Unraveling a rare splenic pathology: a case report of a benign hemorrhagic spleen with primary congenital splenic epidermoid cysts.

Introduction and importance: A primary congenital splenic epidermoid cyst is an immensely rare pathology with mostly unknown epidemiological parameters. Misdiagnosis can easily happen and this results in life-threatening ramifications for patients. Considering this pathology as a potential differential diagnosis allows for the required surgical intervention to be timely accomplished. In this case, the authors are documenting this pathology and presenting how it was successfully managed via proper and informed preoperative analysis and meticulous intraoperative technique. Case presentation: Hereby, we portray the exceptionally rare case of a 7-year-old male who presented to our surgical clinic complaining of a sudden left hypochondriac pain with early satiety for 1 month's duration. The preoperative radiological assessment displayed numerous splenic cystic lesions throughout the splenic parenchyma. Clinical discussion: Resection of the cysts was accomplished via total splenectomy. The ensuing histopathological analysis via Hematoxylin and Eosin of the resected specimens established the diagnosis of a congested hemorrhagic spleen with multiple primary congenital splenic epidermoid cysts. Conclusion: Primary congenital splenic epidermoid cysts are an extremely rare type of splenic pathology. There is profound scarcity amidst the published literature regarding it. This merits in-depth study and apt documentation to raise awareness regarding this pathology as a potential differential diagnosis in cases of abdominal pain. Documentation allows us to set up proper and innovative clinical and surgical protocols for these patients. Based on our conclusive review of the published literature, the authors conclude that ours is the first ever documented case from our country of a primary congenital splenic epidermoid cyst.

Intrinsic polarity inversion in III-nitride waveguides for efficient nonlinear interactions.

III-nitrides provide a versatile platform for nonlinear photonics. In this work, we explore a new promising configuration - composite waveguides containing GaN and AlN layers with inverted polarity, i.e., having opposite signs of the χ(2) nonlinear coefficient. This configuration allows us to address the limiting problem of the mode overlap for nonlinear interactions. Our modelling predicts a significant improvement in the conversion efficiency. We confirm our theoretical prediction with the experimental demonstration of second harmonic generation with an efficiency of 4%W-1cm-2 using a simple ridge waveguide. This efficiency is an order of magnitude higher compared to the previously reported results for III-nitride waveguides. Further improvement, reaching a theoretical efficiency of 30%W-1cm-2, can be achieved by reducing propagation losses.

Low-loss GaN-on-insulator platform for integrated photonics.

III-Nitride semiconductors are promising materials for on-chip integrated photonics. They provide a wide transparency window from the ultra-violet to the infrared that can be exploited for second-order nonlinear conversions. Here we demonstrate a photonics platform based on epitaxial GaN-on-insulator on silicon. The transfer of the epi-material on SiO2 is achieved through wafer bonding. We show that quality factors up to 230 000 can be achieved with this platform at telecommunication wavelengths. Resonant second harmonic generation is demonstrated with a continuous wave conversion efficiency of 0.24%/W.

A rare case of a Low Grade Appendiceal Mucinous Neoplasm in a 46-year-old Middle Eastern female - A case report.

INTRODUCTION AND IMPORTANCE: Mucinous cell neoplasia are rare and conceivably fatal causes of surgical abdomen. Adult manifestations can be obscure and ill-defined, yielding misdiagnoses and wasting precious time and effort to reach the correct one. Clinical awareness ought to be present once presented with a surgical abdomen in such a patient because this neoplasm may present with misleading presentations which mask the actual diagnosis and masquerade as a different one, and in turn, may result in performing a dissimilar treatment intervention. Rapid learnt surgical judgments must be taken and put into action to diminish the morbidity and mortality consequential to this pathology. CASE PRESENTATION: Our case is of a 46-year-old female, who was admitted into our hospital with a 2-month-history of general fatigue. Colicky abdominal pain and discomfort developed shortly prior to admission. Multi-Slice Computed Tomography (MSCT) scan exposed cystic formation in the terminal ileum. Exploratory laparotomy was warranted, in addition to performing a right hemicolectomy. CLINICAL DISCUSSION: We treated our patient via open surgery and performing an appendectomy with right hemicolectomy in addition to the excision of several surrounding lymph nodes. Diagnosis is traditionally reached intraoperatively relying on gross morphology and postoperatively through histopathological analysis of the excised specimens. CONCLUSION: Low Grade Appendiceal Mucinous Neoplasm is a scarce entity and varies critically in its manifestations, hence, it is existential to thoroughly study this kind of neoplasia, document it, and consider it, so that we can construct precise decisions to reach ideal results for patients who suffer from this neoplasm.

Up to 300†K lasing with GeSn-On-Insulator microdisk resonators.

GeSn alloys are the most promising direct band gap semiconductors to demonstrate full CMOS-compatible laser integration with a manufacturing from Group-IV materials. Here, we show that room temperature lasing, up to 300 K, can be obtained with GeSn. This is achieved in microdisk resonators fabricated on a GeSn-On-Insulator platform by combining strain engineering with a thick layer of high Sn content GeSn.

III-nitride on silicon electrically injected microrings for nanophotonic circuits.

Nanophotonic circuits using group III-nitrides on silicon are still lacking one key component: efficient electrical injection. In this paper we demonstrate an electrical injection scheme using a metal microbridge contact in thin III-nitride on silicon mushroom-type microrings that is compatible with integrated nanophotonic circuits with the goal of achieving electrically injected lasing. Using a central buried n-contact to bypass the insulating buffer layers, we are able to underetch the microring, which is essential for maintaining vertical confinement in a thin disk. We demonstrate direct current room-temperature electroluminescence with 440 mW/cm2 output power density at 20 mA from such microrings with diameters of 30 to 50 µm. The first steps towards achieving an integrated photonic circuit are demonstrated.

Increasing the angular sensitivity of two-dimensional photonic crystal based sensors to arbitrary values.

A new design of photonic crystal (PhC) for optical sensing using guided mode resonance (GMR) is presented. We theoretically show that angular sensitivity is inversely proportional to the group velocity of the probed mode and can be made arbitrarily high in a properly designed PhC. PhCs made in polycrystalline diamond on insulator are fabricated. The angular sensitivity dependence is validated. We measured modes with group velocity of c/80 at a wavelength of 800 nm. A sensitivity in the order of 500 ° per refractive index unit is inferred, a value much larger than the one usually encountered in PhCs.

Solving thermal issues in tensile-strained Ge microdisks.

We propose to use Ge-dielectric-metal stacking to allow one to address both thermal management with the metal as an efficient heat sink and tensile strain engineering with the buried dielectric as a stressor layer. This scheme is particularly useful for the development of Ge-based optical sources. We demonstrate experimentally the relevance of this approach by comparing the optical response of tensile-strained Ge microdisks with an Al heat sink or an oxide pedestal. Photoluminescence indicates a much reduced temperature rise in the microdisk (16 K with Al pedestal against 200 K with SiO2 pedestal under a 9 mW continuous wave optical pumping). An excellent agreement is found with finite element modeling of the temperature rise. This original stacking combining metal and dielectrics is promising for integrated photonics where thermal management is an issue.

Phase-matched second harmonic generation with on-chip GaN-on-Si microdisks.

We demonstrate phase-matched second harmonic generation in gallium nitride on silicon microdisks. The microdisks are integrated with side-coupling bus waveguides in a two-dimensional photonic circuit. The second harmonic generation is excited with a continuous wave laser in the telecom band. By fabricating a series of microdisks with diameters varying by steps of 8 nm, we obtain a tuning of the whispering gallery mode resonances for the fundamental and harmonic waves. Phase matching is obtained when both resonances are matched with modes satisfying the conservation of orbital momentum, which leads to a pronounced enhancement of frequency conversion.

Surface-sensitive diamond photonic crystals for high-performance gas detection.

Diamond slotted photonic crystal (PhC) cavities were fabricated and used for gas detection. They exhibit wavelength sensitivity reaching a 350 nm per unit change of the refractive index of the gaseous environment of the PhC. With a simple oxidized surface termination, diamond PhCs display an ultrahigh sensitivity to the surface adsorption of polar molecules. Gaseous concentrations as low as 80 parts per million (ppm) of hexanol vapor in nitrogen are probed, and a detection limit in the ppm range is inferred, demonstrating a high interest of such devices for trace sensing.

Near-infrared III-nitride-on-silicon nanophotonic platform with microdisk resonators.

We have developed a nanophotonic platform with microdisks using epitaxial III-nitride materials on silicon. The two-dimensional platform consists of suspended waveguides and mushroom-type microdisks as resonators side-coupled with a bus waveguide. Loaded quality factors up to 80000 have been obtained in the near-infrared spectral range for microdisk diameters between 8 and 15 µm. We analyze the dependence of the quality factors as a function of coupling efficiency. We have performed continuous-wave second harmonic generation experiments in resonance with the whispering gallery modes supported by the microdisks.

Tensile-strained germanium microdisk electroluminescence.

We report room temperature electroluminescence of tensile-strained germanium microdisks. The strain is transferred into the microdisks using silicon nitride stressors. Carrier injection is achieved with Schottky contacts on n-type doped germanium. We show that a biaxial tensile-strain up to 0.72% can be transferred by optimizing the carrier injection profile. The transferred strain is measured by the electroluminescence spectral red-shift and compared to finite element modeling. We discuss the impact of this strain level to achieve population inversion in germanium.

Tensile Ge microstructures for lasing fabricated by means of a silicon complementary metal-oxide-semiconductor process.

In this work we study, using experiments and theoretical modeling, the mechanical and optical properties of tensile strained Ge microstructures directly fabricated in a state-of-the art complementary metal-oxide-semiconductor fabrication line, using fully qualified materials and methods. We show that these microstructures can be used as active lasing materials in mm-long Fabry-Perot cavities, taking advantage of strain-enhanced direct band gap recombination. The results of our study can be realistically applied to the fabrication of a prototype platform for monolithic integration of near infrared laser sources for silicon photonics.

Effective thermal resistance of a photonic crystal microcavity.

We present a simple method to accurately measure the effective thermal resistance of a photonic crystal microcavity. The cavity is embedded between two Schottky contacts forming a metal-semiconductor-metal device. The photocarriers circulating in the device provide a local temperature rise that can be dominated by Joule effect under certain conditions. We show that the effective thermal resistance (R(th)) can be experimentally deduced from the spectral shift of the cavity resonance wavelength measured at different applied bias. We deduce a value of R(th)1.6×10(4) KW(-1) for a microcavity on silicon-on-insulator, which is in good agreement with 3D thermal modeling by finite elements.

Serum high-sensitivity C-reactive protein and lipoprotein(a) levels: a comparison between diabetic and non-diabetic patients with coronary artery disease.

OBJECTIVE: The aim of this study was to compare high-sensitivity C-reactive protein (hsCRP) and Lipoprotein(a) levels [Lp(a)] levels between diabetic and non-diabetic patients with coronary artery disease (CAD). STUDY DESIGN: Cross sectional Study. PLACE AND DURATION OF STUDY: This study was conducted in the department of Physiology of College of Medicine & King Khalid University Hospital, King Saud University, Riyadh between August 2006 and December 2007. METHODS: One hundred and three individuals with CAD and 30 healthy individuals matched for age and BMI were studied. CAD patients were divided into two groups based on presence (n=62) and absence (n=41) of type 2 diabetes mellitus. Overnight fasting blood samples were collected, and analyzed for total cholesterol (TC), Triglycerides (TG), Low density Lipoprotein (LDL) and High density lipoprotein (HDL), Lp(a) and hsCRP. Data about CAD severity was obtained from medical records. RESULTS: Both groups of CAD without and with DM had significantly higher levels of Lp(a) [mg/dl] (25.58 +/- 25.99, 25.90 +/- 24.67 respectively) and hsCRP [mg/dl] (0.52 +/- 0.71, 0.82 +/- 0.78 respectively) when compared with healthy control subjects (Lp(a) =16.93 +/- 15.34 & hsCRP=0.27 +/- 0.21) [p<0.05]. Lp(a) levels between the two CAD groups were non significant. While, hsCRP levels were significantly high in CAD with DM compared to those without DM [p<0.05]. Gensini Score of CAD severity was also higher in CAD with DM [67.60 +/- 45.94] than those without DM [52.05 +/- 42.27, p<0.05]. CONCLUSION: Elevated Lp(a) and hsCRP levels are associated specifically with angiographically defined CAD. However, hsCRP elevation but not Lp(a) is also associated with CAD in type 2 diabetes mellitus. Measurement of hsCRP and Lp(a) may be considered optional markers for better prediction of cardiovascular risk.

Optical gain in single tensile-strained germanium photonic wire.

We have investigated the optical properties of tensile-strained germanium photonic wires. The photonic wires patterned by electron beam lithography (50 µm long, 1 µm wide and 500 nm thick) are obtained by growing a n-doped germanium film on a GaAs substrate. Tensile strain is transferred in the germanium layer using a Si3N4 stressor. Tensile strain around 0.4% achieved by the technique corresponds to an optical recombination of tensile-strained germanium involving light hole band around 1690 nm at room temperature. We show that the waveguided emission associated with a single tensile-strained germanium wire increases superlinearly as a function of the illuminated length. A 20% decrease of the spectral broadening is observed as the pump intensity is increased. All these features are signatures of optical gain. A 80 cm⁻¹ modal optical gain is derived from the variable strip length method. This value is accounted for by the calculated gain material value using a 30 band k · p formalism. These germanium wires represent potential building blocks for integration of nanoscale optical sources on silicon.

Quality factor of Si-based photonic crystal L3 nanocavities probed with an internal source.

We have investigated the quality factors of silicon-based photonic crystal nanocavities using the photoluminescence of a single layer of Ge/Si self-assembled islands as an internal source. We focus on membrane-type L3 elongated cavities with or without their lateral edge air holes shifted in position. The photoluminescence measurements are performed at room temperature. We show that the quality factor of the fundamental mode observed at a normalized frequency u = a/lambda~_ 0.25 is strongly dependent on the incident pump power. This dependence is associated with the free-carrier absorption of the photogenerated carriers. The slope of the quality factor vs. incident pump power gives access to the carrier recombination dynamics in these Si-based nanocavities. The measurements indicate that the carrier dynamics is controlled by nonradiative recombination associated with surface recombinations. A surface recombination velocity of 4.8 x 10(4) cm/s is deduced from the experiments. The spectral red-shift of the cavity modes as a function of incident pump power is correlated to the temperature rise due to thermo-optic effects. The measured temperature rise, which can reach 190 K, is correlated to the value estimated by a thermal analysis.

[Expression of cytokines and their receptors in left ventricular hypertrophy in TGR(mRen2)27 rats]. / Expression des cytokines et de leurs récepteurs dans le ventricule gauche hypertrophique du rat TGR(mRen2)27.

Variations in the expression of cytokines from the interleukin-6 (IL-6) family: ciliary neurotrophic factor (CNTF), leukaemia inhibitory factor (LIF), and cardiotrophin 1 (CT-1) were studied during cardiac remodelling leading to left ventricular hypertrophy (LVH) in TGR(mRen2)27 rats at the age of 8 and 20 weeks. The cytokines mRNA levels within the free wall of the left ventricle were measured by semi-quantitative RT-PCR standardised with 18S. They were compared between heterozygous rats for the mRen2 transgene (TG+/-) and control rats (TG-/-). No significant difference was observed between results obtained at 8 and 20 weeks of age. At 20 weeks of age, TGR(mRen2)27 rats showed higher levels of mRNA LIF and IL-6 respectively by 52 and 55% compared to the control rats [LIF TG+/-: 3.17 +/- 0.21, TG-/-: 2.09 +/- 0.03; p < 0.001; n = 5; and IL-6 TG+/-: 1.53 +/- 0.13; TG-/-: 0.99 +/- 0.17; p < 0.05; n = 5]. By contrast, no variation of mRNAs levels of CT-1 and gp 130 genes was observed between control and transgenic rats. Concerning the cytokine receptors, the levels of mRNA for IL-6R did not vary while those of receptor subunits LIFR and CNTFR were decreased respectively by 48 and 42% in transgenic rats vs controls [LIFR TG+/-: 0.48 +/- 0.01; TG-/-: 0.92 +/- 0.08 p < 0.001; n = 5; and CNTFR TG+/-: 1.07 +/- 0.08; TG-/-: 1.85 +/- 0.18; p < 0.01; n = 5]. Therefore, these results show a specific pattern of activation of the cytokines pathway in the LVH of the TGR(mRen2)27 rat.

[Toxoplasma infections in early pregnancy: consequences and management]. / Infection toxoplasmique de début de grossesse: conséquences et conduite à tenir.

OBJECTIVE: To assess the consequences for the fetus of maternal toxoplasma infection acquired during the first 8 weeks of gestation and to set guidelines on how to manage these maternal infections. METHODS: Data were prospectively analyzed on 360 pregnancies followed-up in our department due to a toxoplasma infection during the 8 first weeks of pregnancy. Estimates of the risk of fetal infection were based on all cases, including those which could not be followed up until infection was ruled out or confirmed. Severity of infection was estimated based on ultrasound findings during pregnancy, neonatal and long-term postnatal clinical, neurological and ophthalmologic work up. RESULTS: Out of the 360 included women, 336 gave birth to a live born child: 7 (2%) were infected, 302 (90%) were free of infection and follow-up was insufficient to conclude about the 27 (8%) remaining infants. The estimated risk of fetal infection ranged between 2 and 10% based on live born children and between 3 and 14% when the 24 interrupted pregnancies were included. At their last clinical evaluation at 70 months of age, all 7 children, including the 2 who had inactive peripheral eye lesions and the one who had a unique intracranial calcification were free of any ophthalmologic or neurological impairment. CONCLUSION: Our study confirms that in the event of a maternal infection during the first 8 weeks of pregnancy the risk of fetal infection is low and results mainly in a spontaneous termination of pregnancy. Future parents should be assured that conversely to a common opinion, the prognosis of congenital toxoplasmosis in live-born children is good. For these early maternal infections as for those acquired later, we recommend immediate treatment with spiramycin, monthly ultrasound surveillance, amniocentesis and treatment with pyrimethamine and sulphamides if the PCR is positive. Abortion should be restricted to cases with ultrasound lesions