Feedback Beamforming in the Time Domain.

Real-time source localization is crucial for high-end automation and artificial intelligence (AI) products. However, a low signal-to-noise ratio (SNR) and limited processing time can reduce localization accuracy. This work proposes a new architecture for a time-domain feedback-based beamformer that meets real-time processing demands. The main objective of this design is to locate reflective sources by estimating their direction of arrival (DOA) and signal range. Incorporating a feedback mechanism in this architecture refines localization precision, a unique aspect of this approach. We conducted an in-depth analysis to compare the effectiveness of time-domain feedback beamforming against conventional time-domain methods, highlighting their benefits and limitations. Our evaluation of the proposed architecture, based on critical performance indicators such as peak-to-sidelobe ratio, mainlobe width, and directivity factor, demonstrates its ability to improve beamformer effectiveness significantly.

Analysing the ocular biometry of new-born infants.

PURPOSE: To model and analyse the ocular biometry of new-born infants. METHODS: This work is based on previously published data of a cohort of 66 new-born infants aged 0-3 days. After exclusion of seven myopic subjects, the available retinoscopy, keratometry and ultrasound biometry data were analysed, along with calculated parameters such as lens power and whole eye power. RESULTS: Male infants have significantly flatter corneas that female infants (Mann-Whitney U test, p < 0.001), which was associated with a difference in gestational age between genders (multiple linear regression; p = 0.043). No other gender-based differences were seen. Corneal curvature (Pearson, r = 0.575; p < 0.001), lens power (r = -0.681; p < 0.001), and anterior chamber depth (r = 0.654; p < 0.001) were all correlated to axial length, but not refraction (r = -0.114; p = 0.42). Most ocular parameters were associated with gestational age (linear regression analysis; p < 0.05), rather than birth length, birth weight, fertilization method or parental myopia (all p > 0.05), suggesting scaled eye growth during the last weeks before birth. Multivariate Gaussian analysis demonstrated that a statistical eye model can be defined that generates synthetic data that is significantly equal to the original data (non-parametric Mann-Whitney test for equality; all p < 0.05), with similar variability (non-parametric Levene test; all p > 0.05). CONCLUSION: The eye undergoes a scaled growth until birth, at which time male and female infants have similar values. The models presented may serve as an early biometry reference.

Outcome of untreated meningiomas.

BACKGROUND: Nowadays meningiomas are frequently detected incidentally. Their natural history has not yet been established because it is difficult to predict the growth pattern. Therefore, the management, after the radiological diagnosis, is still controversial. OBJECTIVES: To evaluate the clinical outcome and growth rate of conservatively treated meningiomas at our tertiary center, identify prognostic factors of tumor growth, and suggest guidelines based on the available data and our experience. METHODS: We reviewed the clinical records of 56 patients with 63 untreated meningiomas. Most were diagniosed incidentally. Clinical features and imaging findings at diagnosis and during follow-up were compared between growing and non-growing tumors. Potential patient- and tumor-related predictive factors for growth were analyzed. RESULTS: The study group included 46 women (52 meningiomas) and 10 men (11 meningiomas) aged 39-83 years. Mean tumor size was 18 +/- 11 mm (range 3-70 mm) at diagnosis and 22 +/- 11 mm (range 8-70 mm) at last follow-up; mean follow-up time was 65 +/- 34 months (range 15-152 months). During follow-up 24 tumors (38%) grew ata rate of 4 mm per year; none became symptomatic. Only two prognostic factors were statistically significantly associated with low growth rate: older age and tumor calcifications. CONCLUSIONS: Given our finding of a low growth incidence of meningiomas in the elderly, we support conservative management in patients aged 70 years or older. Calcifications into the meningioma are also indicative of slow growth, suggesting a conservative strategy. Surgery is recommended in younger patients in whom tumor growth occurs more often and a longer follow-up is necessary.

Suppression of the oculocephalic reflex (doll's eyes phenomenon) in normal full-term babies.

PURPOSE: To determine the precise age of suppression of the oculocephalic reflex in infants and its relationship to specific clinical characteristics. METHODS: The oculocephalic reflex was prospectively tested in 325 healthy full-term babies aged 1 to 32 weeks attending an orthopedic outpatient clinic. Two ophthalmologists raised the baby's head 30 degrees above horizontal and rapidly rotated it in the horizontal and vertical planes while watching the conjugate eye movement. Suppression of the reflex, by observer agreement, was analyzed in relation to gestational age, postpartum age, postconceptional age, birth weight, and current weight. The data were fitted to a logistic regression model to determine the probability of suppression of the reflex according to the clinical variables. RESULTS: The oculocephalic reflex was suppressed in 75% of babies by the age of 11.5 weeks and in more than 95% of babies aged 20 weeks. Although postpartum age had a greater influence than gestational age, both were significantly correlated with suppression of the reflex (p = 0.01 and p = 0.04, respectively; two-sided t-test). Postpartum age was the best single variable explaining absence of the reflex. On logistic regression with cross-validation, the model including postpartum age and current weight yielded the best results; both these factors were highly correlated with suppression of the reflex (r = 0.74). CONCLUSIONS: The oculocephalic reflex is suppressed in the vast majority of normal infants by age 11.5 weeks. The disappearance of the reflex occurs gradually and longitudinally and is part of the normal maturation of the visual system.

Effect of intravitreal bevacizumab (avastin) on the growing rabbit eye.

PURPOSE: To study the effect of intravitreal bevacizumab (Avastin) on the structure and growth of the young rabbit eye. MATERIALS AND METHODS: Twelve 6-week-old rabbits underwent intravitreal injection of bevacizumab (1.25 mg/0.05 ml) in one eye and no injection in the other (study group). Six additional rabbits served as controls. Slit lamp examination, fundus evaluation, and measurements of corneal power, central corneal thickness, corneal astigmatism, and axial length were performed before treatment and 1, 2, and 3 months after. At 3 months, the rabbits were sacrificed for histological study. RESULTS: Within the study group, there were no significant differences in clinical parameters between the bevacizumab-treated and fellow eyes at any timepoint or overall. The estimated confidence intervals extended to about one standard deviation of their respective values. Comparison of the injected eyes in the study group with the uninjected eyes in the control group yielded similar findings. There were no between-group differences in ocular growth and no abnormalities of the anterior and posterior segments or the retina and retinal vasculature. CONCLUSIONS: Intravitreal bevacizumab apparently has no adverse effect on the growth and development of the young rabbit eye, in a biologically or statistically significant way.

Systemic allergic reaction to tree processionary caterpillar in children.

Contact with the tree processionary caterpillar or ingestion/inhalation of its airborne toxin-containing hairs and spines may cause a direct histamine-releasing or IgE-mediated allergic reaction in humans. The most common manifestations are urticaria and dermatitis; systemic manifestations such as respiratory involvement and anaphylaxis have been reported mainly in foresters. We describe a 12-year-old child who was presented to the emergency department with systemic allergic reaction (pruritic rash, conjunctival hyperemia, dyspnea, and wheezing), which eventually proved to be due to exposure to the pine tree processionary caterpillar. The diagnosis was made only after the child's repeated exposure to the caterpillar. Tree processionary caterpillar should be added to the list of causes of systemic allergic reactions in children, especially in endemic areas, and medical staff should be alerted the range of clinical manifestations to ensure prompt diagnosis and treatment.

Early structural status of the eyes of healthy term neonates conceived by in vitro fertilization or conceived naturally.

PURPOSE: To evaluate the effects of in vitro fertilization (IVF) on early development of the eye in full-term healthy infants. METHODS: A case-control study was performed. The study sample included full-term infants born from March 1 to August 14, 2006, in the Neonatal Department of Helen Schneider Women's Hospital, Rabin Medical Center. Data were collected on sex, gestational age, birth weight, Apgar score, head circumference, body length, and mode of conception (IVF/natural). A full ophthalmologic examination was performed, including measurement of intraocular pressure, keratometry, ultrasound biometry, pachymetry, and funduscopy. RESULTS: Sixty-six infants (132 eyes) were examined; 32 were conceived by IVF, and 34 were conceived naturally. Girls accounted for 56% of the IVF group and 44% of the natural conception group. There were no statistically significant differences between the groups in sex, gestational age, head circumference, intraocular pressure, axial length, anterior chamber depth, and lens thickness. The IVF infants had lower birth weight and body length than the infants born by natural conception (P = 0.032, t-test). Their keratometric and pachymetric values were also higher, but when birth weight and length were controlled, this difference remained statistically significant only for infants with a birth weight of less than 3000 g and a body length of less than 48.5 cm. CONCLUSIONS: IVF apparently has no effect on early development of the eyes in full-term infants. The steeper corneal curvature and greater central corneal thickness in a subset of smaller IVF infants may reflect delayed corneal maturation.

The relationship between diabetic retinopathy, glycemic control, risk factor indicators and patient education.

BACKGROUND: Hyperglycemia, high blood pressure and hypercholesterolemia are risk factors for diabetic retinopathy and vision loss in diabetic patients. OBJECTIVES: To evaluate risk factors in patients treated for diabetic retinopathy in our hospital clinic and assess patients' awareness of the impact of glycemic control; and to compare the findings with those in patients followed in a community clinic. METHODS: We performed a cross-sectional comparative study that included 178 consecutive patients with type 2 diabetes mellitus treated in the Retinal Vascular Service of Rabin Medical Center from 1 September to 31 December 2004, and 107 consecutive patients with type 2 diabetes mellitus examined in a community clinic during the same period. A questionnaire was completed; the main outcome measures were glycemic and risk factor control and their correlation with diabetic retinopathy and visual acuity. RESULTS: Although only 43% of the patients had heard of HbA1c, 98% of them had undergone this analysis, with a mean level of 8.2% (SD 1.9) in the hospital patients and 7.7% (SD 1.6) in the community patients (P= 0.01, t-test). HbA1c was lower in hospital patients who were aware of the test. Correlations were found for visual acuity, diabetic retinopathy and laser treatment with HbA1c < or = 7%, cholesterol level < 200 mg/dl and blood pressure < 130/85 mmHg. CONCLUSIONS: Since our study and previous reports have shown that HbA1c level < or = 7%, serum cholesterol level < 200 mg/dl and blood pressure < 130/85 mmHg are associated with better preservation of vision in patients with type 2 diabetes mellitus, we propose that the ophthalmologist has a role in educating patients about glucose, lipid and blood pressure control as part of the treatment of diabetic retinopathy.

T1799A BRAF mutations in conjunctival melanocytic lesions.

PURPOSE: To gain a better understanding of the molecular events leading to the development of conjunctival melanocytic lesions and conjunctival melanoma, this study was conducted to investigate the presence of T1799A BRAF oncogenic mutation in these lesions. METHODS: Forty-eight surgically excised conjunctival melanocytic lesions from 48 patients were examined for the presence of the BRAF T1799A mutation. Twenty-eight lesions were conjunctival nevi, of which 20 were excised from children younger than 18 years. Fifteen lesions were conjunctival primary acquired melanosis (PAM; 11 without atypia and 4 with atypia) and five were conjunctival melanomas. To detect the BRAF T1799A mutation, both a newly developed kit (Mutector; TrimGen, Sparks, MD) and direct DNA sequence analysis of exon 15 after PCR amplification were used. RESULTS: The T1799A BRAF mutation was identified in 14 of 28 (50%) conjunctival nevi analyzed, but in none of the 15 conjunctival PAMs, with and without atypia. The T1799A BRAF mutation was identified in two of the five (40%) conjunctival melanomas. There was no difference in the BRAF mutation detected in conjunctival nevi in children or adults, as the BRAF mutation was detected in 50%. CONCLUSIONS: The results showed that conjunctival nevi, similar to skin nevi, have a high frequency of oncogenic BRAF mutations. Furthermore, the results suggest that the oncogenic event leading to BRAF mutations affect only conjunctival nevi and not conjunctival PAM. The clinical significance of these observations remains to be determined.