Search

The possibility of observing shallow groundwater depth and areal extent using satellite measurements can support groundwater models and vast irrigation systems management. Moreover, these measurements can help to include the effect of shallow groundwater on surface energy balance within land surface models and climate studies, which broadens the methods that yield more reliable and informative results. To examine the capacity of MODIS in detecting the effect of shallow groundwater on land surface temperature and the surface energy balance in an area within Al-Balikh River basin in northern Syria, we studied the interrelationship between in-situ measured water table depths and land surface temperatures measured by MODIS. We, also, used the Surface Energy Balance System (SEBS) to calculate surface energy fluxes, evaporative fraction and daily evaporation, and inspected their relationships with water table depths. We found out that the daytime temperature increased while the nighttime temperature decreased when the depth of the water table increased. And, when the water table depth increased, net radiation, latent and ground heat fluxes, evaporative fraction and daily evaporation decreased, while sensible heat flux increased. This concords with the findings of a companion paper (Alkhaier et al., 2012). The observed clear relationships were the result of meeting both conditions that were concluded in the companion paper, i.e. high potential evaporation and big contrast in day-night temperature. Moreover, the prevailing conditions in this study area helped SEBS to yield accurate estimates. Under bare soil conditions and under the prevailing weather conditions, we conclude that MODIS is suitable for detecting the effect of shallow groundwater because it has proper imaging times and adequate sensor accuracy; nevertheless, its coarse spatial resolution is disadvantageous.

Understanding when and how groundwater affects surface temperature and energy fluxes is significant for utilizing remote sensing in groundwater studies and for integrating aquifers within land surface models. To investigate the shallow groundwater effect under bare soil conditions, we numerically exposed two soil profiles to identical metrological forcing. One of the profiles had shallow groundwater. The different responses that the two profiles manifested were inspected regarding soil moisture, temperature and energy balance at the land surface. The findings showed that the two profiles differed in three aspects: the absorbed and emitted amounts of energy, the portioning out of the available energy and the heat fluency in the soil. We concluded that due to their lower albedo, shallow groundwater areas reflect less shortwave radiation and consequently get a higher magnitude of net radiation. When potential evaporation demand is sufficiently high, a large portion of the energy received by these areas is consumed for evaporation. This increases the latent heat flux and reduces the energy that could have heated the soil. Consequently, lower magnitudes of both sensible and ground heat fluxes are caused to occur. The higher soil thermal conductivity in shallow groundwater areas facilitates heat transfer between the top soil and the subsurface, i.e. soil subsurface is more thermally connected to the atmosphere. For the reliability of remote sensors in detecting shallow groundwater effect, it was concluded that this effect can be sufficiently clear to be detected if at least one of the following conditions occurs: high potential evaporation and high contrast between day and night temperatures. Under these conditions, most day and night hours are suitable for shallow groundwater depth detection.

Thrombospondin 1 and thrombospondin 2 (TSP1 and TSP2), which comprise the subgroup A thrombospondins, are matricellular proteins. As matricellular proteins, they modulate interactions between cells and the cellular environment, regulate cell adhesion and typically are expressed during tissue formative processes. In general, TSP1 and TSP2 counter angiogenesis (including tumour angiogenesis) and play important but contrasting roles during cutaneous repair. The two proteins are involved in development, including that of the eye, although evidence suggests that they have their greatest impact during tissue production in the adult. In the normal adult eye, they tend to be found at sites of ongoing matrix synthesis or cell-matrix interactions. At these sites, the two proteins possibly influence cellular differentiation and/or basement membrane deposition. TSP1 is also present in the intraocular fluids and drainage pathway, where it may function in maintaining the anti-angiogenic environment and in intraocular pressure control, respectively. TSP1 could also be involved in ocular immune privilege. Unlike in skin wounds, where TSP1 is derived from the blood and is present only in the early phases of repair, ocular tissue damage appears to lead to protacted TSP1 synthesis by local cells. This response might help suppress angiogenesis in the transparent tissues of the eye and so lessen visual axis opacification following injury. However, TSP2, which is also produced by damaged ophthalmic tissue and may be especially important in matrix organisation, seems to augment contraction in anomalous intraocular fibrosis. Elucidating the roles of TSP1 and TSP2 in ocular physiology and pathobiology may lead to improved therapies for neovascular, neoplastic, reparative and other ophthalmic diseases.

Purpose: To evaluate the visual outcome of patients with posteriorly dislocated lens fragments after phacoemulsification managed with pars plana vitrectomy (PPV) and identify risk factors for poor visual outcome. Setting: Vitreo-Retinal Service, St. Paul Eye Unit, Liverpool, United Kingdom. Methods: The medical records of all patients who had PPV for posteriorly dislocated lens fragments after phacoemulsification between March 1993 and August 1998 were retrospectively reviewed. Demographics, preexisting eye conditions, details of the previous cataract surgery, findings at presentation, details of the vitreoretinal procedure, final visual acuity, and complications observed during the follow-up were evaluated. Univariate and multiple regression analyses were used to determine the significance of these clinical variables as determinants of poor visual outcome (visual acuity 6/12 or worse). Results: Of the 106 patients identified, 89 had a full set of data and were included in the study. In 79 patients (89%), PPV was performed from 1 to 357 days (median 15 days) after cataract extraction. In 10 patients (11%), PPV was done on the same day as the cataract surgery. Sixty-two patients (69%) had a final visual acuity of 6/12 or better. Preexisting eye disease (P < .01), PPV delayed for more than 4 weeks (P < .03), occurrence of retinal detachment after vitrectomy (P < .01), and the use of ultrasound (US) fragmentation (P < .01) were statistically significantly correlated with a poor visual outcome. Conclusions: Posterior dislocated lens fragments after phacoemulsification were safely retrieved using PPV. It appears that intervening early (within 4 weeks) and avoiding the use of US fragmentation are associated with a better visual outcome and reduced rate of postoperative complications.

Purpose: Congenital glaucoma is a well-recognized entity that can occur in the presence of anterior segment dysgenesis. Trabeculectomy is an accepted intervention in the management of congenital glaucoma. The surgical technique as well as complications is well described. Methods: This is a case report of a 3-month-old girl with anterior segment dysgenesis and glaucoma. She was referred post-trabeculectomy with persistent corneal opacity to be considered for penetrating keratoplasty and was found to have intrastromal corneal bleb. Results: Ultrasound biomicroscopy confirmed communication of the corneal bleb with the anterior chamber, and the bleb was treated by autologous blood injection at the trabeculectomy site, under acetazolamide cover. Conclusions: We present evidence suggesting that abnormal structure was the etiologic basis for corneal bleb formation and describe our management of this previously unreported complication of trabeculectomy.

Within the foregoing half century, several studies debated over the effect that shallow groundwater has on land surface temperature (Myers & Moore, 1972; Huntley, 1978; Quiel, 1975). As land surface temperature is a key factor when the process of energy and water exchange between land surface and atmosphere occurs, we can presume that shallow groundwater naturally affects the entire surface energy balance system. Shallow groundwater affects thermal properties of the region below its water table. Further on, it alters soil moisture of the zone above its water table which results in affecting its thermal properties, the magnitude of evaporation, albedo and emissivity. Hence shallow groundwater affects land surface temperature and the surface energy balance in two different ways; direct and indirect (Figure 1). The direct way (henceforth referred to as thermodynamic effect) is through its distinctive thermal properties which make groundwater acts as a heat sink in summer and a heat source in winter, and affects heat propagation within soil profile. The indirect way is through its effect on soil moisture above water table and its related effects (i.e. evaporation, soil thermal properties of vadose zone, land surface emissivity and albedo). Studies that investigated the thermodynamic effect commenced by the work of Kappelmeyer (1957), who could successfully use temperature measurements conducted at shallow depth (1.5m) to locate fissures carrying hot water from deep groundwater. Birman (1969) also found a direct relationship between shallow ground temperature and depth to groundwater. Works by Cartwright (1968, 1974), Bense & Kooi, 2004, Furuya et al. (2006) and also works by Takeuchi (1980, 1981, 1996) and Yuhara (1998) cited by Furuya et al. (2006) showed that soil temperature measurements at some depth (0.5-2 m) depth were useful for locating shallow aquifers in summer and winter and also for determining the depth of shallow groundwater and the velocity and direction of its flow. On the other hand, a number of studies considered the indirect effect of shallow groundwater in terms of its effect on soil moisture of the vadose zone and at land surface (York et al., 2002; Liang & Xie, 2003; Chen & Hu, 2004; Yeh et al., 2005; Fan et al., 2007

Eye involvement is a feature of many metabolic diseases; early identification of ocular changes may aid diagnosis and management of the underlying condition. This review aims to describe common metabolic conditions where ocular findings can help the diagnosis.

We report the case of an insulin dependent diabetic who suffered transient blindness as a result of a change of posture following vitrectomy surgery with injection of gas. This 34 year old woman with longstanding diabetic disease, postural hypotension, and proliferative retinopathy had undergone argon laser panretinal photocoagulation (PRP) to both eyes. Her right eye was amblyopic and had visual acuity of counting fingers (CF), whereas the left eye, at best, had vision of 6/12 that was frequently impaired by recurrent vitreous haemorrhage. She underwent left vitrectomy and required 30% sulphur hexafluoride (SF6) gas to support an incidental small, inferior detachment related to a round hole. The patient postured supine overnight and remained under the care of the physicians. The following day her vision dropped suddenly and severely on her way to the …

Whether or not shallow groundwater affects skin temperature (the temperature of soil surface) is important to detect depth and extent of shallow groundwater by dint of remote sensing and important for land surface modelling studies. Although few studies have been conducted to investigate that effect, they have yielded contradicting conclusions and they stopped in 1982. To determine that shallow groundwater affects skin temperature, we measured soil temperature at two different depths (5 and 10 cm) in seven places with variable water table depths every ten minutes and for six days. After that, we correlated the minimum, maximum and average daily temperatures to average groundwater depth. We also built a simple numerical model using a differential equations solver, Flex PDE, to simulate heat transfer into soil profile and used it to simulate groundwater effect on skin temperature. We found quite high negative correlation between the maximum and average daily soil temperature and groundwater depth. Contrarily, we could hardly find any correlation between the daily minimum temperature and groundwater depth. Numerical simulations, though simple, were useful in showing that groundwater shifted skin temperature curves up in the winter and down in the summer without affecting the shape of the curve. We conclude that shallow groundwater affects skin temperature directly by its distinctive thermal properties in the soil profile and indirectly by affecting soil moisture which in turn has many different and contradictory effects on skin temperature. This study recommends building a comprehensive numerical model that simulates the effect of shallow groundwater on skin temperature and on the different energy fluxes at land surface.