533 research outputs found
The Contribution of Three-Dimensional Power Doppler Imaging in the Preoperative Assessment of Breast Tumors: A Preliminary Report
Purpose. The aim of this study was to determine the value of 3D and 3D Power Doppler sonography in the detection of tumor malignancy in breast lesions and to find new diagnostic criteria for differential diagnosis.
Methods. One hundred and twenty five women with clinically or mammographically suspicious findings were referred for 3D Power Doppler ultrasound prior to surgery. Histological diagnosis was conducted after surgery and compared with ultrasound findings. Sonographic criteria used for breast cancer diagnosis were based on a system that included morphological characteristics and criteria of the vascular pattern of a breast mass by Power Doppler imaging.
Results. Seventy-two lesions were histopathologically diagnosed as benign and 53 tumors as malignant. Three-dimensional ultrasound identified 49 out of 53 histologically confirmed breast cancers resulting in a sensitivity of 92.4% and a specificity of 86.1% in diagnosing breast malignancy (PPV: 0.83, NPV:0.94).
Conclusions. 3D ultrasonography is a valuable tool in identifying preoperatively the possibility of a tumor to be malignant
INVAZIVNI DIJAGNOSTIČKI POSTUPCI U VIŠEPLODNOJ TRUDNOĆI
Over the past few years, the rising rate of multiple pregnancies, attributed to both increasing reliance on infertility treatment modalities and delayed childbearing, has expanded the need for prenatal invasive genetic testing. In multiples, first-trimester chorionic villus sampling and second-trimester amniocentesis are relatively safe and efficient alternative procedures, whereas fetal blood sampling is reserved for cases where an indefinite result of fetal karyotyping needs elucidation. The choice of invasive technique should be based on gestational age at referral date, procedure related risks and technical demands, but experience of the center performing the modality should be emphasized in decision making. Technological advances in modern high resolution ultrasound equipment along with increasing operator experience available today result in more accurate and efficacious invasive prenatal diagnosis in twin or higher-order pregnancies, minimizing potential post-procedural fetal loss rate.Monozigotni blizanci čine oko 30% blizanačkih trudnoća, njihova je učestalost stalna, a dvozigotni blizanci čine oko 70% blizanačkih trudnoća, njihova je učestalost u porastu, zbog učestale primjene tehnike pomognute oplodnje i zbog odgađanja prvih trudnoća te posljedične veće životne dobi trudnica. Rizik strukturalnih anomalija u blizanaca je veća nego u jednoplodnih trudnoća, rizik je do tri puta veći u monozigotnih, a u dizigotnih blizanaca je od prilike kao u jednoplodnih trudnoća. Zbog ukupno veće učestalosti višeplodnih trudnoća povećana je potreba za invazivnom prenatalnom dijagnostikom. U višeplodnim trudnoćama su biopsija korionskih resica u prvom i amniocenteza u drugom tromjesečju relativno sigurni i uspješni alternativni postupci, a uzimanje fetalne krvi kordocentezom je rezervirano za slučajeve kada je učinjena kariotipizacija fetusa nesigurna i nejasna. Izbor invazivne tehnike se temelji na dobi trudnoće kad se trudnica javlja, na postojeći rizik postupka i na tehničke zahtjeve, a od velikog je značaja iskustvo prenatalnog centra. Tehnološki napredak suvremene ultrazvučne aparature te rastuće iskustvo prenatalnog operatera doprinose točnoj i učinkovitijoj invazivnoj prenatalnoj dijagnostici u dvojaka i blizanaca višeg stupnja te na najmanju moguću mjeru smanjuju fetalni gubitak nakon invazivnog postupka
Unstable Attractors: Existence and Robustness in Networks of Oscillators With Delayed Pulse Coupling
We consider unstable attractors; Milnor attractors such that, for some
neighbourhood of , almost all initial conditions leave . Previous
research strongly suggests that unstable attractors exist and even occur
robustly (i.e. for open sets of parameter values) in a system modelling
biological phenomena, namely in globally coupled oscillators with delayed pulse
interactions.
In the first part of this paper we give a rigorous definition of unstable
attractors for general dynamical systems. We classify unstable attractors into
two types, depending on whether or not there is a neighbourhood of the
attractor that intersects the basin in a set of positive measure. We give
examples of both types of unstable attractor; these examples have
non-invertible dynamics that collapse certain open sets onto stable manifolds
of saddle orbits.
In the second part we give the first rigorous demonstration of existence and
robust occurrence of unstable attractors in a network of oscillators with
delayed pulse coupling. Although such systems are technically hybrid systems of
delay differential equations with discontinuous `firing' events, we show that
their dynamics reduces to a finite dimensional hybrid system system after a
finite time and hence we can discuss Milnor attractors for this reduced finite
dimensional system. We prove that for an open set of phase resetting functions
there are saddle periodic orbits that are unstable attractors.Comment: 29 pages, 8 figures,submitted to Nonlinearit
"hCG priming" effect in controlled ovarian stimulation through a long protocol
<p>Abstract</p> <p>Background</p> <p>Recently, it has been demonstrated that, in patients down-regulated by GnRH analogues (GnRHa), a short-term pre-treatment with recombinant LH (rLH), prior to recombinant FSH (rFSH) administration, increases the number of small antral follicle prior to FSH stimulation and the yield of normally fertilized embryos. However, no data exist in the literature regarding the potential beneficial effect of "hCG priming" in controlled ovarian hyperstimulation (COH) through a long GnRH-a protocol, which binds the same receptor (LH/hCGR), though it is a much more potent compared to LH. The primary aims of this study were to assess the effect of short-term pre-rFSH administration of hCG in women entering an ICSI treatment cycle on follicular development, quality of oocytes and early embryo development. The secondary endpoints were to record the effects on endometrial quality and pregnancy rate.</p> <p>Methods</p> <p>Patients with a history of at least one previous unsuccessful ICSI cycle were randomly assigned into two groups to receive treatment with either a long protocol with rFSH (control group) or a long protocol with rFSH and pre-treatment with hCG (hCG group). In particular, in the latter group, a fixed 7 days course of 200 IU/day hCG was administered as soon as pituitary desensitization was confirmed.</p> <p>Results</p> <p>The mean number of oocytes retrieved was not significantly different between the two treatment groups, although the percentage of mature oocytes tended to be higher but not significantly different in hCG-treated patients. The percentage of patients with more than one grade 3 embryos was higher in the pre-treatment group, which also showed a higher pregnancy rate.</p> <p>Conclusion</p> <p>All the above clinical observations, in conjunction with previous data, suggest a point towards a beneficial "hCG priming" effect in controlled ovarian hyperstimulation through a long GnRH-a down-regulation protocol, particularly in patients with previous ART failures.</p
Non-blood medical care in gynecologic oncology: a review and update of blood conservation management schemes
This review attempts to outline the alternative measures and interventions used in bloodless surgery in the field of gynecologic oncology and demonstrate their effectiveness. Nowadays, as increasingly more patients are expressing their fears concerning the potential risks accompanying allogenic transfusion of blood products, putting the theory of bloodless surgery into practice seems to gaining greater acceptance. An increasing number of institutions appear to be successfully adopting approaches that minimize blood usage for all patients treated for gynecologic malignancies. Preoperative, intraoperative and postoperative measures are required, such as optimization of red blood cell mass, adequate preoperative plan and invasive hemostatic procedures, assisting anesthetic techniques, individualization of anemia tolerance, autologous blood donation, normovolemic hemodilution, intraoperative cell salvage and pharmacologic agents for controlling blood loss. An individualised management plan of experienced personnel adopting a multidisciplinary team approach should be available to establish non-blood management strategies, and not only on demand of the patient, in the field of gynecologic oncology with the use of drugs, devices and surgical-medical techniques
Producing valid statistics when legislation, culture, and medical practices differ for births at or before the threshold of survival: Report of a European workshop
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Strong stability of discrete-time systems
The paper introduces a new notion of stability for internal (state-space) autonomous system descriptions in discrete-time, referred to as strong stability which extends a parallel notion introduced in the continuous-time case. This is a stronger notion of stability compared to alternative definitions (asymptotic, Lyapunov), which prohibits systems described by natural coordinates to have overshooting responses for arbitrary initial conditions in state-space. Three finer notions of strong stability are introduced and necessary and sufficient conditions are established for each one of them. The class of discrete-time systems for which strong and asymptotic stability coincide is characterized and links between the skewness of the eigen-frame and the violation of strong stability property are obtained. Connections between the notions of strong stability in the continuous and discrete-domains are briefly discussed. Finally strong stabilization problems under state and output feedback are studied. The results of the paper are illustrated with a numerical example
Formalising the Continuous/Discrete Modeling Step
Formally capturing the transition from a continuous model to a discrete model
is investigated using model based refinement techniques. A very simple model
for stopping (eg. of a train) is developed in both the continuous and discrete
domains. The difference between the two is quantified using generic results
from ODE theory, and these estimates can be compared with the exact solutions.
Such results do not fit well into a conventional model based refinement
framework; however they can be accommodated into a model based retrenchment.
The retrenchment is described, and the way it can interface to refinement
development on both the continuous and discrete sides is outlined. The approach
is compared to what can be achieved using hybrid systems techniques.Comment: In Proceedings Refine 2011, arXiv:1106.348
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