoidal sinus biopsies performed revealed extranodal NKTCL. Further imaging showed involvement of the right orbital contents and its adnexa with intracranial extension into the right cavernous sinus and meninges over right temporal fossa. The patient underwent chemotherapy. However he succumbed to his illness two months after the diagnosis. Conclusion: Extranodal NKTCL is a great mimicker. This case demonstrated how an acute initial presentation of extranodal NKTCL can present as orbital cellulitis with pansinusitis. PMID:28194321

Complications and outcomes of grafting of posterior orbital fat into the lower lid-cheek junction during orbital decompression.

PubMed

Litwin, Andre S; Poitelea, Cornelia; Tan, Petrina; Ziahosseini, Kimia; Malhotra, Raman

2018-04-01

To report the complications of grafting of excised posterior orbital fat into the lower lid-cheek junction at the time of orbital decompression surgery. Retrospective review of consecutive patients undergoing orbital decompression combined with grafting of posterior orbital fat to the pre-malar and lateral canthal area (FG). A second group of consecutive patients undergoing orbital decompression but no orbital fat grafting (NoFG) were also studied as a form of comparative control. Standard patient data, including age, sex, visual acuity, degree of proptosis, operative details, diplopia or any other complications was collected. Independent assessment of pre- and post-operative photographs graded the lower lid-cheek junction. Thirty-four orbits of 29 patients, of which 21 orbits underwent orbital decompression with orbital fat grafting (FG). There were no intraoperative complications, postoperative infections, or visual loss. Complications relating to fat grafting included prolonged swelling in 3 (17%) patients at 3 months, in 1 case lasting 6 months, lower lid lumps in 3 (17%), and fat seepage in 1 (6%). The FG group achieved a greater improvement in the appearance of the lower-lid-cheek junction at 12 months in comparison to NoFG. Mean grade improvement 1.24 ± 1.09 vs 0 ± 0.82 (p = 0.025). Median follow-up was 20 months (range 6-30 months). Grafting of excised orbital fat during orbital decompression can improve the appearance of the lower lid-cheek junction in patients being treated for thyroid orbitopathy. However, 24% of patients will experience swelling and/or lumpiness requiring several months to settle or further fat excision.

The use of tethers for payload orbital transfer. Continuation of investigation of electrodynamic stabilization and control of long orbiting tethers, volume 2

NASA Technical Reports Server (NTRS)

Colombo, G.; Martinez-Sanchez, M.; Arnold, D.

1982-01-01

The SKYHOOK program was used to do simulations of two cases of the use of the tether for payload orbital transfer. The transport of a payload along the tether from a heavy lower platform to an upper launching platform is considered. A numerical example of the Shuttle launching a payload using an orbital tether facility is described.

A General Approach to the Geostationary Transfer Orbit Mission Recovery

NASA Technical Reports Server (NTRS)

Faber, Nicolas; Aresini, Andrea; Wauthier, Pascal; Francken, Philippe

2007-01-01

This paper discusses recovery scenarios for geosynchronous satellites injected in a non-nominal orbit due to a launcher underperformance. The theory on minimum-fuel orbital transfers is applied to develop an operational tool capable to design a recovery mission. To obtain promising initial guesses for the recovery three complementary techniques are used: p-optimized impulse function contouring, a numerical impulse function minimization and the solutions to the switching equations. The tool evaluates the feasibility of a recovery with the on-board propellant of the spacecraft and performs the complete mission design. This design takes into account for various mission operational constraints such as e.g., the requirement of multiple finite-duration burns, third-body orbital perturbations, spacecraft attitude constraints and ground station visibility. In a final case study, we analyze the consequences of a premature breakdown of an upper rocket stage engine during injection on a geostationary transfer orbit, as well as the possible recovery solution with the satellite on-board propellant.

Optimal transfers between unstable periodic orbits using invariant manifolds

NASA Astrophysics Data System (ADS)

Davis, Kathryn E.; Anderson, Rodney L.; Scheeres, Daniel J.; Born, George H.

2011-03-01

This paper presents a method to construct optimal transfers between unstable periodic orbits of differing energies using invariant manifolds. The transfers constructed in this method asymptotically depart the initial orbit on a trajectory contained within the unstable manifold of the initial orbit and later, asymptotically arrive at the final orbit on a trajectory contained within the stable manifold of the final orbit. Primer vector theory is applied to a transfer to determine the optimal maneuvers required to create the bridging trajectory that connects the unstable and stable manifold trajectories. Transfers are constructed between unstable periodic orbits in the Sun-Earth, Earth-Moon, and Jupiter-Europa three-body systems. Multiple solutions are found between the same initial and final orbits, where certain solutions retrace interior portions of the trajectory. All transfers created satisfy the conditions for optimality. The costs of transfers constructed using manifolds are compared to the costs of transfers constructed without the use of manifolds. In all cases, the total cost of the transfer is significantly lower when invariant manifolds are used in the transfer construction. In many cases, the transfers that employ invariant manifolds are three times more efficient, in terms of fuel expenditure, than the transfer that do not. The decrease in transfer cost is accompanied by an increase in transfer time of flight.

Orbital extraskeletal osteosarcoma following enucleation in a cat: a case report.

PubMed

Groskopf, Brooke S; Dubielzig, Richard R; Beaumont, Stephanie L

2010-05-01

We present a unique case of a feline orbital extraskeletal osteosarcoma that developed 5 years post-enucleation. In 2002, an ophthalmologist enucleated the left eye of a 2-year-old neutered male DSH and submitted it to the Comparative Ocular Pathology Laboratory of Wisconsin (COPLOW). COPLOW diagnosed the left eye with feline diffuse iris melanoma. In June 2007, the cat presented to another veterinarian for moderate swelling of the enucleation site. Palpation suggested a firm mass along the lateral orbital rim and an exploratory orbitotomy revealed a cyst with a mass adhered to it and the ventrolateral orbital rim. The cyst and mass were excised by the veterinarian and submitted to COPLOW. COPLOW diagnosed the tissue as an orbital conjunctival inclusion cyst and an acquired orbital osteosarcoma. Following the enucleation, retained conjunctival epithelium became embedded in the connective tissue of the orbit and caused a cyst to develop. The cyst wall consisted of a myofibroblastic collagen-rich matrix and acted as a nidus of chronic irritation and tumor growth. This orbital osteosarcoma resembles feline vaccine-associated sarcomas (VAS), feline post-traumatic ocular sarcomas, and microchip-associated sarcomas in terms of it histopathology and its hypothesized pathogenesis related to exposure to antigenic material such as implanted epithelium, lens protein, vaccine components, and microchips as foreign bodies.

Application of Semi-analytical Satellite Theory orbit propagator to orbit determination for space object catalog maintenance

NASA Astrophysics Data System (ADS)

Setty, Srinivas J.; Cefola, Paul J.; Montenbruck, Oliver; Fiedler, Hauke

2016-05-01

Catalog maintenance for Space Situational Awareness (SSA) demands an accurate and computationally lean orbit propagation and orbit determination technique to cope with the ever increasing number of observed space objects. As an alternative to established numerical and analytical methods, we investigate the accuracy and computational load of the Draper Semi-analytical Satellite Theory (DSST). The standalone version of the DSST was enhanced with additional perturbation models to improve its recovery of short periodic motion. The accuracy of DSST is, for the first time, compared to a numerical propagator with fidelity force models for a comprehensive grid of low, medium, and high altitude orbits with varying eccentricity and different inclinations. Furthermore, the run-time of both propagators is compared as a function of propagation arc, output step size and gravity field order to assess its performance for a full range of relevant use cases. For use in orbit determination, a robust performance of DSST is demonstrated even in the case of sparse observations, which is most sensitive to mismodeled short periodic perturbations. Overall, DSST is shown to exhibit adequate accuracy at favorable computational speed for the full set of orbits that need to be considered in space surveillance. Along with the inherent benefits of a semi-analytical orbit representation, DSST provides an attractive alternative to the more common numerical orbit propagation techniques.

[Orbital cellulitis complicated by subperiosteal abscess due to Streptococcus pyogenes infection].

PubMed

Ruíz Carrillo, José Daniel; Vázquez Guerrero, Edwin; Mercado Uribe, Mónica Cecilia

Orbital cellulitis is an infectious disease that is very common in pediatric patients, in which severe complications may develop. Etiological agents related to this disease are Haemophilus influenzae B, Staphylococcus aureus, Streptococcus pneumoniae and Moraxella catarrhalis, which correspond to 95% of cases. Moreover, Streptococcus beta hemolytic and anaerobic microorganisms may also be present corresponding to < 5% of the cases. We present an uncommon case of cellulitis complicated by sub-periosteal abscess caused by Streptococcus pyogenes (Group A beta hemolytic streptococcus). A 9-year-old male patient with a history of deficit disorder and hyperactivity since 5 years of age. His current condition started with erythema in the external edge of the right eye, increase in peri-orbicular volume with limitation of eyelid opening, progression to proptosis, pain with eye movements and conjunctival purulent discharge. Image studies reported subperiosteal abscess and preseptal right with extraocular cellulitis. The patient started with empirical antibiotic treatment, surgical drainage and culture of purulent material from which Streptococcus pyogenes was isolated. Due to the implementation of vaccination schemes against H. influenza and S. pneumoniae since the 90s, the cases by these pathogens have decreased, causing new bacteria to take place as the cause of the infection. The importance of considering S. pyogenes as an etiology of orbital cellulitis is the rapid progression to abscess formation, and the few cases described in the literature. Copyright © 2017 Hospital Infantil de México Federico Gómez. Publicado por Masson Doyma México S.A. All rights reserved.

Stochastic Analysis of Orbital Lifetimes of Spacecraft

NASA Technical Reports Server (NTRS)

Sasamoto, Washito; Goodliff, Kandyce; Cornelius, David

2008-01-01

A document discusses (1) a Monte-Carlo-based methodology for probabilistic prediction and analysis of orbital lifetimes of spacecraft and (2) Orbital Lifetime Monte Carlo (OLMC)--a Fortran computer program, consisting of a previously developed long-term orbit-propagator integrated with a Monte Carlo engine. OLMC enables modeling of variances of key physical parameters that affect orbital lifetimes through the use of probability distributions. These parameters include altitude, speed, and flight-path angle at insertion into orbit; solar flux; and launch delays. The products of OLMC are predicted lifetimes (durations above specified minimum altitudes) for the number of user-specified cases. Histograms generated from such predictions can be used to determine the probabilities that spacecraft will satisfy lifetime requirements. The document discusses uncertainties that affect modeling of orbital lifetimes. Issues of repeatability, smoothness of distributions, and code run time are considered for the purpose of establishing values of code-specific parameters and number of Monte Carlo runs. Results from test cases are interpreted as demonstrating that solar-flux predictions are primary sources of variations in predicted lifetimes. Therefore, it is concluded, multiple sets of predictions should be utilized to fully characterize the lifetime range of a spacecraft.

Chaos in pseudo-Newtonian black holes with halos

NASA Astrophysics Data System (ADS)

Guéron, E.; Letelier, P. S.

2001-03-01

Newtonian as well as special relativistic dynamics are used to study the stability of orbits of a test particle moving around a black hole with a dipolar halo. The black hole is modeled by either the usual monopole potential or the Paczyńki-Wiita pseudo-Newtonian potential. The full general relativistic similar case is also considered. The Poincaré section method and the Lyapunov characteristic exponents show that the orbits for the pseudo-Newtonian potential models are more unstable than the corresponding general relativistic geodesics.

EXAMINING TATOOINE: ATMOSPHERIC MODELS OF NEPTUNE-LIKE CIRCUMBINARY PLANETS

DOE Office of Scientific and Technical Information (OSTI.GOV)

May, E. M.; Rauscher, E.

2016-08-01

Circumbinary planets experience a time-varying irradiation pattern as they orbit their two host stars. In this work, we present the first detailed study of the atmospheric effects of this irradiation pattern on known and hypothetical gaseous circumbinary planets. Using both a one-dimensional energy balance model (EBM) and a three-dimensional general circulation model (GCM), we look at the temperature differences between circumbinary planets and their equivalent single-star cases in order to determine the nature of the atmospheres of these planets. We find that for circumbinary planets on stable orbits around their host stars, temperature differences are on average no more thanmore » 1.0% in the most extreme cases. Based on detailed modeling with the GCM, we find that these temperature differences are not large enough to excite circulation differences between the two cases. We conclude that gaseous circumbinary planets can be treated as their equivalent single-star case in future atmospheric modeling efforts.« less

HMB-45 negative angiomyolipoma of the orbit: a case report and review of the literature.

PubMed

Lin, Che-Yu; Tsai, Chieh-Chih; Kau, Hui-Chuan; Yu, Wei-Kuang; Kao, Shu-Ching; Liu, Catherine Jui-Ling

2016-01-11

Angiomyolipoma is a benign mesenchymal tumor composed of variable amounts of smooth muscle, adipose tissue and thick-walled blood vessels, and usually named PEComas (perivascular epithelioid cell tumors). PEComas share overlapping histopathological features with epithelioid cells along a perivascular distribution and characteristic immunohistochemistry with coexpression of myoid and melanocytic markers (HMB-45 /or Melan-A). We report the first case of primary orbital angiomyolipoma with negative melanocytic marker. An 80-year-old Asian woman had a 2-year history of progressive swelling in the left upper eyelid. External examination revealed 3 cm of relative proptosis of the left eye and a palpable mass in the left superonasal orbit. Computed tomographic scan demonstrated a circumscribed, heterogeneous orbital mass. Excision biopsy was done and the histological finding demonstrated the orbital mass was composed of mature adipocytes, intermingled with spindle or oval-shaped cells, and accompanied by thick-walled blood vessels. Immunohistochemically, tumor cells were positive for CD34 and HHF-35, but negative for cytokeratin, HMB-45 and Melan-A. The diagnosis of angiomyolipoma was made. No recurrence was noted at 2-year follow-up. In our case, the HMB-45 negativity may be explained by the rarity of the epithelioid cells, and the HMB-45 positivity is often weaker or absent in spindle cells. Angiomyolipoma, although rare, should be added to the differential diagnosis of space-occupying orbital lesion.

Traumatic globe luxation associated with orbital fracture in a child: a case report and literature review.

PubMed

Amaral, Márcio Bruno Figueiredo; Carvalho, Matheus Furtado; Ferreira, André Baptista; Mesquita, Ricardo Alves

2015-03-01

Orbital fracture associated with traumatic globe luxation is rare, as it generally requires trauma with high energy for this to occur. The present case report focused on a child who had been hit by a motorcycle, leading to a globe luxation of the left eye and fractures of the superolateral orbital walls. The patient presented initial cosmetic and psychological benefits from the repositioning of the intact globe and the reduction of the orbital fractures. However, a subsequent evisceration of the globe was required due to persistent proptosis and pain. An ocular prosthesis was also implanted, thus recovering the patient's aesthetics. Thirty-four well-documented cases of traumatic globe luxation could be found in the English literature since 1970. The mean age of patients presenting traumatic globe luxation was 29.5 years. The male gender proved to be more prevalent, with traffic collisions representing the most common accident etiology. Direct orbital trauma with fractures of medial and floor walls displacing the globe into the maxillary sinus represented the most common injury mechanism (38.2 %), followed by an elongated object entering the orbit (26.5 %). Optical nerve avulsion is the most serious complication seen in association with traumatic globe luxation, with the repositioning of the initial globe, with no enucleation or evisceration, representing the main form of management.

The structure and stability of orbits in Hoag-like ring systems

NASA Astrophysics Data System (ADS)

Bannikova, Elena Yu

2018-05-01

Ring galaxies are amazing objects exemplified by the famous case of Hoag's Object. Here the mass of the central galaxy may be comparable to the mass of the ring, making it a difficult case to model mechanically. In a previous paper, it was shown that the outer potential of a torus (ring) can be represented with good accuracy by the potential of a massive circle with the same mass. This approach allows us to simplify the problem of the particle motion in the gravitational field of a torus associated with a central mass by replacing the torus with a massive circle. In such a system, there is a circle of unstable equilibrium that we call `Lagrangian circle' (LC). Stable circular orbits exist only in some region limited by the last possible circular orbit related to the disappearance of the extrema of the effective potential. We call this orbit `the outermost stable circular orbit' (OSCO) by analogy with the innermost stable circular orbit (ISCO) in the relativistic case of a black hole. Under these conditions, there is a region between OSCO and LC where the circular motion is not possible due to the competition between the gravitational forces by the central mass and the ring. As a result, a gap in the matter distribution can form in Hoag-like system with massive rings.

[Orbital decompression in Grave's ophtalmopathy].

PubMed

Longueville, E

2010-01-01

Graves disease orbitopathy is a complex progressive inflammatory disease. Medical treatment remains in all cases the proposed treatment of choice. Surgical treatment by bone decompression can be considered as an emergency mainly in cases of optic neuropathy or ocular hypertension not being controlled medically or in post-traumatic exophthalmos stage. Emergency bone decompression eliminates compression or stretching of the optic nerve allowing visual recovery. The uncontrolled ocular hypertension will benefit from decompression. The normalization of intraocular pressure may be obtained by this surgery or if needed by the use of postoperative antiglaucoma drops or even filtration surgery. In all operated cases, the IOP was normalized with an average decrease of 7.71 mmHg and a cessation of eye drops in 3/7 cases. Regarding sequelae, our therapeutic strategy involves consecutively surgery of the orbit, extraocular muscles and eyelids. The orbital expansion gives excellent results on the cosmetic level and facilitates the implementation of subsequent actions.

Development of a Response Surface Thermal Model for Orion Mated to the International Space Station

NASA Technical Reports Server (NTRS)

Miller, Stephen W.; Meier, Eric J.

2010-01-01

A study was performed to determine if a Design of Experiments (DOE)/Response Surface Methodology could be applied to on-orbit thermal analysis and produce a set of Response Surface Equations (RSE) that accurately predict vehicle temperatures. The study used an integrated thermal model of the International Space Station and the Orion Outer mold line model. Five separate factors were identified for study: yaw, pitch, roll, beta angle, and the environmental parameters. Twenty external Orion temperatures were selected as the responses. A DOE case matrix of 110 runs was developed. The data from these cases were analyzed to produce an RSE for each of the temperature responses. The initial agreement between the engineering data and the RSE predictions was encouraging, although many RSEs had large uncertainties on their predictions. Fourteen verification cases were developed to test the predictive powers of the RSEs. The verification showed mixed results with some RSE predicting temperatures matching the engineering data within the uncertainty bands, while others had very large errors. While this study to not irrefutably prove that the DOE/RSM approach can be applied to on-orbit thermal analysis, it does demonstrate that technique has the potential to predict temperatures. Additional work is needed to better identify the cases needed to produce the RSEs

Ground vibration tests of a high fidelity truss for verification of on orbit damage location techniques

NASA Technical Reports Server (NTRS)

Kashangaki, Thomas A. L.

1992-01-01

This paper describes a series of modal tests that were performed on a cantilevered truss structure. The goal of the tests was to assemble a large database of high quality modal test data for use in verification of proposed methods for on orbit model verification and damage detection in flexible truss structures. A description of the hardware is provided along with details of the experimental setup and procedures for 16 damage cases. Results from selected cases are presented and discussed. Differences between ground vibration testing and on orbit modal testing are also described.

Rectal Cancer in the Eye: A Case Report of Orbital Metastasis

PubMed Central

Nabeel, Mohammed; Farooqi, Rehan; Mohebtash, Mahsa; Mansuri, Uvesh; Patel, Smit; Patel, Jinal; Khan, Vinshi Naz

2017-01-01

Orbital metastasis from colorectal cancer is extremely rare. In this case report, we describe a 48-year-old woman who presented with recurrent severe headaches and new onset constipation with no known history of cancer. After vigilant workup, imaging, and biopsies, she was diagnosed with orbital metastasis from a primary rectal carcinoma. She was started on chemotherapy and radiation therapy. Her chemotherapy regimen consisted of FLOX (leucovorin + fluorouracil + oxaliplatin), along with panitumumab, which she tolerated well. She received chemotherapy for seven months before she lost her battle with cancer. PMID:29062621

[Epoxide acrylate maleic resin and hydroxyapatite composite material as a bone graft substitute in surgical correction of orbital reconstruction].

PubMed

Mu, X; Dong, J; Wang, W

1995-11-01

This paper illustrates the results of surgical correction in 11 cases with orbital deformities such as periorbital deficiency after orbitotomy for retinoblastoma and orbital malposition after facial trauma. EH composite material, mixture of hydroxyapatite and epoxide acrylate maleic resin in constant proportion, was used as a good bone graft substitute in all 11 cases. This material was easier to be molded during surgery, safe to human body, had no toxic effects, no irritation and no implant-related complications. The early results obtained in these patients are encouraging.

Newton–Hooke-type symmetry of anisotropic oscillators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, P.M., E-mail: zhpm@impcas.ac.cn; Horvathy, P.A., E-mail: horvathy@lmpt.univ-tours.fr; Laboratoire de Mathématiques et de Physique Théorique, Université de Tours

2013-06-15

Rotation-less Newton–Hooke-type symmetry, found recently in the Hill problem, and instrumental for explaining the center-of-mass decomposition, is generalized to an arbitrary anisotropic oscillator in the plane. Conversely, the latter system is shown, by the orbit method, to be the most general one with such a symmetry. Full Newton–Hooke symmetry is recovered in the isotropic case. Star escape from a galaxy is studied as an application. -- Highlights: ► Rotation-less Newton–Hooke (NH) symmetry is generalized to an arbitrary anisotropic oscillator. ► The orbit method is used to find the most general case for rotation-less NH symmetry. ► The NH symmetry ismore » decomposed into Heisenberg algebras based on chiral decomposition.« less

Noncoplanar minimum delta V two-impulse and three-impulse orbital transfer from a regressing oblate earth assembly parking ellipse onto a flyby trans-Mars asymptotic velocity vector.

NASA Technical Reports Server (NTRS)

Bean, W. C.

1971-01-01

Comparison of two-impulse and three-impulse orbital transfer, using data from a 63-case numerical study. For each case investigated for which coplanarity of the regressing assembly parking ellipse was attained with the target asymptotic velocity vector, a two-impulse maneuver (or a one-impulse equivalent) was found for which the velocity expenditure was within 1% of a reference absolute minimum lower bound. Therefore, for the coplanar cases, use of a minimum delta-V three-impulse maneuver afforded scant improvement in velocity penalty. However, as the noncoplanarity of the parking ellipse and the target asymptotic velocity vector increased, there was a significant increase in the superiority of minimum delta-V three-impulse maneuvers for slowing the growth of velocity expenditure. It is concluded that a multiple-impulse maneuver should be contemplated if nonnominal launch conditions could occur.

The relationship of cranial, orbital and nasal cavity size with the morphology of the supraorbital region in modern Homo sapiens.

PubMed

Nowaczewska, Wioletta; Łapicka, Urszula; Cieślik, Agata; Biecek, Przemysław

2017-09-01

Morphological variation of the supraorbital region (SR) in human crania has been investigated and its potential sources suggested, along with the importance of the size of the facial skeleton, neurocranium, and orbit for the formation of this region. However, previous studies have not indicated whether facial size exhibits a stronger association with SR robusticity than neurocranial size or sex; moreover, the association between orbital volume and SR robusticity has been analysed only in non-human primate skulls. In this study we investigate whether the size of the facial skeleton, neurocranium, two measures of relative orbital size (orbital volume and estimated orbital aperture area), the relative size of the nasal cavity, and the relative estimated area of the anterior nasal cavity opening are related to SR robusticity; we also examine which of these analysed relationships is strongest, as well as independent of the influence of the other traits, in a geographically diverse modern human cranial sample. The results of Spearman's rank and partial rank correlations (encompassing models including or excluding sex and geographic origin) show a relationship between most of the above-mentioned variables and SR robusticity, with the exception of the estimated relative area of the orbital opening (in the case of the results of Spearman's rank correlations) and the traits of the nasal cavity. Of all the analysed traits, sex appears to be the most important for the formation of SR robusticity and, of two measures of cranial size, neurocranial size was the most significant. The strong relationship between SR robusticity and relative orbital volume was observed in models without the geographic origin factor. The results concerning analysed models suggest the influence of this factor on this relationship; however, to explain this influence, further studies are needed.

Coding performance of the Probe-Orbiter-Earth communication link

NASA Technical Reports Server (NTRS)

Divsalar, D.; Dolinar, S.; Pollara, F.

1993-01-01

The coding performance of the Probe-Orbiter-Earth communication link is analyzed and compared for several cases. It is assumed that the coding system consists of a convolutional code at the Probe, a quantizer and another convolutional code at the Orbiter, and two cascaded Viterbi decoders or a combined decoder on the ground.

Orbit attitude processor. STS-1 bench program verification test plan

NASA Technical Reports Server (NTRS)

Mcclain, C. R.

1980-01-01

A plan for the static verification of the STS-1 ATT PROC ORBIT software requirements is presented. The orbit version of the SAPIENS bench program is used to generate the verification data. A brief discussion of the simulation software and flight software modules is presented along with a description of the test cases.

The Capture of Interstellar Dust: The Pure Poynting-Robertson Case

NASA Technical Reports Server (NTRS)

Jackson, A. A.

2001-01-01

Ulysses and Galileo spacecraft have discovered interstellar dust particles entering the solar system. In general, particles trajectories not altered by Lorentz forces or radiation pressure should encounter the sun on open orbits. Under Newtonian forces alone these particles return to the interstellar medium. Dissipative forces, such as Poynting Robertson (PR) and corpuscular drag and non-dissipative Lorentz forces can modify open orbits to become closed. In particular, it is possible for the orbits of particles that pass close to the Sun to become closed due to PR drag. Further, solar irradiation will cause modification of the size of the dust particle by evaporation. The combination of these processes gives rise a class of capture orbits and bound orbits with evaporation. Considering only the case of pure PR drag a minimum impact parameter is derived for initial capture by Poynting-Robertson drag. Orbits in the solar radiation field are computed numerically accounting for evaporation with optical and material properties for ideal interstellar particles modeled. The properties of this kind of particle capture are discussed for the Sun but is applicable to other stars.

On the orbit calculation of visual binaries with a very short arc: application to the PMS binary system, FW Tau AB

NASA Astrophysics Data System (ADS)

Docobo, J. A.; Tamazian, V. S.; Campo, P. P.

2018-05-01

In the vast majority of cases when available astrometric measurements of a visual binary cover a very short orbital arc, it is practically impossible to calculate a good quality orbit. It is especially important for systems with pre-main-sequence components where standard mass-spectrum calibrations cannot be applied nor can a dynamical parallax be calculated. We have shown that the analytical method of Docobo allows us to put certain constraints on the most likely orbital solutions, using an available realistic estimate of the global mass of the system. As an example, we studied the interesting PMS binary, FW Tau AB, located in the Taurus-Auriga as well as investigated a range of its possible orbital solutions combined with an assumed distance between 120 and 160 pc. To maintain the total mass of FW Tau AB in a realistic range between 0.2 and 0.6M_{⊙}, minimal orbital periods should begin at 105, 150, 335, and 2300 yr for distances of 120, 130, 140, and 150 pc, respectively (no plausible orbits were found assuming a distance of 160 pc). An original criterion to establish the upper limit of the orbital period is applied. When the position angle in some astrometric measurements was flipped by 180°, orbits with periods close to 45 yr are also plausible. Three example orbits with periods of 44.6, 180, and 310 yr are presented.

Short arc orbit determination and imminent impactors in the Gaia era

NASA Astrophysics Data System (ADS)

Spoto, F.; Del Vigna, A.; Milani, A.; Tommei, G.; Tanga, P.; Mignard, F.; Carry, B.; Thuillot, W.; David, P.

2018-06-01

Short-arc orbit determination is crucial when an asteroid is first discovered. In these cases usually the observations are so few that the differential correction procedure may not converge. We developed an initial orbit computation method, based on systematic ranging, which is an orbit determination technique that systematically explores a raster in the topocentric range and range-rate space region inside the admissible region. We obtained a fully rigorous computation of the probability for the asteroid that could impact the Earth within a few days from the discovery without any a priori assumption. We tested our method on the two past impactors, 2008 TC3 and 2014 AA, on some very well known cases, and on two particular objects observed by the European Space Agency Gaia mission.

Ocular and orbital porcupine quills in the dog: a review and case series.

PubMed Central

Grahn, B H; Szentimrey, D; Pharr, J W; Farrow, C S; Fowler, D

1995-01-01

A retrospective evaluation of 5 cases of orbital or intraocular porcupine quills in the dog and a literature review from MEDLINE (1983-1995) is presented. This paper reviews the diagnosis, therapy, and visual prognosis of ocular and orbital quills in the dog. Distinguishing penetration and perforation of the eye and intraocular structures is paramount in establishing a visual prognosis and appropriate therapy. Perforation of the cornea or sclera, lens, or the uvea and retina necessitates prompt specialized surgical therapy to save vision. The diagnosis of orbital quills can be readily confirmed with ultrasonography. The characteristic sonographic appearance of a double-banded, linear, hyperechoic object allows accurate localization of the quill, which aids surgical removal. Images Figure 1. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. PMID:7585434

Bilateral orbital bone infarction in sickle-cell disease.

PubMed

Ghafouri, Roya H; Lee, Irene; Freitag, Suzanne K; Pira, Tony N

2011-01-01

This is a case of a 2-year-old boy with sickle cell disease who presented with bilateral eyelid swelling, limited extraocular motility, and lateral subperiosteal fluid collection associated with bilateral lateral orbital wall infarctions on MRI. The patient was managed medically with intravenous fluids, analgesics, broad-spectrum antibiotics, systemic steroids, and clinically improved. Patients with sickle cell disease are susceptible to infarction of the orbital bones during vaso-occlusive crises. Orbital wall infarction can lead to acute proptosis and restricted extraocular motility. Orbital wall infarction should be considered in sickle cell patients with orbital diseases so that appropriate treatment can be instituted promptly to prevent the serious sequelae of orbital compression syndrome.

Waves plus currents at a right angle: The rippled bed case

NASA Astrophysics Data System (ADS)

Faraci, C.; Foti, E.; Musumeci, R. E.

2008-07-01

The present paper deals with wave plus current flow over a fixed rippled bed. More precisely, modifications of the current profiles due to the superimposition of orthogonal cylindrical waves have been investigated experimentally. Since the experimental setup permitted only the wave dominated regime to be investigated (i.e., the regime where orbital velocity is larger than current velocity), also a numerical k-ɛ turbulence closure model has been developed in order to study a wider range of parameters, thus including the current dominated regime (i.e., where current velocity is larger than wave orbital one). In both cases a different response with respect to the flat bed case has been found. Indeed, in the flat bed case laminar wave boundary layers in a wave dominated regime induce a decrease in bottom shear stresses, while the presence of a rippled bed behaves as a macroroughness, which causes the wave boundary layer to become turbulent and therefore the current velocity near the bottom to be smaller than the one in the case of current only, with a consequent increase in the current bottom roughness.

Bilateral orbital infarction and retinal detachment in a previously undiagnosed sickle cell hemoglobinopathy African child

PubMed Central

Helen, Onakpoya Oluwatoyin; Ajite, K. O.; Oyelami, O. A.; Asaleye, C. M.; Adeoye, A. O.

2013-01-01

Bone infarction involving the orbit in sickle cell disease is not common. Bilateral orbital infarction in a previously undiagnosed sickle cell hemoglobinopathy has not been previously reported. In this report, we present a case of an 11-year-old previously undiagnosed sickle cell disease Nigerian girl with severe acute bilateral orbital infarction and retinal detachment to highlight that hemoglobinopathy induced orbital infarction should be considered in African children with acute onset proptosis with or without previous history of sickle cell hemoglobinopathy. PMID:23901183

Acute retinal necrosis complicating chicken pox in a healthy adult: a case report and review of literature.

PubMed

Tajunisah, Iqbal; Reddy, Sagili Chandrasekhara

2007-01-01

We report a case of unilateral acute retinal necrosis (ARN) with marked vitritis and retinal necrosis leading to retinal breaks following chicken pox successfully treated with intravenous acyclovir followed by oral acyclovir, orbital floor triamcinolone injections to contain the inflammation, and barrier laser therapy to secure the retinal breaks with good visual outcome. This case is unusual in its severity and the novel use orbital floor triamcinolone therapy to contain ARN inflammation.

Manipulator trajectories during orbital servicing mission: numerical simulations and experiments on microgravity simulator

NASA Astrophysics Data System (ADS)

Rybus, T.; Seweryn, K.

2018-06-01

It is considered to use a manipulator-equipped satellite for performing On-Orbit Servicing (OOS) or Active Debris Removal (ADR) missions. In this paper, several possible approaches are reviewed for end-effector (EE) trajectory planning in the Cartesian space, such as application of the Bézier curves for singularity avoidance and method for trajectory optimization. The results of numerical simulations for a satellite equipped with a 7 degree-of-freedom (DoF) manipulator and results of experiments performed on a planar air-bearing microgravity simulator for a simplified two-dimensional (2D) case with a 2-DoF manipulator are presented. Differences between the free-floating case and the case where Attitude and Orbit Control Systems (AOCS) keep constant position and orientation of the satellite are also shown.

Locally optimal transfer trajectories between libration point orbits using invariant manifolds

NASA Astrophysics Data System (ADS)

Davis, Kathryn E.

2009-12-01

Techniques from dynamical systems theory and primer vector theory have been applied to the construction of locally optimal transfer trajectories between libration point orbits. When two libration point orbits have different energies, it has been found that the unstable manifold of the first orbit can be connected to the stable manifold of the second orbit with a bridging trajectory. A bounding sphere centered on the secondary, with a radius less than the radius of the sphere of influence of the secondary, was used to study the stable and unstable manifold trajectories. It was numerically demonstrated that within the bounding sphere, the two-body parameters of the unstable and stable manifold trajectories could be analyzed to locate low transfer costs. It was shown that as the two-body parameters of an unstable manifold trajectory more closely matched the two-body parameters of a stable manifold trajectory, the total DeltaV necessary to complete the transfer decreased. Primer vector theory was successfully applied to a transfer to determine the optimal maneuvers required to create the bridging trajectory that connected the unstable manifold of the first orbit to the stable manifold of the second orbit. Transfer trajectories were constructed between halo orbits in the Sun-Earth and Earth-Moon three-body systems. Multiple solutions were found between the same initial and final orbits, where certain solutions retraced interior portions of the trajectory. All of the trajectories created satisfied the conditions for optimality. The costs of transfers constructed using invariant manifolds were compared to the costs of transfers constructed without the use of invariant manifolds, when data was available. In all cases, the total cost of the transfers were significantly lower when invariant manifolds were used in the transfer construction. In many cases, the transfers that employed invariant manifolds were three to four times more efficient, in terms of fuel expenditure, than the transfer that did not. The decrease in transfer cost was accompanied by an increase in transfer time of flight. Transfers constructed in the Earth-Moon system were shown to be particularly viable for lunar navigation and communication constellations, as excellent coverage of the lunar surface can be achieved during the transfer.

Emergence of fully gapped s++-wave and nodal d-wave states mediated by orbital and spin fluctuations in a ten-orbital model of KFe2Se2

NASA Astrophysics Data System (ADS)

Saito, Tetsuro; Onari, Seiichiro; Kontani, Hiroshi

2011-04-01

We study the superconducting state in recently discovered high-Tc superconductor KxFe2Se2 based on the ten-orbital Hubbard-Holstein model without hole pockets. When the Coulomb interaction is large, a spin-fluctuation-mediated d-wave state appears due to the nesting between electron pockets. Interestingly, the symmetry of the body-centered tetragonal structure in KxFe2Se2 requires the existence of nodes in the d-wave gap, although a fully gapped d-wave state is realized in the case of a simple tetragonal structure. In the presence of moderate electron-phonon interaction due to Fe-ion optical modes, however, orbital fluctuations give rise to the fully gapped s++-wave state without sign reversal. Therefore, both superconducting states are distinguishable by careful measurements of the gap structure or the impurity effect on Tc.

Sloshing of Cryogenic Helium Driven by Lateral Impulse/Gravity Gradient-Dominated/or g-Jitter-Dominated Accelerations and Orbital Dynamics

NASA Technical Reports Server (NTRS)

Hung, R. J.; Long, Y. T.; Zu, G. J.

1996-01-01

The coupling of slosh dynamics within a partially filled rotating dewar of superfluid helium 11 with spacecraft orbital dynamics is investigated in response to the environmental disturbances of (a) lateral impulses, (b) gravity gradients and (c) g-jitter forces. The purpose of this study is to investigate how the coupling of helium 11 fluid slosh dynamics driven by three cases of environmental force with spacecraft dynamics can affect the bubble deformations and their associated fluid and spacecraft mass centre fluctuations. The numerical computation of slosh dynamics is based on a rotational frame, while the spacecraft dynamics is associated with a non-rotational frame. Results show that the major contribution of orbital dynamics is driven by coupling with slosh dynamics. Neglecting the effect of slosh dynamics acting on the spacecraft may lead to the wrong results for the development of orbital and attitude control techniques.

A Mössbauer effect study of the bonding in several organoiron carbonyl clusters

NASA Astrophysics Data System (ADS)

Long, Gary J.; O'Brien, James F.

1988-02-01

After a brief review of the applications of the Mössbauer effect to cyclopentadienyl containing compounds, the chemistry and spectral properties of the various iron carbonyl complexes are described. The electronic properties of a series of trinuclear and tetranuclear organoiron clusters have been investigated through Fenske-Hall self-consistent field molecular orbital calculations, and the results are compared with the Mössbauer effect isomer shifts. A linear correlation is found between the Slater effective nuclear charge, as calculated from the Fenske-Hall partial orbital occupancy factors, and the isomer shift. In these compounds the 4s orbital populations are rather constant. However, the cis and trans isomers of [CpFe(CO)2]2 have a significantly lower 4s orbital populations. In this case, the reduced 4s population must be accounted for by adding it to the effective nuclear charge to obtain a good correlation with the isomer shift.

Development and Applications of Advanced Electronic Structure Methods

NASA Astrophysics Data System (ADS)

Bell, Franziska

This dissertation contributes to three different areas in electronic structure theory. The first part of this thesis advances the fundamentals of orbital active spaces. Orbital active spaces are not only essential in multi-reference approaches, but have also become of interest in single-reference methods as they allow otherwise intractably large systems to be studied. However, despite their great importance, the optimal choice and, more importantly, their physical significance are still not fully understood. In order to address this problem, we studied the higher-order singular value decomposition (HOSVD) in the context of electronic structure methods. We were able to gain a physical understanding of the resulting orbitals and proved a connection to unrelaxed natural orbitals in the case of Moller-Plesset perturbation theory to second order (MP2). In the quest to find the optimal choice of the active space, we proposed a HOSVD for energy-weighted integrals, which yielded the fastest convergence in MP2 correlation energy for small- to medium-sized active spaces to date, and is also potentially transferable to coupled-cluster theory. In the second part, we studied monomeric and dimeric glycerol radical cations and their photo-induced dissociation in collaboration with Prof. Leone and his group. Understanding the mechanistic details involved in these processes are essential for further studies on the combustion of glycerol and carbohydrates. To our surprise, we found that in most cases, the experimentally observed appearance energies arise from the separation of product fragments from one another rather than rearrangement to products. The final chapters of this work focus on the development, assessment, and application of the spin-flip method, which is a single-reference approach, but capable of describing multi-reference problems. Systems exhibiting multi-reference character, which arises from the (near-) degeneracy of orbital energies, are amongst the most interesting in chemistry, biology and materials science, yet amongst the most challenging to study with electronic structure methods. In particular, we explored a substituted dimeric BPBP molecule with potential tetraradical character, which gained attention as one of the most promising candidates for an organic conductor. Furthermore, we extended the spin-flip approach to include variable orbital active spaces and multiple spin-flips. This allowed us to perform wave-function-based studies of ground- and excited-states of polynuclear metal complexes, polyradicals, and bond-dissociation processes involving three or more bonds.

Isolated upper eyelid retraction: a sign of idiopathic inflammatory orbital disease.

PubMed

Shome, Debraj; Toshniwal, Svetlana; Jain, Vandana; Natarajan, Sundaram; Vemuganti, Geeta K

2008-01-01

A 41-year-old woman was examined for left upper eyelid retraction. Remaining ocular and systemic examination was unremarkable. Orbital CT demonstrated an ill-defined, extraconal, superior orbital soft-tissue mass involving the levator palpebrae superioris muscle. Incisional biopsy with histopathology demonstrated idiopathic orbital inflammation. The patient was started on a gradually tapering dose of oral steroids, for 6 weeks. On follow-up, the eyelid retraction had resolved. We report this case to demonstrate that idiopathic inflammatory orbital disease, localized to the superior orbit, may cause isolated upper eyelid retraction without associated proptosis. This condition resolves with medical therapy, leading to symmetrical palpebral apertures.

Surgical orbital decompression for thyroid eye disease.

PubMed

Boboridis, Kostas G; Bunce, Catey

2011-12-07

Orbital decompression is an established procedure for the management of exophthalmos and visual rehabilitation from optic neuropathy in cases of thyroid eye disease. Numerous procedures for removal of orbital bony wall, fat or a combination of these for a variety of indications in different stages of the disease have been well reported in the medical literature. However, the relative effectiveness and safety of these procedures in relation to the various indications remains unclear. To review current published evidence for the effectiveness of surgical orbital decompression for disfiguring proptosis in adult thyroid eye disease and summa rise information on possible complications and the quality of life from the studies identified. We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2011, Issue 10), MEDLINE (January 1950 to October 2011), EMBASE (January 1980 to October 2011), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com) and ClinicalTrials.gov (http://clinicaltrials.gov). There were no date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 6 October 2011. We searched oculoplastic textbooks, conference proceedings from the European and American Society of Ophthalmic Plastic and Reconstructive Surgery (ESOPRS, ASOPRS), European Ophthalmological Society (SOE), the Association for Research in Vision and Ophthalmology (ARVO) and American Academy of Ophthalmology (AAO) for the years 2000 to 2009 to identify relevant data. We attempted to contact researchers who are active in this field for information about further published or unpublished studies. We included randomised controlled trials (RCTs) with no restriction on date or language comparing two or more surgical methods for orbital decompression with removal of bony wall, orbital fat or a combination of both for disfiguring proptosis or comparison of surgical techniques with any form of medical decompression. Each review author independently assessed study abstracts identified from the electronic and manual searches. Author analysis was then compared and full papers for appropriate studies were obtained according to the inclusion criteria. Disagreements between the authors were resolved by discussion. We identified two randomised trials eligible for inclusion in the review. There was significant variability between the trials for interventions, methodology and outcome measures and therefore meta-analysis was not performed. One study suggested that the transantral approach and endoscopic transnasal technique had similar effects in reducing exophthalmos but that the endoscopic approach may be safer, relating to fewer complications. This study had short-term follow-up and lacked information on our primary outcome (success or failure of treatment). The second study provided evidence that intravenous steroids may be superior to primary surgical decompression in the management of compressive optic neuropathy requiring less secondary surgical procedures, although it relates more frequently to transient side effects. This study was weakened by a small sample size. Until more credible evidence is available recommendations as to best treatment cannot be reliably made. A single study showed that the transantral approach for orbital decompression was related to more complications than the endoscopic transnasal technique which is preferred by Ear, Nose and Throat (ENT) surgeons, usually as an adjunctive procedure. Intravenous steroids were reported in a single trial to be the most efficient intervention for dysthyroid optic neuropathy. The majority of published literature on orbital decompression for thyroid eye disease consists of retrospective, cohort, or case series studies. Although these provide useful descriptive information, clarification is required to show the relative effectiveness of each intervention for various indications.The two RCTs reviewed are not robust enough to provide credible evidence to our understanding of current decompressive surgery and to support recommendations for clinical practice. There is evidence from currently available uncontrolled studies that removal of the medial and lateral wall (balanced decompression) with or without fat removal may be the most effective surgical method related to only a few complications.There is a clear need for randomised studies evaluating the balanced two-wall, three-wall and orbital fat decompression techniques. Comparison with other surgical techniques for orbital decompression or with immunosuppression in cases of compressive optic neuropathy would also be important. These studies should primarily address the reduction of exophthalmos, disease severity, complication rates, quality of life and cost of the intervention.

Extraosseous Primary Intracranial Ewing Sarcoma/peripheral Primitive Neuroectodermal Tumor: Series of Seven Cases and Review of Literature

PubMed Central

Singh, Amit Kumar; Srivastava, Arun Kumar; Pal, Lily; Sardhara, Jayesh; Yadav, Rajan; Singh, Shalini; Bhaisora, Kamlesh Singh; Das, Kuntal Kanti; Mehrotra, Anant; Sahu, Rabi Narayan; Jaiswal, Awadhesh Kumar; Behari, Sanjay

2018-01-01

Background: The Ewing sarcoma peripheral PNET (ES-pPNET) is very rare small round cell tumour that involves the CNS as either a primary dural neoplasm or by direct extension from contiguous bone or soft tissue. Materials and Methods: Biopsy proven cases of intracranial ES/pPNET with orbital involvement operated during Jan 2010-Jan 2014 were retrospectively included and their clinical data, operative and histological findings were reviewed from institutional oncology register. Results: seven patients (4 males; 3 female) were studied with mean age at presentation of 13 years. Six patients had orbital involvement in one or other form. Surgical excision was gross total in five, near total in one, and subtotal in one patient. All patients received adjuvant therapy, only chemotherapy in 2, only Radiotherapy in four, both in one. MRI characteristics were studied in six patients. Four patients died with average survival of 33.2 months and three patients are having Progression free survival of average 23.3 months. Conclusions: The EWS-pPNET is very rare tumour and very poorly described in literature. These tumours are showing special predilection for the frontotemporal dura and erode through the flat bone of cranium like orbital roof and lateral wall of the orbit. These tumours are aggressive, multi compartmental, vascular and very rapidly growing, so missing or overlooking the primary symptoms of dural stretching/bony involvement leads to delay in management and poor outcome. PMID:29682023

Forecasting the Economic Impact of Future Space Station Operations

NASA Technical Reports Server (NTRS)

Summer, R. A.; Smolensky, S. M.; Muir, A. H.

1967-01-01

Recent manned and unmanned Earth-orbital operations have suggested great promise of improved knowledge and of substantial economic and associated benefits to be derived from services offered by a space station. Proposed application areas include agriculture, forestry, hydrology, public health, oceanography, natural disaster warning, and search/rescue operations. The need for reliable estimates of economic and related Earth-oriented benefits to be realized from Earth-orbital operations is discussed and recent work in this area is reviewed. Emphasis is given to those services based on remote sensing. Requirements for a uniform, comprehensive and flexible methodology are discussed. A brief review of the suggested methodology is presented. This methodology will be exercised through five case studies which were chosen from a gross inventory of almost 400 user candidates. The relationship of case study results to benefits in broader application areas is discussed, Some management implications of possible future program implementation are included.

Observational signatures of spherically-symmetric black hole spacetimes

NASA Astrophysics Data System (ADS)

De Laurentis, Mariafelicia; Younsi, Ziri; Porth, Oliver; Mizuno, Yosuke; Fromm, Christian; Rezzolla, Luciano; Olivares, Hector

2017-12-01

A binary system composed of a supermassive black hole and a pulsar orbiting around it is studied. The motivation for this study arises from the fact that pulsar timing observations have proven to be a powerful tool in identifying physical features of the orbiting companion. In this study, taking into account a general spherically-symmetric metric, we present analytic calculations of the geodesic motion, and the possible deviations with respect to the standard Schwarzschild case of General Relativity. In particular, the advance at periastron is studied with the aim of identifying corrections to General Relativity. A discussion of the motion of a pulsar very close the supermassive central black hole in our Galaxy (Sgr A*) is reported.

Compressed air blast injury with palpebral, orbital, facial, cervical, and mediastinal emphysema through an eyelid laceration: a case report and review of literature.

PubMed

Hiraoka, Takahiro; Ogami, Tomohiro; Okamoto, Fumiki; Oshika, Tetsuro

2013-11-07

To the best of our knowledge, only 14 cases of orbital or periorbital compressed air injuries from air guns or hoses have been reported in the literature. A 30-year-old man was accidentally injured when a compressed air hose nozzle hit his right eye. The right half of his face was markedly swollen and a skin laceration near the right medial canthus was identified. A computed tomography scan showed subcutaneous and intraorbital emphysema around the right eye as well as cervical and mediastinal emphysema. He was prophylactically treated with systemic and topical antibiotics to prevent infection. All emphysemas had completely resolved 2 weeks after the injury. A review of all 15 cases (including ours) showed that all patients were male and that 6 of the 15 (40.0%) cases were related to industrial accidents. Although emphysema was restricted to the subconjunctival space in 2 (13.3%) cases, it spread to the orbit in the remaining 13 (86.7%) cases. Cervical and mediastinal emphysemas were found in 3 (20.0%) cases, and intracranial emphysema was confirmed in 6 (40.0%) cases. Prophylactic antibiotics were used in most cases and the prognosis was generally good in all but one patient, who developed optic atrophy and blindness.

Hypersonic Navier Stokes Comparisons to Orbiter Flight Data

NASA Technical Reports Server (NTRS)

Campbell, Charles H.; Nompelis, Ioannis; Candler, Graham; Barnhart, Michael; Yoon, Seokkwan

2009-01-01

Hypersonic chemical nonequilibrium simulations of low earth orbit entry flow fields are becoming increasingly commonplace as software and computational capabilities become more capable. However, development of robust and accurate software to model these environments will always encounter a significant barrier in developing a suite of high quality calibration cases. The US3D hypersonic nonequilibrium Navier Stokes analysis capability has been favorably compared to a number of wind tunnel test cases. Extension of the calibration basis for this software to Orbiter flight conditions will provide an incremental increase in confidence. As part of the Orbiter Boundary Layer Transition Flight Experiment and the Hypersonic Thermodynamic Infrared Measurements project, NASA is performing entry flight testing on the Orbiter to provide valuable aerothermodynamic heating data. An increase in interest related to orbiter entry environments is resulting from this activity. With the advent of this new data, comparisons of the US3D software to the new flight testing data is warranted. This paper will provide information regarding the framework of analyses that will be applied with the US3D analysis tool. In addition, comparisons will be made to entry flight testing data provided by the Orbiter BLT Flight Experiment and HYTHIRM projects. If data from digital scans of the Orbiter windward surface become available, simulations will also be performed to characterize the difference in surface heating between the CAD reference OML and the digitized surface provided by the surface scans.

Molecular orbital study of some eight-coordinate sulfur chelate complexes of molybdenum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perkins, P.G.; Schultz, F.A.

1983-03-30

A number of molybdenum complexes involving the formal oxidation states Mo(IV) and Mo(V) have been studied by a self-consistent-field molecular orbital technique. All the complexes were of dodecahedral geometry and had eight sulfurs chelated to the central metal atom. In all, a series of five tetrakis complexes was studied, including the ligands dithiocarbamate (dtc), thioxanthate (txn), 1,1-dicyano-2,2-ethylenedithiolate (i-mnt), 1-cyano-1-carbethoxy-2,2-ethylenedithiolate (ced), and 1,1-dicarbethoxy-2,2-ethylenedithiolate (ded). The 4d orbitals were included on molybdenum, and the empty 3d levels on all sulfur atoms. The results show that the highest occupied molecular orbital in each case has over 90% metal d/sub xy/ character. Further, themore » energy of this orbital is linearly related to the reversible half-wave potentials for Mo(IV) ..-->.. Mo(V) and Mo(V) ..-->.. Mo(VI) oxidations of the complexes. A further irreversible oxidation observed experimentally also is closely related to the calculated energy levels. Relationships between the calculated results and Mo 3d/sub 5///sub 2/ X-ray photoelectron binding energies, EPR parameters, and charge-transfer absorption energies are discussed. Electrochemical and spectroscopic properties of these MoS/sub 8/ complexes can be understood in terms of a manifold of orbital energies that retain approximately constant spacings between one another and that move up or down in absolute energy in response to the charge donated or withdrawn by the ligands.« less

Testing of Selected Geopotential Models in Terms of GOCE Satellite Orbit Determination Using Simulated GPS Observations

NASA Astrophysics Data System (ADS)

Bobojc, Andrzej; Drozyner, Andrzej

2016-04-01

This work contains a comparative study of performance of twenty geopotential models in an orbit estimation process of the satellite of the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) mission. For testing, among others, such models as JYY_GOCE02S, ITG-GOCE02, ULUX_CHAMP2013S, GOGRA02S, ITG-GRACE2010S, EIGEN-51C, EGM2008, EGM96, JGM3, OSU91a, OSU86F were adopted. A special software package, called the Orbital Computation System (OCS), based on the classical method of least squares was used. In the frame of OCS, initial satellite state vector components are corrected in an iterative process, using the given geopotential model and the models describing the remaining gravitational perturbations. An important part of the OCS package is the 8th order Cowell numerical integration procedure, which enables a satellite orbit computation. Different sets of pseudorange simulations along reference GOCE satellite orbital arcs were obtained using real orbits of the Global Positioning System (GPS) satellites. These sets were the basic observation data used in the adjustment. The centimeter-accuracy Precise Science Orbit (PSO) for the GOCE satellite provided by the European Space Agency (ESA) was adopted as the GOCE reference orbit. Comparing various variants of the orbital solutions, the relative accuracy of geopotential models in an orbital aspect is determined. Full geopotential models were used in the adjustment process. However, the solutions were also determined taking into account truncated geopotential models. In such case, an accuracy of the orbit estimated was slightly enhanced. The obtained solutions refer to the orbital arcs with the lengths of 90-minute and 1-day.

Systems analysis of solid fuel nuclear engines in cislunar space

NASA Astrophysics Data System (ADS)

Thomas, U.; Koelle, H. H.; Balzer-Sieb, R.; Bernau, D.; Czarnitzki, J.; Floete, A.; Goericke, D.; Lindenthal, A.; Protsch, R.; Teschner, O.

1984-12-01

The use of nuclear engines in cislunar space was studied and the restrictions imposed on nuclear ferries by the chemical Earth to lower Earth orbit (LEO) transportation system were analyzed. The operating conditions are best met by tungsten-water-moderated reactors due to a high specific impulse and long durability. Specific transportation cost for LEO to geostationary orbit (GEO) and LEO to lunar orbit flights were calculated for a transportation system life of 50 yr. Average transportation costs are estimated to be 141 $/kg. No difference is made for both routes. An additional analysis of smaller and larger flight units shows only small cost reductions by employing larger ferries but a significant cost increase in case smaller flight units are used.

Charge orbits of extremal black holes in five-dimensional supergravity

NASA Astrophysics Data System (ADS)

Cerchiai, Bianca L.; Ferrara, Sergio; Marrani, Alessio; Zumino, Bruno

2010-10-01

We derive the U-duality charge orbits, as well as the related moduli spaces, of “large” and “small” extremal black holes in nonmaximal ungauged Maxwell-Einstein supergravities with symmetric scalar manifolds in d=5 space-time dimensions. The stabilizer groups of the various classes of orbits are obtained by determining and solving suitable U-invariant sets of constraints, both in “bare” and “dressed” charge bases, with various methods. After a general treatment of attractors in real special geometry (also considering nonsymmetric cases), the N=2 “magic” theories, as well as the N=2 Jordan symmetric sequence, are analyzed in detail. Finally, the half-maximal (N=4) matter-coupled supergravity is also studied in this context.

Canine low-grade intra-orbital myxosarcoma: case report.

PubMed

Campos, Cecília B; Nunes, Fernanda C; Gamba, Conrado O; Damasceno, Karine A; Souza, Cristina M; Campos, Liliane C; Cassali, Geovanni D

2015-05-01

The aim of this study was to evaluate important clinical, morphological, histopathological, histochemical, and immunohistochemical characteristics in order to establish the diagnosis and prognosis of a low-grade intra-orbital myxosarcoma. A mongrel dog presented a 2-year history of a neoplastic mass behind the right eye. The neoplasm presented a mesenchymal spindle and stellate cell proliferation with an abundant myxoid matrix, moderate anisocariosis, and a low mitotic index. It stained positive for vimentin, moderately positive for periodic acid-Schiff, and negative for Gomori trichrome stain and α-smooth muscle actin. One year following surgical excision, the patient remains disease free. The histological findings established a diagnosis of a rare canine intra-orbital low-grade myxosarcoma. © 2014 American College of Veterinary Ophthalmologists.

STK/Lifetime as a Replacement for Heritage Orbital Lifetime Software

NASA Technical Reports Server (NTRS)

Dove, Edwin

2004-01-01

The Flight Dynamics Analysis Branch (FDAB) of NASNGSFC is tasked with determining the orbital lifetime of several developmental and operational satellites, which include the Hubble Space Telescope. A DOS based program developed by the FDAB many years ago, called PC Lifetime, is used to determine a satellite s lifetime and could soon be in need of a replacement. STK s Lifetime Object Tool is a possible candidate. Due to the reduced support of the PC Lifetime program, and the growing incompatibility of older programs with new operating systems, a comparative analysis was done to determine if STWLifetime could meet the stringent requirements that were laid before it. The use of highly accurate numerical propagators such as STK s High Precision Orbit Propagator ( OP) and the Goddard Trajectory Determination System (GTDS) provided a basis on which to compare STWLifetime s results. Several test cases were run, but the main four test cases would determine whether or not STWLifetime could be PC- Lifetime s replacement. These four cases include a geotransfer orbit, two circular LEOS, and a Poiar LEO. Following rigorous testmg procedures, a conclusion will be determined. STK has proved to be a versatile program on many satellite missions and the FDAB has high hopes that it can pass FDAB s requirements for orbital lifetime prediction.

Transconjunctival orbital emphysema caused by compressed air injury: a case report.

PubMed

Mathew, Sunu; Vasu, Usha; Francis, Febson; Nazareth, Colin

2008-01-01

Orbital emphysema following conjunctival tear in the absence of orbital wall fracture, caused by air under pressure is rare. Usually orbital emphysema is seen in facial trauma associated with damage to the adjacent paranasal sinuses or facial bones. To the best of our knowledge, there have been only eight reports of orbital emphysema following use of compressed air during industrial work. The air under pressure is pushed through the subconjunctival space into the subcutaneous and retrobulbar spaces. We present here a rare cause of orbital emphysema in a young man working with compressed air gun. Although the emphysema was severe, there were no orbital bone fracture and the visual recovery of the patient was complete without attendant complications.

Transconjunctival orbital emphysema caused by compressed air injury: A case report

PubMed Central

Vasu, Usha; Francis, Febson; Nazareth, Colin

2008-01-01

Orbital emphysema following conjunctival tear in the absence of orbital wall fracture, caused by air under pressure is rare. Usually orbital emphysema is seen in facial trauma associated with damage to the adjacent paranasal sinuses or facial bones. To the best of our knowledge, there have been only eight reports of orbital emphysema following use of compressed air during industrial work. The air under pressure is pushed through the subconjunctival space into the subcutaneous and retrobulbar spaces. We present here a rare cause of orbital emphysema in a young man working with compressed air gun. Although the emphysema was severe, there were no orbital bone fracture and the visual recovery of the patient was complete without attendant complications. PMID:18417833

Multi-Body Capture to Low-altitude Circular Orbits at Europa

NASA Technical Reports Server (NTRS)

Grebow, Daniel J.; Petropoulos, Anastassios E.; Finlayson, Paul A.

2011-01-01

For capture to a 200-km circular orbit around Europa, millions of different points along the orbit are simulated in the Jupiter-Europa Restricted 3-Body Problem. The transfers exist as members of families of trajectories, where certain families consistently outperform the others. The trajectories are not sensitive to changes in inclination for the final circular orbit. The top performing trajectories appear to follow the invariant manifolds of L2 Lyapunov orbits for capture into a retrograde orbit, and in some cases saving up to 40% of the from the patched 2-body problem. Transfers are attached to the current nominal mission for NASA's Jupiter-Europa Orbiter, where the total cost is roughly 100 m/s less than the baseline mission.

Climate of an Earth-Like World with Changing Eccentricity

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2017-02-01

Having a giant planet like Jupiter next door can really wreak havoc on your orbit! A new study examines what such a bad neighbor might mean for the long-term climate of an Earth-like planet.Influence of a Bad NeighborThe presence of a Jupiter-like giant planet in a nearby orbit can significantly affect how terrestrial planets evolve dynamically, causing elements like the planets orbital eccentricities and axial tilts to change over time. Earth is saved this inconvenience Jupiter isnt close enough to significantly influence us, and our large moon stabilizes our orbit against Jupiters tugs.Top panels: Authors simulationoutcomes for Case1, in which the planets eccentricity varies from 0 to 0.283 over 6500 years. Bottom panels: Outcomes for Case 2, in which the planets eccentricity varies from 0 to 0.066 over 4500 years. The highereccentricities reached in Case 1 causes the climate parameters to vary more widely. Click for a better look! [Way Georgakarakos 2017]Mars, on the other hand, isnt as lucky: its possible that Jupiters gravitational pull causes Marss axial tilt, for instance, to evolve through a range as large as 0 to 60 degrees on timescales of millions of years! Marss orbital eccentricity is similarly thought to vary due to Jupiters influence, and both of these factors play a major role in determining Marss climate.As exoplanet missions discover more planets many of which are Earth-like we must carefully consider which among these are most likely to be capable of sustaining life. If having a nearby neighbor like a Jupiter can tug an Earth-like world into an orbit with varying eccentricity, how does this affect the planets climate? Will the planet remain temperate? Or will it develop a runaway heating or cooling effect as it orbits, rendering it uninhabitable?Oceans and OrbitsTo examine these questions, two scientists have built the first ever 3D global climate model simulations of an Earth-like world using a fully coupled ocean (necessary for understanding the transport of heat across the planet) with a planetary orbit that evolves over time.The surface air temperature variation of a planet with orbital eccentricity of 0.283. The top panel shows the surface temperature when the planet is closest to the star in its orbit (periastron); the bottom when the planet is furthest from the star in its orbit (apoastron). [Way Georgakarakos 2017]The scientists, Michael Way (NASA Goddard and Uppsala University, Sweden) and Nikolaos Georgakarakos (New York University Abu Dhabi), focus in this study on the specific effects of a varying orbital eccentricity on an Earth-like planets climate, holding the planets axial tilt steady at Earths 23.5. They explore two scenarios: one in which the planets eccentricity evolves from 0 to 0.283 over 6500 years, and the other in which it evolves from 0 to 0.066 over 4500 years.Temperate OutcomesWay and Georgakarakos find that the planet with the more widely varying eccentricity has a greater increase rainfall and humidity as the planet approaches its host star in its orbit. Nonetheless, this effect is not enough to cause a runaway greenhouse scenario in which the planet becomes too warm for habitability. Similarly, the ocean ice fraction remains low enough even at apoastron in high-eccentricity scenarios for the planet to remain temperate.What does these results imply? Having a changing eccentricity caused by the gravitational pull of a nearby Jupiter-like neighbor may make a planets climate more variable, but not to the extent where the planet is no longer able to support life. Therefore, as we discover more such planets with current and upcoming exoplanet missions, we know that we neednt necessarily assume that they arent interest for habitability.CitationM. J. Way and Nikolaos Georgakarakos 2017 ApJL 835 L1. doi:10.3847/2041-8213/835/1/L1

Technetium tc 99m-labeled red blood cells in the preoperative diagnosis of cavernous hemangioma and other vascular orbital tumors.

PubMed

Polito, Ennio; Burroni, Luca; Pichierri, Patrizia; Loffredo, Antonio; Vattimo, Angelo G

2005-12-01

To evaluate technetium Tc 99m (99mTc) red blood cell scintigraphy as a diagnostic tool for orbital cavernous hemangioma and to differentiate between orbital masses on the basis of their vascularization. We performed 99mTc red blood cell scintigraphy on 23 patients (8 female and 15 male; mean age, 47 years) affected by an orbital mass previously revealed with computed tomography (CT) and magnetic resonance imaging (MRI) and suggesting cavernous hemangioma. In our diagnosis, we considered the orbital increase delayed uptake with the typical scintigraphic pattern known as perfusion blood pool mismatch. The patients underwent biopsy or surgical treatment with transconjunctival cryosurgical extraction when possible. Single-photon emission tomography (SPET) showed intense focal uptake in the orbit corresponding to radiologic findings in 11 patients who underwent surgical treatment and pathologic evaluation (9 cavernous hemangiomas, 1 hemangiopericytoma, and 1 lymphangioma). Clinical or histologic examination of the remaining 22 patients revealed the presence of 5 lymphoid pseudotumors, 2 lymphomas, 2 pleomorphic adenomas of the lacrimal gland, 1 astrocytoma, 1 ophthalmic vein thrombosis, and 1 orbital varix. The confirmation of the preoperative diagnosis by 99mTc red blood cell scintigraphy shows that this technique is a reliable tool for differentiating cavernous hemangiomas from other orbital masses (sensitivity, 100%; specificity, 86%) when ultrasound, CT, and MRI are not diagnostic. Unfortunately, 99mTc red blood cell scintigraphy results were positive in 1 patient with hemangiopericytoma and 1 patient with lymphangioma, which showed increased uptake in the lesion on SPET images because of the vascular nature of these tumors. Therefore, in these cases, the SPET images have to be integrated with data regarding clinical preoperative evaluation and CT scans or MRI studies. On the basis of our study, a complete diagnostic picture, CT scans or MRI studies, and scintigraphic patterns can establish the preoperative diagnosis of vascular orbital tumors such as cavernous hemangioma, adult-type lymphangioma, and hemangiopericytoma.

[Orbital apex syndrome of the aspergillus etiology--a case report].

PubMed

Fric, E; Rehák, M; Vlcková, I; Burval, S; Chrapek, O; Rehák, J

2007-04-01

The authors present a case report of a patient, in whom after a head injury the monolateral blindness occurred. Because of autoimmune thrombocytopeny the patient was treated with long-term corticosteroids. The clinical findings corresponded with the orbital apex syndrome. According to the results of the CT and MRI examinations, the sphenoidotomy was indicated, and the histological findings verified fragments of paranasal sinuses' aspergiloma. During the next course of the disease, despite antimycotic therapy, the progression of the aspergiloma in to the anterior cranial fossa occurred. Invasive sino-orbital aspergilosis, after the penetration of the infectious agent across the wall of the sinus, may cause the orbital apex syndrome with paralysis of all three cranial nerves innervating the extraocular muscles, sensoric defect in the area of the ophthalmic nerve and the involvement of the optic nerve.

Effects of Space Weather on Geosynchronous Electromagnetic Spacecraft Perturbations Using Statistical Fluxes

NASA Astrophysics Data System (ADS)

Hughes, J.; Schaub, H.

2017-12-01

Spacecraft can charge to very negative voltages at GEO due to interactions with the space plasma. This can cause arcing which can damage spacecraft electronics or solar panels. Recently, it has been suggested that spacecraft charging may lead to orbital perturbations which change the orbits of lightweight uncontrolled debris orbits significantly. The motions of High Area to Mass Ratio objects are not well explained with just perturbations from Solar Radiation Pressure (SRP) and earth, moon, and sun gravity. A charged spacecraft will experience a Lorentz force as the spacecraft moves relative to Earth's magnetic field, as well as a Lorentz torque and eddy current torques if the object is rotating. Prior work assuming a constant "worst case" voltage has shown that Lorentz and eddy torques can cause quite large orbital changes by rotating the object to experience more or less SRP. For some objects, including or neglecting these electromagnetic torques can lead to differences of thousands of kilometers after only two orbits. This paper will further investigate the effects of electromagnetic perturbations by using a charging model that uses measured flux distributions to better simulate natural charging. This differs from prior work which used a constant voltage or Maxwellian distributions. This is done to a calm space weather case of Kp = 2 and a stormy case where Kp = 8. Preliminary analysis suggests that electrostatics will still cause large orbital changes even with the more realistic charging model.

Diagnostic features of feline restrictive orbital myofibroblastic sarcoma.

PubMed

Bell, C M; Schwarz, T; Dubielzig, R R

2011-05-01

A progressive debilitating disease of the orbit and adjacent connective tissues of cats has historically been called feline orbital pseudotumor. The authors reviewed clinical, histopathologic, and diagnostic imaging features of this disease in 12 cases from the Comparative Ocular Pathology Laboratory of Wisconsin. The cats' ages ranged from 7 to 16 years (mean, 10.8 years). All cats had a history of severely restricted mobility of the globe and eyelids with secondary corneal disease. Eleven cats (92%) had concurrent involvement of the contralateral eye and/or the oral cavity. Diffuse scleral or episcleral thickening was seen with computed tomography in all clinically affected eyes. Histologically, an insidious infiltration of neoplastic spindle cells in the orbit, eyelids, and periorbital skin and soft tissues, with collagen deposition and a few perivascular lymphocytes, led to entrapment and restricted mobility of the eyelids and orbital tissues. The tumor failed to form a discrete mass, and it spread along fascial planes to the contralateral orbit and eyelids and/or the lips and oral cavity. In all tested cases (n = 10), neoplastic cells were immunohistochemically positive for vimentin, S100 protein, and smooth muscle actin. The authors adopted the term feline restrictive orbital myofibroblastic sarcoma to reflect the restricted mobility of the eyelids and globe and the imaging and histologic features of an invasive yet low-grade myofibroblastic sarcoma.

Spacecraft Orbit Anomaly Representation Using Thrust-Fourier-Coefficients with Orbit Determination Toolbox

NASA Astrophysics Data System (ADS)

Ko, H.; Scheeres, D.

2014-09-01

Representing spacecraft orbit anomalies between two separate states is a challenging but an important problem in achieving space situational awareness for an active spacecraft. Incorporation of such a capability could play an essential role in analyzing satellite behaviors as well as trajectory estimation of the space object. A general way to deal with the anomaly problem is to add an estimated perturbing acceleration such as dynamic model compensation (DMC) into an orbit determination process based on pre- and post-anomaly tracking data. It is a time-consuming numerical process to find valid coefficients to compensate for unknown dynamics for the anomaly. Even if the orbit determination filter with DMC can crudely estimate an unknown acceleration, this approach does not consider any fundamental element of the unknown dynamics for a given anomaly. In this paper, a new way of representing a spacecraft anomaly using an interpolation technique with the Thrust-Fourier-Coefficients (TFCs) is introduced and several anomaly cases are studied using this interpolation method. It provides a very efficient way of reconstructing the fundamental elements of the dynamics for a given spacecraft anomaly. Any maneuver performed by a satellite transitioning between two arbitrary orbital states can be represented as an equivalent maneuver using an interpolation technique with the TFCs. Given unconnected orbit states between two epochs due to a spacecraft anomaly, it is possible to obtain a unique control law using the TFCs that is able to generate the desired secular behavior for the given orbital changes. This interpolation technique can capture the fundamental elements of combined unmodeled anomaly events. The interpolated orbit trajectory, using the TFCs compensating for a given anomaly, can be used to improve the quality of orbit fits through the anomaly period and therefore help to obtain a good orbit determination solution after the anomaly. Orbit Determination Toolbox (ODTBX) is modified to adapt this technique in order to verify the performance of this interpolation approach. Spacecraft anomaly cases are based on either single or multiple low or high thrust maneuvers and the unknown thrust accelerations are recovered and compared with the true thrust acceleration. The advantage of this approach is to easily append TFCs and its dynamics to the pre-built ODTBX, which enables us to blend post-anomaly tracking data to improve the performance of the interpolation representation in the absence of detailed information about a maneuver. It allows us to improve space situational awareness in the areas of uncertainty propagation, anomaly characterization and track correlation.

A new method for computing the gyrocenter orbit in the tokamak configuration

NASA Astrophysics Data System (ADS)

Xu, Yingfeng

2013-10-01

Gyrokinetic theory is an important tool for studying the long-time behavior of magnetized plasmas in Tokamaks. The gyrocenter trajectory determined by the gyrocenter equations of motion can be computed by using a special kind of the Lie-transform perturbation method. The corresponding Lie-transform called I-transform makes that the transformed equations of motion have the same form as the unperturbed ones. The gyrocenter trajectory in short time is divided into two parts. One is along the unperturbed orbit. The other one, which is related to perturbation, is determined by the I-transform generating vector. The numerical gyrocenter orbit code based on this new method has been developed in the tokamak configuration and benchmarked with the other orbit code in some simple cases. Furthermore, it is clearly demonstrated that this new method for computing gyrocenter orbit is equivalent to the gyrocenter Hamilton equations of motion up to the second order in timestep. The new method can be applied to the gyrokinetic simulation. The gyrocenter orbit of the unperturbed part determined by the equilibrium fields can be computed previously in the gyrokinetic simulation, and the corresponding time consumption is neglectable.

Evaluating Precipitation from Orbital Data Products of TRMM and GPM over the Indian Subcontinent

NASA Astrophysics Data System (ADS)

Jayaluxmi, I.; Kumar, D. N.

2015-12-01

The rapidly growing records of microwave based precipitation data made available from various earth observation satellites have instigated a pressing need towards evaluating the associated uncertainty which arise from different sources such as retrieval error, spatial/temporal sampling error and sensor dependent error. Pertaining to microwave remote sensing, most of the studies in literature focus on gridded data products, fewer studies exist on evaluating the uncertainty inherent in orbital data products. Evaluation of the latter are essential as they potentially cause large uncertainties during real time flood forecasting studies especially at the watershed scale. The present study evaluates the uncertainty of precipitation data derived from the orbital data products of the Tropical Rainfall Measuring Mission (TRMM) satellite namely the 2A12, 2A25 and 2B31 products. Case study results over the flood prone basin of Mahanadi, India, are analyzed for precipitation uncertainty through these three facets viz., a) Uncertainty quantification using the volumetric metrics from the contingency table [Aghakouchak and Mehran 2014] b) Error characterization using additive and multiplicative error models c) Error decomposition to identify systematic and random errors d) Comparative assessment with the orbital data from GPM mission. The homoscedastic random errors from multiplicative error models justify a better representation of precipitation estimates by the 2A12 algorithm. It can be concluded that although the radiometer derived 2A12 precipitation data is known to suffer from many sources of uncertainties, spatial analysis over the case study region of India testifies that they are in excellent agreement with the reference estimates for the data period considered [Indu and Kumar 2015]. References A. AghaKouchak and A. Mehran (2014), Extended contingency table: Performance metrics for satellite observations and climate model simulations, Water Resources Research, vol. 49, 7144-7149; J. Indu and D. Nagesh Kumar (2015), Evaluation of Precipitation Retrievals from Orbital Data Products of TRMM over a Subtropical basin in India, IEEE Transactions on Geoscience and Remote Sensing, in press, doi: 10.1109/TGRS.2015.2440338.

Canine orbital rhabdomyosarcoma: a report of 18 cases.

PubMed

Scott, Erin M; Teixeira, Leandro B C; Flanders, David J; Dubielzig, Richard R; McLellan, Gillian J

2016-03-01

To describe clinical and pathological features of canine orbital rhabdomyosarcoma (COR). Retrospective review of patients with COR from the archives of the Comparative Ocular Pathology Laboratory of Wisconsin and the University of Wisconsin Veterinary Medical Teaching Hospital (1983-2014). Eighteen cases of COR were identified, all diagnosed in an 8-year period (2006-2014). Affected dogs were typically young (range 1-8; median 2 years), and both sexes were equally represented. Common clinical signs included exophthalmos (16/18) with dorsolateral deviation of the globe (10/18) and elevation of the nictitans (12/18). Ultrasonography, performed in nine cases, revealed an orbital mass with mixed echogenicity and posterior globe indentation. Advanced imaging, performed in nine cases, demonstrated a soft tissue mass with variable contrast enhancement and lysis of the orbital bones (5/9). Histologically, all tumors were subclassified as embryonal rhabdomyosarcoma. All neoplasms demonstrated positive immunohistochemical labeling for desmin, and 14/18 were positive for skeletal muscle actin. Follow-up information was available for 15/18 cases. Older dogs, aged 6-8 years, had no clinical signs of recurrence or metastasis 8-13 months postdiagnosis (4/4). Most younger dogs (9/11), aged 1-4 years, were euthanized within 6 months (median 2.5 months) of diagnosis due to recurrence at the surgical site (5/9) and/or metastasis (5/9). Canine orbital rhabdomyosarcoma is a highly malignant neoplasm in juvenile dogs, but may be amenable to surgical resection in older dogs. This duality in biologic behavior may reflect differences in tissue of origin between juvenile onset tumors and adult onset tumors. © 2015 American College of Veterinary Ophthalmologists.

Trends in Orbital Decompression Techniques of Surveyed American Society of Ophthalmic Plastic and Reconstructive Surgery Members.

PubMed

Reich, Shani S; Null, Robert C; Timoney, Peter J; Sokol, Jason A

To assess current members of the American Society of Ophthalmic Plastic and Reconstructive Surgery (ASOPRS) regarding preference in surgical techniques for orbital decompression in Graves' disease. A 10-question web-based, anonymous survey was distributed to oculoplastic surgeons utilizing the ASOPRS listserv. The questions addressed the number of years of experience performing orbital decompression surgery, preferred surgical techniques, and whether orbital decompression was performed in collaboration with an ENT surgeon. Ninety ASOPRS members participated in the study. Most that completed the survey have performed orbital decompression surgery for >15 years. The majority of responders preferred a combined approach of floor and medial wall decompression or balanced lateral and medial wall decompression; only a minority selected a technique limited to 1 wall. Those surgeons who perform fat decompression were more likely to operate in collaboration with ENT. Most surgeons rarely remove the orbital strut, citing risk of worsening diplopia or orbital dystopia except in cases of optic nerve compression or severe proptosis. The most common reason given for performing orbital decompression was exposure keratopathy. The majority of surgeons perform the surgery without ENT involvement, and number of years of experience did not correlate significantly with collaboration with ENT. The majority of surveyed ASOPRS surgeons prefer a combined wall approach over single wall approach to initial orbital decompression. Despite the technological advances made in the field of modern endoscopic surgery, no single approach has been adopted by the ASOPRS community as the gold standard.

The anatomy of the palpebral branch of the infraorbital artery relating to midface lift.

PubMed

Hwang, Kun; Kim, Dong Hyun; Huan, Fan; Nam, Yong Seok; Han, Seung Ho

2011-07-01

The aim of this study was to elucidate a branch of the infraorbital artery (IOA) crossing the arcus marginalis into the orbit that might be vulnerable during a procedure of midface lift or fat sliding or a transposition in lower blepharoplasty.Eleven orbits of 6 Korean cadavers were dissected after injecting red latex into the external carotid artery. The IOA and nerve were identified. A branch of the IOA running upward was traced. In 28 cases of blow-out fracture, a branch of the IOA crossing the arcus marginalis into the orbit was identified, and the location was measured from each medial and lateral canthus.The palpebral branch of the IOA (PIOA) emerged from the infraorbital foramen and ran superior and lateral to the orbital septum. After passing through the orbital septum near the arcus marginalis, PIOA was distributed to the orbital fat. The palpebral branch of the IOA was identified in 21 (75.0%) of 28 fractured orbits. Twenty orbits had 1 PIOA, and 1 orbit had 2 PIOAs. The location of PIOA from the medial canthus (49.0%) was approximately half of the eye width in average. Most of the PIOAs (91%, 20 of 22 arteries found) were included in the range of 40% to 80% of the eye width from the medial canthus.Knowledge of the anatomic course of the PIOA crossing the arcus marginalis is conducive to cauterizing the vessels, as needed, in the subciliary or transconjunctival approach for lower blepharoplasty.

Are Comets 42P/Neujmin 3 and 53P/Van Biesbroeck Parts of one Comet?

NASA Astrophysics Data System (ADS)

Pittichova, J.; Meech, K. J.; Valsecchi, G. B.; Pittich, E. M.

2003-05-01

We want to present preliminary results of the observations of the physical parameters of comets 42P/Neujmin 3 and 53P/Van Biesbroeck: brightness, nucleus activity, rotation period, light-curve and color changes from our first three optical observing runs (March, and May 2003) at Mauna Kea, using UH 2.2m telescope and Tek2048 CCD camera. Comets 42P/Neujmin 3 and 53P/Van Biesbroeck have very well determined orbits, and their orbital histories are very interesting. Their current orbits are not very similar to each other; however, numerical integrations have shown that both comets had a rather close approach to Jupiter in January 1850, and that, before 1850, the two orbits were nearly identical. Given the extremely low probability of a chance coincidence of the six orbital elements at a given time, the natural conclusion is that the two objects are fragments of a single comet that split sometime in the late 1849 or early 1850. Among the known cases of split periodic comets, this one is peculiar for a number of reasons: 1. the splitting was probably not due to tidal stresses, since the 1850 encounter with Jupiter took place well outside the Roche lobe; 2. it is the only case discovered through a dynamical study; 3. in the only other case of splitting of a Jupiter family comet, that of 3D/Biela, the fragments did not survive for more than a couple of revolutions, whereas in the present case both fragments have passed perihelion more than ten times since the splitting. If these two comets are fragments of a single parent body, then they should show a certain degree of physical and chemical similarity, which we would like to obtain from spectroscopic observation in 2004, when both comets are close to their perihelion. Acknowledgments: Support for this work was provided by NASA Grant No. NAG5-12236 and Scientific Grant Agency VEGA of the Slovak Academy of Sciences, grant No. 2/1005/21.

An Efficient Method for Studying the Stability and Dynamics of the Rotational Motions of Celestial Bodies

NASA Astrophysics Data System (ADS)

Pavlov, A. I.; Maciejewski, A. J.

2003-08-01

We use the alternative MEGNO (Mean Exponential Growth of Nearby Orbits) technique developed by Cincotta and Simo to study the stability of orbital-rotational motions for plane oscillations and three-dimensional rotations. We present a detailed numerical-analytical study of a rigid body in the case where the proper rotation of the body is synchronized with its orbital motion as 3: 2 (Mercurian-type synchronism). For plane rotations, the loss of stability of the periodic solution that corresponds to a 3: 2 resonance is shown to be soft, which should be taken into account to estimate the upper limit for the ellipticity of Mercury. In studying stable and chaotic translational-rotational motions, we point out that the MEGNO criterion can be effectively used. This criterion gives a clear picture of the resonant structures and allows the calculations to be conveniently presented in the form of the corresponding MEGNO stability maps for multidimensional systems. We developed an appropriate software package.

Sinus involvement in inflammatory orbital pseudotumor.

PubMed

Eshaghian, J; Anderson, R L

1981-04-01

Orbital pseudotumor is a difficult diagnosis to establish preoperatively. The relationship between sinus disease and orbital pseudotumor is controversial. We describe two patients with unilateral proptosis, diplopia, palpable orbital masses, ocular discomfort, and sinus problems of short duration. Echographically, both had low reflective masses in the orbit and the adjacent sinuses. Roentgenograms and echograms were interpreted as showing erosion of the bony orbital wall. A presumptive diagnosis of sinus malignant neoplasm with orbital extension was made. Sinus histopathologic examination in one case and nasal histopathologic examination in the other showed chronic inflammatory changes compatible with the diagnosis of pseudotumor. At orbitotomy, one patient had vessels communicating between the orbital and sinus lesions, and both patients had irregular pitting of the bone next to the histologically proved orbital pseudotumors. The lytic erosive changes predicted preoperatively were not present. Simultaneous orbital and sinus pseudotumors seem to be a distinct clinicopathologic entity. Those concerned with the diagnosis and management of orbital disease should be aware of this entity.

Transit timing variations for planets co-orbiting in the horseshoe regime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vokrouhlický, David; Nesvorný, David, E-mail: vokrouhl@cesnet.cz, E-mail: davidn@boulder.swri.edu

2014-08-10

Although not yet detected, pairs of exoplanets in 1:1 mean motion resonance probably exist. Low eccentricity, near-planar orbits, which in the comoving frame follow horseshoe trajectories, are one of the possible stable configurations. Here we study transit timing variations (TTVs) produced by mutual gravitational interaction of planets in this orbital architecture, with the goal to develop methods that can be used to recognize this case in observational data. In particular, we use a semi-analytic model to derive parametric constraints that should facilitate data analysis. We show that characteristic traits of the TTVs can directly constrain the (1) ratio of planetarymore » masses and (2) their total mass (divided by that of the central star) as a function of the minimum angular separation as seen from the star. In an ideal case, when transits of both planets are observed and well characterized, the minimum angular separation can also be inferred from the data. As a result, parameters derived from the observed transit timing series alone can directly provide both planetary masses scaled to the central star mass.« less

Rashba quantum wire: exact solution and ballistic transport.

PubMed

Perroni, C A; Bercioux, D; Ramaglia, V Marigliano; Cataudella, V

2007-05-08

The effect of Rashba spin-orbit interaction in quantum wires with hard-wall boundaries is discussed. The exact wavefunction and eigenvalue equation are worked out, pointing out the mixing between the spin and spatial parts. The spectral properties are also studied within perturbation theory with respect to the strength of the spin-orbit interaction and diagonalization procedure. A comparison is made with the results of a simple model, the two-band model, that takes account only of the first two sub-bands of the wire. Finally, the transport properties within the ballistic regime are analytically calculated for the two-band model and through a tight-binding Green function for the entire system. Single and double interfaces separating regions with different strengths of spin-orbit interaction are analysed by injecting carriers into the first and the second sub-band. It is shown that in the case of a single interface the spin polarization in the Rashba region is different from zero, and in the case of two interfaces the spin polarization shows oscillations due to spin-selective bound states.

Cassini UVIS Auroral Observations in 2016 and 2017

NASA Astrophysics Data System (ADS)

Pryor, Wayne R.; Esposito, Larry W.; Jouchoux, Alain; Radioti, Aikaterini; Grodent, Denis; Gustin, Jacques; Gerard, Jean-Claude; Lamy, Laurent; Badman, Sarah; Dyudina, Ulyana A.; Cassini UVIS Team, Cassini VIMS Team, Cassini ISS Team, HST Saturn Auroral Team

2017-10-01

In 2016 and 2017, the Cassini Saturn orbiter executed a final series of high-inclination, low-periapsis orbits ideal for studies of Saturn's polar regions. The Cassini Ultraviolet Imaging Spectrograph (UVIS) obtained an extensive set of auroral images, some at the highest spatial resolution obtained during Cassini's long orbital mission (2004-2017). In some cases, two or three spacecraft slews at right angles to the long slit of the spectrograph were required to cover the entire auroral region to form auroral images. We will present selected images from this set showing narrow arcs of emission, more diffuse auroral emissions, multiple auroral arcs in a single image, discrete spots of emission, small scale vortices, large-scale spiral forms, and parallel linear features that appear to cross in places like twisted wires. Some shorter features are transverse to the main auroral arcs, like barbs on a wire. UVIS observations were in some cases simultaneous with auroral observations from the Cassini Imaging Science Subsystem (ISS) the Cassini Visual and Infrared Mapping Spectrometer (VIMS), and the Hubble Space Telescope Space Telescope Imaging Spectrograph (STIS) that will also be presented.

Glial Heterotopia of the orbit: A rare presentation

PubMed Central

2011-01-01

Background Glial heterotopias are rare, benign, congenital, midline, non-teratomatous extracranial glial tissue. They may masquerade as encephalocoele or dermoid cyst and mostly present in nose. Herein, we present an unusual case of glial heterotopia of the orbit with unilateral blindness. Case presentation A 6 year-old-boy presented with a progressive painless mass over the nose and medial aspect of the left eye noticed since birth. On examination, the globe was displaced laterally by a firm, regular, mobile, non-pulsatile and non-tender medial mass. The affected eye had profound loss of vision. Computed tomography scan showed a large hypodense mass in the extraconal space with no intracranial connectivity and bony erosion. The child underwent total surgical excision of the mass and histopathological examination confirmed glial heterotopia of the orbit. Conclusion Though the incidence of this condition is rare, the need of appropriate diagnosis and management of such mass to prevent the visual and cosmetic deterioration is warranted. To our knowledge this is the first reported case of Glial heterotopia of orbit causing unilateral blindness. PMID:22088230

Transfrontal orbitotomy in the dog: an adaptable three-step approach to the orbit.

PubMed

Håkansson, Nils Wallin; Håkansson, Berit Wallin

2010-11-01

To describe an adaptable and extensive method for orbitotomy in the dog. An adaptable three-step technique for orbitotomy was developed and applied in nine consecutive cases. The steps are zygomatic arch resection laterally, temporalis muscle elevation medially and zygomatic process osteotomy anteriorly-dorsally. The entire orbit is accessed with excellent exposure and room for surgical manipulation. Facial nerve, lacrimal nerve and lacrimal gland function are preserved. The procedure can easily be converted into an orbital exenteration. Exposure of the orbit was excellent in all cases and anatomically correct closure was achieved. Signs of postoperative discomfort were limited, with moderate, reversible swelling in two cases and mild in seven. Wound infection or emphysema did not occur, nor did any other complication attributable to the operative procedure. Blinking ability and lacrimal function were preserved over follow-up times ranging from 1 to 4 years. Transfrontal orbitotomy in the dog offers excellent exposure and room for manipulation. Anatomically correct closure is easily accomplished, postoperative discomfort is limited and complications are mild and temporary. © 2010 American College of Veterinary Ophthalmologists.

[Development of ocular motility following modified 3-wall decompression of the orbita in endocrine orbitopathy for functional and rehabilitative indication].

PubMed

Grenzebach, Ulrike H; Schnorbus, Ulrike; Büchner, Thomas; Busse, Holger; Stoll, Wolfgang

2003-05-01

Permanent visual damage due to an increase in volume of the orbital contents may be the result of the failure of conservative therapeutic concepts in the treatment of endocrine orbitopathy. Considerable progress has been achieved in developing successful orbital decompression techniques with regard to functional and cosmetic outcome. Decompression techniques with resection of the bony orbital walls are adequate tools in restoring visual acuity and reducing exophthalmus. A considerable degree of deterioration of motility disorders has been described in the literature depending on the techniques being used. The purpose of this study was to investigate whether a modified technique of 3-wall orbital decompression with preservation of a medial part of the periorbital tissue to support the medial rectus muscle, is able to reduce the postoperative risk of diplopia. A modified technique of orbital 3-wall decompression with resection of the medial orbital wall, the medial orbital floor and the floor of the frontal sinus has been used in patients with compressive optic neuropathy (n = 20) and for cosmetic reasons (n = 7) in cases of uni- or bilateral proptosis. Analysis of the results was performed concerning visual outcome, exophthalmus reduction and development of horizontal and vertical motility changes. In all cases of optic neuropathy improvement of visual function at an average of 4.63 +/- 4.5 lines could be achieved. Exophthalmus reduction was 3.2 +/- 2.4 mm in the functional group and 3.9 +/- 1.7 mm in the rehabilitative group. In this group motility of the medial rectus muscle remained unaffected except in one eye. In the functional group motility deterioration was observed in 62 %. The modified 3-wall decompression technique with preservation of a medial periorbital tissue strip is an adequate alternative technique in the therapy of optic neuropathy and exophthalmus reduction in endocrine orbitopathy with a low risk of postoperative motility disorders.

Traumatic orbital CSF leak

PubMed Central

Borumandi, Farzad

2013-01-01

Compared to the cerebrospinalfluid (CSF) leak through the nose and ear, the orbital CSF leak is a rare and underreported condition following head trauma. We present the case of a 49-year-old woman with oedematous eyelid swelling and ecchymosis after a seemingly trivial fall onto the right orbit. Apart from the above, she was clinically unremarkable. The CT scan revealed a minimally displaced fracture of the orbital roof with no emphysema or intracranial bleeding. The fractured orbital roof in combination with the oedematous eyelid swelling raised the suspicion for orbital CSF leak. The MRI of the neurocranium demonstrated a small-sized CSF fistula extending from the anterior cranial fossa to the right orbit. The patient was treated conservatively and the lid swelling resolved completely after 5 days. Although rare, orbital CSF leak needs to be included in the differential diagnosis of periorbital swelling following orbital trauma. PMID:24323381

Orbital Osteoblastoma: Technical Innovations in Resection and Reconstruction Using Virtual Surgery Simulation.

PubMed

Novelli, Giorgio; Gramegna, Marco; Tonellini, Gabriele; Valente, Gabriella; Boni, Pietro; Bozzetti, Alberto; Sozzi, Davide

2016-09-01

Osteoblastoma is a benign tumor of bone, representing less than 1% of bone tumors. Craniomaxillofacial localizations account for up to 15% of the total and frequently involve the posterior mandible. Endo-orbital localization is very rare, with most occurring in young patients. Very few of these tumors become malignant. Orbital localization requires radical removal of the tumor followed by careful surgical reconstruction of the orbit to avoid subsequent aesthetic or functional problems. Here, we present a clinical case of this condition and describe a surgical protocol that uses and integrates state-of-the art technologies to achieve orbital reconstruction.

Radiation Pressure, Poynting-Robertson Drag, and Solar Wind Drag in the Restricted Three-Body Problem

NASA Technical Reports Server (NTRS)

Liou, Jer-Chyi; Zook, Herbert A.; Jackson, A. A.

1995-01-01

In this paper, we examine the effects of radiation pressure, Poynting-Robertson (PR) drag, and solar wind drag on dust grains trapped in mean motion resonances with the Sun and Jupiter in the restricted (negligible dust mass) three-body Problem. We especially examine the evolution of dust grains in the 1:1 resonance. As a first step, the Sun and Jupiter are idealized to both be in circular orbit about a common center of mass (circular restricted three-body problem). From the equation of motion of the dust particle in the rotating reference frame, the drag-induced time rate of change of its Jacobi "constant," C, is then derived and expressed in spherical coordinates. This new mathematical expression in spherical coordinates shows that C, in the 1:1 resonance, both oscillates and secularly increases with increasing time. The new expression gives rise to an easy understanding of how an orbit evolves when the radiation force and solar wind drag are included. All dust grain orbits are unstable in time when PR and solar wind drag are included in the Sun-Jupiter-dust system. Tadpole orbits evolve into horseshoe orbits; and these orbits continuously expand in size to lead to close encounters with Jupiter. Permanent trapping is impossible. Orbital evolutions of a dust grain trapped in the 1:1 resonance in the planar circular, an inclined case, an eccentric case, and the actual Sun-Jupiter case are numerically simulated and compared with each other and show grossly similar time behavior. Resonances other than 1:1 are also explored with the new expression. Stable exterior resonance trapping may be possible under certain conditions. One necessary condition for such a trap is derived. Trapping in interior resonances is shown to be always unstable.

Intraocular pressure lowering effect of orbital decompression is related to increased venous outflow in Graves orbitopathy.

PubMed

Onaran, Zafer; Konuk, Onur; Oktar, Suna Özhan; Yücel, Cem; Unal, Mehmet

2014-07-01

To investigate the effects of combined orbital bone and fat decompression on intraocular pressure (IOP) and superior ophthalmic vein blood flow velocity (SOV-BFV), and their association with the clinical features of Graves orbitopathy (GO). During the 2002-2008 period, 72 eyes of 36 GO cases demonstrating moderate to severe orbitopathy were evaluated according to their clinical features as: cases with or without dysthyroid optic neuropathy (DON), and underwent orbital decompression. A control group comprised 40 eyes of 20 healthy subjects. In both groups, a full ophthalmic examination including IOP and Hertel measurements was performed, and SOV-BFV was analyzed with color Doppler imaging. Examinations were repeated after orbital decompression in GO patients. All the cases demonstrated clinical features of inactive disease. Among the patients 24 of 72 eyes (33.3%) showed clinical features of DON. After surgery, the mean decrease in Hertel values was 6.2 ± 1.8 mm (p = 0.001). The mean decrease in IOP was 3.0 ± 1.7 mmHg (from 17.3 ± 2.7 to 14.3 ± 2.0 mmHg) after orbital decompression where the post-operative values were comparable with the control group (12.9 ± 1.4 mmHg, p = 0.36). The mean increase in SOV-BFV achieved with decompression was 1.2 ± 0.6 cm/s (from 4.8 ± 1.7 to 6.0 ± 1.8 cm/s) and post-operative SOV-BFV values were also comparable with the control group (6.6 ± 1.3 cm/s, p = 0.26). The increase in SOV-BFV in cases with DON did not differ from cases without DON (p = 0.32), however, post-operative SOV-BFV of cases with DON was stil lower than cases without DON (p = 0.035). Combined orbital bone and fat decompression significantly reduced the IOP levels and increased the SOV-BFV in GO. This could be the confirmative finding of prediction that elevated IOP in GO is associated with increased episcleral venous pressure. The post-operative changes in IOP and SOV-BFV show differences regarding the clinical features of disease.

Low-energy transfers to cislunar periodic orbits visiting triangular libration points

NASA Astrophysics Data System (ADS)

Lei, Hanlun; Xu, Bo

2018-01-01

This paper investigates the cislunar periodic orbits that pass through triangular libration points of the Earth-Moon system and studies the techniques on design low-energy transfer trajectories. In order to compute periodic orbits, families of impulsive transfers between triangular libration points are taken to generate the initial guesses of periodic orbits, and multiple shooting techniques are applied to solving the problem. Then, varieties of periodic orbits in cislunar space are obtained, and stability analysis shows that the majority of them are unstable. Among these periodic orbits, an unstable periodic orbit in near 3:2 resonance with the Moon is taken as the nominal orbit of an assumed mission. As the stable manifolds of the target orbit could approach the Moon, low-energy transfer trajectories can be designed by combining lunar gravity assist with the invariant manifold structure of the target orbit. In practice, both the natural and perturbed invariant manifolds are considered to obtain the low-energy transfers, which are further refined to the Sun-perturbed Earth-Moon system. Results indicate that (a) compared to the case of natural invariant manifolds, the optimal transfers using perturbed invariant manifolds could reduce flight time at least 50 days, (b) compared to the cheapest direct transfer, the optimal low-energy transfer obtained by combining lunar gravity assist and invariant manifolds could save on-board fuel consumption more than 200 m/s, and (c) by taking advantage of the gravitational perturbation of the Sun, the low-energy transfers could save more fuel consumption than the corresponding ones obtained in the Earth-Moon system.

Single-stage-to-orbit versus two-stage-two-orbit: A cost perspective

NASA Astrophysics Data System (ADS)

Hamaker, Joseph W.

1996-03-01

This paper considers the possible life-cycle costs of single-stage-to-orbit (SSTO) and two-stage-to-orbit (TSTO) reusable launch vehicles (RLV's). The analysis parametrically addresses the issue such that the preferred economic choice comes down to the relative complexity of the TSTO compared to the SSTO. The analysis defines the boundary complexity conditions at which the two configurations have equal life-cycle costs, and finally, makes a case for the economic preference of SSTO over TSTO.

Neptune Orbiters Utilizing Solar and Radioisotope Electric Propulsion

NASA Technical Reports Server (NTRS)

Fiehler, Douglas I.; Oleson, Steven R.

2004-01-01

In certain cases, Radioisotope Electric Propulsion (REP), used in conjunction with other propulsion systems, could be used to reduce the trip times for outer planetary orbiter spacecraft. It also has the potential to improve the maneuverability and power capabilities of the spacecraft when the target body is reached as compared with non-electric propulsion spacecraft. Current missions under study baseline aerocapture systems to capture into a science orbit after a Solar Electric Propulsion (SEP) stage is jettisoned. Other options under study would use all REP transfers with small payloads. Compared to the SEP stage/Aerocapture scenario, adding REP to the science spacecraft as well as a chemical capture system can replace the aerocapture system but with a trip time penalty. Eliminating both the SEP stage and the aerocapture system and utilizing a slightly larger launch vehicle, Star 48 upper stage, and a combined REP/Chemical capture system, the trip time can nearly be matched while providing over a kilowatt of science power reused from the REP maneuver. A Neptune Orbiter mission is examined utilizing single propulsion systems and combinations of SEP, REP, and chemical systems to compare concepts.

Gap formation by inclined massive planets in locally isothermal three-dimensional discs

NASA Astrophysics Data System (ADS)

Chametla, Raúl O.; Sánchez-Salcedo, F. J.; Masset, F. S.; Hidalgo-Gámez, A. M.

2017-07-01

We study gap formation in gaseous protoplanetary discs by a Jupiter mass planet. The planet's orbit is circular and inclined relative to the mid-plane of the disc. We use the impulse approximation to estimate the gravitational tidal torque between the planet and the disc, and infer the gap profile. For low-mass discs, we provide a criterion for gap opening when the orbital inclination is ≤30°. Using the fargo3d code, we simulate the disc response to an inclined massive planet. The dependence of the depth and width of the gap obtained in the simulations on the inclination of the planet is broadly consistent with the scaling laws derived in the impulse approximation. Although we mainly focus on planets kept on fixed orbits, the formalism permits to infer the temporal evolution of the gap profile in the cases where the inclination of the planet changes with time. This study may be useful to understand the migration of massive planets on inclined orbit, because the strength of the interaction with the disc depends on whether a gap is opened or not.

Orbital nature of electronic states and elementary acts of their deactivation in a homologous series of phenylmethane molecules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pak, M.A.; Shigorin, D.N.; Konoplev, G.G.

1986-11-01

The aim of this work is to establish the mechanisms of the elementary acts of photophysical and photochemical processes in an homologous series of phenylmethane molecules Ph/sub n/C-H/sub m-n/, where m = 4, n = 1,...,4, and pH is a phenyl radical. The molecules that form the homologous series belong to the same orbital class (in this case sigma..pi..) and the same spectral-luminescence systematization group (SLG). In the studied series of molecules, as a result of the change of the number of the (Ph) and (C-H) systems, an evolution of the orbital nature of the states occurs (in the givenmore » orbital class) on insignificant change of their relative position. As a result of this a considerable redistribution of the relaxation channels of the electron-excitation energy and the rate constants of the radiation and radiationless processes takes place. To establish the character of these changes they performed experimental and theoretical studies of the mentioned series of molecules.« less

Low-thrust chemical orbit to orbit propulsion system propellant management study

NASA Technical Reports Server (NTRS)

Dergance, R. H.

1980-01-01

Propellant requirements, tankage configurations, preferred propellant management techniques, propulsion systems weights, and technology deficiencies for low thrust expendable propulsion systems are examined. A computer program was utilized which provided a complete propellant inventory (including boil-off for cryogenic cases), pressurant and propellant tank dimensions for a given ullage, pressurant requirements, insulation requirements, and miscellaneous masses. The output also includes the masses of all tanks; the mass of the insulation, engines and other components; total wet system and burnout mass; system mass fraction; total impulse and burn time.

Geocentric solar electric propulsion vehicle design.

NASA Technical Reports Server (NTRS)

Harney, E. D.; Lapins, U. E.; Molitor, J. H.

1972-01-01

Mission applications have been studied that use solar electric propulsion (SEP) to inject payloads into geocentric orbits. Two specific applications feasible with current technology are described that approximate practical bounds for the next decade. In the lower extreme, SEP is used on a Thor-Delta launched satellite to maximize the weight injected into synchronous orbits. In the other extreme, SEP is used in a reusable interorbital tug together with an all-chemical shuttle/tug transportation system. Different trajectory profiles are required to most efficiently accomplish the overall mission objectives in the two cases.

Mars - Satellite and ring search from Viking

NASA Technical Reports Server (NTRS)

Duxbury, Thomas C.; Ocampo, Adriana C.

1988-01-01

Viking Orbiter 1 imaging data were used in a search for possible satellites and rings of Mars in 1980, giving attention to a region within the Phobos orbit and + or - 350 km about the Martian equatorial plane. After picture processing, no images other than stars and Phobos itself were found to be a few brightnesses (or more) above their surrounding, as would be expected in the case of a point-spread, 'smeared' image of either satellites or rings. There is therefore no evidence of any such phenomenon in the 78 pictures studied.

Particle orbits in model current sheet with a nonzero B(y) component

NASA Technical Reports Server (NTRS)

Zhu, Zhongwei; Parks, George

1993-01-01

The problem of charged particle motions in magnetotaillike model current sheets is revisited with the inclusion of a nonzero dawn-dusk magnetic field component. Three cases are examined considering both trapped and escaped orbits. The results show that a nonzero B(y) component disturbs the particle orbits by destroying orbit symmetry in the phase space about the z = 0 plane. It also changes the bounce frequency of particle orbits. The presence of B(y) thus modifies the Speiser orbits, particularly near the ejection phase. The process of ejected particle such as ejection direction, ejection velocity, and pitch angles are shown to depend on the sign of the charge.

Initial Assessment of a Rapid Method of Calculating CEV Environmental Heating

NASA Technical Reports Server (NTRS)

Pickney, John T.; Milliken, Andrew H.

2010-01-01

An innovative method for rapidly calculating spacecraft environmental absorbed heats in planetary orbit is described. The method employs reading a database of pre-calculated orbital absorbed heats and adjusting those heats for desired orbit parameters. The approach differs from traditional Monte Carlo methods that are orbit based with a planet centered coordinate system. The database is based on a spacecraft centered coordinated system where the range of all possible sun and planet look angles are evaluated. In an example case 37,044 orbit configurations were analyzed for average orbital heats on selected spacecraft surfaces. Calculation time was under 2 minutes while a comparable Monte Carlo evaluation would have taken an estimated 26 hours

Trade Study for Neutron Transport at Low Earth Orbit: Adding Fidelity to DIORAMA

DOE Office of Scientific and Technical Information (OSTI.GOV)

McClanahan, Tucker Caden; Wakeford, Daniel Tyler

The Distributed Infrastructure Offering Real-Time Access to Modeling and Analysis (DIORAMA) software provides performance modeling capabilities of the United States Nuclear Detonation Detection System (USNDS) with a focus on the characterization of Space-Based Nuclear Detonation Detection (SNDD) instrument performance [1]. A case study was done to add the neutron propagation capabilities of DIORAMA to low earth orbit (LEO), and compare the back-calculated incident energy from the time-of- ight (TOF) spectrum with the scored incident energy spectrum. As the scoring altitude lowers, the time increase due to scattering takes up much more of the fraction of total TOF; whereas at geosynchronousmore » earth orbit (GEO), the time increase due to scattering is a negligible fraction of the total TOF [2]. The scattering smears out the TOF enough to make the back-calculation of the initial energy spectrum from the TOF spectrum very convoluted.« less

A Potential Proxy of the Second Integral of Motion (I2) in a Rotating Barred Potential

NASA Astrophysics Data System (ADS)

Shen, Juntai; Qin, Yujing

2017-06-01

The only analytically known integral of motion in a 2-D rotating barred potential is the Jacobi constant (EJ). In addition to EJ, regular orbits also obey a second integral of motion (I2) whose analytical form is unknown. We show that the time-averaged characteristics of angular momentum in a rotating bar potential resemble the behavior of the analytically-unknown I2. For a given EJ, regular orbits of various families follow a continuous sequence in the space of net angular momentum and its dispersion ("angular momentum space"). In the limiting case where regular orbits of the well-known x1/x4 orbital families dominate the phase space, the orbital sequence can be monotonically traced by a single parameter, namely the ratio of mean angular momentum to its dispersion. This ratio behaves well even in the 3-D case, and thus may be used as a proxy of I2. The potential proxy of I2 may be used as an efficient way to probe the phase space structure, and a convenient new scheme of orbit classification in addition to the frequency mapping technique.

Gear Tooth Root Stresses of a Very Heavily Loaded Gear Pair-Case Study: Orbiter Body Flap Actuator Pinion and Ring Gear

NASA Technical Reports Server (NTRS)

Krantz, Timothy L.; Handschuh, Robert F.

2015-01-01

The space shuttle orbiter's body flap actuator gearing was assessed as a case study of the stresses for very heavily loaded external-internal gear pairs (meshing pinion and ring gear). For many applications, using the high point of single tooth contact (HPSTC) to locate the position of the tooth force is adequate for assessing the maximum tooth root stress condition. But for aerospace gearing such an approach may be inadequate for assessing the stress condition while also simultaneously minimizing mass. In this work specialized contact analyses and finite element methods were used to study gear tooth stresses of body flap actuator gears. The analytical solutions considered the elastic deformations as an inherent part of the solutions. The ratio for the maximum tooth stresses using the HPSTC approach solutions relative to the contact analysis and finite element solutions were 1.40 for the ring gear and 1.28 for the pinion gear.

Compressed air blast injury with palpebral, orbital, facial, cervical, and mediastinal emphysema through an eyelid laceration: a case report and review of literature

PubMed Central

2013-01-01

Background To the best of our knowledge, only 14 cases of orbital or periorbital compressed air injuries from air guns or hoses have been reported in the literature. Case presentation A 30-year-old man was accidentally injured when a compressed air hose nozzle hit his right eye. The right half of his face was markedly swollen and a skin laceration near the right medial canthus was identified. A computed tomography scan showed subcutaneous and intraorbital emphysema around the right eye as well as cervical and mediastinal emphysema. He was prophylactically treated with systemic and topical antibiotics to prevent infection. All emphysemas had completely resolved 2 weeks after the injury. Conclusions A review of all 15 cases (including ours) showed that all patients were male and that 6 of the 15 (40.0%) cases were related to industrial accidents. Although emphysema was restricted to the subconjunctival space in 2 (13.3%) cases, it spread to the orbit in the remaining 13 (86.7%) cases. Cervical and mediastinal emphysemas were found in 3 (20.0%) cases, and intracranial emphysema was confirmed in 6 (40.0%) cases. Prophylactic antibiotics were used in most cases and the prognosis was generally good in all but one patient, who developed optic atrophy and blindness. PMID:24195485

Idiopathic orbital inflammatory disease successfully treated with rituximab.

PubMed

Schafranski, Marcelo Derbli

2009-02-01

We report a case of a 66-year-old Caucasian female with a diagnosis of idiopathic orbital inflammatory disease (OID) refractory to azathioprine therapy. The coexistence of diabetes mellitus represented a relative contraindication to chronic prednisone use. After two infusions of rituximab, a chimeric anti-CD20+ antibody, ophthalmic signs and symptoms remarkably improved. To our knowledge, this is the first case of idiopathic OID successfully treated with rituximab.

EOL performance comparison of GaAs/Ge and Si BSF/R solar arrays

NASA Technical Reports Server (NTRS)

Woike, Thomas J.

1993-01-01

EOL power estimates for solar array designs are significantly influenced by the predicted degradation due to charged particle radiation. New radiation-induced power degradation data for GaAs/Ge solar arrays applicable to missions ranging from low earth orbit (LEO) to geosynchronous earth orbit (GEO) and compares these results to silicon BSF/R arrays. These results are based on recently published radiation damage coefficients for GaAs/Ge cells. The power density ratio (GaAs/Ge to Si BSF/R) was found to be as high as 1.83 for the proton-dominated worst-case altitude of 7408 km medium Earth orbit (MEO). Based on the EOL GaAs/Ge solar array power density results for MEO, missions which were previously considered infeasible may be reviewed based on these more favorable results. The additional life afforded by using GaAs/Ge cells is an important factor in system-level trade studies when selecting a solar cell technology for a mission and needs to be considered. The data presented supports this decision since the selected orbits have characteristics similar to most orbits of interest.

Successful subtotal orbitectomy in a cat with osteoma

PubMed Central

Corgozinho, Katia B; Cunha, Simone CS; Siqueira, Ricardo S; Souza, Heloisa JM

2015-01-01

Case summary A 14-year-old Siamese neutered male cat was evaluated for anorexia and a left periorbital mass. Skull radiographic findings showed a well-defined lesion resembling new compact bone formation without destruction. A subtotal orbitectomy was indicated. The tumor was removed intact with a normal tissue margin of at least 1 cm. There were no postsurgical complications. Histopathologic examination revealed an osteoma. The cat returned to normal appetite and activity 15 days after surgery. Six months after surgery, there were no gross signs of recurrence. Relevance and novel information Periorbital tumors are infrequently diagnosed in companion animals and most are malignant. In this case, the diagnosis was orbital osteoma. The most commonly affected bone for osteoma in cats is the mandibular bone; few cases have been identified in orbital bones. Orbital surgery has the potential to be challenging owing to complex anatomy, difficult exposure and the tendency to bleed. Surgical complications are common. In this case, although the disease was advanced, subtotal orbitectomy was successfully performed. PMID:28491397

Accessible Near-Earth Objects (NEOs)

NASA Technical Reports Server (NTRS)

Barbee, Brent W.

2015-01-01

Near Earth Objects (NEOs) are asteroids and comets whose orbits are in close proximity to Earth's orbit; specifically, they have perihelia less than 1.3 astronomical units. NEOs particularly near Earth asteroids (NEAs) are identified as potential destinations for future human exploration missions. In this presentation I provide an overview of the current state of knowledge regarding the astrodynamical accessibility of NEAs according to NASA's Near Earth Object Human Space Flight Accessible Targets Study (NHATS). I also investigate the extremes of NEA accessibility using case studies and illuminate the fact that a space-based survey for NEOs is essential to expanding the set of known accessible NEAs for future human exploration missions.

Case Studies in NASA High-Technology Risk Assessment and Management

NASA Technical Reports Server (NTRS)

Lambright, W. Henry

1998-01-01

This study discusses the approach of NASA managers in the assessment of risk in three critical decisions: the Apollo 8 decision to orbit the Moon in 1968, the servicing of the Hubble Space Telescope in 1993, and the privitization of the Space Shuttle in the latter 1990s.

PHOTOMETRIC ORBITS OF EXTRASOLAR PLANETS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brown, Robert A.

We define and analyze the photometric orbit (PhO) of an extrasolar planet observed in reflected light. In our definition, the PhO is a Keplerian entity with six parameters: semimajor axis, eccentricity, mean anomaly at some particular time, argument of periastron, inclination angle, and effective radius, which is the square root of the geometric albedo times the planetary radius. Preliminarily, we assume a Lambertian phase function. We study in detail the case of short-period giant planets (SPGPs) and observational parameters relevant to the Kepler mission: 20 ppm photometry with normal errors, 6.5 hr cadence, and three-year duration. We define a relevantmore » 'planetary population of interest' in terms of probability distributions of the PhO parameters. We perform Monte Carlo experiments to estimate the ability to detect planets and to recover PhO parameters from light curves. We calibrate the completeness of a periodogram search technique, and find structure caused by degeneracy. We recover full orbital solutions from synthetic Kepler data sets and estimate the median errors in recovered PhO parameters. We treat in depth a case of a Jupiter body-double. For the stated assumptions, we find that Kepler should obtain orbital solutions for many of the 100-760 SPGP that Jenkins and Doyle estimate Kepler will discover. Because most or all of these discoveries will be followed up by ground-based radial velocity observations, the estimates of inclination angle from the PhO may enable the calculation of true companion masses: Kepler photometry may break the 'msin i' degeneracy. PhO observations may be difficult. There is uncertainty about how low the albedos of SPGPs actually are, about their phase functions, and about a possible noise floor due to systematic errors from instrumental and stellar sources. Nevertheless, simple detection of SPGPs in reflected light should be robust in the regime of Kepler photometry, and estimates of all six orbital parameters may be feasible in at least a subset of cases.« less

Analysis of Parallel Burn, No-Crossfeed TSTO RLV Architectures and Comparison to Parallel Burn with Crossfeed and Series Burn Architectures

NASA Technical Reports Server (NTRS)

Smith, Garrett; Philips, Alan

2003-01-01

Three dominant Two Stage To Orbit (TSTO) class architectures were studied: Series Burn (SB), Parallel Bum with crossfeed (PBw/cf), and Parallel Burn, no-crossfeed (PBncf). The study goal was to determine what factors uniquely affect PBncf architectures, how each of these factors interact, and to determine from a performance perspective whether a PBncf vehicle could be competitive with a PBw/cf or a SB vehicle using equivalent technology and assumptions. In all cases, performance was evaluated on a relative basis for a fixed payload and mission by comparing gross and dry vehicle masses of a closed vehicle. Propellant combinations studied were LOX: LH2 propelled booster and orbiter (HH) and LOX: Kerosene booster with LOX: LH2 orbiter (KH). The study observations were: 1) A PBncf orbiter should be throttled as deeply as possible after launch until the staging point. 2) A PBncf TSTO architecture is feasible for systems that stage at mach 7. 2a) HH architectures can achieve a mass growth relative to PBw/cf of <20%. 2b) KH architectures can achieve a mass growth relative to Series Burn of <20%. 3) Center of gravity (CG) control will be a major issue for a PBncf vehicle, due to the low orbiter specific thrust to weight ratio and to the position of the orbiter required to align the nozzle heights at liftoff. 4) Thrust to weight ratios of 1.3 at liftoff and between 1.0 and 0.9 when staging at mach 7 appear to be close to ideal for PBncf vehicles. 5) Performance for HH vehicles was better when staged at mach 7 instead of mach 5. The study suggests possible methods to maximize performance of PBncf vehicle architectures in order to meet mission design requirements.

Orbital hydatid cyst of Echinococcus oligarthrus in a human in Venezuela.

PubMed

Lopera, R D; Meléndez, R D; Fernandez, I; Sirit, J; Perera, M P

1989-06-01

This study reports the first known case of human hydatid disease caused by the larval stage of Echinococcus oligarthrus. The patient, a native Venezuelan female, presented a single cyst localized intraorbitally behind the left eye (retroocular), which was discovered by computed tomography. The cyst was removed by surgery, and after parasitological studies it was identified as an E. oligarthrus hydatid cyst. This is also the first case of intraorbital hydatid cyst in humans in Venezuela.

Update in Pathological Diagnosis of Orbital Infections and Inflammations

PubMed Central

Lam Choi, Vincent B.; Yuen, Hunter K. L.; Biswas, Jyotirmay; Yanoff, Myron

2011-01-01

Orbital infections and inflammations include a broad spectrum of orbital diseases that can be idiopathic, infectious, from primary or secondary inflammatory processes. Being able to properly diagnose and manage these orbital diseases in a timely manner can avoid permanent vision loss and possibly save a patient's life. When clinicians are faced with such patients, quite often the exact diagnosis cannot be made just based on clinical examination, various laboratory tests and imaging are needed. Moreover, orbital biopsies with histopathological analyses are often required, especially for the atypical cases. Thus, it is important for the clinicians to be familiar with the pathological features and characteristics of these orbital diseases. This review provides a comprehensive update on the clinical and pathological diagnosis of these orbital infections and inflammations. PMID:22224014

Pediatric orbital cellulitis in the Haemophilus influenzae vaccine era.

PubMed

Sharma, Abhishek; Liu, Eugene S; Le, Tran D; Adatia, Feisal A; Buncic, J Raymond; Blaser, Susan; Richardson, Susan

2015-06-01

To evaluate the microbiology of pediatric orbital cellulitis in blood cultures and abscess drainage cultures following the introduction of the Haemophilus influenzae serotype b (Hib) vaccine. The medical records of all pediatrics patients (aged <18 years) at a tertiary pediatric hospital during the period January 2000 to July 2011 with a computed tomography orbital imaging querying "orbital cellulitis," "periorbital cellulitis," "preseptal cellulitis," or "post-septal cellulitis" were retrospectively reviewed. The records, microbiology, and radiology of these patients were reviewed to assess the rates and complications of H. influenzae orbital cellulitis, including bacteremia and meningitis. A total of 149 patients were diagnosed with preseptal or orbital cellulitis, of whom 101 (mean age, 7.2 ± 4.0) had true orbital cellulitis. No patients grew H. influenzae from blood cultures. Of the 101 patients, 30 (29.7%) required surgical drainage and had abscess drainage fluid sent for microbiology. Of these, 18 (64.3%) had a positive culture: 4 (13.3%) grew H. influenzae from their abscess drainage fluid samples; 1 grew H. influenzae alone; and 3 had mixed growth that included H. influenzae. The patients positive for H. influenzae were significantly older and had significantly larger abscesses. Although there were no cases of H. influenzae bacteremia or meningitis in our cases of orbital cellulitis, abscess drainage fluid microbiology indicated that H. influenzae remains a cause of orbital cellulitis. H. influenzae abscess volume was significantly larger than other bacterial abscesses and was associated with abscesses of mixed bacterial growth in older children. Crown Copyright © 2015. Published by Elsevier Inc. All rights reserved.

[Orbital inflammation].

PubMed

Mouriaux, F; Coffin-Pichonnet, S; Robert, P-Y; Abad, S; Martin-Silva, N

2014-12-01

Orbital inflammation is a generic term encompassing inflammatory pathologies affecting all structures within the orbit : anterior (involvement up to the posterior aspect of the globe), diffuse (involvement of intra- and/or extraconal fat), apical (involvement of the posterior orbit), myositis (involvement of only the extraocular muscles), dacryoadenitis (involvement of the lacrimal gland). We distinguish between specific inflammation and non-specific inflammation, commonly referred to as idiopathic inflammation. Specific orbital inflammation corresponds to a secondary localization of a "generalized" disease (systemic or auto-immune). Idiopathic orbital inflammation corresponds to uniquely orbital inflammation without generalized disease, and thus an unknown etiology. At the top of the differential diagnosis for specific or idiopathic orbital inflammation are malignant tumors, represented most commonly in the adult by lympho-proliferative syndromes and metastases. Treatment of specific orbital inflammation begins with treatment of the underlying disease. For idiopathic orbital inflammation, treatment (most often corticosteroids) is indicated above all in cases of visual loss due to optic neuropathy, in the presence of pain or oculomotor palsy. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

[Malignant Choroidal Melanoma in T4 Orbital Stage; Prosthesis of the Orbit].

PubMed

Furdová, A; Ferková, A; Krásnik, V; Krčová, I; Horkovičová, K

2015-06-01

Diagnosis and treatment of tumors of the eye is extremely difficul; surgical treatment in advanced stages, when the tumor grows in the orbit, leads to extensive radical surgery of the face. The extent and nature of surgical procedures depends on the nature of the tumor process, in advanced stages is indicated mutilating surgery--exenteration of the orbit. Exenteration of the orbit due to the extrascleral extension of malignant melanoma of the uvea is very rare, unfortunately, even today in certain cases it is necessary to make such a mutilating surgery. Case report--65 year old female patient, sent to our Departement in 2008 with the finding of the pigment deposits on the posterior pole of the left eye. Ultrasound study found elevations of up to 3 mm, she was asked to come for further control in three months interval. She did not coma, furthermore she sporadically attended another eye clinic. In 2011 she was treated for secondary glaucoma--cyclocryopexia. Due to pain another surgery--tarzoraphia was indicated. In 2012 she underwent surgery at St. Elisabeth Cancer Institute in Bratislava--Nefrectomia transperitoneally l. dx., excision hepatis. Histological examination in addition to the primary papillary renal carcinoma--mucinous tubular T1 Nx Mx type, found the metastasis of malignant melanoma to the liver and right kidney. She underwent the diagnostic procedure to find the origo of the melanoma. The patient was subsequently admitted to our clinic with blind painfull eye for enucleation. During the surgery the was found retrobulbar tumor ingrowth. Histopatholigical findings confirmed malignant melanoma. Indicated was exenteration of the orbit due to malignant melanoma T4 N0 M2 stage in June 2012. After healing of the cavity she was recommended to design an individual prosthesis. After completing several courses of palliative chemotherapy during a recent review in January 2015 the patient is without recurrence of the melanoma in the orbit Histological examination confirmed malignant melanoma in stage G2, predominantly epithelioid type, spindle cell type in part B of pips, tumor fills the entire back and part of the anterior chamber, grows through the sclera and optic nerve is completely overgrown by tumor mass and spreads into orbit. The immunophenotype is suggesting a better prognosis (S100+, melanoma+, +HMB45, cyklin D1 3%, 10% of p53, Ki67 3%). Tissue eyelashes were infiltrated by numerous micrometastases. The patient after exenteration of the orbit after 3 months got an individual epithesis. Local orbit cavity is more than 24 months after exenteration without recurrence of melanoma. The patient is still undergoing outpatient chemotherapy and feels good. The treatment of malignant tumors of the orbit and the eye is difficult, in most cases surgical treatment is indicated, with the additional radiation therapy and chemotherapy. Malignant tumors at an advanced stage should to be solved radically. Exenteration of the orbit leads to produce a large defect in the orbit and this part of the face. Patients in the active age after surgery followed by facial defects after such procedures have disadvantage in work and thie defect leads to serious socio-economic challenges. Patients with individually made prosthesis comprising a refund of the eyeball and the surrounding soft tissues allow active life and full application of the private as well as professional life.

Efficacy of High Frequency Ultrasound in Localization and Characterization of Orbital Lesions

PubMed Central

Gurushankar, G; Bhimarao; Kadakola, Bindushree

2015-01-01

Background The complicated anatomy of orbit and the wide spectrum of pathological conditions present a formidable challenge for early diagnosis, which is critical for management. Ultrasonography provides a detailed cross sectional anatomy of the entire globe with excellent topographic visualization and real time display of the moving organ. Objectives of the study To evaluate the efficacy of high frequency Ultrasound in localization of orbital diseases and to characterize various orbital pathologies sonologically. Materials and Methods Hundred eyes of 85 patients were examined with ultrasound using linear high frequency probe (5 to 17 MHz) of PHILPS IU22 ultrasound system. Sonological diagnosis was made based on location, acoustic characteristics, kinetic properties and Doppler flow dynamics. Final diagnosis was made based on clinical & laboratory findings/higher cross-sectional imaging/surgery & histopathology (as applicable). Diagnostic accuracy of ultrasonography was evaluated and compared with final diagnosis. Results The distinction between ocular and extraocular pathologies was made in 100% of cases. The overall sensitivity, specificity, NPV and accuracy of ultrasonography were 94.2%, 98.8%, 92.2% & 94.9% respectively for diagnosis of ocular pathologies and 94.2%, 99.2%, 95.9% & 95.2% respectively for extra ocular pathologies. Conclusion Ultrasonography is a readily available, simple, cost effective, non ionizing and non invasive modality with overall high diagnostic accuracy in localising and characterising orbital pathologies. It has higher spatial and temporal resolution compared to CT/MRI. However, CT/MRI may be indicated in certain cases for the evaluation of calcifications, bony involvement, extension to adjacent structures and intracranial extension. PMID:26500977

Relative motion of orbiting satellites

NASA Technical Reports Server (NTRS)

Eades, J. B., Jr.

1972-01-01

The relative motion problem is analyzed, as a linearized case, and as a numerically determined solution to provide a time history of the geometries representing the motion state. The displacement history and the hodographs for families of solutions are provided, analytically and graphically, to serve as an aid to understanding this problem area. Linearized solutions to relative motion problems of orbiting particles are presented for the impulsive and fixed thrust cases. Second order solutions are described to enhance the accuracy of prediction. A method was developed to obtain accurate, numerical solutions to the intercept and rendezvous problem; and, special situations are examined. A particular problem related to relative motions, where the motion traces develop a cusp, is examined in detail. This phenomenon is found to be dependent on a particular relationship between orbital eccentricity and the inclination between orbital planes. These conditions are determined, and, example situations are presented and discussed.

Management of orbital emphysema secondary to rhegmatogenous retinal detachment repair with hyperbaric oxygen therapy.

PubMed

Iniesta-Sanchez, Dante L; Romero-Caballero, Fatima; Aguirre-Alvarado, Adriana; Rebollo-Hurtado, Victoria; Velez-Montoya, Raul

2016-04-01

To describe the case of orbital subcutaneous emphysema who was successfully treated with hyperbaric oxygen therapy. Case report. Retrospective analysis of medical records and computer tomography images. A 40 years-old female, with retinal detachment who was seen at the emergency department, two weeks after undergoing a combined procedure of pars plana vitrectomy, scleral buckle and Sulfur hexafluoride tamponade. The patient complained of pain, decrease eye movement and edema of the upper eyelid. Clinical examination revealed periorbital crepitus. She was treated immediately with soft tissue decompression with small-gauge needle. Orbital emphysema recurred quickly, indicating possible gas trapped in the soft tissue. Using the US NAVY decompression protocol we were able to achieve fast clinical improvement. The protocol was repeated in several occasions until complete resolution. Hyperbaric oxygen therapy is an effective treatment for orbital and periorbital emphysema, due to its property of helping accelerate N 2 elimination from adipose tissue.

Congenital Arteriovenous Malformation of the Scalp Involving the Orbit.

PubMed

Feletti, Alberto; Dimitriadis, Stavros; Vallone, Stefano; Pavesi, Giacomo

2018-06-15

 Arteriovenous malformations (AVMs) of the scalp are rare and infrequently encountered by the neurosurgeon.  We report a unique case of a 42-year-old patient who presented with a progressive worsening of visual acuity in the right eye (lower quadrantanopia) and palpebral ptosis. Physical examination revealed a right exophthalmos and a right frontoparietal scalp soft swelling when the patient was in the supine position. Neurologic work-up showed a scalp AVM extending into the orbit and connected to an intraorbital cavernous angioma. The patient was treated with a frontotemporal craniotomy and decompression of the orbit.  In the rare case of intraorbital extension of a scalp AVM, neurologic symptoms may appear when the size of the vascular malformation increases with age. The aims of surgery should be decompression of the orbit and aesthetic preservation, rather than complete excision. A review of the literature is also provided. Georg Thieme Verlag KG Stuttgart · New York.

The problems of cosmic ray particle simulation for the near-Earth orbital and interplanetary flight conditions.

PubMed

Nymmik, R A

1999-10-01

A wide range of the galactic cosmic ray and SEP event flux simulation problems for the near-Earth satellite and manned spacecraft orbits and for the interplanetary mission trajectories are discussed. The models of the galactic cosmic ray and SEP events in the Earth orbit beyond the Earth's magnetosphere are used as a basis. The particle fluxes in the near-Earth orbits should be calculated using the transmission functions. To calculate the functions, the dependences of the cutoff rigidities on the magnetic disturbance level and on magnetic local time have to be known. In the case of space flights towards the Sun and to the boundary of the solar system, particular attention is paid to the changes in the SEP event occurrence frequency and size. The particle flux gradients are applied in this case to galactic cosmic ray fluxes.

Inadvertent Evisceration of Eyes Containing Uveal Melanoma

PubMed Central

Eagle, Ralph C.; Grossniklaus, Hans E.; Syed, Nasreen; Hogan, R. Nick; Lloyd, William C.; Folberg, Robert

2010-01-01

Objectives To report an important complication of ocular evisceration therapy for blind, painful eyes that has been unreported in the literature, and to stress the need for careful preoperative evaluation to exclude occult neoplasms prior to therapy. Design Multicenter, retrospective, nonrandomized clinicopathological case series of patients found to have previously unsuspected uveal malignant melanoma during histopathological examination of blind, painful eyes treated by evisceration. Results Histopathological examination of evisceration specimens disclosed previously unsuspected uveal melanoma in 7 patients who were treated for blind, painful eyes. Inflammation caused by necrosis of the tumor and other ocular tissues led to misdiagnosis as endophthalmitis, orbital cellulitis, or idiopathic orbital inflammation in several cases. Preoperative imaging was not performed in 3 cases and failed to detect tumors in the remaining 4 cases. Failure of necrotic tumors to enhance contributed to misdiagnosis. Conclusions The presence of a malignant intraocular neoplasm should be excluded prior to evisceration of any blind eye or blind, painful eye, particularly with opaque media. Necrosis-related inflammation can confound the clinical diagnosis of occult lesions, as can failure of necrotic tumors to enhance on imaging studies. PMID:19204229

Satellite scheduling considering maximum observation coverage time and minimum orbital transfer fuel cost

NASA Astrophysics Data System (ADS)

Zhu, Kai-Jian; Li, Jun-Feng; Baoyin, He-Xi

2010-01-01

In case of an emergency like the Wenchuan earthquake, it is impossible to observe a given target on earth by immediately launching new satellites. There is an urgent need for efficient satellite scheduling within a limited time period, so we must find a way to reasonably utilize the existing satellites to rapidly image the affected area during a short time period. Generally, the main consideration in orbit design is satellite coverage with the subsatellite nadir point as a standard of reference. Two factors must be taken into consideration simultaneously in orbit design, i.e., the maximum observation coverage time and the minimum orbital transfer fuel cost. The local time of visiting the given observation sites must satisfy the solar radiation requirement. When calculating the operational orbit elements as optimal parameters to be evaluated, we obtain the minimum objective function by comparing the results derived from the primer vector theory with those derived from the Hohmann transfer because the operational orbit for observing the disaster area with impulse maneuvers is considered in this paper. The primer vector theory is utilized to optimize the transfer trajectory with three impulses and the Hohmann transfer is utilized for coplanar and small inclination of non-coplanar cases. Finally, we applied this method in a simulation of the rescue mission at Wenchuan city. The results of optimizing orbit design with a hybrid PSO and DE algorithm show that the primer vector and Hohmann transfer theory proved to be effective methods for multi-object orbit optimization.

Definitive treatment of the negative vector orbit.

PubMed

Mommaerts, Maurice Y

2018-05-09

In a negative vector orbit, the most anterior globe portion protrudes past the malar eminence. As bulging eyes are considered unaesthetic, patients usually seek correction. However, most current correction techniques produce suboptimal results. Here, we present a surgical technique that sets back the globe and protrudes the malar bone using an intraoral approach. All five patients (aged 17-41 years) in our case series reported being satisfied with the improvement achieved using this technique. Based on our experience, a transoral approach to malar augmentation by valgisation osteotomy may address the bulging eyes aspect through transantral orbital fat reduction in select cases. Copyright © 2018 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Performance of a recoverable tug for planetary missions including use of perigee propulsion and corrections for nodal regression

NASA Technical Reports Server (NTRS)

Borsody, J.

1976-01-01

Mathematical equations are derived by using the Maximum Principle to obtain the maximum payload capability of a reusable tug for planetary missions. The mathematical formulation includes correction for nodal precession of the space shuttle orbit. The tug performs this nodal correction in returning to this precessed orbit. The sample case analyzed represents an inner planet mission as defined by the declination (fixed) and right ascension of the outgoing asymptote and the mission energy. Payload capability is derived for a typical cryogenic tug and the sample case with and without perigee propulsion. Optimal trajectory profiles and some important orbital elements are also discussed.

Frontoethmoidal osteoma with orbital extension. A case report.

PubMed

Blanco Domínguez, I; Oteiza Álvarez, A V; Martínez González, L M; Moreno García-Rubio, B; Franco Iglesias, G; Riba García, J

2016-07-01

A case is presented of a right frontoethmoidal osteoma with intraorbital invasion in a 43-year-old male, who was seen in the clinic with a proptosis, retro-orbital pain, peri-palpebral inflammation, and binocular diplopia due to muscular route limitation. Open surgery was performed using a subcranial approach, with removal of several fragments of osteoma. Histological analysis confirmed the diagnosis. Osteomas are benign bone-forming tumours with slow growth. They are usually asymptomatic until mass effect complications occur in the brain or in the orbit, or locally, generating mucoceles due to sinus drainage obstruction. Copyright © 2016 Sociedad Española de Oftalmología. Published by Elsevier España, S.L.U. All rights reserved.

New variational principles for locating periodic orbits of differential equations.

PubMed

Boghosian, Bruce M; Fazendeiro, Luis M; Lätt, Jonas; Tang, Hui; Coveney, Peter V

2011-06-13

We present new methods for the determination of periodic orbits of general dynamical systems. Iterative algorithms for finding solutions by these methods, for both the exact continuum case, and for approximate discrete representations suitable for numerical implementation, are discussed. Finally, we describe our approach to the computation of unstable periodic orbits of the driven Navier-Stokes equations, simulated using the lattice Boltzmann equation.

SPECTROSCOPIC ORBITS FOR 15 LATE-TYPE STARS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Willmarth, Daryl W.; Abt, Helmut A.; Fekel, Francis C.

2016-08-01

Spectroscopic orbital elements are determined for 15 stars with periods from 8 to 6528 days with six orbits computed for the first time. Improved astrometric orbits are computed for two stars and one new orbit is derived. Visual orbits were previously determined for four stars, four stars are members of multiple systems, and five stars have Hipparcos “G” designations or have been resolved by speckle interferometry. For the nine binaries with previous spectroscopic orbits, we determine improved or comparable elements. For HD 28271 and HD 200790, our spectroscopic results support the conclusions of previous authors that the large values of their massmore » functions and lack of detectable secondary spectrum argue for the secondary in each case being a pair of low-mass dwarfs. The orbits given here may be useful in combination with future interferometric and Gaia satellite observations.« less

Rehabilitation of orbital cavity after orbital exenteration using polymethyl methacrylate orbital prosthesis.

PubMed

Jain, Sumeet; Jain, Parul

2016-01-01

Squamous cell carcinoma of the eyelid is the second most common malignant neoplasm of the eye with the incidence of 0.09 and 2.42 cases/100 000 people. Orbital invasion is a rare complication but, if recognized early, can be treated effectively with exenteration. Although with advancements in technology such as computer-aided design and computer-aided manufacturing, material science, and retentive methods like implants, orbital prosthesis with stock ocular prosthesis made of methyl methacrylate retained by anatomic undercuts is quiet effective and should not be overlooked and forgotten. This clinical report describes prosthetic rehabilitation of two male patients with polymethyl methacrylate resin orbital prosthesis after orbital exenteration, for squamous cell carcinoma of the upper eyelid. The orbital prosthesis was sufficiently retained by hard and soft tissue undercuts without any complications. The patients using the prosthesis are quite satisfied with the cosmetic results and felt comfortable attending the social events.

Demonstration of the DSST State Transition Matrix Time-Update Properties Using the Linux GTDS Program

DTIC Science & Technology

2011-09-01

by a single mean equinoctial element set . EGP Orbit Determination Test Cases Rev 25 14 All of the EGP test cases employ the same observation...the non-singular equinoctial mean elements is more linear and this has positive implications for orbit determination processes based on the semi...by a single mean equinoctial element set . 5. CONCLUSIONS The GTDS Semi-analytical Satellite Theory (DSST) architecture has been extended to

Use of orbital floor steroids in the management of patients with uniocular non-necrotising scleritis.

PubMed Central

Hakin, K N; Ham, J; Lightman, S L

1991-01-01

Most cases of non-necrotising scleritis can be successfully treated with non-steroidal anti-inflammatory drugs. If these are ineffective, then high-dose systemic corticosteroids, with all their attendant side-effects, are usually required. We have used orbital floor injections of depot steroid in the management of nine patients with non-necrotising scleritis in an attempt to avoid the use of systemic steroids, or to allow the dose of steroids to be reduced while maintaining disease control. A temporary reduction in inflammation was achieved in all cases, which allowed the use of systemic steroids to be avoided altogether in two patients and delayed in the others. Non-steroidal anti-inflammatory drugs and systemic corticosteroids remain the mainstay of treatment for non-necrotising scleritis, but orbital floor injections may be a useful adjunct in certain cases. Images PMID:2043574

Comparison between numerical-relativity and post-Newtonian waveforms from spinning binaries: The orbital hang-up case

NASA Astrophysics Data System (ADS)

Hannam, Mark; Husa, Sascha; Brügmann, Bernd; Gopakumar, Achamveedu

2008-11-01

We compare results from numerical simulations of spinning binaries in the “orbital hang-up” case, where the binary completes at least nine orbits before merger, with post-Newtonian results using the approximants Taylor T1, T4, and Et. We find that, over the ten cycles before the gravitational-wave frequency reaches Mω=0.1, the accumulated phase disagreement between numerical relativity (NR) and 2.5 post-Newtonian (PN) results is less than three radians, and is less than 2.5 radians when using 3.5PN results. The amplitude disagreement between NR and restricted PN results increases with the black holes’ spin, from about 6% in the equal-mass case to 12% when the black holes’ spins are Si/Mi2=0.85. Finally, our results suggest that the merger waveform will play an important role in estimating the spin from such inspiral waveforms.

Analytical performance assessment of orbital configurations

NASA Astrophysics Data System (ADS)

Hitzl, D. L.; Krakowski, D. C.

1981-08-01

The system analysis of an orbital communication network of N satellites has been conducted. Specifically, the problem of connecting, in an optimal way, a set of ground-based laser transmitters to a second set of ground receivers on another part of the earth via a number of relay satellites fitted with retroreflectors has been addressed. A computer program has been developed which can treat either the so-called 'single-bounce' or 'double-bounce' cases. Sample results included in this paper consider a double-bounce orbital network composed of 12 relay satellites in 6 hour elliptical orbits together with 16 transceiver (delivery) satellites in 4.8 hour elliptical orbits.

Solution of the flyby problem for large space debris at sun-synchronous orbits

NASA Astrophysics Data System (ADS)

Baranov, A. A.; Grishko, D. A.; Medvedevskikh, V. V.; Lapshin, V. V.

2016-05-01

the paper considers the flyby problem related to large space debris (LSD) objects at low earth orbits. The data on the overall dimensions of known last and upper stages of launch vehicles makes it possible to single out five compact groups of such objects from the NORAD catalog in the 500-2000 km altitude interval. The orbits of objects of each group have approximately the same inclinations. The features of the mutual distribution of the orbital planes of LSD objects in the group are shown in a portrait of the evolution of deviations of the right ascension of ascending nodes (RAAN). In the case of the first three groups (inclinations of 71°, 74°, and 81°), the straight lines of relative RAAN deviations of object orbits barely intersect each other. The fourth (83°) and fifth (97°-100°) LSD groups include a considerable number of objects whose orbits are described by straight lines (diagonals), which intersect other lines many times. The use of diagonals makes it possible to significantly reduce the temporal and total characteristic velocity expenditures required for object flybys, but it complicates determination of the flyby sequence. Diagonal solutions can be obtained using elements of graph theory. A solution to the flyby problem is presented for the case of group 5, formed of LSD objects at sun-synchronous orbits.

Averaged model to study long-term dynamics of a probe about Mercury

NASA Astrophysics Data System (ADS)

Tresaco, Eva; Carvalho, Jean Paulo S.; Prado, Antonio F. B. A.; Elipe, Antonio; de Moraes, Rodolpho Vilhena

2018-02-01

This paper provides a method for finding initial conditions of frozen orbits for a probe around Mercury. Frozen orbits are those whose orbital elements remain constant on average. Thus, at the same point in each orbit, the satellite always passes at the same altitude. This is very interesting for scientific missions that require close inspection of any celestial body. The orbital dynamics of an artificial satellite about Mercury is governed by the potential attraction of the main body. Besides the Keplerian attraction, we consider the inhomogeneities of the potential of the central body. We include secondary terms of Mercury gravity field from J_2 up to J_6, and the tesseral harmonics \\overline{C}_{22} that is of the same magnitude than zonal J_2. In the case of science missions about Mercury, it is also important to consider third-body perturbation (Sun). Circular restricted three body problem can not be applied to Mercury-Sun system due to its non-negligible orbital eccentricity. Besides the harmonics coefficients of Mercury's gravitational potential, and the Sun gravitational perturbation, our average model also includes Solar acceleration pressure. This simplified model captures the majority of the dynamics of low and high orbits about Mercury. In order to capture the dominant characteristics of the dynamics, short-period terms of the system are removed applying a double-averaging technique. This algorithm is a two-fold process which firstly averages over the period of the satellite, and secondly averages with respect to the period of the third body. This simplified Hamiltonian model is introduced in the Lagrange Planetary equations. Thus, frozen orbits are characterized by a surface depending on three variables: the orbital semimajor axis, eccentricity and inclination. We find frozen orbits for an average altitude of 400 and 1000 km, which are the predicted values for the BepiColombo mission. Finally, the paper delves into the orbital stability of frozen orbits and the temporal evolution of the eccentricity of these orbits.

Space shuttle system program definition. Volume 2: Technical report

NASA Technical Reports Server (NTRS)

1972-01-01

The Phase B Extension of the Space Shuttle System Program Definition study was redirected to apply primary effort to consideration of space shuttle systems utilizing either recoverable pressure fed liquids or expendable solid rocket motor boosters. Two orbiter configurations were to be considered, one with a 15x60 foot payload bay with a 65,000 lb, due East, up-payload capability and the other with a 14x45 payload bay with 45,000 lb, of due East, up-payload. Both were to use three SSME engines with 472,000 lb of vacuum thrust each. Parallel and series burn ascent modes were to be considered for the launch configurations of primary interest. A recoverable pump-fed booster is included in the study in a series burn configuration with the 15x60 orbiter. To explore the potential of the swing engine orbiter configuration in the pad abort case, it is included in the study matrix in two launch configurations, a series burn pressure fed BRB and a parallel burn SRM. The resulting matrix of configuration options is shown. The principle objectives of this study are to evaluate the cost and technical differences between the liquid and solid propellant booster systems and to assess the development and operational cost savings available with a smaller orbiter.

Differentiation between inflammatory and neoplastic orbital conditions based on computed tomographic signs.

PubMed

Lederer, Kristina; Ludewig, Eberhard; Hechinger, Harald; Parry, Andrew T; Lamb, Christopher R; Kneissl, Sibylle

2015-07-01

To identify computed tomographic (CT) signs that could be used to differentiate inflammatory from neoplastic orbital conditions in small animals. Fifty-two animals (25 cats, 21 dogs, 4 rabbits, and 2 rodents). Case-control study in which CT images of animals with histopathologic diagnosis of inflammatory (n = 11), neoplastic orbital conditions (n = 31), or normal control animals (n = 10) were reviewed independently by five observers without the knowledge of the history or diagnosis. Observers recorded their observations regarding specific anatomical structures within the orbit using an itemized form containing the following characteristics: definitely normal; probably normal; equivocal; probably abnormal; and definitely abnormal. Results were statistically analyzed using Fleiss' kappa and logistic regression analyses. The overall level of agreement between observers about the presence or absence of abnormal CT signs in animals with orbital disease was poor to moderate, but was highest for observations concerning orbital bones (κ = 0.62) and involvement of the posterior segment (κ = 0.52). Significant associations between abnormalities and diagnosis were found for four structures: Abnormalities affecting orbital bones (odds ratio [OR], 1.7) and anterior ocular structures (OR, 1.5) were predictive of neoplasia, while abnormalities affecting extraconal fat (OR, 1.7) and skin (OR, 1.4) were predictive of inflammatory conditions. Orbital CT is an imaging test with high specificity. Fat stranding, a CT sign not previously emphasized in veterinary medicine, was significantly associated with inflammatory conditions. Low observer agreement probably reflects the limited resolution of CT for small orbital structures. © 2014 American College of Veterinary Ophthalmologists.

Chartering Launchers for Small Satellites

NASA Astrophysics Data System (ADS)

Hernandez, Daniel

The question of how to launch small satellites has been solved over the years by the larger launchers offering small satellites the possibility of piggy-backing. Specific fixtures have been developed and commercialized: Arianespace developed the ASAP interface, the USAF studied ESPA, NASA has promoted Shuttle launch possibilities, Russian authorities and companies have been able to find solutions with many different launchers... It is fair to say that most launcher suppliers have worked hard and finally often been able to find solutions to launch most small satellites into orbit. It is also true, however, that most of these small satellites were technology demonstration missions capable of accepting a wide range of orbit and launch characteristics: orbit altitude and inclination, launch date, etc. In some cases the small satellite missions required a well-defined type of orbit and have therefore been obliged to hire a small launcher on which they were the prime passenger. In our paper we would like to propose an additional solution to all these possibilities: launchers could plan well in advance (for example about 3 years), trips to precisely defined orbits to allow potential passengers to organize themselves and be ready on the D-Day. On the scheduled date the chartered launcher goes to the stated orbit while on another date, another chartered launcher goes to another orbit. The idea is to organize departures for space like trains or airplanes leaving on known schedules for known destinations.

Technical Modifications for Intraoral Quadrangular Le Fort II Osteotomy.

PubMed

Klug, Clemens; Cede, Julia

2017-02-01

The intraoral quadrangular Le Fort II osteotomy (IQLFIIO) represents a reliable surgical method in cases of midfacial deficiency with good functional, esthetic, and stable long-term results. In this technical note, we present 3 surgical modifications to previous reports: 1) inferior orbital rim osteotomy by angulated piezosurgical instruments, thereby avoiding the use of chisels in the orbital region; 2) osteosynthetic fixation only laterally at the zygomatic buttress with 2 L-shaped miniplates, thus avoiding paranasal osteosynthesis; and 3) advancement step camouflage in the lateral infraorbital region with a compound mass of autologous bone chips and fibrin glue with the intention to reduce bone block-associated side effects. Thirteen consecutive patients presenting with midfacial deficiency and Class III malocclusion were treated by IQLFIIO and mandibular osteotomy. In all cases, osteotomy and consecutive down fracture could be conducted as planned using the piezotome. No atypical fractures were encountered. No cases of infraorbital nerve anesthesia developed. Midfacial hypesthesia was found in 54% of the operated sides after 3 months, in 23% after 6 months, and in 13% after 12 months. The 5-month postoperative 3-dimensional scans revealed osseous healing at the infraorbital advancement step. Our results suggest that IQLFIIO can be conducted fully without chisels in the orbital region. Implementation of piezosurgery in IQLFIIO allows for safe bone cutting in the orbital region. Two miniplates and step camouflage with fibrin glue-stabilized bone chips were sufficient for osseous healing. Future studies will focus on quantitative soft to hard tissue changes that occur with IQLFIIO advancement. Copyright © 2016 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Accretion as a function of Orbital Phase in Young Close Binaries

NASA Astrophysics Data System (ADS)

Ardila, David R.; Herczeg, G.; Johns-Krull, C. M.; Mathieu, R. D.; Vodniza, A.; Tofflemire, B. M.

2014-01-01

Many planets are known to reside around binaries and the study of young binary systems is crucial to understand their formation. Young ($<10$ Myrs) low-mass binaries are generally surrounded by circumbinary disk with an inner gap. Gas from the disk must cross this gap for accretion to take place and here we present observations of this process as a function of orbital phase. We have obtained time-resolved FUV and NUV spectroscopy (1350 to 3000 A) of DQ Tau and UZ Tau E, using the Cosmic Origins Spectrograph on-board the Hubble Space Telescope. Each target was observed 2 to 4 times per binary orbit, over three or four consecutive orbits. For DQ Tau, we find some evidence that accretion occurs equally into both binary members, while for UZ Tau E this is not the case. H2 emission for DQ Tau most likely originates within the circumbinary gap, while for UZ Tau E no 1000 K gas is detected within the gap, although magnetospheric accretion does take place.

Orbital nerve seath myxoma with extraocular muscle involvement: a rare case.

PubMed

Rodríguez-Uña, Ignacio; Troyano-Rivas, Juan A; González-García, Cristina; Chícharo-de-Freitas, Reinaldo; Ortiz-Zapata, Juan J; Ortega-Medina, Luis; Toledano-Fernández, Nicolás; García-Feijoo, Julián

2015-07-01

A 66-year-old woman with breast cancer presented with a painless mass in the left orbit. MRI revealed a well-defined intraconal mass in the temporal quadrant of the orbit. Fifteen months later, a further MRI indicated the mass had grown, displacing the left optic nerve and making contact with the lateral rectus muscle, suggesting its possible intramuscular origin. Despite the clinical and radiological characteristics of the lesion and its slow growth, a PET/CT study was developed because of the history of malignant disease. No metabolic activity of the mass or malignant lesion in other locations was observed. After surgical excision, histopathological examination revealed an abundant myxoid matrix with few spindle-shaped cells and no signs of malignancy. The cells were immunopositive for CD34, positive for S-100 protein, and negative for EMA, actin, and CD57. A diagnosis was made of a nerve sheath myxoma. The orbital location of these tumors is extremely rare.

Spin-orbit coupling effects in zinc-blende InSb and wurtzite InAs nanowires: Realistic calculations with multiband k .p method

NASA Astrophysics Data System (ADS)

Campos, Tiago; Faria Junior, Paulo E.; Gmitra, Martin; Sipahi, Guilherme M.; Fabian, Jaroslav

2018-06-01

A systematic numerical investigation of spin-orbit fields in the conduction bands of III-V semiconductor nanowires is performed. Zinc-blende (ZB) InSb nanowires are considered along [001], [011], and [111] directions, while wurtzite (WZ) InAs nanowires are studied along [0001] and [10 1 ¯0 ] or [11 2 ¯0 ] directions. Robust multiband k .p Hamiltonians are solved by using plane-wave expansions of real-space parameters. In all cases, the linear and cubic spin-orbit coupling parameters are extracted for nanowire widths from 30 to 100 nm. Typical spin-orbit energies are on the μ eV scale, except for WZ InAs nanowires grown along [10 1 ¯0 ] or [11 2 ¯0 ] , in which the spin-orbit energy is about meV, largely independent of the wire diameter. Significant spin-orbit coupling is obtained by applying a transverse electric field, causing the Rashba effect. For an electric field of about 4 mV/nm, the obtained spin-orbit energies are about 1 meV for both materials in all investigated growth directions. The most favorable system, in which the spin-orbit effects are maximal, are WZ InAs nanowires grown along [1010] or [11 2 ¯0 ] since here spin-orbit energies are giant (meV) already in the absence of electric field. The least favorable are InAs WZ nanowires grown along [0001] since here even the electric field does not increase the spin-orbit energies beyond 0.1 meV. The presented results should be useful for investigations of optical orientation, spin transport, weak localization, and superconducting proximity effects in semiconductor nanowires.

Analytic model for the long-term evolution of circular Earth satellite orbits including lunar node regression

NASA Astrophysics Data System (ADS)

Zhu, Ting-Lei; Zhao, Chang-Yin; Zhang, Ming-Jiang

2017-04-01

This paper aims to obtain an analytic approximation to the evolution of circular orbits governed by the Earth's J2 and the luni-solar gravitational perturbations. Assuming that the lunar orbital plane coincides with the ecliptic plane, Allan and Cook (Proc. R. Soc. A, Math. Phys. Eng. Sci. 280(1380):97, 1964) derived an analytic solution to the orbital plane evolution of circular orbits. Using their result as an intermediate solution, we establish an approximate analytic model with lunar orbital inclination and its node regression be taken into account. Finally, an approximate analytic expression is derived, which is accurate compared to the numerical results except for the resonant cases when the period of the reference orbit approximately equals the integer multiples (especially 1 or 2 times) of lunar node regression period.

Role of degeneracy, hybridization, and nesting in the properties of multiorbital systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nicholson, Andrew D; Liu, Jia-Ming; Ge, Weihao

2011-01-01

To understand the role that degeneracy, hybridization, and nesting play in the magnetic and pairing properties of multiorbital Hubbard models we here study numerically two types of two-orbital models, both with holelike and electron-like Fermi surfaces (FS s) that are related by nesting vectors ( ,0) and (0, ). In one case the bands that determine the FS s arise from strongly hybridized degenerate dxz and dyz orbitals, while in the other the two bands are determined by nondegenerate and nonhybridized s-like orbitals. Using a variety of techniques, in the weak-coupling regime it is shown that only the model withmore » hybridized bands develops metallic magnetic order, while the other model exhibits an ordered excitonic orbital-transverse spin state that is insulating and does not have a local magnetization. However, both models display similar insulating magnetic stripe ordering in the strong-coupling limit. These results indicate that nesting is a necessary but not sufficient condition for the development of ordered states with finite local magnetization in multiorbital Hubbard systems; the additional ingredient appears to be that the nested portions of the bands need to have the same orbital flavor. This condition can be achieved via strong hybridization of the orbitals in weak coupling or via the FS reconstruction induced by the Coulomb interactions in the strong-coupling regime. This effect also affects the pairing symmetry as demonstrated by the study of the dominant pairing channels for the two models.« less

Trajectory optimization and guidance law development for national aerospace plane applications

NASA Technical Reports Server (NTRS)

Calise, A. J.; Flandro, G. A.; Corban, J. E.

1988-01-01

The work completed to date is comprised of the following: a simple vehicle model representative of the aerospace plane concept in the hypersonic flight regime, fuel-optimal climb profiles for the unconstrained and dynamic pressure constrained cases generated using a reduced order dynamic model, an analytic switching condition for transition to rocket powered flight as orbital velocity is approached, simple feedback guidance laws for both the unconstrained and dynamic pressure constrained cases derived via singular perturbation theory and a nonlinear transformation technique, and numerical simulation results for ascent to orbit in the dynamic pressure constrained case.

Low-Dose Radiation Therapy (2 Gy × 2) in the Treatment of Orbital Lymphoma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fasola, Carolina E.; Jones, Jennifer C.; Huang, Derek D.

2013-08-01

Purpose: Low-dose radiation has become increasingly used in the management of indolent non-Hodgkin lymphoma (NHL), but has not been studied specifically for cases of ocular adnexal involvement. The objective of this study is to investigate the effectiveness of low-dose radiation in the treatment of NHL of the ocular adnexa. Methods and Materials: We reviewed the records of 20 NHL patients with 27 sites of ocular adnexal involvement treated with low-dose radiation consisting of 2 successive fractions of 2 Gy at our institution between 2005 and 2011. The primary endpoint of this study is freedom from local relapse (FFLR). Results: Atmore » a median follow-up time of 26 months (range 7-92), the overall response rate for the 27 treated sites was 96%, with a complete response (CR) rate of 85% (n=23) and a partial response rate of 11% (n=3). Among all treated sites with CR, the 2-year FFLR was 100%, with no in-treatment field relapses. The 2-year freedom from regional relapse rate was 96% with 1 case of relapse within the ipsilateral orbit (outside of the treatment field). This patient underwent additional treatment with low-dose radiation of 4 Gy to the area of relapse achieving a CR and no evidence of disease at an additional 42 months of follow-up. Orbital radiation was well tolerated with only mild acute side effects (dry eye, conjunctivitis, transient periorbital edema) in 30% of treated sites without any reports of long-term toxicity. Conclusions: Low-dose radiation with 2 Gy × 2 is effective and well tolerated in the treatment of indolent NHL of the ocular adnexa with high response rates and durable local control with the option of reirradiation in the case of locoregional relapse.« less

Interplay between Magnetism, Superconductivity, and Orbital Order in 5-Pocket Model for Iron-Based Superconductors: Parquet Renormalization Group Study.

PubMed

Classen, Laura; Xing, Rui-Qi; Khodas, Maxim; Chubukov, Andrey V

2017-01-20

We report the results of the parquet renormalization group (RG) analysis of the phase diagram of the most general 5-pocket model for Fe-based superconductors. We use as an input the orbital structure of excitations near the five pockets made out of d_{xz}, d_{yz}, and d_{xy} orbitals and argue that there are 40 different interactions between low-energy fermions in the orbital basis. All interactions flow under the RG, as one progressively integrates out fermions with higher energies. We find that the low-energy behavior is amazingly simple, despite the large number of interactions. Namely, at low energies the full 5-pocket model effectively reduces either to a 3-pocket model made of one d_{xy} hole pocket and two electron pockets or a 4-pocket model made of two d_{xz}/d_{yz} hole pockets and two electron pockets. The leading instability in the effective 4-pocket model is a spontaneous orbital (nematic) order, followed by s^{+-} superconductivity. In the effective 3-pocket model, orbital fluctuations are weaker, and the system develops either s^{+-} superconductivity or a stripe spin-density wave. In the latter case, nematicity is induced by composite spin fluctuations.

Towards Relaxing the Spherical Solar Radiation Pressure Model for Accurate Orbit Predictions

NASA Astrophysics Data System (ADS)

Lachut, M.; Bennett, J.

2016-09-01

The well-known cannonball model has been used ubiquitously to capture the effects of atmospheric drag and solar radiation pressure on satellites and/or space debris for decades. While it lends itself naturally to spherical objects, its validity in the case of non-spherical objects has been debated heavily for years throughout the space situational awareness community. One of the leading motivations to improve orbit predictions by relaxing the spherical assumption, is the ongoing demand for more robust and reliable conjunction assessments. In this study, we explore the orbit propagation of a flat plate in a near-GEO orbit under the influence of solar radiation pressure, using a Lambertian BRDF model. Consequently, this approach will account for the spin rate and orientation of the object, which is typically determined in practice using a light curve analysis. Here, simulations will be performed which systematically reduces the spin rate to demonstrate the point at which the spherical model no longer describes the orbital elements of the spinning plate. Further understanding of this threshold would provide insight into when a higher fidelity model should be used, thus resulting in improved orbit propagations. Therefore, the work presented here is of particular interest to organizations and researchers that maintain their own catalog, and/or perform conjunction analyses.

Hypothetical Reentry Thermostructural Performance of Space Shuttle Orbiter With Missing or Eroded Thermal Protection Tiles

NASA Technical Reports Server (NTRS)

Ko, William L.; Gong, Leslie; Quinn, Robert D.

2004-01-01

This report deals with hypothetical reentry thermostructural performance of the Space Shuttle orbiter with missing or eroded thermal protection system (TPS) tiles. The original STS-5 heating (normal transition at 1100 sec) and the modified STS-5 heating (premature transition at 800 sec) were used as reentry heat inputs. The TPS missing or eroded site is assumed to be located at the center or corner (spar-rib juncture) of the lower surface of wing midspan bay 3. For cases of missing TPS tiles, under the original STS-5 heating, the orbiter can afford to lose only one TPS tile at the center or two TPS tiles at the corner (spar-rib juncture) of the lower surface of wing midspan bay 3. Under modified STS-5 heating, the orbiter cannot afford to lose even one TPS tile at the center or at the corner of the lower surface of wing midspan bay 3. For cases of eroded TPS tiles, the aluminum skin temperature rises relatively slowly with the decreasing thickness of the eroded central or corner TPS tile until most of the TPS tile is eroded away, and then increases exponentially toward the missing tile case.

Multi-Organization Multi-Discipline Effort Developing a Mitigation Concept for Planetary Defense

NASA Technical Reports Server (NTRS)

Leung, Ronald Y.; Barbee, Brent W.; Seery, Bernard D.; Bambacus, Myra; Finewood, Lee; Greenaugh, Kevin C.; Lewis, Anthony; Dearborn, David; Miller, Paul L.; Weaver, Robert P.;

[Bilateral anophthalmia and left-sided orbital tumor : case of an eight-month-old infant].

PubMed

Hundertmark, P; Dierks, P; Gottschalk, J; Kreusch, T; Wiegand, W

2011-08-01

An 8-month-old infant from Russia with bilateral anophthalmia presented with an expanding orbital tumor. The tumor was extirpated and the histological examination revealed a non-malignant pseudocystic process with residual neuro-ectodermal structures.

Mit castor satellite: Design, implementation, and testing of the communication system

NASA Astrophysics Data System (ADS)

Babuscia, Alessandra; McCormack, Matthew Michael; Munoz, Michael; Parra, Spencer; Miller, David W.

2012-12-01

Cathode Anode Satellite Thruster for Orbital Reposition (CASTOR) is an orbital manoeuvre and transfer micro-satellite bus developed at MIT Space System Laboratory. The technical objective of the mission is achieving 1 km/s of delta-V over a 1 year mission in Low Earth Orbit (LEO). This will be accomplished using a novel electric propulsion system, the Diverging Cusped Field Thruster (DCFT), which enables high efficiency orbital changes of the ESPA-ring class satellite. CASTOR is capable of improving rapid access to space capabilities by providing an orbital transfer platform with a very high performance to mass ratio, thus greatly reducing launch costs and allowing for highly efficient orbital manoeuvre. Furthermore, CASTOR is highly scalable and modular, allowing it to be adapted to a wide range of scales and applications. CASTOR is developed as part of the University Nanosatellite Program (UNP) funded by Air Force Research Laboratory (AFRL). In order to accomplish CASTOR mission objective, a highly optimized, scalable, light weight, and low cost communication system needed to be developed. These constraints imply the development of trade studies to select the final communication system architecture able to maximize the amount of data transmitted, while guaranteeing reliability, redundancy and limited mass, power consumption, and cost. A special attention is also required to guarantee a reliable communication system in cases of tumbling, or in case of strong Doppler shift which is inevitable due to the high delta-V capabilities of the vehicle. In order to accomplish all the mission requirements, different features have been introduced in the design of the communication system for this mission. Specifically, customized patch antennas have been realized, and a customized communication protocol has been designed and implemented. The communication subsystem has been validated through an intense testing campaign which included software tests in the laboratory, hardware tests in anechoic chamber, and in flight tests through a balloon experiment. The article presents an overview of CASTOR mission, a presentation of the trade studies analysis and of the final communication architecture selected, a description of the customized antenna developed, of the customized protocol designed, and a presentation of the results of the tests performed.

Numerical study on exciton transport and light emission for organic light emitting diodes with an emission layer.

PubMed

Kim, K S; Hwang, Y W; Won, T Y

2013-12-01

This paper reports the results of a numerical study on carrier injection and exciton transport in an organic light emitting diode (OLED) structure based on tris (8-hydroxyquinolinato) aluminum (Alq3). Because charge accumulation at the interfaces between the emission layer (EML) and transport layer are believed to increase the recombination rate, which also increases the exciton density, a numerical study was performed on the effect of inserting an EML in the bilayer structure. In the first case considered, the lowest unoccupied molecular orbital (LUMO) of the EML was aligned with the LUMO of the hole transport layer (HTL), whereas the highest occupied molecular orbital (HOMO) of the EML was aligned with the HOMO of the electron transport layer (ETL). In the second case, the LUMO of the EML was aligned with the LUMO of the ETL and the HOMO of the EML was aligned with the HOMO of the HTL. In case of a charge-blocking device, most of the recombination appeared to occur at both edges of the EML because the electric field exhibited a peak in these areas. On the other hand, in the case of the charge-confining device, the electric field was confined at the interface between the EML and ETL. This paper also discussed the effect of the insertion of a doping layer as transport layer.

Design of Optimal Cyclers Using Solar Sails

DTIC Science & Technology

2002-12-01

more perturbations are desired in the dynamics model (in this case, more nodes should be used). Equinoctial elements provide a set of singularity...the time to complete the whole EME double rendezvous. Setting the intermediate destination at the Mars orbit and the final destination with Earth...it is necessary to know the relative orbital shapes and orientations of the departure and destination planets. The orbital elements of Earth and Mars

The stability of steady motion of magnetic domain wall: Role of higher-order spin-orbit torques

DOE Office of Scientific and Technical Information (OSTI.GOV)

He, Peng-Bin, E-mail: hepengbin@hnu.edu.cn; Yan, Han; Cai, Meng-Qiu

The steady motion of magnetic domain wall driven by spin-orbit torques is investigated analytically in the heavy/ferromagnetic metal nanowires for three cases with a current transverse to the in-plane and perpendicular easy axis, and along the in-plane easy axis. By the stability analysis of Walker wall profile, we find that if including the higher-order spin-orbit torques, the Walker breakdown can be avoided in some parameter regions of spin-orbit torques with a current transverse to or along the in-plane easy axis. However, in the case of perpendicular anisotropy, even considering the higher-order spin-orbit torques, the velocity of domain wall cannot bemore » efficiently enhanced by the current. Furthermore, the direction of wall motion is dependent on the configuration and chirality of domain wall with a current along the in-plane easy axis or transverse to the perpendicular one. Especially, the direction of motion can be controlled by the initial chirality of domain wall. So, if only involving the spin-orbit mechanism, it is preferable to adopt the scheme of a current along the in-plane easy axis for enhancing the velocity and controlling the direction of domain wall.« less

Comparison of TOPEX/Poseidon orbit determination solutions obtained by the Goddard Space Flight Center Flight Dynamics Division and Precision Orbit Determination Teams

NASA Technical Reports Server (NTRS)

Doll, C.; Mistretta, G.; Hart, R.; Oza, D.; Cox, C.; Nemesure, M.; Bolvin, D.; Samii, Mina V.

1993-01-01

Orbit determination results are obtained by the Goddard Space Flight Center (GSFC) Flight Dynamics Division (FDD) using the Goddard Trajectory Determination System (GTDS) and a real-time extended Kalman filter estimation system to process Tracking Data and Relay Satellite (TDRS) System (TDRSS) measurements in support of the Ocean Topography Experiment (TOPEX)/Poseidon spacecraft navigation and health and safety operations. GTDS is the operational orbit determination system used by the FDD, and the extended Kalman fliter was implemented in an analysis prototype system, the Real-Time Orbit Determination System/Enhanced (RTOD/E). The Precision Orbit Determination (POD) team within the GSFC Space Geodesy Branch generates an independent set of high-accuracy trajectories to support the TOPEX/Poseidon scientific data. These latter solutions use the Geodynamics (GEODYN) orbit determination system with laser ranging tracking data. The TOPEX/Poseidon trajectories were estimated for the October 22 - November 1, 1992, timeframe, for which the latest preliminary POD results were available. Independent assessments were made of the consistencies of solutions produced by the batch and sequential methods. The batch cases were assessed using overlap comparisons, while the sequential cases were assessed with covariances and the first measurement residuals. The batch least-squares and forward-filtered RTOD/E orbit solutions were compared with the definitive POD orbit solutions. The solution differences were generally less than 10 meters (m) for the batch least squares and less than 18 m for the sequential estimation solutions. The differences among the POD, GTDS, and RTOD/E solutions can be traced to differences in modeling and tracking data types, which are being analyzed in detail.

Signature Intensity Derivative and its Application to Resident Space Object Typing

DTIC Science & Technology

2009-09-01

photometric signatures is change in their brightness and color with time . It has been discovered that because of the illumination angle dependency of this...temporal nature, time alone is insufficient to characterize the intrinsic nature of change in signature brightness. In this paper, we present a...materials contained in the RSO signature. It is shown for the case of the geosynchronous orbit satellite and the results of a test case in this orbit

[MRI in Duane retraction syndrome: Preliminary results].

PubMed

Denis, D; Cousin, M; Zanin, E; Toesca, E; Girard, N

2011-09-01

Duane retraction syndrome (DRS) is a congenital ocular motility disorder with innervational dysgenesis. MRI improves our understanding of this disease by providing in vivo access to nerves and oculomotor muscles. The goal of this prospective study (2000-2008) was to analyze DRS clinically and neuroradiologically. Twenty-four patients (27 eyes) received a complete ophthalmologic evaluation and a brain-orbital MRI. The average age was 6.1 years. MRI was performed with 3D T2 CISS-weighted images through the brainstem to visualize the cisternal segments of the cranial nerves and the orbit (lateral and medial recti muscles). MRI anomalies were classified according to type I, II, and III and depending on their condition in the posterior fossa (absence, hypoplasia) and in the orbit (muscle anomalies). Of 27 eyes, 70% were type I, 19% type II, and 11% type III. MRI showed abducens nerve abnormalities in 93% of the cases (78% absence) and muscle abnormalities in 57.5% of the cases. A detailed description showed 100% abducens nerve abnormalities and 58% abnormal lateral rectus muscle in type I, 60% abducens nerve abnormalities and 60% abnormal lateral rectus muscle in type II, and 100% abducens nerve abnormalities and 66% abnormal lateral rectus in type III. This study presents two major findings: detection of abducens nerve abnormalities in most cases of DRS whatever the type, associated with muscle abnormalities, and the confirmation that this absence may exist in type II (2/5). Thus MRI proved to be a valuable tool for investigating these patients, improving the comprehension of the physiopathogenics of this disease. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

Transcriptome Analysis of Orbital Adipose Tissue in Active Thyroid Eye Disease Using Next Generation RNA Sequencing Technology

PubMed Central

Lee, Bradford W.; Kumar, Virender B.; Biswas, Pooja; Ko, Audrey C.; Alameddine, Ramzi M.; Granet, David B.; Ayyagari, Radha; Kikkawa, Don O.; Korn, Bobby S.

2018-01-01

Objective: This study utilized Next Generation Sequencing (NGS) to identify differentially expressed transcripts in orbital adipose tissue from patients with active Thyroid Eye Disease (TED) versus healthy controls. Method: This prospective, case-control study enrolled three patients with severe, active thyroid eye disease undergoing orbital decompression, and three healthy controls undergoing routine eyelid surgery with removal of orbital fat. RNA Sequencing (RNA-Seq) was performed on freshly obtained orbital adipose tissue from study patients to analyze the transcriptome. Bioinformatics analysis was performed to determine pathways and processes enriched for the differential expression profile. Quantitative Reverse Transcriptase-Polymerase Chain Reaction (qRT-PCR) was performed to validate the differential expression of selected genes identified by RNA-Seq. Results: RNA-Seq identified 328 differentially expressed genes associated with active thyroid eye disease, many of which were responsible for mediating inflammation, cytokine signaling, adipogenesis, IGF-1 signaling, and glycosaminoglycan binding. The IL-5 and chemokine signaling pathways were highly enriched, and very-low-density-lipoprotein receptor activity and statin medications were implicated as having a potential role in TED. Conclusion: This study is the first to use RNA-Seq technology to elucidate differential gene expression associated with active, severe TED. This study suggests a transcriptional basis for the role of statins in modulating differentially expressed genes that mediate the pathogenesis of thyroid eye disease. Furthermore, the identification of genes with altered levels of expression in active, severe TED may inform the molecular pathways central to this clinical phenotype and guide the development of novel therapeutic agents. PMID:29760827

Aerodynamic Interaction between Delta Wing and Hemisphere-Cylinder in Supersonic Flow

NASA Astrophysics Data System (ADS)

Nishino, Atsuhiro; Ishikawa, Takahumi; Nakamura, Yoshiaki

As future space vehicles, Reusable Launch Vehicle (RLV) needs to be developed, where there are two kinds of RLV: Single Stage To Orbit (SSTO) and Two Stage To Orbit (TSTO). In the latter case, the shock/shock interaction and shock/boundary layer interaction play a key role. In the present study, we focus on the supersonic flow field with aerodynamic interaction between a delta wing and a hemisphere-cylinder, which imitate a TSTO, where the clearance, h, between the delta wing and hemisphere-cylinder is a key parameter. As a result, complicated flow patterns were made clear, including separation bubbles.

NSTS Orbiter auxiliary power unit turbine wheel cracking risk assessment

NASA Technical Reports Server (NTRS)

Cruse, T. A.; Mcclung, R. C.; Torng, T. Y.

1992-01-01

The present investigation of turbine-wheel cracking problems in the hydrazine-fueled APU turbine wheel of the Space Shuttle Orbiter's Main Engines has indicated the efficacy of systematic probabilistic risk assessment in flight certification and safety resolution. Nevertheless, real crack-initiation and propagation problems do not lend themselves to purely analytical studies. The high-cycle fatigue problem is noted to generally be unsuited to probabilistic modeling, due to its extremely high degree of intrinsic scatter. In the case treated, the cracks appear to trend toward crack arrest in a low cycle fatigue mode, due to a detuning of the resonance model.

Analytical studies of the Space Shuttle orbiter nose-gear tire

NASA Technical Reports Server (NTRS)

Noor, Ahmed K.; Tanner, John A.; Peters, Jeanne M.; Robinson, Martha P.

1991-01-01

A computational procedure is presented for evaluating the analytic sensitivity derivatives of the tire response with respect to material and geometrical properties of the tire. The tire is modeled by using a two-dimensional laminated anisotropic shell theory with the effects of variation in material and geometric parameters included. The computational procedure is applied to the case of the Space Shuttle orbiter nose-gear tire subjected to uniform inflation pressure. Numerical results are presented which show the sensitivity of the different tire response quantities to variations in the material characteristics of both the cord and rubber.

Improving the Estimates of International Space Station (ISS) Induced K-Factor Failure Rates for On-Orbit Replacement Unit (ORU) Supportability Analyses

NASA Technical Reports Server (NTRS)

Anderson, Leif F.; Harrington, Sean P.; Omeke, Ojei, II; Schwaab, Douglas G.

2009-01-01

This is a case study on revised estimates of induced failure for International Space Station (ISS) on-orbit replacement units (ORUs). We devise a heuristic to leverage operational experience data by aggregating ORU, associated function (vehicle sub -system), and vehicle effective' k-factors using actual failure experience. With this input, we determine a significant failure threshold and minimize the difference between the actual and predicted failure rates. We conclude with a discussion on both qualitative and quantitative improvements the heuristic methods and potential benefits to ISS supportability engineering analysis.

TDRSS system configuration study for space shuttle program

NASA Technical Reports Server (NTRS)

1978-01-01

This study was set up to assure that operation of the shuttle orbiter communications systems met the program requirements when subjected to electrical conditions similar to those which will be encountered during the operational mission. The test program intended to implement an integrated test bed, consisting of applicable orbiter, EVA, payload simulator, STDN, and AF/SCF, as well as the TDRSS equipment. The stated intention of Task 501 Program was to configure the test bed with prototype hardware for a system development test and production hardware for a system verification test. In case of TDRSS when the hardware was not available, simulators whose functional performance was certified to meet appropriate end item specification were used.

Exoplanet-induced Radio Emission from M Dwarfs

NASA Astrophysics Data System (ADS)

Turnpenney, Sam; Nichols, Jonathan D.; Wynn, Graham A.; Burleigh, Matthew R.

2018-02-01

We consider the magnetic interaction of exoplanets orbiting M dwarfs, calculating the expected Poynting flux carried upstream along Alfvén wings to the central star. A region of emission analogous to the Io footprint observed in Jupiter’s aurora is produced, and we calculate the radio flux density generated near the surface of the star via the electron-cyclotron maser instability. We apply the model to produce individual case studies for the TRAPPIST-1, Proxima Centauri, and dwarf NGTS-1 systems. We predict steady-state flux densities of up to ∼10 μJy and sporadic bursts of emission of up to ∼1 mJy from each case study, suggesting these systems may be detectable with the Very Large Array and the Giant Metrewave Radio Telescope, and perhaps the Square Kilometre Array in the future. Finally, we present a survey of 85 exoplanets orbiting M dwarfs, identifying 11 such objects capable of generating radio emission above 10 μJy.

Limit cycles in planar piecewise linear differential systems with nonregular separation line

NASA Astrophysics Data System (ADS)

Cardin, Pedro Toniol; Torregrosa, Joan

2016-12-01

In this paper we deal with planar piecewise linear differential systems defined in two zones. We consider the case when the two linear zones are angular sectors of angles α and 2 π - α, respectively, for α ∈(0 , π) . We study the problem of determining lower bounds for the number of isolated periodic orbits in such systems using Melnikov functions. These limit cycles appear studying higher order piecewise linear perturbations of a linear center. It is proved that the maximum number of limit cycles that can appear up to a sixth order perturbation is five. Moreover, for these values of α, we prove the existence of systems with four limit cycles up to fifth order and, for α = π / 2, we provide an explicit example with five up to sixth order. In general, the nonregular separation line increases the number of periodic orbits in comparison with the case where the two zones are separated by a straight line.

Using Satellite Measurements to Investigate Regional-scale Chemistry: The Case for Geostationary Observations

NASA Technical Reports Server (NTRS)

Fishman, Jack; Wozniak, Amy; Creilson, Jack

2007-01-01

One of the recommendations of the Decadal Survey that was recently released by the National Academy of Science was that of a geostationary platform from which to obtain trace gas measurements. The use of such a platform is particularly advantageous when applied to understanding the formation of regional air pollution. This study demonstrates the challenges of trying to utilize information from instruments on satellites in low-earth orbit (LEO). We also demonstrate the advantage gained through a simulation that would provide hourly observations. In this case study, we take advantage of the high resolution Level-2 orbital data available from the Ozone Monitoring Instrument (OMI), in conjunction with assimilated stratospheric column ozone fields, to evaluate if meaningful tropospheric ozone information can be obtained on a regional scale. We focus on a period on late June 2005 when a widespread pollution episode enveloped the Houston metropolitan area as well as a large region in southeast Texas.

On the life and death of satellite haloes

NASA Astrophysics Data System (ADS)

Taffoni, Giuliano; Mayer, Lucio; Colpi, Monica; Governato, Fabio

2003-05-01

We study the evolution of dark matter satellites orbiting inside more massive haloes using semi-analytical tools coupled with high-resolution N-body simulations. We select initial satellite sizes, masses, orbital energies, and eccentricities as predicted by hierarchical models of structure formation. Both the satellite (of initial mass Ms,0) and the main halo (of mass Mh) are described by a Navarro, Frenk & White density profile with various concentrations. We explore the interplay between dynamic friction and tidal mass loss/evaporation in determining the final fate of the satellite. We provide a user-friendly expression for the dynamic friction time-scale τdf,live and for the disruption time for a live (i.e. mass-losing) satellite. This can be easily implemented into existing semi-analytical models of galaxy formation improving considerably the way they describe the evolution of satellites. Massive satellites (Ms,0 > 0.1Mh) starting from typical cosmological orbits sink rapidly (irrespective of the initial circularity) toward the centre of the main halo where they merge after a time τdf,rig, as if they were rigid. Satellites of intermediate mass (0.01Mh < Ms,0 < 0.1Mh) suffer severe tidal mass losses as dynamic friction reduces their pericentre distance. In this case, mass loss increases substantially their decay time with respect to a rigid satellite. The final fate depends on the concentration of the satellite, cs, relative to that of the main halo, ch. Only in the unlikely case where cs/ch<~ 1 are satellites disrupted. In this mass range, τdf,live gives a measure of the merging time. Among the satellites whose orbits decay significantly, those that survive must have been moving preferentially on more circular orbits since the beginning as dynamical friction does not induce circularization. Lighter satellites (Ms,0 < 0.01Mh) do not suffer significant orbital decay and tidal mass loss stabilizes the orbit even further. Their orbits should map those at the time of entrance into the main halo. After more than a Hubble time satellites have masses Ms~ 1-10 per cent Ms,0, typically, implying Ms < 0.001Mh for the remnants. In a Milky-Way-like halo, light satellites should be present even after several orbital times with their baryonic components experimenting morphological changes due to tidal stirring. They coexist with the remnants of more massive satellites depleted in their dark matter content by the tidal field, which should move preferentially on tightly bound orbits.

Virtual surgical planning and 3D printing in prosthetic orbital reconstruction with percutaneous implants: a technical case report

PubMed Central

Huang, Yu-Hui; Seelaus, Rosemary; Zhao, Linping; Patel, Pravin K; Cohen, Mimis

2016-01-01

Osseointegrated titanium implants to the cranial skeleton for retention of facial prostheses have proven to be a reliable replacement for adhesive systems. However, improper placement of the implants can jeopardize prosthetic outcomes, and long-term success of an implant-retained prosthesis. Three-dimensional (3D) computer imaging, virtual planning, and 3D printing have become accepted components of the preoperative planning and design phase of treatment. Computer-aided design and computer-assisted manufacture that employ cone-beam computed tomography data offer benefits to patient treatment by contributing to greater predictability and improved treatment efficiencies with more reliable outcomes in surgical and prosthetic reconstruction. 3D printing enables transfer of the virtual surgical plan to the operating room by fabrication of surgical guides. Previous studies have shown that accuracy improves considerably with guided implantation when compared to conventional template or freehand implant placement. This clinical case report demonstrates the use of a 3D technological pathway for preoperative virtual planning through prosthesis fabrication, utilizing 3D printing, for a patient with an acquired orbital defect that was restored with an implant-retained silicone orbital prosthesis. PMID:27843356

Virtual surgical planning and 3D printing in prosthetic orbital reconstruction with percutaneous implants: a technical case report.

PubMed

Huang, Yu-Hui; Seelaus, Rosemary; Zhao, Linping; Patel, Pravin K; Cohen, Mimis

2016-01-01

Osseointegrated titanium implants to the cranial skeleton for retention of facial prostheses have proven to be a reliable replacement for adhesive systems. However, improper placement of the implants can jeopardize prosthetic outcomes, and long-term success of an implant-retained prosthesis. Three-dimensional (3D) computer imaging, virtual planning, and 3D printing have become accepted components of the preoperative planning and design phase of treatment. Computer-aided design and computer-assisted manufacture that employ cone-beam computed tomography data offer benefits to patient treatment by contributing to greater predictability and improved treatment efficiencies with more reliable outcomes in surgical and prosthetic reconstruction. 3D printing enables transfer of the virtual surgical plan to the operating room by fabrication of surgical guides. Previous studies have shown that accuracy improves considerably with guided implantation when compared to conventional template or freehand implant placement. This clinical case report demonstrates the use of a 3D technological pathway for preoperative virtual planning through prosthesis fabrication, utilizing 3D printing, for a patient with an acquired orbital defect that was restored with an implant-retained silicone orbital prosthesis.

Real weights, bound states and duality orbits

NASA Astrophysics Data System (ADS)

Marrani, Alessio; Riccioni, Fabio; Romano, Luca

2016-01-01

We show that the duality orbits of extremal black holes in supergravity theories with symmetric scalar manifolds can be derived by studying the stabilizing subalgebras of suitable representatives, realized as bound states of specific weight vectors of the corresponding representation of the duality symmetry group. The weight vectors always correspond to weights that are real, where the reality properties are derived from the Tits-Satake diagram that identifies the real form of the Lie algebra of the duality symmetry group. Both 𝒩 = 2 magic Maxwell-Einstein supergravities and the semisimple infinite sequences of 𝒩 = 2 and 𝒩 = 4 theories in D = 4 and 5 are considered, and various results, obtained over the years in the literature using different methods, are retrieved. In particular, we show that the stratification of the orbits of these theories occurs because of very specific properties of the representations: in the case of the theory based on the real numbers, whose symmetry group is maximally noncompact and therefore all the weights are real, the stratification is due to the presence of weights of different lengths, while in the other cases it is due to the presence of complex weights.

Unusual intraconal localization of orbital giant cell angiofibroma.

PubMed

Ekin, Meryem Altin; Ugurlu, Seyda Karadeniz; Cakalagaoglu, Fulya

2018-01-01

Giant cell angiofibroma (GCA) is a recently reported rare soft-tissue tumor that can develop in various sites including orbit. Orbital GCAs were mainly located in the eyelid or extraconal regions such as lacrimal gland and conjunctiva. We report an atypical case of a GCA arising in the intraconal area of the orbit in a 65-year-old male patient. The tumor was excised in total by lateral orbitotomy. Histological and immunohistochemical features were consistent with the diagnosis of GCA. No recurrence was observed during the follow-up of over 2 years. GCA is a rare tumor that should be considered in the differential diagnosis of intraconal orbital tumors. Complete surgical removal is the current optimal treatment option.

Pyrite oxidation and reduction - Molecular orbital theory considerations. [for geochemical redox processes

NASA Technical Reports Server (NTRS)

Luther, George W., III

1987-01-01

In this paper, molecular orbital theory is used to explain a heterogeneous reaction mechanism for both pyrite oxidation and reduction. The mechanism demonstrates that the oxidation of FeS2 by Fe(3+) may occur as a result of three important criteria: (1) the presence of a suitable oxidant having a vacant orbital (in case of liquid phase) or site (solid phase) to bind to the FeS2 via sulfur; (2) the initial formation of a persulfido (disulfide) bridge between FeS2 and the oxidant, and (3) an electron transfer from a pi(asterisk) orbital in S2(2-) to a pi or pi(asterisk) orbital of the oxidant.

Management of periorbital basal cell carcinoma with orbital invasion.

PubMed

Sun, Michelle T; Wu, Albert; Figueira, Edwin; Huilgol, Shyamala; Selva, Dinesh

2015-11-01

Basal cell carcinoma (BCC) is the most common eyelid malignancy; however, orbital invasion by periocular BCC is rare, and management remains challenging. Established risk factors for orbital invasion by BCC include male gender, advanced age, medial canthal location, previous recurrences, large tumor size, aggressive histologic subtype and perineural invasion. Management requires a multidisciplinary approach with orbital exenteration remaining the treatment of choice. Globe-sparing treatment may be appropriate in selected patients and radiotherapy and chemotherapy are often used as adjuvant therapies for advanced or inoperable cases, although the evidence remains limited. We aim to summarize the presentation and treatment of BCC with orbital invasion to better guide the management of this complex condition.

A Survey of Exoplanetary Spin-Orbit Angles

NASA Astrophysics Data System (ADS)

Winn, Josh

2010-02-01

Are the orbits of exoplanets aligned with the spin axes of their parent stars? One might expect a close alignment, but some of the proposed migration mechanisms predict otherwise. Indeed at least 4 planets with strongly tilted orbits are now known, including the first case of a retrograde or polar orbit. This raises the questions of how commonly misalignments occur, and which types of planets have them. We request 10 half-nights with Keck/HIRES spread over 2010A and 2010B, to measure spin-orbit angles for 9 exoplanets spanning a range of masses, periods, and eccentricities. Our measurement is based on the Rossiter-McLaughlin effect: the anomalous Doppler shift observed during planetary transits.

A Survey of Exoplanetary Spin-Orbit Angles

NASA Astrophysics Data System (ADS)

Winn, Josh

2010-08-01

Are the orbits of exoplanets aligned with the spin axes of their parent stars? One might expect a close alignment, but some of the proposed migration mechanisms predict otherwise. Indeed at least 4 planets with strongly tilted orbits are now known, including the first case of a retrograde or polar orbit. This raises the questions of how commonly misalignments occur, and which types of planets have them. We request 4 half-nights with Keck/HIRES spread over the 2010B semester, to measure spin-orbit angles for 4 exoplanets spanning a range of masses, periods, and eccentricities. Our measurement is based on the Rossiter-McLaughlin effect: the anomalous Doppler shift observed during planetary transits.

Charge Transfer and Orbital Level Alignment at Inorganic/Organic Interfaces: The Role of Dielectric Interlayers.

PubMed

Hollerer, Michael; Lüftner, Daniel; Hurdax, Philipp; Ules, Thomas; Soubatch, Serguei; Tautz, Frank Stefan; Koller, Georg; Puschnig, Peter; Sterrer, Martin; Ramsey, Michael G

2017-06-27

It is becoming accepted that ultrathin dielectric layers on metals are not merely passive decoupling layers, but can actively influence orbital energy level alignment and charge transfer at interfaces. As such, they can be important in applications ranging from catalysis to organic electronics. However, the details at the molecular level are still under debate. In this study, we present a comprehensive analysis of the phenomenon of charge transfer promoted by a dielectric interlayer with a comparative study of pentacene adsorbed on Ag(001) with and without an ultrathin MgO interlayer. Using scanning tunneling microscopy and photoemission tomography supported by density functional theory, we are able to identify the orbitals involved and quantify the degree of charge transfer in both cases. Fractional charge transfer occurs for pentacene adsorbed on Ag(001), while the presence of the ultrathin MgO interlayer promotes integer charge transfer with the lowest unoccupied molecular orbital transforming into a singly occupied and singly unoccupied state separated by a large gap around the Fermi energy. Our experimental approach allows a direct access to the individual factors governing the energy level alignment and charge-transfer processes for molecular adsorbates on inorganic substrates.

[A study on pathology and immunoglobulin of orbital tissues from cases with Grave's ophthalmopathy].

PubMed

Zhou, X; Luo, Q; Xia, R

1999-07-01

To investigate pathological changes and the expression, localization of immunoglobulins (IgA & IgE) in orbital tissues from patients with Grave's ophthalmopathy. Orbital tissues were obtained at surgery from 19 patients with Grave's ophthalmopathy and 17 control subjects. Immunohistochemical studies were carried out by using anti-IgA, anti-IgE antibody and a streptavidin-biotin-peroxidase detection system. In addition, hematoxylin-eosin, alcian blue and Masson trichrome stains were employed to demonstrate the pathologic changes in the tissues. 12 of 17 samples from patients exhibited IgA positive staining for the connective tissue associated with the extraocular muscles and orbicularis oculi, however only 2 control muscles reacted minimally. IgE positive material was found in association with the majority of leukocytes and with muscle fibers in 13 patients, but only 4 control subjects displayed mild reactions. Significant expression of IgE was more often demonstrated in patients with eye disease of short course than in those of longer course. These results support the notion that the eye muscle fiber and fibroblast are important targets of the orbital autoimmune reaction in Graves' ophthalmopathy in which IgA and IgE both play important roles.

DFT study of ethyl xanthate interaction with sphalerite (1 1 0) surface in the absence and presence of copper

NASA Astrophysics Data System (ADS)

Liu, Jian; Wen, Shuming; Deng, Jiushuai; Chen, Xiumin; Feng, Qicheng

2014-08-01

The interaction among sphalerite (1 1 0) surface, copper and ethyl xanthate (EX) was simulated using the density functional theory (DFT). The results of DFT indicate that four types of stable interaction models exist among sphalerite surface, copper and EX, i.e., EX interacts with the Cu substituted for Zn, Cu adsorbed on the top site of S, Cu adsorbed on the bridge site of S and Cu(OH)2 adsorbed on the sphalerite surface. The four interaction models can result in the activation flotation of sphalerite. Density of states (DOS) analysis shows that the energy level discrepancy of the Zn 3d orbital in ZnS and the bonding S 3p orbital in EX results in the weak adsorption of EX on un-activated sphalerite surface. However, after copper activation, the Cu 3d orbital peak and bonding S 3p orbital peak are just maximally overlapped nearby the Fermi level. This study provides an insight into the nature that sphalerite responds not well to EX and also a comprehensive understanding on the possible interaction cases existing among sphalerite surface, copper and EX.

Gauge-origin dependence in electronic g-tensor calculations

NASA Astrophysics Data System (ADS)

Glasbrenner, Michael; Vogler, Sigurd; Ochsenfeld, Christian

2018-06-01

We present a benchmark study on the gauge-origin dependence of the electronic g-tensor using data from unrestricted density functional theory calculations with the spin-orbit mean field ansatz. Our data suggest in accordance with previous studies that g-tensor calculations employing a common gauge-origin are sufficiently accurate for small molecules; however, for extended molecules, the introduced errors can become relevant and significantly exceed the basis set error. Using calculations with the spin-orbit mean field ansatz and gauge-including atomic orbitals as a reference, we furthermore show that the accuracy and reliability of common gauge-origin approaches in larger molecules depends strongly on the locality of the spin density distribution. We propose a new pragmatic ansatz for choosing the gauge-origin which takes the spin density distribution into account and gives reasonably accurate values for molecules with a single localized spin center. For more general cases like molecules with several spatially distant spin centers, common gauge-origin approaches are shown to be insufficient for consistently achieving high accuracy. Therefore the computation of g-tensors using distributed gauge-origin methods like gauge-including atomic orbitals is considered as the ideal approach and is recommended for larger molecular systems.

Minimum Number of Observation Points for LEO Satellite Orbit Estimation by OWL Network

NASA Astrophysics Data System (ADS)

Park, Maru; Jo, Jung Hyun; Cho, Sungki; Choi, Jin; Kim, Chun-Hwey; Park, Jang-Hyun; Yim, Hong-Suh; Choi, Young-Jun; Moon, Hong-Kyu; Bae, Young-Ho; Park, Sun-Youp; Kim, Ji-Hye; Roh, Dong-Goo; Jang, Hyun-Jung; Park, Young-Sik; Jeong, Min-Ji

2015-12-01

By using the Optical Wide-field Patrol (OWL) network developed by the Korea Astronomy and Space Science Institute (KASI) we generated the right ascension and declination angle data from optical observation of Low Earth Orbit (LEO) satellites. We performed an analysis to verify the optimum number of observations needed per arc for successful estimation of orbit. The currently functioning OWL observatories are located in Daejeon (South Korea), Songino (Mongolia), and Oukaïmeden (Morocco). The Daejeon Observatory is functioning as a test bed. In this study, the observed targets were Gravity Probe B, COSMOS 1455, COSMOS 1726, COSMOS 2428, SEASAT 1, ATV-5, and CryoSat-2 (all in LEO). These satellites were observed from the test bed and the Songino Observatory of the OWL network during 21 nights in 2014 and 2015. After we estimated the orbit from systematically selected sets of observation points (20, 50, 100, and 150) for each pass, we compared the difference between the orbit estimates for each case, and the Two Line Element set (TLE) from the Joint Space Operation Center (JSpOC). Then, we determined the average of the difference and selected the optimal observation points by comparing the average values.

Optimised low-thrust mission to the Atira asteroids

NASA Astrophysics Data System (ADS)

Di Carlo, Marilena; Romero Martin, Juan Manuel; Ortiz Gomez, Natalia; Vasile, Massimiliano

2017-04-01

Atira asteroids are recently-discovered celestial bodies characterised by orbits lying completely inside the heliocentric orbit of the Earth. The study of these objects is difficult due to the limitations of ground-based observations: objects can only be detected when the Sun is not in the field of view of the telescope. However, many asteroids are expected to exist in the inner region of the Solar System, many of which could pose a significant threat to our planet. In this paper, a small, low-cost, mission to visit the known Atira asteroids and to discover new Near Earth Asteroids (NEA) is proposed. The mission is realised using electric propulsion. The trajectory is optimised to maximise the number of visited asteroids of the Atira group using the minimum propellant consumption. During the tour of the Atira asteroids an opportunistic NEA discovery campaign is proposed to increase our knowledge of the asteroid population. The mission ends with a transfer to an orbit with perihelion equal to Venus's orbit radius. This orbit represents a vantage point to monitor and detect asteroids in the inner part of the Solar System and provide early warning in the case of a potential impact.

Electric Propulsion for Low Earth Orbit Constellations

NASA Technical Reports Server (NTRS)

Oleson, Steven R.; Sankovic, John M.

1998-01-01

Hall Effect electric propulsion was evaluated for orbit insertion, satellite repositioning, orbit maintenance and de-orbit applications for a sample low earth orbit satellite constellation. Since the low masses of these satellites enable multiple spacecraft per launch, the ability to add spacecraft to a given launch was used as a figure of merit. When compared to chemical propulsion, the Hall thruster system can add additional spacecraft per launch using planned payload power levels. One satellite can be added to the assumed four satellite baseline chemical launch without additional mission times. Two or three satellites may be added by providing part of the orbit insertion with the Hall system. In these cases orbit insertion times were found to be 35 and 62 days. Depending on the electric propulsion scenario, the resulting launch vehicle savings is nearly two, three or four Delta 7920 launch vehicles out of the chemical baseline scenarios eight Delta 7920 launch vehicles.

Electric Propulsion for Low Earth Orbit Constellations

NASA Technical Reports Server (NTRS)

Oleson, Steven R.; Sankovic, John M.

1998-01-01

Hall effect electric propulsion was evaluated for orbit insertion, satellite repositioning, orbit maintenance and de-orbit applications for a sample low earth orbit satellite constellation. Since the low masses of these satellites enable multiple spacecraft per launch, the ability to add spacecraft to a given launch was used as a figure of merit. When compared to chemical propulsion, the Hall thruster system can add additional spacecraft per launch using planned payload power levels. One satellite can be added to the assumed four satellite baseline chemical launch without additional mission times. Two or three satellites may be added by providing part of the orbit insertion with the Hall system. In these cases orbit insertion times were found to be 35 and 62 days. Depending, on the electric propulsion scenario, the resulting launch vehicle savings is nearly two, three or four Delta 7920 launch vehicles out of the chemical baseline scenario's eight Delta 7920 launch vehicles.

Some considerations on measuring the Newtonian gravitational constant G in an orbiting laboratory

NASA Technical Reports Server (NTRS)

Baker, Stephen D.

1986-01-01

A common suggestion for measuring the Newtonian gravitational constant G in a near-earth orbiting laboratory is simply to put two balls in orbit around each other and observe the resulting motion, thereby determining G. However, the radial variation with distance of the gravitational field of the earth is so large that tidal forces on the balls in near-earth orbit can be several times greater than the gravitational attraction between the two masses, leading some writers to assume that two objects will not stably orbit about each other and that this method of measuring G in low-earth is impossible, or at least impractical. Certain orbits were identified which are stable (at least over many periods of the spacecraft about the earth). In this case, the objects experience their gravitational interaction for a long time, and it becomes reasonable to consider such orbits as candidates for measurements of G.

Acute Acquired Concomitant Esotropia

PubMed Central

Chen, Jingchang; Deng, Daming; Sun, Yuan; Shen, Tao; Cao, Guobin; Yan, Jianhua; Chen, Qiwen; Ye, Xuelian

2015-01-01

Abstract Acute acquired concomitant esotropia (AACE) is a rare, distinct subtype of esotropia. The purpose of this retrospective study was to describe the clinical characteristics and discuss the classification and etiology of AACE. Charts from 47 patients with AACE referred to our institute between October 2010 and November 2014 were reviewed. All participants underwent a complete medical history, ophthalmologic and orthoptic examinations, and brain and orbital imaging. Mean age at onset was 26.6 ± 12.2 years. Of the 18 cases with deviations ≤ 20 PD, 16 presented with diplopia at distance and fusion at near vision at the onset of deviation; differences between distance and near deviations were < 8 PD; all cases except one were treated with prism and diplopia resolved. Of the 29 cases with deviations > 20 PD, 5 were mild hypermetropic with age at onset between 5 and 19 years, 16 were myopic, and 8 were emmetropic with age at onset > 12 years; 24 were surgically treated and 5 cases remained under observation; all 24 cases achieved normal retinal correspondence or fusion or stereopsis on postoperative day 1 in synoptophore; in 23 cases diplopia or visual confusion resolved postoperatively. Of the 47 cases, brain and orbital imaging in 2 cases revealed a tumor in the cerebellopontine angle and 1 case involved spinocerebellar ataxia as revealed by genetic testing. AACE in this study was characterized by a sudden onset of concomitant nonaccommodative esotropia with diplopia or visual confusion at 5 years of age or older and the potential for normal binocular vision. We suggest that AACE can be divided into 2 subgroups consisting of patients with relatively small versus large angle deviations. Coexisting or underlying neurological diseases were infrequent in AACE. PMID:26705210

Asteroid-type orbit evolution near the 5:2 resonance

NASA Technical Reports Server (NTRS)

Ipatov, S. I.

1992-01-01

In this case of the 5:2 commensurability with the motion of Jupiter, an asteroid can reach the orbits of Mars, Earth, and Venus when eccentricity e is greater than 0.41, 0.65, and 0.74, respectively. For individual fictitious asteroids, Ipatov and Yoshikawa obtained a growth in e from 0.15 to 074-0.76. Rates of changes in orbital orientations are different for Mars, Earth, Venus, and the asteroid. Therefore, for corresponding values of e, the asteroid could encounter these planets and leave the gap at those encounters. In order to investigate this hypothesis of the 5:2 Kirkwood gap formation, Ipatov studied the regions of initial data for which the eccentricities of asteroids located near the 5:2 commensurability exceeded 0.41 during evolution. The orbit evolution for 500 fictitious asteroids was investigated by numerical integration of the complete (unaveraged) equations of motion for the three-body problem (Sun-Jupiter-asteroid). The equations of motion were integrated in the time intervals T is greater than or equal to 5(10)(exp 3)t(sub J) (t(sub J) is the heliocentric orbital period of Jupiter) in the planar model, T is greater than or equal to 10(exp 4)t(sub J) at initial inclination 5 deg is less than or equal to i(sub 0) is less than or equal to 20 deg and T = 10(exp 5)t(sub J) at i(sub 0) = 40 deg. The larger interval T was taken at i(sub 0) = 40 deg because in this case for the majority of runs maximum values of e and i were reached in the time delta(t) is greater than 2(10)(exp 4)t(sub J).

Pluto and Charon: A Case of Precession-Orbit Resonance?

NASA Technical Reports Server (NTRS)

Rubincam, David Parry; Smith, David E. (Technical Monitor)

2000-01-01

Pluto may be the only known case of precession-orbit resonance in the solar system. The Pluto-Charon system orbits the Sun with a period of 1 Plutonian year, which is 250.8 Earth years. The observed parameters of the system are such that Charon may cause Pluto to precess with a period near 250.8 Earth years. This gives rise to two possible resonances, heretofore unrecognized. The first is due to Pluto's orbit being highly eccentric, giving solar torques on Charon with a period of 1 Plutonian year. Charon in turn drives Pluto near its precession period. Volatiles, which are expected to shuttle across Pluto's surface between equator and pole as Pluto's obliquity oscillates, might change the planet's dynamical flattening enough so that Pluto crosses the nearby resonance, forcing the planet's equatorial plane to depart from Charon's orbital plane. The mutual tilt can reach as much as 2 deg after integrating over 5.6 x 10(exp 6) years, depending upon how close Pluto is to the resonance and the supply of volatiles. The second resonance is due to the Sun's traveling above and below Charon's orbital plane; it has a period half that of the eccentricity resonance. Reaching this half-Plutonian year resonance requires a much larger but still theoretically possible amount of volatiles. In this case the departure of Charon from an equatorial orbit is about 1 deg after integrating for 5.6 x 10(exp 6) years. The calculations ignore libration and tidal friction. It is not presently known how large the mutual tilt can grow over the age of the solar system, but if it remains only a few degrees, then observing such small angles from a Pluto flyby mission would be difficult. It is not clear why the parameters of the Pluto-Charon system are so close to the eccentricity resonance.

Electronic Properties of Cyclacenes from TAO-DFT

PubMed Central

Wu, Chun-Shian; Lee, Pei-Yin; Chai, Jeng-Da

2016-01-01

Owing to the presence of strong static correlation effects, accurate prediction of the electronic properties (e.g., the singlet-triplet energy gaps, vertical ionization potentials, vertical electron affinities, fundamental gaps, symmetrized von Neumann entropy, active orbital occupation numbers, and real-space representation of active orbitals) of cyclacenes with n fused benzene rings (n = 4–100) has posed a great challenge to traditional electronic structure methods. To meet the challenge, we study these properties using our newly developed thermally-assisted-occupation density functional theory (TAO-DFT), a very efficient method for the study of large systems with strong static correlation effects. Besides, to examine the role of cyclic topology, the electronic properties of cyclacenes are also compared with those of acenes. Similar to acenes, the ground states of cyclacenes are singlets for all the cases studied. In contrast to acenes, the electronic properties of cyclacenes, however, exhibit oscillatory behavior (for n ≤ 30) in the approach to the corresponding properties of acenes with increasing number of benzene rings. On the basis of the calculated orbitals and their occupation numbers, the larger cyclacenes are shown to exhibit increasing polyradical character in their ground states, with the active orbitals being mainly localized at the peripheral carbon atoms. PMID:27853249

Improvements to a Response Surface Thermal Model for Orion Mated to the International Space Station

NASA Technical Reports Server (NTRS)

Miller, StephenW.; Walker, William Q.

2011-01-01

This study is an extension of previous work to evaluate the applicability of Design of Experiments (DOE)/Response Surface Methodology to on-orbit thermal analysis. The goal was to determine if the methodology could produce a Response Surface Equation (RSE) that predicted the thermal model temperature results within +/-10 F. An RSE is a polynomial expression that can then be used to predict temperatures for a defined range of factor combinations. Based on suggestions received from the previous work, this study used a model with simpler geometry, considered polynomials up to fifth order, and evaluated orbital temperature variations to establish a minimum and maximum temperature for each component. A simplified Outer Mold Line (OML) thermal model of the Orion spacecraft was used in this study. The factors chosen were the vehicle's Yaw, Pitch, and Roll (defining the on-orbit attitude), the Beta angle (restricted to positive beta angles from 0 to 75), and the environmental constants (varying from cold to hot). All factors were normalized from their native ranges to a non-dimensional range from -1.0 to 1.0. Twenty-three components from the OML were chosen and the minimum and maximum orbital temperatures were calculated for each to produce forty-six responses for the DOE model. A customized DOE case matrix of 145 analysis cases was developed which used analysis points at the factor corners, mid-points, and center. From this data set, RSE s were developed which consisted of cubic, quartic, and fifth order polynomials. The results presented are for the fifth order RSE. The RSE results were then evaluated for agreement with the analytical model predictions to produce a +/-3(sigma) error band. Forty of the 46 responses had a +/-3(sigma) value of 10 F or less. Encouraged by this initial success, two additional sets of verification cases were selected. One contained 20 cases, the other 50 cases. These cases were evaluated both with the fifth order RSE and with the analytical model. For the maximum temperature predictions, 12 of the 23 components had all predictions within +/-10 F and 17 were within +/-20 F. For the minimum temperature predictions, only 4 of the 23 components (the four radiator temperatures), were within the 10 F goal. The maximum temperature RSEs were then run through 59,049 screening cases. The RSE predictions were then filtered to find 55 cases that produced the hottest temperatures. These 55 cases were then analyzed using the thermal model and the results compared against the RSE predictions. As noted earlier, 12 of the 23 responses were within +/-10 F at 17 within +/-20 F. These results demonstrate that if properly formulated, an RSE can provide a reliable, fast temperature prediction. Despite this progress, additional work is needed to determine why the minimum temperatures responses and 6 of the hot temperature responses did not produce reliable RSEs. Recommend focus areas are the model itself (arithmetic vs. diffusion nodes) and seeking consultations with statistical application experts.

Comparison of mission design options for manned Mars missions

NASA Technical Reports Server (NTRS)

Babb, Gus R.; Stump, William R.

1986-01-01

A number of manned Mars mission types, propulsion systems, and operational techniques are compared. Conjunction and opposition class missions for cryogenic, hybrid (cryo/storable), and NERVA propulsion concepts are addressed. In addition, both Earth and Mars orbit aerobraking, direct entry of landers, hyperbolic rendezvous, and electric propulsion cases are examined. A common payload to Mars was used for all cases. The basic figure of merit used was weight in low Earth orbit (LEO) at mission initiation. This is roughly proportional to launch costs.

The variations in eccentricity and apse precession rate of a narrow ring perturbed by a close satellite

NASA Technical Reports Server (NTRS)

Borderies, N.; Goldreich, P.; Tremaine, S.

1983-01-01

The first-order perturbations of orbital eccentricity and apse precession rate for the case of a narrow ring, due to a close satellite whose orbit is also eccentric, are described by means of a Hamiltonian. The present treatment covers cases in which the satellite crosses the ring, and the level curves of the Hamiltonian are displayed for several parameter values. The results obtained are applied to the interaction of Saturn's F ring with its inner shepherd satellite.

Frontal and orbital bone infarctions causing periorbital swelling in patients with sickle cell anemia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garty, I.; Koren, A.; Garzozi, H.

1984-10-01

Two cases of unilateral and bilateral periorbital hematomas occurred in patients with sickle cell anemia. The cause of periorbital swelling in these cases was found to be orbital and frontal bone infarctions, respectively, diagnosed by technetium Tc 99m medronate bone scintigraphy. To our knowledge, periorbital bone infarction, as a part of the differential diagnosis of periorbital hematoma and as part of the possible ocular manifestations in patients with sickle cell anemia, has not previously been described.

Multifocal amelanotic conjunctival melanoma and acquired melanosis sine pigmento.

PubMed Central

Paridaens, A D; McCartney, A C; Hungerford, J L

1992-01-01

Clinical and histopathological features of four cases of multifocal amelanotic malignant melanoma of the conjunctiva in association with 'acquired melanosis sine pigmento' are reported. The absence of conjunctival pigmentation in this extremely rare combination of lesions prevented early diagnosis and clinical monitoring. As a result orbital exenteration was required in three cases. This multicentric non-pigmented variety of conjunctival malignant melanoma tends to present later than pigmented forms and may require exenteration of the orbit as a primary procedure. Images PMID:1540561

Multifocal amelanotic conjunctival melanoma and acquired melanosis sine pigmento.

PubMed

Paridaens, A D; McCartney, A C; Hungerford, J L

1992-03-01

Clinical and histopathological features of four cases of multifocal amelanotic malignant melanoma of the conjunctiva in association with 'acquired melanosis sine pigmento' are reported. The absence of conjunctival pigmentation in this extremely rare combination of lesions prevented early diagnosis and clinical monitoring. As a result orbital exenteration was required in three cases. This multicentric non-pigmented variety of conjunctival malignant melanoma tends to present later than pigmented forms and may require exenteration of the orbit as a primary procedure.

Orbital apex syndrome secondary to a fungal nasal septal abscess caused by Scedosporium apiospermum in a patient with uncontrolled diabetes: a case report.

PubMed

Kishimoto, Ippei; Shinohara, Shogo; Ueda, Tetsuhiro; Tani, Shoichi; Yoshimura, Hajime; Imai, Yukihiro

2017-09-26

Orbital apex syndrome is a localized type of orbital cellulitis, where mass lesions occur at the apex of the cranial nerves. Although nasal septal abscess is uncommon, the organism most likely to cause nasal septal abscess is Staphylococcus aureus, and fungal septal abscesses are rare. Here we present an extremely rare and serious case of orbital apex syndrome secondary to fungal nasal septal abscess caused by Scedosporium apiospermum in a patient with uncontrolled diabetes. A 59-year-old man with a 1-month history of headache underwent consultation in an otolaryngological clinic of a general hospital. He was diagnosed with nasal septal abscess and was treated with incisional drainage and 1 month of an antibiotic drip; however, his symptoms persisted. The patient later complained of diplopia due to bilateral abducens nerve palsy, and was then referred to the department of Otolaryngology - Head and Neck Surgery, Kobe City Medical Center General Hospital. The septal lesion was biopsied under general anesthesia, and S. apiospermum was detected using polymerase chain reaction. The patient was treated with an antifungal drug and surgical resection of the lesion was performed. Although the patient survived, he lost his eyesight. This patient represents the second reported case of nasal septal abscess and orbital apex syndrome caused by S. apiospermum. If not treated properly, septal abscess can be life-threatening and cause severe complications, such as ablepsia.

Orbit-associated tumors: navigation and control of resection using intraoperative computed tomography.

PubMed

Terpolilli, Nicole A; Rachinger, Walter; Kunz, Mathias; Thon, Niklas; Flatz, Wilhelm H; Tonn, Jörg-Christian; Schichor, Christian

2016-05-01

OBJECT Treatment of skull base lesions is complex and usually requires a multidisciplinary approach. In meningioma, which is the most common tumor entity in this region, resection is considered to be the most important therapeutic step to avoid tumor recurrence. However, resection of skull base lesions with orbital or optic nerve involvement poses a challenge due to their anatomical structure and their proximity to eloquent areas. Therefore the main goal of surgery should be to achieve the maximum extent of resection while preserving neurological function. In the postoperative course, medical and radiotherapeutic strategies may then be successfully used to treat possible tumor residues. Methods to safely improve the extent of resection in skull base lesions therefore are desirable. The current study reports the authors' experience with the use of intraoperative CT (iCT) combined with neuronavigation with regard to feasibility and possible benefits of the method. METHODS Those patients with tumorous lesions in relationship to the orbit, sphenoid wing, or cavernous sinus who were surgically treated between October 2008 and December 2013 using iCT-based neuronavigation and in whom an intraoperative scan was obtained for control of resection were included. In all cases a second iCT scan was performed under sterile conditions after completion of navigation-guided microsurgical tumor resection. The surgical strategy was adapted accordingly; if necessary, resection was continued. RESULTS Twenty-three patients (19 with WHO Grade I meningioma and 4 with other lesions) were included. The most common clinical symptoms were loss of visual acuity and exophthalmus. Intraoperative control of resection by iCT was successfully obtained in all cases. Intraoperative imaging changed the surgical approach in more than half (52.2%) of these patients, either because iCT demonstrated unexpected residual tumor masses or because the second scan revealed additional tumor tissue that was not detected in the first scan due to overlay by osseous tumor parts; in these cases resection was continued. In the remaining cases resection was concluded as planned because iCT verified the surgeon's microscopic estimation of tumor resection status. Postoperative visual outcome was favorable in more than 80% of patients. CONCLUSIONS Intraoperative CT allows control of resection in case of uncertainty and can help to improve the extent of maximal safe resection, especially in case of osseous tumor parts and masses within the orbit.

Tidal synchronization of an anelastic multi-layered body: Titan's synchronous rotation

NASA Astrophysics Data System (ADS)

Folonier, Hugo A.; Ferraz-Mello, Sylvio

2017-12-01

Tidal torque drives the rotational and orbital evolution of planet-satellite and star-exoplanet systems. This paper presents one analytical tidal theory for a viscoelastic multi-layered body with an arbitrary number of homogeneous layers. Starting with the static equilibrium figure, modified to include tide and differential rotation, and using the Newtonian creep approach, we find the dynamical equilibrium figure of the deformed body, which allows us to calculate the tidal potential and the forces acting on the tide generating body, as well as the rotation and orbital elements variations. In the particular case of the two-layer model, we study the tidal synchronization when the gravitational coupling and the friction in the interface between the layers is added. For high relaxation factors (low viscosity), the stationary solution of each layer is synchronous with the orbital mean motion ( n) when the orbit is circular, but the rotational frequencies increase if the orbital eccentricity increases. This behavior is characteristic in the classical Darwinian theories and in the homogeneous case of the creep tide theory. For low relaxation factors (high viscosity), as in planetary satellites, if friction remains low, each layer can be trapped in different spin-orbit resonances with frequencies n/2,n,3n/2,2n,\\ldots . When the friction increases, attractors with differential rotations are destroyed, surviving only commensurabilities in which core and shell have the same velocity of rotation. We apply the theory to Titan. The main results are: (i) the rotational constraint does not allow us to confirm or reject the existence of a subsurface ocean in Titan; and (ii) the crust-atmosphere exchange of angular momentum can be neglected. Using the rotation estimate based on Cassini's observation (Meriggiola et al. in Icarus 275:183-192, 2016), we limit the possible value of the shell relaxation factor, when a deep subsurface ocean is assumed, to γ _s≲ 10^{-9} s^{-1}, which corresponds to a shell's viscosity η _s≳ 10^{18} Pa s, depending on the ocean's thickness and viscosity values. In the case in which a subsurface ocean does not exist, the maximum shell relaxation factor is one order of magnitude smaller and the corresponding minimum shell's viscosity is one order higher.

[Therapy of orbital neoplasms in small animals].

PubMed

Spiess, B M; Rühli, M B; Bauer, G A

1995-10-01

The incidence, clinical signs and diagnostic work-up of orbital neoplasms is briefly discussed. The surgical management of such tumors is discussed in detail on the basis of three clinical cases. Long-term functional and cosmetic results are shown. Intraoperative and postoperative complications are discussed.

Proposal for extension of ORSA to include phasing in to prove successive encounters of an asteroid between Earth and Mars

NASA Astrophysics Data System (ADS)

Jolitz, Benjamin

Ben Jolitz 2/6/10 Proposal for extension of ORSA to include phasing in to prove successive encounters of an asteroid between Earth and Mars Phasing is the act of changing the phase angle between two sinusoidal functions. In the case of orbits, which are ellipses drawn by sinusoidal functions, phasing is the act of matching one orbit to another. Finding the phasing parameters of a captured asteroid, a non-Keplarian object, in a resonant bi-elliptic orbit and simulation thereof is rather difficult without specialized and esoteric applications. However, open source in the last ten years has made incredible advance-ments, and some projects originally designed for orbital reconstruction have been released to the public on an AS IS basis; one such project is ORSA -Orbital Reconstruction, Simulation, Analysis. ORSA, however, does not have methods for evaluating the relative changes to a phase angle of a bi-elliptic orbit in a recursive manner for successive encounters. For years, space shuttles and other celestial transport vessels have been faced with the difficulty of docking with the International Space Station, a task which involves matching the craft to the unique elliptical orbit of the ISS such that the shuttle will meet the ISS with the appropriate orbital parameters. However, calculation of such requires consideration of only the Earth and it's effect on rather small, man-made objects. In electrical engineering, the concept of a phase lock loop is used to match the frequency and phase of a controlled oscillator with a given set of input signals. In our test case, we wish compute the successive bi-elliptic half orbits of a captured asteroid that traverses between Earth and Mars using gravitational interactions with the intent of computing the relative phase angle between the desired half orbit and current orbit such that a timed encounter with Earth or Mars is possible. The goal of this proposal is to extend ORSA to maintain relative phase angle between bi-elliptic orbits for successive encounters.

Modeling Photodetachment from HO2- Using the pd Case of the Generalized Mixed Character Molecular Orbital Model

NASA Astrophysics Data System (ADS)

Blackstone, Christopher C.; Sanov, Andrei

2016-06-01

Using the generalized model for photodetachment of electrons from mixed-character molecular orbitals, we gain insight into the nature of the HOMO of HO2- by treating it as a coherent superpostion of one p- and one d-type atomic orbital. Fitting the pd model function to the ab initio calculated HOMO of HO2- yields a fractional d-character, γp, of 0.979. The modeled curve of the anisotropy parameter, β, as a function of electron kinetic energy for a pd-type mixed character orbital is matched to the experimental data.

Exact solutions for a type of electron pairing model with spin-orbit interactions and Zeeman coupling.

PubMed

Liu, Jia; Han, Qiang; Shao, L B; Wang, Z D

2011-07-08

A type of electron pairing model with spin-orbit interactions or Zeeman coupling is solved exactly in the framework of the Richardson ansatz. Based on the exact solutions for the case with spin-orbit interactions, it is shown rigorously that the pairing symmetry is of the p + ip wave and the ground state possesses time-reversal symmetry, regardless of the strength of the pairing interaction. Intriguingly, how Majorana fermions can emerge in the system is also elaborated. Exact results are illustrated for two systems, respectively, with spin-orbit interactions and Zeeman coupling.

In-Orbit Operation of the ASTRO-H SXS

NASA Technical Reports Server (NTRS)

Tsujimoto, Masahiro; Mitsuda, Kazuhisa; Kelley, Richard L.; den Herder, Jan-Willem A.; Akamatsu, Hiroki; Bialas, Thomas G.; Boyce, Kevin R.; Brown, Gregory V.; Chiao, Meng P.; Costantini, Elisa;

In-Orbit Operation of the ASTRO-H SXS

NASA Technical Reports Server (NTRS)

Tsujimoto, Masahiro; Mitsuda, Kazuhisa; Kelley, Richard L.; den Herder, Jan-Willem A.; Akamatsu, Hiroki; Bialas, Thomas G.; Boyce, Kevin R.; Brown, Gregory V.; Chiao, Meng P.; Costantini, Elisa;

In-orbit operation of the ASTRO-H SXS

NASA Astrophysics Data System (ADS)

Tsujimoto, Masahiro; Mitsuda, Kazuhisa; Kelley, Richard L.; den Herder, Jan-Willem A.; Akamatsu, Hiroki; Bialas, Thomas G.; Boyce, Kevin R.; Brown, Gregory V.; Chiao, Meng P.; Costantini, Elisa; de Vries, Cor P.; DiPirro, Michael J.; Eckart, Megan E.; Ezoe, Yuichiro; Fujimoto, Ryuichi; Haas, Daniel; Hoshino, Akio; Ishikawa, Kumi; Ishisaki, Yoshitaka; Iyomoto, Naoko; Kilbourne, Caroline A.; Kitamoto, Shunji; Koyama, Shu; Leutenegger, Maurice A.; McCammon, Dan; Mitsuishi, Ikuyuki; Murakami, Hiroshi; Murakami, Masahide; Noda, Hirofumi; Ogawa, Mina; Ota, Naomi; Paltani, Stéphane; Porter, Frederick S.; Sato, Kosuke; Sato, Yoichi; Sawada, Makoto; Seta, Hiromi; Shinozaki, Keisuke; Shirron, Peter J.; Sneiderman, Gary A.; Sugita, Hiroyuki; Szymkowiak, Andrew E.; Takei, Yoh; Tamagawa, Toru; Tashiro, Makoto S.; Terada, Yukikatsu; Yamada, Shinya; Yamasaki, Noriko Y.; Yatsu, Yoichi

2016-07-01

We summarize all the in-orbit operations of the Soft X-ray Spectrometer (SXS) onboard the ASTRO-H (Hit- omi) satellite. The satellite was launched on 2016/02/17 and the communication with the satellite ceased on 2016/03/26. The SXS was still in the commissioning phase, in which the setups were progressively changed. This article is intended to serve as a reference of the events in the orbit to properly interpret the SXS data taken during its short life time, and as a test case for planning the in-orbit operation for future micro-calorimeter missions.

Geographically correlated orbit error

NASA Technical Reports Server (NTRS)

Rosborough, G. W.

1989-01-01

The dominant error source in estimating the orbital position of a satellite from ground based tracking data is the modeling of the Earth's gravity field. The resulting orbit error due to gravity field model errors are predominantly long wavelength in nature. This results in an orbit error signature that is strongly correlated over distances on the size of ocean basins. Anderle and Hoskin (1977) have shown that the orbit error along a given ground track also is correlated to some degree with the orbit error along adjacent ground tracks. This cross track correlation is verified here and is found to be significant out to nearly 1000 kilometers in the case of TOPEX/POSEIDON when using the GEM-T1 gravity model. Finally, it was determined that even the orbit error at points where ascending and descending ground traces cross is somewhat correlated. The implication of these various correlations is that the orbit error due to gravity error is geographically correlated. Such correlations have direct implications when using altimetry to recover oceanographic signals.

Malignant perivascular epithelioid cell tumor of the orbit: Report of a case and review of literature.

PubMed

Alam, Md Shahid; Mukherjee, Bipasha; Krishnakumar, S; Biswas, Jyotirmay

2017-09-01

Perivascular epithelioid cell tumor (PEComa) is a rare neoplasm considered to arise from myomelanocytic cell lineage. The uterus is reportedly the most common site to be involved. Orbital PEComa is extremely rare with only two cases reported till date. A 5-year-old male presented with a right medial orbital mass for the last 6 months. The patient was diagnosed with alveolar soft part sarcoma elsewhere. Magnetic resonance imaging features were suggestive of lymphangioma with bleeding. The excision biopsy revealed multiple tumor cells comprising epithelioid cells with clear cytoplasm, along with nuclear atypia and mitosis. Immunohistochemistry was positive for HMB-45, smooth muscle actin, vimentin, and CD-34. It was negative for cytokeratin, S-100, and synaptophysin, which clinched the diagnosis of malignant orbital PEComa. Neoadjuvant chemotherapy was administered. There was no recurrence at 24 months of follow-up. At present, there is no consensus on management protocol for malignant PEComa. Complete surgical excision with chemotherapy appears to offer the best prognosis.

Malignant perivascular epithelioid cell tumor of the orbit: Report of a case and review of literature

PubMed Central

Alam, Md. Shahid; Mukherjee, Bipasha; Krishnakumar, S; Biswas, Jyotirmay

2017-01-01

Perivascular epithelioid cell tumor (PEComa) is a rare neoplasm considered to arise from myomelanocytic cell lineage. The uterus is reportedly the most common site to be involved. Orbital PEComa is extremely rare with only two cases reported till date. A 5-year-old male presented with a right medial orbital mass for the last 6 months. The patient was diagnosed with alveolar soft part sarcoma elsewhere. Magnetic resonance imaging features were suggestive of lymphangioma with bleeding. The excision biopsy revealed multiple tumor cells comprising epithelioid cells with clear cytoplasm, along with nuclear atypia and mitosis. Immunohistochemistry was positive for HMB-45, smooth muscle actin, vimentin, and CD-34. It was negative for cytokeratin, S-100, and synaptophysin, which clinched the diagnosis of malignant orbital PEComa. Neoadjuvant chemotherapy was administered. There was no recurrence at 24 months of follow-up. At present, there is no consensus on management protocol for malignant PEComa. Complete surgical excision with chemotherapy appears to offer the best prognosis. PMID:28905842

Space Tourism in the Context of a Diverse Market

NASA Astrophysics Data System (ADS)

Hempsell, M.

Most discussion of the potential space tourism business considers it as an isolated activity. In the case of sub-orbital tourism this is probably the case and this means any business has to pay to develop its infrastructure before it can start any revenue earning. This can lead to an investment trap were the upfront investment costs can never be recovered if commercially attractive rates of return are assumed. By contrast orbital tourism would be undertaken in the context of other space activity and these can have a significant impact on its commercial viability, particularly as a means to overcome the investment trap. A strategy is outlined showing that a mixed market approach to passenger transport to orbit can both provide savings for government activity and tourist costs around half a million dollars per person. However to take advantage of this market synergy the orbital personnel transport system must have the requirements of space tourism operations incorporated into the system during its initial development.

Unconventional Bose—Einstein Condensations from Spin-Orbit Coupling

NASA Astrophysics Data System (ADS)

Wu, Cong-Jun; Ian, Mondragon-Shem; Zhou, Xiang-Fa

2011-09-01

According to the “no-node" theorem, the many-body ground state wavefunctions of conventional Bose—Einstein condensations (BEC) are positive-definite, thus time-reversal symmetry cannot be spontaneously broken. We find that multi-component bosons with spin-orbit coupling provide an unconventional type of BECs beyond this paradigm. We focus on a subtle case of isotropic Rashba spin-orbit coupling and the spin-independent interaction. In the limit of the weak confining potential, the condensate wavefunctions are frustrated at the Hartree—Fock level due to the degeneracy of the Rashba ring. Quantum zero-point energy selects the spin-spiral type condensate through the “order-from-disorder" mechanism. In a strong harmonic confining trap, the condensate spontaneously generates a half-quantum vortex combined with the skyrmion type of spin texture. In both cases, time-reversal symmetry is spontaneously broken. These phenomena can be realized in both cold atom systems with artificial spin-orbit couplings generated from atom-laser interactions and exciton condensates in semi-conductor systems.

Reduced risk of compressive optic neuropathy using orbital radiotherapy in patients with active thyroid eye disease.

PubMed

Shams, Pari N; Ma, Roy; Pickles, Tom; Rootman, Jack; Dolman, Peter J

2014-06-01

To compare the risk of developing compressive optic neuropathy in patients with active thyroid eye disease (TED) treated with corticosteroids with or without orbital radiotherapy. Retrospective single-center case-control study. The clinical charts of 351 patients with active TED who received corticosteroids with or without orbital radiotherapy between 1999 and 2010 were reviewed. Patients with compressive optic neuropathy at the time of presentation were excluded. Group 1 received corticosteroids only and Group 2 received corticosteroids as well as orbital radiotherapy. The primary outcome measure was the development of compressive optic neuropathy. Secondary outcome measures were changes in other parameters indicating the activity of TED, including soft tissue inflammation, diplopia, ocular motility restriction, and appearance. There were 144 cases in Group 1 and 105 in Group 2. Both groups were matched for age, sex, and stability of thyroid function. The 2 groups differed only in the modality of treatment for active TED. The main indication for treatment in both groups was soft tissue inflammation. Corticosteroids were initiated an average of 2.6 months following symptom onset in Group 1 and 2.5 months in Group 2. Group 2 received orbital radiotherapy on average 4.2 months following the initiation of corticosteroid therapy and 8% (9/105) were intolerant to corticosteroids. At an average of 3.2 years follow-up, compressive optic neuropathy had developed in 17% (25/144) of Group 1 and 0% of Group 2 (P < .0001), on average 5.5 months following the initiation of corticosteroid therapy. Although both groups experienced a significant reduction in periocular inflammation, the radiotherapy-treated group demonstrated a significantly greater improvement in ocular motility. The rate of compressive optic neuropathy was significantly lower and improvement in ocular motility greater in patients receiving orbital radiotherapy in addition to corticosteroids. Patients with active TED appear to have an effective and sustained response to orbital radiotherapy combined with corticosteroids that is protective against disease progression and the development of compressive optic neuropathy. Copyright © 2014 Elsevier Inc. All rights reserved.

A mission-oriented orbit design method of remote sensing satellite for region monitoring mission based on evolutionary algorithm

NASA Astrophysics Data System (ADS)

Shen, Xin; Zhang, Jing; Yao, Huang

2015-12-01

Remote sensing satellites play an increasingly prominent role in environmental monitoring and disaster rescue. Taking advantage of almost the same sunshine condition to same place and global coverage, most of these satellites are operated on the sun-synchronous orbit. However, it brings some problems inevitably, the most significant one is that the temporal resolution of sun-synchronous orbit satellite can't satisfy the demand of specific region monitoring mission. To overcome the disadvantages, two methods are exploited: the first one is to build satellite constellation which contains multiple sunsynchronous satellites, just like the CHARTER mechanism has done; the second is to design non-predetermined orbit based on the concrete mission demand. An effective method for remote sensing satellite orbit design based on multiobjective evolution algorithm is presented in this paper. Orbit design problem is converted into a multi-objective optimization problem, and a fast and elitist multi-objective genetic algorithm is utilized to solve this problem. Firstly, the demand of the mission is transformed into multiple objective functions, and the six orbit elements of the satellite are taken as genes in design space, then a simulate evolution process is performed. An optimal resolution can be obtained after specified generation via evolution operation (selection, crossover, and mutation). To examine validity of the proposed method, a case study is introduced: Orbit design of an optical satellite for regional disaster monitoring, the mission demand include both minimizing the average revisit time internal of two objectives. The simulation result shows that the solution for this mission obtained by our method meet the demand the users' demand. We can draw a conclusion that the method presented in this paper is efficient for remote sensing orbit design.

Reconstruction of Midface and Orbital Wall Defects After Maxillectomy and Orbital Content Preservation With Titanium Mesh and Fascia Lata: 3-Year Follow-Up.

PubMed

Motiee-Langroudi, Maziar; Harirchi, Iraj; Amali, Amin; Jafari, Mehrdad

2015-12-01

To describe the authors' experience in the reconstruction of patients after total maxillectomy with preservation of orbital contents for maxillary tumors using titanium mesh and autogenous fascia lata, where no setting for free flap reconstruction is available. Twelve consecutive patients with paranasal sinus tumors underwent total maxillectomy without orbital exenterations and primary reconstruction. The defects were reconstructed by titanium mesh in combination with autogenous fascia lata in the orbital floor performed by 1 surgical team. Titanium mesh (0.2 mm thick) was contoured and fixed to reconstruct the orbital floor and obtain midface projection. Fascia lata was used to cover the titanium mesh along the orbital floor to prevent fat entrapment in the mesh holes. The most common pathology was squamous cell carcinoma (50%). Patients' mean age was 45.66 years (33 to 74 yr). The mean follow-up period was 35.2 months (30 to 49 months). During follow-up, no infection or foreign body reaction was encountered. Extrusion of titanium mesh occurred in 4 patients who underwent postoperative radiotherapy. Two cases of mild diplopia at extreme gaze occurred early during the postoperative period that resolved after a few months. Placing fascia lata between the titanium mesh surface of the orbital implant and the orbital contents was successful in preventing long-term diplopia or dystopia. Nevertheless, exposure of the titanium implant through the skin surface represented a complication of this technique in 25% of patients. Further studies are required with head-to-head comparisons of artificial materials and free flaps for reconstruction of maxillectomy defects. Copyright © 2015 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

An independent determination of Fomalhaut b's orbit and the dynamical effects on the outer dust belt

NASA Astrophysics Data System (ADS)

Beust, H.; Augereau, J.-C.; Bonsor, A.; Graham, J. R.; Kalas, P.; Lebreton, J.; Lagrange, A.-M.; Ertel, S.; Faramaz, V.; Thébault, P.

2014-01-01

Context. The nearby star Fomalhaut harbors a cold, moderately eccentric (e ~ 0.1) dust belt with a sharp inner edge near 133 au. A low-mass, common proper motion companion, Fomalhaut b (Fom b), was discovered near the inner edge and was identified as a planet candidate that could account for the belt morphology. However, the most recent orbit determination based on four epochs of astrometry over eight years reveals a highly eccentric orbit (e = 0.8 ± 0.1) that appears to cross the belt in the sky plane projection. Aims: We perform here a full orbital determination based on the available astrometric data to independently validate the orbit estimates previously presented. Adopting our values for the orbital elements and their associated uncertainties, we then study the dynamical interaction between the planet and the dust ring, to check whether the proposed disk sculpting scenario by Fom b is plausible. Methods: We used a dedicated MCMC code to derive the statistical distributions of the orbital elements of Fom b. Then we used symplectic N-body integration to investigate the dynamics of the dust belt, as perturbed by a single planet. Different attempts were made assuming different masses for Fom b. We also performed a semi-analytical study to explain our results. Results: Our results are in good agreement with others regarding the orbit of Fom b. We find that the orbit is highly eccentric, is close to apsidally aligned with the belt, and has a mutual inclination relative to the belt plane of <29° (67% confidence). If coplanar, this orbit crosses the disk. Our dynamical study then reveals that the observed planet could sculpt a transient belt configuration with a similar eccentricity to what is observed, but it would not be simultaneously apsidally aligned with the planet. This transient configuration only occurs a short time after the planet is placed on such an orbit (assuming an initially circular disk), a time that is inversely proportional to the planet's mass, and that is in any case much less than the 440 Myr age of the star. Conclusions: We constrain how long the observed dust belt could have survived with Fom b on its current orbit, as a function of its possible mass. This analysis leads us to conclude that Fom b is likely to have low mass, that it is unlikely to be responsible for the sculpting of the belt, and that it supports the hypothesis of a more massive, less eccentric planet companion Fomalhaut c.

Scalar self-force for highly eccentric equatorial orbits in Kerr spacetime

NASA Astrophysics Data System (ADS)

Thornburg, Jonathan; Wardell, Barry

2017-04-01

If a small "particle" of mass μ M (with μ ≪1 ) orbits a black hole of mass M , the leading-order radiation-reaction effect is an O (μ2) "self-force" acting on the particle, with a corresponding O (μ ) "self-acceleration" of the particle away from a geodesic. Such "extreme-mass-ratio inspiral" systems are likely to be important gravitational-wave sources for future space-based gravitational-wave detectors. Here we consider the "toy model" problem of computing the self-force for a scalar-field particle on a bound eccentric orbit in Kerr spacetime. We use the Barack-Golbourn-Vega-Detweiler effective-source regularization with a 4th-order puncture field, followed by an ei m ϕ ("m -mode") Fourier decomposition and a separate time-domain numerical evolution in 2 +1 dimensions for each m . We introduce a finite worldtube that surrounds the particle worldline and define our evolution equations in a piecewise manner so that the effective source is only used within the worldtube. Viewed as a spatial region, the worldtube moves to follow the particle's orbital motion. We use slices of constant Boyer-Lindquist time in the region of the particle's motion, deformed to be asymptotically hyperboloidal and compactified near the horizon and J+ . Our numerical evolution uses Berger-Oliger mesh refinement with 4th-order finite differencing in space and time. Our computational scheme allows computation for highly eccentric orbits and should be generalizable to orbital evolution in the future. Our present implementation is restricted to equatorial geodesic orbits, but this restriction is not fundamental. We present numerical results for a number of test cases with orbital eccentricities as high as 0.98. In some cases we find large oscillations ("wiggles") in the self-force on the outgoing leg of the orbit shortly after periastron passage; these appear to be caused by the passage of the orbit through the strong-field region close to the background Kerr black hole.

Mars Aeronomy Explorer (MAX): Study Employing Distributed Micro-Spacecraft

NASA Technical Reports Server (NTRS)

Shotwell, Robert F.; Gray, Andrew A.; Illsley, Peter M.; Johnson, M.; Sherwood, Robert L.; Vozoff, M.; Ziemer, John K.

2005-01-01

An overview of a Mars Aeronomy Explorer (MAX) mission design study performed at NASA's Jet Propulsion Laboratory is presented herein. The mission design consists of ten micro-spacecraft orbiters launched on a Delta IV to Mars polar orbit to determine the spatial, diurnal and seasonal variation of the constituents of the Martian upper atmosphere and ionosphere over the course of one Martian year. The spacecraft are designed to allow penetration of the upper atmosphere to at least 90 km. This property coupled with orbit precession will yield knowledge of the nature of the solar wind interaction with Mars, the influence of the Mars crustal magnetic field on ionospheric processes, and the measurement of present thermal and nonthermal escape rates of atmospheric constituents. The mission design incorporates alternative design paradigms that are more appropriate for-and in some cases motivate-distributed micro-spacecraft. These design paradigms are not defined by a simple set of rules, but rather a way of thinking about the function of instruments, mission reliability/risk, and cost in a systemic framework.

On the use of a sunward-libration-point orbiting spacecraft as an IMF monitor for magnetospheric studies

NASA Technical Reports Server (NTRS)

Kelly, T. J.; Crooker, N. U.; Siscoe, G. L.; Russell, C. T.; Smith, E. J.

1984-01-01

Magnetospheric studies often require knowledge of the orientation of the IMF. In order to test the accuracy of using magnetometer data from a spacecraft orbiting the sunward libration point for this purpose, the angle between the IMF at ISEE 3, when it was positioned around the libration point, and at ISEE 1, orbiting Earth, has been calculated for a data set of two-hour periods covering four months. For each period, a ten-minute average of ISEE 1 data is compared with ten-minute averages of ISEE 3 data at successively lagged intervals. At the lag time equal to the time required for the solar wind to convect from ISEE 3 to ISEE 1, the median angle between the IMF orientation at the two spacecraft is 20 deg, and 80% of the cases have angles less than 38 deg. The results for the angles projected on the y-z plane are essentially the same.

Study of hollow corner retroreflectors for use in a synchronous orbit

NASA Technical Reports Server (NTRS)

Yoder, P. R., Jr.

1975-01-01

The performance of a hollow corner cube retroreflector made up of three mutually perpendicular optically flat mirrors when undergoing the thermal-mechanical strains induced by a spacecraft environment was studied. Of particular interest was a device of 200 square centimeter optical aperture used on a satellite in a synchronous orbit. It was assumed that the reflector always faces the earth. The effects of direct solar irradiance, earthshine, and albedo were considered. The results included the maximum mirror surface temperature during the orbit as well as the worst-case loss of optical performance due to thermally-induced mirror distortions. It was concluded that a device made of three suitably coated flat ULE mirrors, optically contacted to each other and supported mechanically in a nonrigid mount, would be expected to concentrate over 80 percent of the theoretical maximum energy in the central of the far field diffraction pattern. Continued development of the device through a detailed design, fabrication, and test phase was recommended.

On the Distribution of Orbital Poles of Milky Way Satellites

NASA Astrophysics Data System (ADS)

Palma, Christopher; Majewski, Steven R.; Johnston, Kathryn V.

2002-01-01

In numerous studies of the outer Galactic halo some evidence for accretion has been found. If the outer halo did form in part or wholly through merger events, we might expect to find coherent streams of stars and globular clusters following orbits similar to those of their parent objects, which are assumed to be present or former Milky Way dwarf satellite galaxies. We present a study of this phenomenon by assessing the likelihood of potential descendant ``dynamical families'' in the outer halo. We conduct two analyses: one that involves a statistical analysis of the spatial distribution of all known Galactic dwarf satellite galaxies (DSGs) and globular clusters, and a second, more specific analysis of those globular clusters and DSGs for which full phase space dynamical data exist. In both cases our methodology is appropriate only to members of descendant dynamical families that retain nearly aligned orbital poles today. Since the Sagittarius dwarf (Sgr) is considered a paradigm for the type of merger/tidal interaction event for which we are searching, we also undertake a case study of the Sgr system and identify several globular clusters that may be members of its extended dynamical family. In our first analysis, the distribution of possible orbital poles for the entire sample of outer (Rgc>8 kpc) halo globular clusters is tested for statistically significant associations among globular clusters and DSGs. Our methodology for identifying possible associations is similar to that used by Lynden-Bell & Lynden-Bell, but we put the associations on a more statistical foundation. Moreover, we study the degree of possible dynamical clustering among various interesting ensembles of globular clusters and satellite galaxies. Among the ensembles studied, we find the globular cluster subpopulation with the highest statistical likelihood of association with one or more of the Galactic DSGs to be the distant, outer halo (Rgc>25 kpc), second-parameter globular clusters. The results of our orbital pole analysis are supported by the great circle cell count methodology of Johnston, Hernquist, & Bolte. The space motions of the clusters Pal 4, NGC 6229, NGC 7006, and Pyxis are predicted to be among those most likely to show the clusters to be following stream orbits, since these clusters are responsible for the majority of the statistical significance of the association between outer halo, second-parameter globular clusters and the Milky Way DSGs. In our second analysis, we study the orbits of the 41 globular clusters and six Milky Way-bound DSGs having measured proper motions to look for objects with both coplanar orbits and similar angular momenta. Unfortunately, the majority of globular clusters with measured proper motions are inner halo clusters that are less likely to retain memory of their original orbit. Although four potential globular cluster/DSG associations are found, we believe three of these associations involving inner halo clusters to be coincidental. While the present sample of objects with complete dynamical data is small and does not include many of the globular clusters that are more likely to have been captured by the Milky Way, the methodology we adopt will become increasingly powerful as more proper motions are measured for distant Galactic satellites and globular clusters, and especially as results from the Space Interferometry Mission (SIM) become available.

Elameer-Idrus Orbital E-Education Framework for the University of Mustansiriyah (Uomust)

ERIC Educational Resources Information Center

Elameer, Amer Saleem; Idrus, Rozhan M.

2011-01-01

The study of the university of Mustansiriyah case show us very clear that university suffers from a lot of problems start from the security, technology, management, pedagogical and ethical. Based on a pre-questionnaire survey about e-learning results, interviews and studies show us the need to the complete e-education system. Continuous scrutiny…

The Stability of Tidal Equilibrium for Hierarchical Star-Planet-Moon Systems

NASA Astrophysics Data System (ADS)

Adams, Fred C.

2018-04-01

Motivated by the current search for exomoons, this talk considers the stability of tidal equilibrium for hierarchical three-body systems containing a star, a planet, and a moon. In this treatment, the energy and angular momentum budgets include contributions from the planetary orbit, lunar orbit, stellar spin, planetary spin, and lunar spin. The goal is to determine the optimized energy state of the system subject to the constraint of constant angular momentum. Due to the lack of a closed form solution for the full three-body problem, however, we must use use an approximate description of the orbits. We first consider the Keplerian limit and find that the critical energy states are saddle points, rather than minima, so that these hierarchical systems have no stable tidal equilibrium states. We then generalize the calculation so that the lunar orbit is described by a time-averaged version of the circular restricted three-body problem. In this latter case, the critical energy state is a shallow minimum, so that a tidal equilibrium state exists. In both cases, however, the lunar orbit for the critical point lies outside the boundary (roughly half the Hill radius) where (previous) numerical simulations indicate dynamical instability.

Interplay between resonant tunneling and spin precession oscillations in all-electric all-semiconductor spin transistors

NASA Astrophysics Data System (ADS)

Alomar, M. I.; Serra, Llorenç; Sánchez, David

2016-08-01

We investigate the transmission properties of a spin transistor coupled to two quantum point contacts acting as a spin injector and detector. In the Fabry-Pérot regime, transport is mediated by quasibound states formed between tunnel barriers. Interestingly, the spin-orbit interaction of the Rashba type can be tuned in such a way that nonuniform spin-orbit fields can point along distinct directions at different points of the sample. We discuss both spin-conserving and spin-flipping transitions as the spin-orbit angle of orientation increases from parallel to antiparallel configurations. Spin precession oscillations are clearly seen as a function of the length of the central channel. Remarkably, we find that these oscillations combine with the Fabry-Pérot motion, giving rise to quasiperiodic transmissions in the purely one-dimensional case. Furthermore, we consider the more realistic case of a finite width in the transverse direction and find that the coherent oscillations become deteriorated for moderate values of the spin-orbit strength. Our results then determine the precise role of the spin-orbit intersubband coupling potential in the Fabry-Pérot-Datta-Das intermixed oscillations.

Spontaneous Retro-Orbital Subperiosteal Hemorrhage with Complete Resolution Following Percutaneous Coronary Intervention for Acute Myocardial Infarction.

PubMed

Wu, Hsu-Ping; Tsai, Chia-Jung; Tsai, Jui-Peng; Hung, Chung-Lieh; Kuo, Jen-Yuan; Hou, Charles Jia-Yin

2013-03-01

Among the several treatment strategies available for acute myocardial infarction, primary percutaneous coronary intervention concomitant with antithrombotic agents is the primary treatment used to facilitate coronary reperfusion. However, bleeding can create major complications. Here we have presented a case of acute myocardial infarction treated with reperfusion therapy, after which developed a sudden onset of proptosis, with high intraocular pressure, blurred vision, and ecchymosis of the left eye. Spontaneous retro-orbital subperiosteal hemorrhage, a rare complication, was diagnosed based on those symptoms as noted above, as well as other orbital signs and imaging evaluation. Multiple antithrombotic agents, including antiplatelets, low molecular weight heparin, and glycoprotein IIb/IIIa receptor inhibitor were thought to be the main precipitating factors of this complication. Thereafter, conservative medical treatment was applied. In the following 2 weeks, all the patient's orbital signs resolved gradually without visual impairment. In conclusion, our experience with a rare case of complications arising from reperfusion therapy used to treat myocardial infarction suggests that clinicians should remain vigilant for any hemorrhagic events during acute myocardial infarction treatment. Acute myocardial infarction; Percutaneous coronary intervention; Retro-orbital subperiosteal hemorrhage.

Lunar based massdriver applications

NASA Astrophysics Data System (ADS)

Ehresmann, Manfred; Gabrielli, Roland Atonius; Herdrich, Georg; Laufer, René

2017-05-01

The results of a lunar massdriver mission and system analysis are discussed and show a strong case for a permanent lunar settlement with a site near the lunar equator. A modular massdriver concept is introduced, which uses multiple acceleration modules to be able to launch large masses into a trajectory that is able to reach Earth. An orbital mechanics analysis concludes that the launch site will be in the Oceanus Procellarum a flat, Titanium rich lunar mare area. It is further shown that the bulk of massdriver components can be manufactured by collecting lunar minerals, which are broken down into its constituting elements. The mass to orbit transfer rates of massdriver case study are significant and can vary between 1.8 kt and 3.3 megatons per year depending on the available power. Thus a lunar massdriver would act as a catalyst for any space based activities and a game changer for the scale of feasible space projects.

Effect of Spacecraft Rotation on Fluid Convection Under Microgravity

NASA Technical Reports Server (NTRS)

Yuferev, Valentin S.; Kolesnikova, Elvira N.; Polovko, Yuri A.; Zhmakin, Alexander I.

1996-01-01

The influence of the rotational effects on two-dimensional fluid convection in a rectangular enclosure with rigid walls during the orbital flight is considered. It is shown that the Coriolis force influence both on steady and oscillatory convection becomes significant at Ekman numbers which are quite attainable in the space orbital conditions. In the case of harmonic oscillations of the gravity force appearance of the resonance phenomena is demonstrated. Dependence of the height and shape of the resonance peak on aspect ratio of a rectangular domain and orientation of vectors of the gravity force and the angular rotation velocity is studied. Special attention is given to non-linear effects caused by convective terms of Navier-Stokes equations. The convection produced by variations of the angular rotation velocity of a spacecraft is also discussed. It is shown that in some cases the latter convection can be comparable with another kinds of convection.

Optimal Electrodynamic Tether Phasing Maneuvers

NASA Technical Reports Server (NTRS)

Bitzer, Matthew S.; Hall, Christopher D.

2007-01-01

We study the minimum-time orbit phasing maneuver problem for a constant-current electrodynamic tether (EDT). The EDT is assumed to be a point mass and the electromagnetic forces acting on the tether are always perpendicular to the local magnetic field. After deriving and non-dimensionalizing the equations of motion, the only input parameters become current and the phase angle. Solution examples, including initial Lagrange costates, time of flight, thrust plots, and thrust angle profiles, are given for a wide range of current magnitudes and phase angles. The two-dimensional cases presented use a non-tilted magnetic dipole model, and the solutions are compared to existing literature. We are able to compare similar trajectories for a constant thrust phasing maneuver and we find that the time of flight is longer for the constant thrust case with similar initial thrust values and phase angles. Full three-dimensional solutions, which use a titled magnetic dipole model, are also analyzed for orbits with small inclinations.

Wave Excitation in Accretion Disks by Protoplanets

NASA Astrophysics Data System (ADS)

Koller, J.; Li, H.

2002-05-01

The ongoing discoveries of extrasolar planets in the recent years revealed remarkable properties and unexpected results concerning the formation process. We studied the perturbation of a protostellar accretion disk by a companion utilizing APOLLO, a fast hydro disk code well tested in the case of accretion disks without a companion (Li et al. 2001, ApJ, 551, 874). We consider limiting cases where the companion's mass is much smaller than the central protostar and resides in a circular keplerian orbit. The gravitational field of the protoplanet, embedded in a numerically thin disk, generates spiral density waves and Rossby instabilities resulting in a non-axisymmetric density distribution. We present nonlinear hydro simulations to investigate those non-axisymmetric density distribution with different disk and planet parameters in order to understand how disks respond to a fixed companion in orbit. This work has been supported by IGPP at LANL (award # 1109) and NASA (grant # NAG5-9223).

Surgical management of temple-related problems following lateral wall rim-sparing orbital decompression for thyroid-related orbitopathy.

PubMed

Siah, We Fong; Patel, Bhupendra Ck; Malhotra, Raman

2016-08-01

To report a case series of patients with persistent temple-related problems following lateral wall rim-sparing (LWRS) orbital decompression for thyroid-related orbitopathy and to discuss their management. Retrospective review of medical records of patients referred to two oculoplastic centres (Corneoplastic Unit, Queen Victoria Hospital, East Grinstead, UK and Moran Eye Center, University of Utah, Salt Lake City, USA) for intervention to improve/alleviate temple-related problems. All patients were seeking treatment for their persistent, temple-related problems of minimum 3 years' duration post decompression. The main outcome measure was the resolution or improvement of temple-related problems. Eleven orbits of six patients (five females) with a median age of 57 years (range 23-65) were included in this study. Temple-related problems consisted of cosmetically bothersome temple hollowness (n=11; 100%), masticatory oscillopsia (n=8; 73%), temple tenderness (n=4; 36%), 'clicking' sensation (n=4; 36%) and gaze-evoked ocular pain (n=4; 36%). Nine orbits were also complicated by proptosis and exposure keratopathy. Preoperative imaging studies showed the absence of lateral wall in all 11 orbits and evidence of prolapsed lacrimal gland into the wall defect in four orbits. Intervention included the repair of the lateral wall defect with a sheet implant, orbital decompression involving fat, the medial wall or orbital floor and autologous fat transfer or synthetic filler for temple hollowness. Postoperatively, there was full resolution of masticatory oscillation, temple tenderness, 'clicking' sensation and gaze-evoked ocular pain, and an improvement in temple hollowness. Pre-existing diplopia in one patient resolved after surgery while two patients developed new-onset diplopia necessitating strabismus surgery. This is the first paper to show that persistent, troublesome temple-related problems following LWRS orbital decompression can be surgically corrected. Patients should be counselled about the potential risk of these complications when considering LWRS orbital decompression. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Two-craft Coulomb formation study about circular orbits and libration points

NASA Astrophysics Data System (ADS)

Inampudi, Ravi Kishore

This dissertation investigates the dynamics and control of a two-craft Coulomb formation in circular orbits and at libration points; it addresses relative equilibria, stability and optimal reconfigurations of such formations. The relative equilibria of a two-craft tether formation connected by line-of-sight elastic forces moving in circular orbits and at libration points are investigated. In circular Earth orbits and Earth-Moon libration points, the radial, along-track, and orbit normal great circle equilibria conditions are found. An example of modeling the tether force using Coulomb force is discussed. Furthermore, the non-great-circle equilibria conditions for a two-spacecraft tether structure in circular Earth orbit and at collinear libration points are developed. Then the linearized dynamics and stability analysis of a 2-craft Coulomb formation at Earth-Moon libration points are studied. For orbit-radial equilibrium, Coulomb forces control the relative distance between the two satellites. The gravity gradient torques on the formation due to the two planets help stabilize the formation. Similar analysis is performed for along-track and orbit-normal relative equilibrium configurations. Where necessary, the craft use a hybrid thrusting-electrostatic actuation system. The two-craft dynamics at the libration points provide a general framework with circular Earth orbit dynamics forming a special case. In the presence of differential solar drag perturbations, a Lyapunov feedback controller is designed to stabilize a radial equilibrium, two-craft Coulomb formation at collinear libration points. The second part of the thesis investigates optimal reconfigurations of two-craft Coulomb formations in circular Earth orbits by applying nonlinear optimal control techniques. The objective of these reconfigurations is to maneuver the two-craft formation between two charged equilibria configurations. The reconfiguration of spacecraft is posed as an optimization problem using the calculus of variations approach. The optimality criteria are minimum time, minimum acceleration of the separation distance, minimum Coulomb and electric propulsion fuel usage, and minimum electrical power consumption. The continuous time problem is discretized using a pseudospectral method, and the resulting finite dimensional problem is solved using a sequential quadratic programming algorithm. The software package, DIDO, implements this approach. This second part illustrates how pseudospectral methods significantly simplify the solution-finding process.

The anatomical location and laterality of orbital cavernous haemangiomas.

PubMed

McNab, Alan A; Selva, Dinesh; Hardy, Thomas G; O'Donnell, Brett

2014-10-01

To determine the anatomical location and laterality of orbital cavernous haemangiomas (OCH). Retrospective case series. The records of 104 patients with OCH were analyzed. The anatomical location of each OCH defined by the location of a point at the centre of the lesion, and its laterality. There were 104 patients included in the study. No patient had more than one lesion. Sixteen (15.4%) were located in the anterior third of the orbit, 74 (71.2%) were in the middle third, and 14 (13.5%) in the posterior third. In the middle third, 10 of 74 (13.5%) were extraconal and 64 intraconal (86.5%), with 30 of 64 (46.9%) middle third intraconal lesions lying lateral to the optic nerve. Of 104 lesions, 56 (53.8%) were left sided, showing a trend towards a predilection for the left side (p = 0.065). If data from other published series which included data on laterality is added to our own data and analysed, 270 of 468 (57.7%) OCH occurred in the left orbit (p < 0.005). OCH may occur at almost any location within the orbit. The commonest location is the middle third of the orbit, in the intraconal space lateral to the optic nerve. This may reflect an origin of these lesions from the arterial side of the circulation, as there are more small arteries in the intraconal space lateral to the optic nerve than in other locations. A predilection for the left orbit remains unexplained.

Orbital dynamics of high area-to-mass ratio spacecraft with J2 and solar radiation pressure for novel Earth observation and communication services

NASA Astrophysics Data System (ADS)

Colombo, Camilla; Lücking, Charlotte; McInnes, Colin R.

2012-12-01

This paper investigates the effect of planetary oblateness and solar radiation pressure on the orbits of high area-to-mass spacecraft. A planar Hamiltonian model shows the existence of equilibrium orbits with the orbit apogee pointing towards or away from the Sun. These solutions are numerically continued to non-zero inclinations and considering the obliquity of the ecliptic plane relative to the equator. Quasi-frozen orbits are identified in eccentricity, inclination and the angle between the Sun-line and the orbit perigee. The long-term evolution of these orbits is then verified through numerical integration. A set of 'heliotropic' orbits with apogee pointing in the direction of the Sun is proposed for enhancing imaging and telecommunication on the day side of the Earth. The effects of J2 and solar radiation pressure are exploited to obtain a passive rotation of the apsides line following the Sun; moreover the effect of solar radiation pressure enables such orbits at higher eccentricities with respect to the J2 only case.