102,356 research outputs found

    A novel life prediction model based on monitoring electrical properties of self-sensing cement-based materials

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    Assessing the damage level in concrete infrastructures over time is a critical issue to plan their timely maintenance with proper actions. Self-sensing concretes offer new opportunities for damage assessment by monitoring their electrical properties and relating their variations to damage levels. In this research, fatigue tests were conducted to study the response of a self-sensing concrete under high-cycle dynamic loading. The concept of G-value was defined as the slope of the voltage response baseline of the self-sensing concrete over time that reflects the damage created under the fatigue-loading test. Based on this definition, log (G)–log (N) curves were obtained using a linear regression approach, with N representing the number of cycles during the fatigue tests. While traditional fatigue curves S-log (N) are used to estimate the remaining life under fatigue loading, log (G)–log (N) diagrams can be used to determine the damage level based on the voltage response of the self-sensing concrete as a function of the loading history. This finding can be useful for the estimation of the lifetime and remaining life of self-sensing concrete structures and infra-structure, eventually helping to optimize the related maintenance operations

    Cervicogenic headache: evaluation of the original diagnostic criteria

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    A variety of headaches are frequently associated with the occurrence of neck pain. The purpose of this paper was to describe the adherence to diagnostic criteria of a series of patients enrolled on the basis of two clinical criteria: (1) unilateral headache without side-shift, and (2) pain starting in the neck and spreading to the fronto-ocular area. One hundred and thirty-two patients (36 male and 96 female) entered the study. Sixty-two patients were assigned to Group A (patients fulfilling criteria 1 and 2), 40 to Group B (criterion 2 only) and 12 to Group C (criterion 1, only). Eighteen subjects were excluded because X-rays of the neck were not available. Patients were evaluated regardless of whether or not they fell into one or more of the following diagnostic categories: cervicogenic headache (CEH), migraine without aura (M) and headache associated with disorders of the neck (HN) (IHS definitions). Fulfillment of the diagnostic criteria for CEH was found to be particularly frequent in Group A. A higher frequency of CEH diagnosis was found when two criteria were used (Group A) than in Group B (P = 0.001); in the former group a higher mean number of diagnostic criteria for CEH were also present (P = 0.001). Group A patients more frequently presented pain episodes of varying duration or fluctuating, continuous pain and moderate, non-excruciating, non-throbbing pain than Group B patients (P = 0.04 and P = 0.08, respectively). In Group C patients, the frequency of these two criteria was relatively low (17%) especially of the first mentioned variable. The presence of at least five of the seven 'pooled' CEH criteria (present in > or = 50% of the patients) might be deemed a reliable cut-off point, allowing the headache to be diagnosed as 'probable' CEH. If patients fulfilling M or HN criteria in addition to the CEH criteria are added to the 'pure' CEH group a total of 74% of Group A patients may have a CEH picture. The temporal pattern of pain and the quality of pain in Group A showed good sensitivity and specificity (> or = 75) when compared with Group B; therefore, the chances of diagnosing a definite CEH are significantly more frequent in patients presenting with unilateral pain that also begins as a neck pain. Head/neck trauma and radiological abnormalities in the cervical spine were not significantly associated with CEH, M or HN diagnoses. An improvement of the current diagnostic IHS criteria might make it possible to avoid the existing, partial overlap of CEH with HN and M. Extensive use should be made of the GON, and other, blockades in the routine work-up of CEH, both in the differential diagnosis and in the mixed forms (CEH + M, and CEH + HN), in order to improve the efficiency of the current diagnostic system

    Diagnosing cervicogenic headache.

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    The notion that disorders of the cervical spine can cause headache is more than a century old, yet there is still a great deal of debate about cervicogenic headache (CEH) in terms of its underlying mechanisms, its signs and symptoms, and the most appropriate treatments for it. CEH is typically a unilateral headache that can be provoked by neck movement, awkward head positions or pressure on tender points in the neck. The headaches can last hours or days, and the pain is usually described as either dull or piercing. Convergence of the upper cervical roots on the nucleus caudalis of the trigeminal tract is the most commonly accepted neurophysiological explanation for CEH. In most cases, CEH is caused by pathology in the upper aspect of the cervical spine, but the type and exact location of the pathology varies substantially among individual cases. Anaesthetic blocks may be necessary to confirm the diagnosis of CEH, showing that the source of pain is in the neck. Differential diagnosis is sometimes a challenge because CEH can be mistaken for other forms of unilateral headache, especially unilateral migraine without aura. Neuroimaging and kinematic analysis of neck motion may aid in diagnosing difficult CEH
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