1,720,978 research outputs found
Finding Damage in Truss Structures Exploiting Modal Strains
Full text linkThe detection of potentially damaged elements in planar truss structures is a challenging
task. Among the different methods proposed in literature, one promising procedure exploits the
modal strains of the structure that are calculated from the flexibility matrix, which is, in turn,
estimated from the lowest frequencies and corresponding modes of vibration. The benefit of this
approach stems from the possibility of using a reduced number of mode shapes, usually available
from the dynamic monitoring of the structure to perform the damage detection. In this work, a
novel damage detection index based on modal strains is proposed, and its reliability in detecting
stiffness reduction in elements of a planar truss is tested numerically
Damage Detection in Truss Structures Using Modal Expansion and Flexibility Matrix
No full text. In this study, a new index for damage detection in truss structures is
presented. The technique exploits incomplete mode shapes obtained from pseu do-experimental data which mimic the records of a limited number of sensors
placed on the structure. The modes are completed using a multi-step modal ex pansion technique based on the subspace iteration method. Stiffness and mass
matrices are computed only after the dynamic condensation matrix converges,
thus making the iteration procedure computationally efficient. Once the modes
are expanded and mass normalized, the identification method is developed by
computing the flexibility matrices of healthy and damaged structures. Each
flexibility matrix is approximated as the product of the first circular frequencies
and complete mode shapes of the truss where each column represents the node
displacements associated with unitary forces applied to the corresponding de gree of freedom. From the flexibility matrix, it is possible to construct a matrix
of strain changes induced by the presence of damage in the structure. The dam age identification exploits a novel index based on Singular Value Decomposi tion of the strain change matrix and identifies the damaged elements as bars
with the highest values. Two numerical examples on planar truss structures
show the potentialities of the method
Dissociative Disorders: Neuroimaging as a New Narrative
No full textNeuroimaging techniques have led to specific evidence into the neuroanatomical and neurofunctional correlates of dissociative disorders. The diagnosis of dissociative amnesia correlated with dysfunctions in the prefrontal, temporal, limbic, and paralimbic regions. Such dysfunctions may impact the symptoms of the disorder, including memory deficit (hippocampus), affective disturbance (temporal, limbic, and paralimbic areas), and cognitive dysfunctions (prefrontal areas).
In dissociative identity disorder (DID), structural imaging showed significant chances in hippocampal subregions. Functional alterations of different brain areas in DID are linked to memory symptoms (hippocampus–parahippocampus), personality switches (prefrontal cortex–striatum–hippocampus), and emotional processing issues (insula, prefrontal cortex, striatum). The same neural DID correlates have been linked to neural development changes after childhood trauma. In depersonalization disorder (DPD), structural changes are seen in the thalamus, caudate, dorsomedial prefrontal, and somatosensory cortices, with reported functional changes in prefrontal regions, anterior cingulate cortex, hypothalamus, and amygdala. All these changes could affect symptom expression, including changes in bodily experience, hypervigilance, anxiety, spatial
perception, and emotional processing disturbance. Further studies on structural and functional neural correlates of dissociative disorders could lead to better comprehension of their etiology, prevention strategies, tailored treatments, and development of new drug treatment and psychological interventions
“Verum Ipsum Factum”, Factum Ipsum Bellum: Death Drive or Driving towards Death?
Full text linkIs war evitable? Besides being a question to which humanity is struggling to answer, it is the title of the letter exchange between Freud and Einstein that inspired this editorial. The aim is to address this question and analyse whether there is a pattern behind some historical events and mass behaviour, starting with Freud and ending with the possibility of applying chaos theory. What has been hypothesized for centuries is that the masses behave in a manner that can overcome the individual’s interest but are subject to the same risks and patterns as the individual is, i.e., hypernarcissism that fuels the vicious circle of victims and executioners. Is there a reason why historical memory does not stop humankind from pursuing war? Is there an intrinsic death drive that fuels man against one another, or are there other, more complex reasons why war could be (or could not be) inevitable
Migrants and Mental Health: Equal Rights but Different Needs
No full textIn 2020, the number of international migrants worldwide—people residing in a country other than their country of birth—reached almost 281 million [...
Functional Neuroimaging in Dissociative Disorders: A Systematic Review
Full text linkBackground: Dissociative disorders encompass loss of integration in essential functions such as memory, consciousness, perception, motor control, and identity. Nevertheless, neuroimaging studies, albeit scarce, have suggested the existence of particular brain activation patterns in patients belonging to this diagnostic category. The aim of this review is to identify the main functional neuroimaging correlates of dissociative disorders. Methods: we searched the PubMed database to identify functional neuroimaging studies conducted on subjects with a diagnosis of a dissociative disorder, following the PRISMA guidelines. In the end, we included 13 studies in this systematic review, conducted on 51 patients with dissociative identity disorder (DID), 28 subjects affected by depersonalization disorder, 24 with dissociative amnesia, and 6 with other or not specified dissociative disorders. Results: Prefrontal cortex dysfunction seems prominent. In addition, changes in the functional neural network of the caudate are related to alterations of identity state and maintenance of an altered mental status in DID. Another role in DID seems to be played by a dysfunction of the anterior cingulate gyrus. Other regions, including parietal, temporal, and insular cortices, and subcortical areas were reported to be dysfunctional in dissociative disorders. Conclusions: Prefrontal dysfunction is frequently reported in dissociative disorders. Functional changes in other cortical and subcortical areas can be correlated with these diagnoses. Further studies are needed to clarify the neurofunctional correlations of each dissociative disorder in affected patients, in order to identify better tailored treatments
COVID-19-related stress in Italy: a comparison between patients with mental disorders and the general population.
No full textIntroduction: Following the surge of the COVID-19 pandemic, some people have been experiencing severe mental health consequences related to pandemic stress, fear of contagion, lockdown, and measures to avoid contagion and virus spread. These aspects contributed to an increase in anxious-depressive symptoms in the general population (Asmundson et al. J Anx Dis 2020; 70 102196).
Objectives: The study aims at verifying the hypothesis that Italian patients with a diagnosis of a mental disorder showed more severe depressive, anxiety and stress-related symptoms compared to the general Italian population in the context of the current pandemic.
Methods: Nine hundred sixty-one volunteer subjects (542 females, 415 males; mean age 39.42, SD = 14.5) completed the Covid-Stress-Scale (CSS) (Taylor et al. J Anx Dis 2020; 72 102232) and the Depression-Anxiety-Stress Scales-21 (DASS-21) (Bottesi et al. Compr Psych 2015; 60 170-81) through a self-report survey. Participants have been assessed for between-group differences through the chi-square test for categoric variables and one-way ANOVA for continuous variables.
Results: One hundred and thirty subjects (13.53% of the whole sample) reported a diagnosis of a mental disorder for which they received medications. Among these subjects, 47.8% reported a diagnosis of anxiety disorder, 29% major depressive disorder, 2.7% bipolar disorder, and 20.4% other mental disorders. Among patients, there was a prevalence of females (chi-square = 15.84; p < 0.001), more severe depressive (F = 34.25; p < 0.001), anxiety (F = 46.15; p < 0.001), and stress-related symptoms (F = 39.38; p < 0.001) at the DASS-21 scale. The patient group also showed a tendency to more severe traumatic stress related to the pandemic (F = 3.64; p = 0.057) at factor IV of the CSS, without significant differences in the other factors of the CSS.
Conclusions: The hypothesis is partially confirmed, considering that patients showed more severe depressive, anxiety and stress-related symptoms and a tendency to more severe pandemic traumatic stress. Nevertheless, in all other pandemic-related symptoms we analyzed (i.e., xenophobia, increase of medical assessments, fear of contagion), there were no differences between the group of patients and the general population. In this sense, in the current scenario in Italy, symptoms directly related to pandemic stress are almost the same in both the general population and patients with mental disorders
Clinical Aspects of Manic Episodes After SARS-CoV-2 Contagion or COVID-19
Full text linkAs COVID-19 pandemic spread all over the world, it brought serious health consequences in every medical field, including mental health. Not only healthcare professionals were more prone to develop anxiety, depression, and stress, but the general population suffered as well. Some of those who had no prior history of a psychiatric disease developed peculiar symptoms following infection with SARS-CoV-2, mostly because of psychological and social issues triggered by the pandemic. People developed traumatic memories, and hypochondria, probably triggered by social isolation and stress. Infection with SARS-CoV-2 has influenced the mental health of psychiatric patients as well, exacerbating prior psychiatric conditions. In this review, we focus on analyzing those cases of mania in the context of bipolar disorder (BD) reported after COVID-19 disease, both in people with no prior psychiatric history and in psychiatric patients who suffered an exacerbation of the disease. Results have shown that COVID-19 may trigger a pre-existing BD or unmask an unknown BD, due to social and psychological influences (decreased social interaction, change in sleep patterns) and through biological pathways both (neuroinflammation and neuroinvasion through ACE-2 receptors expressed in the peripheral and central nervous systems (PNS and CNS respectively). No direct correlation was found between the severity of COVID-19 disease and manic symptoms. All cases presenting severe symptoms of both diseases needed specific medical treatment, meaning that they concur but are separate in the treatment strategy needed. This review highlights the importance of a now widespread viral disease as a potential agent unmasking and exacerbating bipolar mood disorder, and it can hopefully help physicians in establishing a rapid diagnosis and treatment, and pave the road for future research on neuroinflammation triggered by SARS-CoV-2
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
