Self calibrating wavelength multiplexed heterodyne interferometer for angstrom precision measurements

Measurement of refractive index, surface quality and temperature of the process materials in defense, petrochemical, power systems, glass, and metal industries is a fundamental need for precision systems performance. However, making these measurements in a super noisy defense or industrial environment is a big challenge faced by sensor technologies. Reported in this paper is the first ever demonstration of a wavelength multiplexed heterodyne interferometer using a single acousto-optic device (AOD). Heterodyne interferometry is pivotal in realizing a highly stable low noise interferometer. Inspite of the physical separation of the two arms of the interferometer, the sensor demonstrates Angstrom level optical path length sensitivity. The proposed sensor can be used in optical path length measurement-based sensing of parameters such as surface profile, refractive index, temperature, and pressure. Proof-of-concept experiment features a high resolution, low-loss, ultra compact, free space scanning interferometer implementation. Results include measurement of surface quality of a test mirror

Harsh environments minimally invasive optical sensing technique for extreme temperatures: 1000 degrees C and approaching 2500 degrees C

To the best of our knowledge, for the first time is designed and demonstrated a single crystal Silicon Carbide (SiC)-based minimally invasive smart optical sensor suited for harsh environments and temperatures reaching 2500 °C. The novel sensor design is based on an agile wavelength source, instantaneous single wavelength interferometry, full optical power cycle data acquisition, free-space targeted laser beam, multiple single crystal thick SiC optical frontend chips, and multi-wavelength signal processing for unambiguous temperature measurements to form a fast and distributed smart optical sensor system. Experiments conducted using a 1550 nm eye safe band tunable laser and a 300 micron coating-free thick SiC chip demonstrate temperature sensing from room temperature to 1000 °C with a measured 1.3 °C resolution. Applications for the proposed sensor include use in fossil fuel-based power systems, aerospace/aircraft systems, satellite systems, deep space exploration systems, and drilling and oil mining industries

Major causes of problems between contractors and subcontractors in the Gaza Strip

Purpose – Subcontractors play a significant role in the Palestinian construction industry as about 90 per cent of the work is performed by subcontractors. The main objective of this paper is to identify and analyse the major problems which exist between the contractors and subcontractors in the construction industry in the Gaza Strip. Design/methodology/approach – A questionnaire was designed to elicit contractors' and subcontractors' viewpoints regarding the most important causes of problems that affect the relationship between them. A total of 53 problems were identified based on a literature review, a pilot study was considered in this study and was listed under five groups. A total of 150 questionnaires were randomly sent to contractors and subcontractors. The respondents had extensive experience in the construction industry with average working experience of 20 years. The questionnaire was validated by the

6-H single-crystal silicon carbide thermo-optic coefficient measurements for ultrahigh temperatures up to 1273 K in the telecommunications infrared band

6H single-crystal silicon carbide (SiC) is an excellent optical material for extremely high temperature applications. Furthermore, the telecommunication infrared band (e.g., 1500-1600 nm) is an eye safe and high commercial maturity optical technology. With this motivation, the thermo-optic coefficient partial derivative n/partial derivative T for 6H single-crystal SiC is experimentally measured and analyzed from near room temperature to a high temperature of 1273 K with data taken at the 1550 nm wavelength. Specifically, the natural etalon behavior of 6-H single-crystal SiC is exploited within a simple polarization-insensitive hybrid fiber-free-space optical interferometric system to take accurate and rapid optical power measurements leading to partial derivative n/partial derivative T data. The reported results are in agreement with the previously reported research at the lower \u3c 600 K temperatures

Subcontractor prequalification practices in Palestine

The construction industry is a major part of the Palestinian economy. Contracting companies carry out important construction projects in cooperation with subcontractors. The majority of elements of a construction project (such as shuttering, building, plastering, painting, carpentry, and ironmongery works) are implemented by subcontractors through the main contractors. The aim of this paper is to identify and rank the factors used by main contractors in the selection of suitable subcontractors in the Gaza Strip, and to propose recommendations for improving the selection of subcontractors. A survey was conducted of 57 main contractors and 57 subcontractors randomly selected from the Gaza Strip. The study revealed the important factors used by main contractors for selection of suitable subcontractors. These include adherence of the subcontractor to contract terms, adherence to time schedule, commitment to prices

A rare case of simple hereditary recessive optic atrophy

Simple Autosomal Recessive Optic Atrophy (AROA) is a rare hereditary disorder that belongs to a group of disorders called Hereditary Optic Atrophy. Patients diagnosed with simple AROA have complete blindness since birth or from first few months of life. This blindness does not improve with age. However, no other organ or system is affected in this disorder. There is no known cause or gene mutation associated with it. Here we report a case of a two year old child diagnosed with simple AROA. Family history of the patient revealed that an older deceased relative also suffered from similar symptoms. Identification of this and similar cases of the simple AROA can help us better understand this disorder and hopefully one day help us develop a treatment for it

Nasogastric tube self-knotting

Complications associated with nasogastric tube (NGT) are rare. We report one of these rare complications, NGT knotting, in the pediatric population. Our patient was a 7-year-old boy, a known case of β-thalassemia, who underwent laparoscopic splenectomy. He experienced NGT knotting. NGT knotting detection needs a high index of suspicion; if not detected and managed in a proper way, it may lead to serious complications. Recommended techniques to avoid this complication are discussed in this article

Sonographic fetal biometry charts for a Pakistani cohort.

This study aimed to develop growth centiles at different gestational weeks for fetal biparietal diameter, abdominal circumference, femur length and head circumference in a Pakistani cohort. Data were collected at a tertiary referral hospital from pregnant women at gestational ages 13-40 weeks referred for obstetric ultrasound as a part of routine antenatal care. A total of 1599 fetal sonographic biometric measurements were collected after screening for the inclusion criteria. For each measurement, separate regression models were derived to estimate the mean, standard deviation and reference percentiles at each week of gestational age for this cohort. The best fitting model for each variable was selected. These charts will help radiologists and clinicians in predicting dates of delivery, assessing fetal growth and identifying intrauterine fetal insufficiency in the Pakistani population

A new model of master of philosophy in physiological sciences

The objectives of Master of Philosophy (MPhil) in Physiological Sciences are: 1) to describe the new ways in which anatomy, biochemistry and physiology on one hand, and microbiology, pathology and pharmacology on other hand meet their functional requirements through multidisciplinary integrated concepts; 2) to elucidate relationships between cell biology, molecular biology and molecular genetics by connecting dots of how cell functions are driven by molecules and being controlled by genes. This forms the basis of cell, molecular and genetics [CMG] module upon which 7 multidisciplinary modules of Physiological Sciences follow; 3) these 24 credit hours provide the physiological basis for PhD studies as well as faculty development to enhance learning abilities of medical student; 4) the modules constitute Cardio- Respiratory Physiological Sciences, GI and Renal Physiological Sciences, Neurosciences, Endo-Reproductive Physiological Sciences.; 5) it has integrated microbiology, pathology and pharmacology in a unique way through CMG of microbes leading to associated pathology and mechanisms of prescribed drugs; 6) it has additional synopsis and thesis friendly course work leading to comprehensive examinations; 7) the year two deals with research work of 6 credit hours leading to defense of thesis; 8) The MPhil in Physiological Sciences is fundamentally different from what is being offered elsewhere. It prepares and offers a good spring board to dovetail PhD studies as well as faculty and institutional development. This is the first study that deals with innovative programmes in research, learning and education in the field of physiological sciences. This broad-based MPhil would make its recipients competent, critical, confident and productive learner. This is a completely unique design of a curriculum that has no comparable examples elsewhere. Our mission is to educate graduate students in the field of Physiological Sciences such that they have a complete grasp over the broad-based integrated concepts of basic health sciences. Upon completion of their education, the students will be able to use the duality of imagination and skepticism. Hence, the students will contribute to their fields by unfolding their creative energy