Relative Size Reduction Research Articles

Efficacy of Oral Doxycycline in Reducing the Size of Pterygium lesions

Objective: To assess the efficacy of oral Doxycycline in reducing the size of pterygium lesions in a Pakistani population
 Study Design: Quasi-experimental study.
 Place and Duration of Study: Armed Forces Institute of Ophthalmology, Rawalpindi, from Sep 2018 and May 2019.
 Methodology: Sixty patients above 20 years of age were enrolled in the study. Oral Doxycycline 200m/day was given for thirty consecutive days. Photographs of the lesions were taken at the time of recruitment and at the end of the study for assessment of pterygium size. Difference between pre-treatment and post-treatment size was analysed and comparison was made with age, gender and initial lesion size.
 Results: Twenty-two females and thirty-eight males were examined. The mean age of the participants was 48.8 ± 13.8 years. The mean size of the pterygium lesions before commencing the treatment was 12.24 ± 6.28 mm2. The mean size of the lesions after the treatment was 11.24 ± 5.39 mm2. The mean difference size was 1.00 ± 1.62 mm2 (p <0.001). The relative change in size (i.e. post-treatment size divided by pre-treatment size) was 0.94 ± 0.09 which was found to be statistically significant (p<0.001). There was correlation between larger initial lesion size and greater relative reduction in size (r = -0.42, p = 0.001).
 Conclusion: The change in the size of pterygium lesions produced by Doxycycline was found to be statistically significant but was not deemed clinically significant. Therefore, oral Doxycycline is not recommended for the treatment of pterygium in our population.

Sublethal toxicity of graphene oxide in Caenorhabditis elegans under multi-generational exposure

Nanomaterials have received increasing attentions owing to their potential hazards to the environment and human health; however, the multi-generational toxicity of graphene oxide under consecutive multi-generational exposure scenario still remains unclear. In the present study, Caenorhabditis elegans as an in vivo model organism was employed to explore the multi-generational toxicity effects of graphene oxide and the underlying mechanisms. Endpoints including development and lifespan, locomotion behaviors, defecation cycle, brood sizes, and oxidative response were evaluated in the parental generation and subsequent five filial generations. After continuous exposure for several generations, worms grew smaller and lived shorter. The locomotion behaviors were reduced across the filial generations and these reduced trends were following the impairments of locomotion-related neurons. In addition, the extended defecation cycles from the third filial generation were in consistency with the relative size reduction of the defecation related neuron. Simultaneously, the fertility function of the nematode was impaired under consecutive exposure as reduced brood sizes and oocytes numbers, increased apoptosis of germline, and aberrant expression of reproductive related genes ced-3, ced-4, ced-9, egl-1 and ced-13 were detected in exposed worms. Furthermore, the antioxidant enzyme, SOD-3 was significantly increased in the parent and filial generations. Thus, continuous multi-generational exposure to graphene oxide caused damage to the neuron development and the reproductive system in nematodes. These toxic effects could be reflected by indicators such as growth inhibition, shortened lifespan, and locomotion behavior impairment and induced oxidative response.

Proton Therapy Specific Salivary Gland Volume Changes After Head and Neck Radiotherapy

Salivary glands are exquisitely sensitive to radiotherapy. Patients treated with radiotherapy to the head and neck region commonly develop salivary gland volume loss and associated xerostomia. Salivary volume loss is associated with salivary function loss, making it a useful surrogate indicator of xerostomia. Previous studies have correlated the degree of salivary gland volume loss with mean radiation doses in patients undergoing photon head and neck radiation. However, change in salivary gland volume relative to radiation dose has not been evaluated in patients undergoing proton therapy. Currently, a constant value of 1.1 is used to relate physical dose (PD) to biological dose (BD) for proton therapy. However, specific tissues may respond differently and thus require a different PD to BD conversion. Herein, we evaluate changes in salivary gland volumes relative to radiation dose in head and neck cancer patients receiving proton therapy to examine the validity of current PD to BD conversions for head and neck salivary glands.Dosimetric data and pre-radiation parotid gland and submandibular gland (SMG) volumes were collected for 20 head and neck cancer patients that received proton therapy at our institution between 2018-2020. Pre-radiation volumes of the SMGs and parotids were collected from treatment planning scans. Post-treatment salivary gland volumes were contoured on 3-month post-treatment diagnostic scans. Mean doses to the glands were gathered from dose-volume histograms generated from treatment plans. Linear logistical regression was performed to measure the effect of dose on volume change.Volume changes of 27 parotids and 38 SMGs were evaluated. Mean doses were 10.0 Gy (standard deviation (SD) 13.2) and 25.2 Gy (SD 25.0) for parotids and SMGs, respectively. Mean dose was < 1 Gy, < 30 Gy, and < 50 Gy in 59.3%, 92.6%, and 100% of parotids compared to 39.5%, 55.3%, and 81.6% of SMGs, respectively. Mean ratios of gland volumes at 3 months post-treatment relative to pre-treatment were 0.962 (SD 0.210) and 1.106 (SD 0.273) for parotids and SMGs, respectively. Effect of mean dose on gland volume change was not statistically significant for either parotids or SMGs.The greater relative size reduction in parotids versus SMGs was consistent with previous photon data. The mean increase in SMG volume could represent post-treatment functional compensation in preserved glands, but this requires additional investigation. Also, determination of the effect of proton dose on salivary gland volume change requires further analysis. Currently, no conclusions can be drawn whether salivary glands are equally or differentially sensitive to proton therapy relative to photon therapy.

Ultrasound Elastography Predicts Thyroid Nodule Volume Reduction Rate After Percutaneous Ethanol Ablation.

To evaluate the safety and efficacy of percutaneous ethanol ablation (PEA) on indeterminate thyroid nodules (Bethesda III and IV) based on ultrasound (US) elastography by assessing the volume reduction rate (VRR), relative reduction in size, resolution of compressive symptoms, and post-procedural complications. This is a retrospective cohort study of all thyroid nodules treated with PEA by a single surgeon at a North American tertiary referral center. Study variables included demographics, nodule characteristics, Bethesda classification, US elastography, presence of compressive symptoms, thyroid function, and post-procedural complications. Relative volume reductions and VRR were calculated at 3- and 6-month follow-ups. Thirty-four thyroid nodules were evaluated in 22 patients. All thyroid nodules underwent a fine needle aspiration prior to PEA. After 6months, 45% of all thyroid nodules exhibited a VRR of ≥50%. A significant VRR was achieved in the soft thyroid nodules at 6months (42.15% ± 31), compared to the stiff nodules with 30.92% ± 91.53, P < .05. Post-PEA thyroid stimulating hormone levels did not significantly change after the procedure. Compressive symptoms resolved in all 5 patients who reported it. One patient developed transient vocal cord paresis that resolved in 3months. To the best of our knowledge, this is the largest series of PEA for thyroid nodules in North America. Ultrasound elastography is a useful adjunct in predicting the success of PEA for nonmalignant thyroid nodules. Percutaneous ethanol ablation is both a safe and effective alternative to surgery for relief of compressive symptoms in select patients.

Ontogenetic braincase development in Psittacosaurus lujiatunensis (Dinosauria: Ceratopsia) using micro-computed tomography.

Ontogenetic sequences are relatively rare among dinosaurs, with Ceratopsia being one of the better represented clades, and especially among geologically earlier forms, such as Psittacosaurus. Psittacosaurus is a small, bipedal basal ceratopsian abundant in the Lower Cretaceous deposits of Asia, whose cranial and endocranial morphology has been well studied, but only cursory details have been published on the bones surrounding the brain. Using reconstructions created from micro-computed tomography scans of well-preserved skulls from the Barremian–Aptian Yixian Formation, China, we document morphological changes in the braincase of Psittacosaurus lujiatunensis through three growth stages, hatchling, juvenile, and adult, thus providing the first detailed study of ceratopsian braincase morphology through ontogeny. Notable ontogenetic changes in the braincase of P. lujiatunensis include a dramatic relative reduction in size of the supraoccipital, an increase in the lateral expansion of the paroccipital processes and a decrease in the angle between the lateral semicircular canal and the palatal plane. These ontogenetic morphological changes in the braincase relate to expansion of the cranium and brain through growth, as well as reflecting the switch from quadrupedal juveniles to bipedal adults as documented in the changing orientation of the horizontal semicircular canal through ontogeny. Recognition of these patterns in a basal ceratopsian has implications for understanding key events in later ceratopsian evolution, such as the development of the parieto-squamosal frill in derived neoceratopsians.

Somatostatin and the “Small-For-Size” Liver

“Small-for-size” livers arising in the context of liver resection and transplantation are vulnerable to the effects of increased portal flow in the immediate postoperative period. Increased portal flow is an essential stimulus for liver regeneration. If the rise in flow and stimulus for regeneration are excessive; however, liver failure and patient death may result. Somatostatin is an endogenous peptide hormone that may be administered exogenously to not only reduce portal blood flow but also offer direct protection to different cells in the liver. In this review article, we describe key changes that transpire in the liver following a relative size reduction occurring in the context of resection and transplantation and the largely beneficial effects that peri-operative somatostatin therapy may help achieve in this setting.

OPTICALLY TRANSPARENT COMPACT 4×4 BUTLER MATRIX FOR WI-FI APPLICATIONS

In this paper, an optically transparent (OT) compact 4 × 4 Butler matrix (BM) operating at 2.4 GHz for Wi-Fi applications is proposed. The device has structured grids refined in quadrilateral cell shapes. The dimensions of cells are chosen based on a simple formula which guarantees a minimum required transparency level in conjunction with a limited rounds of optimizations. A theoretical optical transparency value of 76.2% has been obtained without affecting the excellent electrical performance of the BM. Moreover, complimentary square split ring resonators (CS-SRRs) are patterned in the ground plane of each transparent transmission line in the BM. This loading technique provides a relative size reduction of 16.6% compared to a conventional structure. Simulated and measured results of the proposed design agree well with conventional BM's results. The proposed technique and its related features can be expanded to other microwave devices.

Anatomical and biomechanical traits of broiler chickens across ontogeny. Part I. Anatomy of the musculoskeletal respiratory apparatus and changes in organ size.

Genetic selection for improved meat yields, digestive efficiency and growth rates have transformed the biology of broiler chickens. Modern birds undergo a 50-fold multiplication in body mass in just six weeks, from hatching to slaughter weight. However, this selection for rapid growth and improvements in broiler productivity is also widely thought to be associated with increased welfare problems as many birds suffer from leg, circulatory and respiratory diseases. To understand growth-related changes in musculoskeletal and organ morphology and respiratory skeletal development over the standard six-week rearing period, we present data from post-hatch cadaveric commercial broiler chickens aged 0, 2, 4 and 6 weeks. The heart, lungs and intestines decreased in size for hatch to slaughter weight when considered as a proportion of body mass. Proportional liver size increased in the two weeks after hatch but decreased between 2 and 6 weeks. Breast muscle mass on the other hand displayed strong positive allometry, increasing in mass faster than the increase in body mass. Contrastingly, less rapid isometric growth was found in the external oblique muscle, a major respiratory muscle that moves the sternum dorsally during expiration. Considered together with the relatively slow ossification of elements of the respiratory skeleton, it seems that rapid growth of the breast muscles might compromise the efficacy of the respiratory apparatus. Furthermore, the relative reduction in size of the major organs indicates that selective breeding in meat-producing birds has unintended consequences that may bias these birds toward compromised welfare and could limit further improvements in meat-production and feed efficiency.

Size-dependent enhancement of water relations during post-fire resprouting

In resprouting species, fire-induced topkill causes a reduction in height and leaf area without a comparable reduction in the size of the root system, which should lead to an increase in the efficiency of water transport after fire. However, large plants undergo a greater relative reduction in size, compared with small plants, so we hypothesized that this enhancement in hydraulic efficiency would be greatest among large growth forms. In the ecotone between long-leaf pine (Pinus palustris Mill.) savannas and wetlands, we measured stomatal conductance (gs), mid-day leaf water potential (Ψleaf), leaf-specific whole-plant hydraulic conductance (KL.p), leaf area and height of 10 species covering a range of growth forms in burned and unburned sites. As predicted, KL.p was higher in post-fire resprouts than in unburned plants, and the post-fire increase in KL.p was positively related to plant size. Specifically, large-statured species tended to undergo the greatest relative reductions in leaf area and height, and correspondingly experienced the greatest increases in KL.p. The post-fire increase in KL.p was smaller than expected, however, due to a decrease in absolute root hydraulic conductance (i.e., not scaled to leaf area). The higher KL.p in burned sites was manifested as an increase in gs rather than an increase in Ψleaf. Post-fire increases in gs should promote high rates of photosynthesis for recovery of carbohydrate reserves and aboveground biomass, which is particularly important for large-statured species that require more time to recover their pre-fire size.

Efficient Fuel Pretreatment: Simultaneous Torrefaction and Grinding of Biomass

Combining torrefaction and grinding of biomass in one reactor may be an attractive fuel pretreatment process. A combined laboratory torrefaction and ball mill reactor has been constructed for studies of the influence of temperature and residence time on the product yields and particle size reductions of Danish wheat straw, spruce chips, and pine chips. On the basis of initial experiments, which evaluated the influence of reactor mass loading, gas flow, and grinding ball size and material, a standard experimental procedure was developed. The particle size reduction capability of the torrefaction process has been evaluated by the relative change in d50, and this method was compared to the Hardgrove grindability index (HGI), showing reasonably similar results. Significant differences in torrefaction behavior have been observed for straw and spruce chips torrefied at 270–330 °C. Torrefaction of straw for 90 min yielded a higher mass loss (27–60 wt %) and relative size reduction (59–95%) compared with spruce (mass loss of 10–56 wt % and size reduction of 20–60%). The two types of biomass investigated differ with respect to hemicellulose type, lignocellulosic composition, particle morphology, and ash composition, where straw has a higher alkali content. This and other studies indicate that the large difference in the alkali contents of the biomasses is the main cause for the observed difference in torrefaction characteristics. Experiments with separate particle heating and grinding showed a swift grinding of the torrefied biomass. This implies that the rate-limiting step in the laboratory reactor is the heat transfer and not the grinding process. Large pine particles (8–16 mm) showed a slightly higher mass loss than 4–8 and <4 mm particles. This could be the consequence of exothermic reactions in the particle core, which locally increase the temperature and conversion.

Poor Sensitivity and Specificity

A CME article published in Deutsches Arzteblatt gives rise to the expectation that it reflects confirmed results. The article by Fuhrer et al. clearly does not meet this expectation. The authors postulate that in every case of a thyroid nodule, scintigraphy should be undertaken at least once. The sensitivity and specificity of this investigation are poor with regard to malignancies (2, 3). It is easy to form an impression of unjustifiably excessive diagnostic testing (seeing that the material that is mass-handled is radioactive). The recommendation to measure calcitonin in every patient with nodular goiter is controversial, to say the least. This recommendation may be appropriate for specialist endocrinology outpatient clinics. For general practice, with its low incidence of thyroid malignancies, it is definitely excessive. The recommendation to measure thyroid antibodies is not sufficiently supported—especially with regard to the relevance of the result for subsequent clinical action. The authors finally recommend a combination of iodine and L-thyroxine. The LISA study cited by the authors (4) investigated iodine and L-thyroxin in isolation as well as in combination. The treated nodules were 1.47–1.96 mL in size. The relative reduction in size by 17.3% therefore corresponded to an absolute reduction of 0.25–0.33 mL—a completely irrelevant order of magnitude. The thyroid volume of 18.2–18.8mL decreased by 1.5 mL, which is similarly irrelevant. Clinically relevant end points, such as frequency of thyroidectomies or development of thyrotoxicosis, were not studied. The recommendation given in the article is not supported by this study. To publish a CME article full of unconfirmed, not evidence-based, recommendations for maximum diagnostic testing and treatment as a CME article in Deutsches Arzteblatt suggests, in my opinion unjustifiably, that the authors are describing the current gold standard.

Evaluation of sublingual microcirculatory blood flow in the critically ill

The microcirculation regulates the supply of oxygen and nutrients to tissues. The sublingual region is frequently used as a window to microcirculation in critically ill patients. Numerous studies have reported impaired sublingual microcirculatory flow. We hypothesized that the quality of sidestream dark field imaging (SDF) recordings could be systematically analyzed to justify the monitoring of sublingual microcirculation in interventional studies or in clinical practice. The sublingual microcirculation in critically ill patients with septic shock, open heart surgery, or alcoholic pancreatitis, and healthy subjects was recorded with a hand held SDF device by one trained investigator in observational setting. A total of 82 video recording sessions were performed and 240 video clips eligible for quality assessment were identified. Quality assessment was performed offline by two investigators independently and blinded for the origin of the video file. Of the 240 clips, pressure artifact was detected in 86 (36%), major blood in 5 (2.1%), major saliva in 21 (8.8%) and extreme brightness causing loss of visible capillaries in 16 (6.7%) clips. The dominating vessel architecture was multiple size vessels in 228 (95%) and repeating capillary loop motif in 12 (5.0%). The mean (± SD) relative size reduction during stabilization was -6.9% (± 4.7%). Excellent technical quality was detected in 74 of 240 (30.8%) recordings. Our findings highlight the need of a comprehensive training period and reporting of data quality before findings with SDF imaging can be accepted as surrogate end points in interventional studies or as guidance in clinical practice.

Tumor Shrinkage Assessed by Volumetric MRI in Long-Term Follow-Up After Fractionated Stereotactic Radiotherapy of Nonfunctioning Pituitary Adenoma

To evaluate tumor control and side effects associated with fractionated stereotactic radiotherapy (FSRT) in the management of residual or recurrent nonfunctioning pituitary adenomas (NFPAs). We assessed exact tumor volume shrinkage in 16 patients with NFPA after FSRT. All patients had previously undergone surgery. Gross tumor volume (GTV) was outlined on contrast-enhanced magnetic resonance imaging (MRI) before and median 63 months (range, 28-100 months) after FSRT. MRI was performed as an axial three-dimensional gradient echo T1-weighted sequence at 1.6-mm slice thickness without gap (3D MRI). Mean tumor size of all 16 pituitary adenomas before treatment was 7.4 mL (3.3-18.9 mL). We found shrinkage of the treated pituitary adenoma in all patients. Within a median follow-up of 63 months (28-100 months) an absolute mean volume reduction of 3.8 mL (0.9-12.4 mL) was seen. The mean relative size reduction compared with the volume before radiotherapy was 51% (22%-95%). Shrinkage measured by 3D MRI was greater at longer time intervals after radiotherapy. A strong negative correlation between the initial tumor volume and the absolute volume reduction after FSRT was found. There was no correlation between tumor size reduction and patient age, sex, or number of previous surgeries. By using 3D MRI in all patients undergoing FSRT of an NFPA, tumor shrinkage is detected. Our data demonstrate that volumetric assessment based on 3D MRI adds additional information to routinely used radiological response measurements. After FSRT a mean relative size reduction of 51% can be expected within 5 years.

Tumor Shrinkage Assessed by Volumetric MRI in the Long-Term Follow-Up after Stereotactic Radiotherapy of Meningiomas

To evaluate tumor volume reduction in the follow-up of meningiomas after fractionated stereotactic radiotherapy (FSRT) or linac radiosurgery (RS) by using magnetic resonance imaging (MRI). In 59 patients with skull base meningiomas, gross tumor volume (GTV) was outlined on contrast-enhanced MRI before and median 50 months (range 11-92 months) after stereotactic radiotherapy. MRI was performed as an axial three-dimensional gradient-echo T1-weighted sequence at 1.6 mm slice thickness without gap (3D-MRI). Results were compared to the reports of diagnostic findings. Mean tumor size of all 59 meningiomas was 13.9 ml (0.8-62.9 ml) before treatment. There was shrinkage of the treated meningiomas in all but one patient. Within a median volumetric follow-up of 50 months (11-95 months), an absolute mean volume reduction of 4 ml (0-18 ml) was seen. The mean relative size reduction compared to the volume before radiotherapy was 27% (0-73%). Shrinkage measured by 3D-MRI was greater at longer time intervals after radiotherapy. The mean size reduction was 17%, 23%, and 30% (at < 24 months, 24-48 months, and 48-72 months). By using 3D-MRI in almost all patients undergoing radiotherapy of a meningioma, tumor shrinkage is detected. The data presented here demonstrate that volumetric assessment from 3D-MRI provides additional information to routinely used radiologic response measurements. After FSRT or RS, a mean size reduction of 25-45% can be expected within 4 years.

The Improvement of Wound-Associated Pain and Healing Trajectory With a Comprehensive Foot and Leg Ulcer Care Model

Pain is a major concern for subjects with chronic wounds, but its optimal management remains elusive. The aim of this study was to validate an organized pain management approach using the Wound Associated Pain model in subjects with chronic leg and foot ulcers. We completed a prospective cohort study that documented pain in chronic wound subjects over a 4-week period. A total of 111 subjects with chronic leg and foot ulcers were recruited from the community and ambulatory wound care clinics. Using a systematic approach based on the Wound Associated Pain model, we demonstrated improved overall wound healing outcomes in 111 subjects with chronic leg and foot ulcers. Using an 11-point numerical rating scale, the average level of pain was reduced from 6.3 at week 0 to 2.8 at week 4 (P < .001). The average healing rate was 0.39 cm per week and the average relative reduction in size was 59.36% (t = 2.31; P = .023). To examine the relationship between pain and wound healing, pain levels were compared in subjects who achieved wound closure and those who did not. The mean pain score was 1.67 for the healed subjects in contrast to 3.21 for those who did not achieve complete wound closure (P < .041). A comprehensive patient assessment can improve chronic leg and foot ulcer wound-related pain and healing rates. The mean pain scores are lower for patients with healed ulcers than for those who do not obtain complete wound closure.

Uterine artery embolisation for massive uterine fibroids in the presence of submassive pulmonary emboli

A 46-year-old woman was admitted to our hospital with acute shortness of breath and pre-syncope. She had known massive uterine fibroids with a history of menorrhagia and dysmenorrhoea, and had been awaiting total abdominal hysterectomy and bilateral salpingo-oophorectomy. She had no past or family history of venous thromboembolism (VTE). She was an ex-smoker with a 16-pack/year smoking history. On examination, she looked unwell, was sweaty and clammy, but apyrexial. Her heart rate was 130 per minute and her blood pressure was 140/95 mmHg. She was tachypnoeic with a respiratory rate of 28 breaths per minute; however, her chest was clear. Abdominal examination revealed an enormous uterus, equivalent to the size of a 30-week pregnancy. There was no clinical evidence of deep vein thrombosis (DVT). She was hypoxic: oxygen saturation on air was 88%; arterial blood gas measurement on 100% oxygen—pH 7.4, PO2 29.0mmHg, PCO2 3.5mmHg, bicarbonate 18.5mmol/L, base excess of 7.5 mol/L. Her full blood count revealed a microcytic anaemia with a mean cellular volume of 67.9 fl (normal: 81–99 fl) and haemoglobin of 9.4 g/dL (normal: 12.0–15.0 g/L). Her D-dimer was significantly elevated at 1.7 Ag/mL (normal: <0.5 Ag/mL). Other blood tests including renal profile, liver function, thyroid function, C-reactive protein and clotting profile were all within normal limits. Her 12 lead electrocardiogram demonstrated sinus rhythm with right bundle branch block and T wave inversion in V1-3 with classic ‘S1QIIITIII’ changes. Her Chest X-ray showed blunting of the basal pulmonary arteries particularly on the right. Transthoracic echocardiography findings were consistent with submassive pulmonary embolism: the left ventricular size and function was normal; the right ventricle was dilated with moderately impaired systolic function; the right atrium was also dilated; the inferior vena cava was distended and failed to collapsewith inspiration; the estimated right ventricular systolic pressure was 50 mmHg. A contrast CT pulmonary angiogram revealed occlusive thrombus in the proximal basal left and mid and basal right pulmonary arteries. She was initially managed with aggressive fluid resuscitation and was commenced on intravenous unfractionated heparin (target APTT ratio of 2.0–3.0). On day 3 she began to heavily menstruate and required a total of nine units of blood over the ensuing 10 days. She was given subcutaneous Zoladex and 30 mg TDS provera to reduce her menstrual blood loss. On day 13 she underwent iliac venography and inferior cavography with insertion of a temporary IVC filter. No free intravascular thrombus was seen in either common iliac vein or within the IVC. There was however significant compression on all three of these veins. Immediately following this, she underwent uterine artery embolisation (UAE). At the time of UAE, her uterus and dominant fibroid measured 3800 and 3220 mL, respectively. Two weeks post-UAE her caval filter was removed, via a jugular route, without complication. A follow up pelvic MRI, one month later, confirmed complete fibroid degeneration with migration of the fibroid into the endometrial cavity (Fig. 1). The uterus measured 2200 mL and the fibroid 1000 mL, correlating with a 42% and 69% respective relative reduction in size. At six weeks she passed a large ‘steak-sized’ degenerate fibroid. At three months pelvic ultrasound showed that the uterus had reduced to 315 mL and the fibroid volume was 1.5 mL. The patient has made a complete recovery and has been given life-long warfarin.

The impact of large scale wind power generation on power system oscillations

Increasing amounts of wind turbines are connected to electrical power systems. This affects many aspects of their operation and behaviour. In this paper, the impact of large scale wind power generation on power system oscillations is treated. The three main types of power system oscillations, namely oscillations of a group of generators against a strong system and intra- and inter-area oscillations are studied. To this end, test systems are used. The effect of wind power on the oscillations is investigated by gradually replacing the power generated by the synchronous generators in the system by power from either constant or variable speed wind turbines, while observing the movement of the eigenvalues through the complex plane. From the results, it is concluded that the effect of wind power on power system oscillations depends on the wind turbine concept (constant or variable speed) and on the wind power penetration. In most cases, an increase in frequency and damping of power system oscillations was observed. This observation is caused by a relative reduction in size of the synchronous generators that engage in power system oscillations, which is equivalent to strengthening their mutual coupling. Further, it was shown that constant speed wind turbines damp power system oscillations more than variable speed turbines. This is caused by the damping effect of the squirrel cage induction generator used in constant speed wind turbines.

The effects of X monosomy on brain development: monozygotic twins discordant for Turner's syndrome.

Monosomy for the X chromosome is the most frequent cause of Turner's syndrome, a common clinical syndrome associated with particular physical and neurobehavioral features. The results from comprehensive assessment of prepubertal monozygotic female twins discordant for X monosomy are presented. Zygosity was established with DNA Fingerprinting and no evidence of chromosomal mosaicism was seen in either child. Physical features in the affected twin were relatively mild with respect to the full spectrum of physical malformations and disabilities associated with Turner's syndrome. The neurobehavioral phenotypes of the twins were compared. Although both sisters scored in the superior range of intelligence, the affected twin's Performance IQ was 18 points less than her sister, whereas Verbal IQ showed only a 3-point difference between the sisters. Other relative differences were noted within the executive, visuospatial, and visuomotor domains of function. Behavioral evaluation indicated greater problems with attention, hyperactivity, and anxiety in the affected twin. Quantitative analysis of brain anatomy revealed evidence of both general and regional effects of X monosomy on neurodevelopment. Cerebrospinal fluid volume was increased by 25% in the affected twin compared with her sister with a corresponding decrease in gray matter volume. The right frontal, right parietal-occipital, and left parietal-perisylvian regions showed the greatest discrepancy between the sisters with respect to increased cerebrospinal fluid and decreased gray matter volumes in twin with X monosomy. Differences in the posterior fossa were also noted with a 50% relative increase in the volumes of the fourth ventricle and cisterna magna and a 10 to 15% relative reduction in size of the cerebellar vermis, pons, and medulla in the affected twin. The association between the neurobehavioral and neuroanatomical findings in the affected twin is discussed. The unique nature of the naturally occurring genetic phenomenon seen in this twin pair provides an opportunity to more fully elucidate the neurobehavioral phenotype associated with X monosomy and Turner's syndrome.

The sinu-atrial node of the rat heart.

1. The sinu‐atrial node can be observed in the rat as a thickening, composed of modified myocardium, in the medial wall of the right cranial vena cava from the 15th day of prenatal life onwards.2. The node is most obvious, and has its maximum size relative to the body weight from one day before to three days after birth.3. In the embryonic and neonatal rat the node is a compact syncytium, with few poorly striated myofibrils and very numerous dark, spherical nuclei. During post‐natal life the relative reduction in size, the progressive invasion by connective tissue, and the decrease in nuclear density are the main factors which make the node a less obvious structure.4. In the adult rat, the node, composed of paler fibres, has the shape of an inverted horseshoe in the cranial part of the sinu‐atrial orifice.5. From the 18th day of prenatal life onwards nervous structures are closely associated with the node.