1,721,305 research outputs found
La mortalità embrionale nella specie bufalina.
No full textLa mortalità embrionale è considerata una delle principali cause di perdita di fertilità nella specie bufalina, in particolar modo se gli animali non vengono fatti accoppiare durante la propria stagione riproduttiva, per l’applicazione della tecnica di destagionalizzazione. Il fenomeno della mortalità embrionale in animali fecondati mediante inseminazione strumentale (IS) risulta intorno al 20-40% durante le stagioni caratterizzate da un alto numero di ore di luce giornaliera, mentre si riduce al 7% nelle stagioni caratterizzate da un prevalere delle ore di buio. Ad ogni modo, una percentuale di circa il 20% di tale fenomeno sembra riguardare anche soggetti fecondati con monta naturale. Una maggiore incidenza di riassorbimenti embrionali si è osservata tra i 28 e i 60 giorni di gestazione, in bufale che avevano concepito in periodi caratterizzati da ore di luce crescente. Il fenomeno potrebbe essere almeno parzialmente spiegato con una ridotta secrezione di progesterone, il principale ormone coinvolto durante la gestazione. Un basso livello di progesterone durante la fase luteinica, infatti, è associato ad una ridotta secrezione di specifici fattori embriotrofici (in particolare le IGF-I e –II e le IGF binding proteins) nel lume oviduttale ed uterino, riducendo la crescita dell’embrione, che produce una minor quantità Interferon-τ (IFN-τ) e, di conseguenza, non è in grado di bloccare i meccanismi luteolitici. Tuttavia, altri fattori non ancora pienamente identificati contribuiscono per almeno il 40-50% dei casi. Nella specie bovina, ai fini di ridurre le perdite legate a mortalità embrionale, sono utilizzate 2 tipologie di trattamenti, quelli che prevedono la supplementazione con progesterone esogeno e quelli che stimolano la produzione di progesterone endogeno. Tuttavia, a differenza di quanto osservato nella specie bovina, trattamenti ormonali con hCG, agonisti del GnRH o progesterone effettuati 5 giorni dopo l’inseminazione strumentale non sembrano essere sempre in grado di ridurre la mortalità embrionale nella bufala. Infatti, la mortalità embrionale in quest’ultima sembra avvenire in epoca più tardiva (25-40 giorni) rispetto alla bovina, e, di conseguenza, i trattamenti dovrebbero forse essere applicati successivamente. È stato, infatti, osservato che trattamenti effettuati al 25° giorno post-inseminazione, sono in grado di incrementare la percentuale di gravidanza. Tuttavia, in quegli animali che presentano bassi livelli di progesterone sia al giorno 20 che 25, l’embrione è probabilmente compromesso, per cui i trattamenti sono inefficaci nel ridurre il fenomeno della mortalità embrionale. Da quanto esposto finora, si confermerebbe che la concentrazione di progesterone riveste un ruolo fondamentale anche nella specie bufalina, sebbene ulteriori studi siano necessari al fine di comprendere i meccanismi che sono alla base del fenomeno della mortalità embrionale e cercare di ridurne l’incidenza
An unusual oral swelling
No full textA
7-year-old female was admitted for worsening
swelling under her tongue associated with fever and
difficulty swallowing. She had sustained head and
neck bicycle handlebar trauma 2 weeks before the admission.
She was noted to have a cystic and ballotable mass appearing
in the floor of mouth. The lesion was evaluated by
an otorhinolaryngologist who aspirated 15 mL of mucoid-
appearing fluid, which led to collapse of the floor of mouth
swelling and alleviation of dysphagia. The patient was
placed on a clear liquid diet, which was advanced to a
regular diet over 3 days and completed a 10-day course of
clindamycin.
Neck magnetic resonance imaging revealed persistence of
a single cystic mass of approximately 1 cm in diameter
medial to the right submandibular gland. At her 2-week post-discharge
visit, she was healing well without evidence of recurrence,
and there have been no complications at the 3-month
follow-up. The diagnosis of an extensive post-traumatic
ranula was made based on her clinical history, the neck
magnetic resonance imaging findings, as well as the
presence of mucin in the aspirate. The term “ranula,”
derived from the ancient Latin word “rana” (meaning
frog), is descriptive of the translucent swelling of the floor
of mouth reminiscent of a frog’s belly.
It consists of a
mucous extravasation pseudocyst in the floor of the
mouth, which arises from the sublingual salivary gland.
The pathogenesis is thought to be a result of obstructive
scar tissue in sublingual salivary gland ductules,
attributable to previous surgery or minor trauma, leading
to backpressure of secretions and subsequent extravasation
of mucus into the surrounding tissues.
There are
numerous nonsurgical and surgical methods that have
been used to treat ranulas; however, it remains unclear
what is the most appropriate treatment procedure.
However, recent evidence recommends a conservative
approach for no longer than 3 months followed by the
surgical resection of a symptomatic and recurrent ranula
that exceeds 2 cm in diameter
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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
The impact of retroactivity on information exchange in molecular communications
Full text linkInformation exchange is a key process in all communication systems, including biological ones. This paper presents first results on the study of the impact of retroactivity, the loads that downstream modules apply on their upstream systems, on different biological signaling system models. The aim is to provide analytical tools to maximize the reliable information exchange in biomolecular circuits
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
- …
