570 research outputs found

    Holomorphic symmetric differentials and a birational characterization of Abelian Varieties

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    A generically generated vector bundle on a smooth projective variety yields a rational map to a Grassmannian, called Kodaira map. We answer a previous question, raised by the asymptotic behaviour of such maps, giving rise to a birational characterization of abelian varieties. In particular we prove that, under the conjectures of the Minimal Model Program, a smooth projective variety is birational to an abelian variety if and only if it has Kodaira dimension 0 and some symmetric power of its cotangent sheaf is generically generated by its global sections.Comment: UPDATED: more details added on main proo

    B735: Ectomycorrhizae of Maine 1: A Listing of Boletaceae with the Associated Hosts

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    Forty-nine boletes have been collected and identified with their possible ectomycorrhizal associates for Maine. Most of the boletes are new reports for Maine. Acer negundo is a new host report for Boletinellus merulioides. Most of the ectomycorrhizal relationships reported here for Maine are confirmed by the work of others. Colored photos of thirty-seven Maine boletes are included.https://digitalcommons.library.umaine.edu/aes_bulletin/1014/thumbnail.jp

    Message handling system concepts and services in a land mobile satellite system

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    A network architecture containing the capabilities offered by the Message Handling System (MHS) to the PRODAT Land Mobile Satellite System (LMSS) is described taking into account the constraints of a preexisting satellite system which is going to become operational. The mapping between MHS services and PRODAT requirements is also reported and shows that the supplied performance can be significantly enhanced to both fixed and mobile users. The impact of the insertion of additional features on the system structure, especially on the centralized control unit, are also addressed

    Ionospheric refraction effects on orbit determination using the orbit determination error analysis system

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    The influence of ionospheric refraction on orbit determination was studied through the use of the Orbit Determination Error Analysis System (ODEAS). The results of a study of the orbital state estimate errors due to the ionospheric refraction corrections, particularly for measurements involving spacecraft-to-spacecraft tracking links, are presented. In current operational practice at the Goddard Space Flight Center (GSFC) Flight Dynamics Facility (FDF), the ionospheric refraction effects on the tracking measurements are modeled in the Goddard Trajectory Determination System (GTDS) using the Bent ionospheric model. While GTDS has the capability of incorporating the ionospheric refraction effects for measurements involving ground-to-spacecraft tracking links, such as those generated by the Ground Spaceflight Tracking and Data Network (GSTDN), it does not have the capability to incorporate the refraction effects for spacecraft-to-spacecraft tracking links for measurements generated by the Tracking and Data Relay Satellite System (TDRSS). The lack of this particular capability in GTDS raised some concern about the achievable accuracy of the estimated orbit for certain classes of spacecraft missions that require high-precision orbits. Using an enhanced research version of GTDS, some efforts have already been made to assess the importance of the spacecraft-to-spacecraft ionospheric refraction corrections in an orbit determination process. While these studies were performed using simulated data or real tracking data in definitive orbit determination modes, the study results presented here were obtained by means of covariance analysis simulating the weighted least-squares method used in orbit determination

    TERRESTRIAL LASER SCANNER FOR MONITORING THE DEFORMATIONS AND THE DAMAGES OF BUILDINGS

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    scanner provides the ability to detect the geometric 3D model of a building without any physical contact with the structure. Knowledge of the 3D model will give the opportunity to study the deformation and quantify the damages. Three case studies are presented relating to damaged and/or unsafe buildings: Sivillier Castle (Villasor - Sardinia- Italy), the Bell Tower of Mores (Sardinia-Italy) and industrial building (Cagliari - Italy). The first two cases concern buildings of historical and architectural importance that present a state of compromised conservation; the last, an industrial building compromised by fire. In all cases, a laser scanner survey was carried out that not only provided valuable information but also highlighted structural metric deformation and degradation

    Biochemical and nutritional traits of sea bass (Dicentrachus labrax) from different rearing systems.

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    Farmed European sea bass (Dicentrarchus labrax), sampled from three different culture systems (intensive in sea-cages, intensive in land-based basins and extensive in lagoon and storage basins of salt-work), of the Northern, Central and Southern Italy, were analyzed with the aim to employ nutritional trait to describe and to distinguish the "origin" of the product. Lipid and fatty acid profile, strongly affected by the feeding history and environmental factors, responsible of the nu- tritional and perceived quality of fish product, are proposed as marker of origin

    The European Mobile System (EMS)

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    The European Space Agency is presently procuring an L band payload in order to promote a regional European L band system coping with the specific needs of the European market. The payload, and the two communications systems to be supported, are described below. The potential market for EMS in Europe is discussed

    Life cycle energy and environmental assessment of the thermal insulation improvement in residential buildings

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    The refurbishment of the building stock is a key strategy towards the achievement of the climate and energy goals of the European Union. This study aims at evaluating the energy and environmental impacts associated with retrofitting a residential apartment to improve its vertical envelope thermal insulation. Two insulation materials, stone wool and cellulose fibers, are compared. The life cycle assessment methodology is applied assuming 1 m2 of retrofitted vertical envelope as functional unit. Moreover, to estimate the net energy and environmental benefits achievable in the retrofitted scenario compared with the non‐retrofitted one, a second analysis is performed in which the system boundaries are expanded to include the building operational phase, and 1 m2 of walkable floor per year is assumed as reference. The results show that the use of cellulose fibers involve lower impacts in most of the assessed categories compared to stone wool, except for abiotic resource depletion. In detail, the use of cellulose fibers allows to reduce the impact on climate change up to 20% and the consumption of primary energy up to 10%. The evaluation of the net energy and environmental benefits shows the effectiveness of the retrofit energy policies

    Surgical management of retraction pockets: Does mastoidectomy have a role?

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    Introduction Retraction pocket is a condition in which the eardrum lies deeper within the middle ear. Its management has no consensus in literature. Objective To assess the role of mastoidectomy in the management of retraction pockets added to a tympanoplasty. Methods Prospective study of patients with retraction pocket and referred to surgery. The patients were randomly assigned to two groups: one managed with tympanoplasty and mastoidectomy and the other group with tympanoplasty only. The minimum follow-up considered was 12 months. The outcomes were: integrity of eardrum, recurrence, and hearing status. Results This study included 43 patients. In 24 cases retraction occurred in the posterior half of the eardrum, and in 19 patients there was clinical evidence of ossicular interruption. The two groups of treatment were composed by: 21 patients that underwent tympanoplasty with mastoidectomy and 22 patients had only tympanoplasty. One case of the first group had a recurrence. In 32 cases patients follow up was longer than 48 months. The average air-bone gap changed from 22.1 dB to 5 dB. The percentage of air-bone gap improvement was assessed at 60% in those patients treated with mastoidectomy, and 64.3% in those without it (p > 0.5). Conclusion Tympanoplasty and ossiculoplasty should be considered to treat atelectatic middle ear and ossicular chain interruption. Mastoidectomy as a way to increase air volume in the ear seems to be a paradox; it does not add favorable prognostic factor to management of retraction pockets

    management of blast and inhalation injury

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    Key points All patients with facial burns may be suspected of having 'difficult-to-control' airways owing to smoke inhalation injury (SII). Many of them either have an incorrect diagnosis, or mild-to-moderate injury with unrecognised aggravating respiratory failure. For a diagnosis of inhalation injury, it is necessary to follow the patient closely for >48 h. Inhalation injury is a condition with different clinical presentations. Clinical follow-up is necessary to improve patient care, to help guide treatment and to provide clues for therapeutic interventions. Notwithstanding intensive care treatment including airway intubation and mechanical ventilation, many patients with severe inhalation injury remain under-treated. Educational aims To discuss the initial approach and assessment of a patient with SII. To help the reader recognise different clinical pictures of inhalation injury. To outline management and discuss treatment. Summary "Inhalation injury" describes a variety of insults caused by the aspiration of superheated gases, steam or noxious products of incomplete combustion. Inhalation injury involves the entire respiratory system. Early diagnosis based on history and physical examination, in addition to careful monitoring for respiratory complications, is mandatory. As there is no specific treatment for inhalation injury, management involves providing the necessary degree of support required to compensate for upper airway swelling and impairment in gas exchange. Airway intubation and mechanical ventilation may be required while the endobronchial and alveolar mucosa are regenerating. Primary blast injury (BI) is caused by immediate pressure variations, which are the product of rapid sequences of compression and decompression. Secondary and tertiary BI include lesions caused when the subject is thrown against rigid structures or is hit by flying objects. Its diagnosis and therapy follows guidelines for emergency care
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