A Theory of Errors in Quantum Measurement

It is common to model random errors in a classical measurement by the normal (Gaussian) distribution, because of the central limit theorem. In the quantum theory, the analogous hypothesis is that the matrix elements of the error in an observable are distributed normally. We obtain the probability distribution this implies for the outcome of a measurement, exactly for the case of 2x2 matrices and in the steepest descent approximation in general. Due to the phenomenon of `level repulsion', the probability distributions obtained are quite different from the Gaussian.Comment: Based on talk at "Spacetime and Fundamental Interactions: Quantum Aspects" A conference to honor A. P. Balachandran's 65th Birthda

Pseudotumor cerebri and ciprofloxacin: a case report

INTRODUCTION: We present a case of ciprofloxacin-associated pseudotumor cerebri in a 22-year-old African American woman. Withdrawal of ciprofloxacin in our patient resulted in complete resolution of ciprofloxacin-associated pseudotumor, as evidenced by a normal neuro-ophthalmic examination and a cerebrospinal fluid opening pressure of 140 mmH20. CASE PRESENTATION: A 22-year-old African American woman presented with a headache of two weeks duration, visual blurring and horizontal diplopia after starting ciprofloxacin for pyelonephritis. An ophthalmic examination revealed that she had left eye esotropia, and a picture of the fundus demonstrated bilateral disc swelling without spontaneous venous pulsations. Magnetic resonance imaging of the brain and a magnetic resonance venogram were normal. A diagnostic lumbar puncture demonstrated an elevated opening pressure of 380mmH2O in a supine position. Laboratory examinations, including a cerebrospinal fluid exam, were unremarkable. CONCLUSION: ciprofloxacin-associated pseudotumor can cause chronic disabling headache and visual complications. Therapy is sub-optimal, often symptomatic, insufficient and complicated by side effects. When ciprofloxacin-associated pseudotumor presents in an atypical population, an inciting agent must be suspected because prompt withdrawal of the agent may lead to complete resolution of symptoms and prevent recurrence of similar episodes

Anaesthetic management of giant encephalocele

One of the several challenges to the anaesthesiologists, is management of child with difficult airway. Management of even normal airway in a neonate is different and complex as compared to airway of two year old child and that of adult. Definition of the difficult airway is related solely to tracheal intubation or problems with mask ventilation1.Among the different causes of difficult airway cranio facial and neoplastic anomalies are very common. We present a case report of difficult airway management in encephalocele patient

Risk of cardio-respiratory abnormalities in preterm infants placed in car seats: a cross-sectional study

BACKGROUND: Little is known about the factors that predispose to the occurrence and severity of cardio-respiratory symptoms during the placement of a prematurely born infant in a car seat. The impact of gestational age, weight at discharge and infant's pre-existing cardio-respiratory status (in the supine position) on cardio-respiratory function during pre-discharge testing in a car seat (semi-upright position) has not been investigated. METHODS: The cardio-respiratory function of 42 preterm neonates with gestational age 24 to 35 weeks and discharge weight 1790 to 2570 grams were monitored for 45 minutes before, during, and after placement in a car seat. The occurrence of periodic breathing, apnea, bradycardia, or decreased oxygen saturation (SaO2) was analyzed. RESULTS: Prior to the car seat testing, 15 (35.7%) infants displayed one or more abnormalities of cardio-respiratory function. During the car seat testing, 25 (59.6%) infants had periodic breathing, 33 (78.2%) had oxygen saturation <90%, 14 (33.3%) had bradycardia less than 80 beats per minute, and 35 (83.3%) had a combination of these symptoms. Infants, both with and without pre-existing cardio-respiratory abnormalities, had an almost equal probability (80% vs. 83.3%) for the development of cardio-respiratory symptoms during placement in the car seat. Weight at discharge ([less than or equal to] 2,000 grams) but not the gestational age (<28 weeks or [greater than or equal to] 28<37 weeks), was associated with either increased episodes of oxygen desaturation or the combination of cardio-respiratory symptoms that were seen during the placement of these infants in the car seat. Repositioning from the car seat to the supine position showed normalization of cardio-respiratory function in the majority (83%) of the tested infants. None of the tested clinical factors were associated with the severity of the cardio-respiratory symptoms. CONCLUSION: Pre-discharge testing of the cardio-respiratory function of preterm infants during placement in a car seat is important for the prevention of cardio-respiratory symptoms during their transportation. However, the high risk for developing cardio-respiratory symptoms will require the consideration of an alternative mode of safe home transportation for preterm infants; especially those with a discharge weight less than 2,000 grams

Rheology of Fumed Silica and Polyethylene Glycol Shear Thickening Suspension with Nanoclay as an Additive

Shear thickening properties of fumed silica-polyethylene glycol (PEG) with shear thickening fluid (STF) of different concentrations and with an organically modified clay, Nanomer I.28 E as nano-additive have been investigated by both steady-state and dynamic state rheology. Difference in rheology if instead of nanoclay, an equal wt% of additional fumed silica is added to 20 per cent fumed silica-PEG200 STF, has been studied. At 25 °C, in case of addition of nanoclay the increase in critical viscosity is less than that observed for same additional amount of fumed silica. Interestingly, an opposite result is seen at higher temperatures i.e. 45 °C and 55 °C. Moreover, the difference in steady-state and dynamic state viscosity values decreases on addition of nanoclay. It is noted that an increase in concentration of clay increases the value of dynamic parameters whereas for STF of only fumed silica particles the values are constant irrespective of the change in concentration. More importantly, ease of processing, elasticity, stability and consistency of rheological results of STF increases to a significant extent on addition of relatively inexpensive nano-additive

Management of neonatal hyperbilirubinemia: Pediatricians' practices and educational needs

BACKGROUND: Early detection and treatment of neonatal hyperbilirubinemia is important in the prevention of bilirubin-induced encephalopathy. In this study, we evaluated the New Jersey pediatricians' practices and beliefs regarding the management of neonatal hyperbilirubinemia and their compliance with the recommendations made by the American Academy of Pediatrics (AAP) in 1994. METHODS: A survey questionnaire was mailed to a random sample of 800 pediatricians selected from a list of 1623 New Jersey Fellows of the AAP initially in October 2003 and then in February 2004 for the non-respondents. In addition to the physicians' demographic characteristics, the questionnaire addressed various aspects of neonatal hyperbilirubinemia management including the diagnosis, treatment, and follow up as well as the pediatricians' beliefs regarding the significance of risk factors in the development of severe hyperbilirubinemia. RESULTS: The adjusted response rate of 49.1% (n = 356) was calculated from the 725 eligible respondents. Overall, the practicing pediatricians reported high utilization (77.9%) of the cephalocaudal progression of jaundice and low utilization (16.1%) of transcutaneous bilirubinometry for the quantification of the severity of jaundice. Most of the respondents (87.4%) identified jaundice as an indicator for serum bilirubin (TSB) testing prior to the neonate's discharge from hospital, whereas post-discharge, only 57.7% felt that a TSB was indicated (P < 0.01). If the neonate's age was under 72 hours, less than one-third of the respondents reported initiation of phototherapy at TSB levels lower than the treatment parameters recommended by the AAP in 1994, whereas if the infant was more than 72 hours old, almost 60% were initiating phototherapy at TSB lower than the 1994 AAP guidelines. Most respondents did not regard neonatal jaundice noted after discharge and gestational ages 37–38 weeks as being significant in the development of severe hyperbilirubinemia. However, the majority did recognize the importance of jaundice presenting within the first 24 hours and Rh/ABO incompatibility. CONCLUSION: The pediatricians' practices regarding the low utilization of laboratory diagnosis for the quantification of jaundice after discharge and underestimation of risk factors that contribute to the development of severe hyperbilirubinemia are associated with initiation of phototherapy at lower than AAP recommended treatment parameters and recognition of neonatal hyperbilirubinemia as an important public health concern

High-Q CMOS-integrated photonic crystal microcavity devices

Integrated optical resonators are necessary or beneficial in realizations of various functions in scaled photonic platforms, including filtering, modulation, and detection in classical communication systems, optical sensing, as well as addressing and control of solid state emitters for quantum technologies. Although photonic crystal (PhC) microresonators can be advantageous to the more commonly used microring devices due to the former's low mode volumes, fabrication of PhC cavities has typically relied on electron-beam lithography, which precludes integration with large-scale and reproducible CMOS fabrication. Here, we demonstrate wavelength-scale polycrystalline silicon (pSi) PhC microresonators with Qs up to 60,000 fabricated within a bulk CMOS process. Quasi-1D resonators in lateral p-i-n structures allow for resonant defect-state photodetection in all-silicon devices, exhibiting voltage-dependent quantum efficiencies in the range of a few 10 s of %, few-GHz bandwidths, and low dark currents, in devices with loaded Qs in the range of 4,300–9,300; one device, for example, exhibited a loaded Q of 4,300, 25% quantum efficiency (corresponding to a responsivity of 0.31 A/W), 3 GHz bandwidth, and 30 nA dark current at a reverse bias of 30 V. This work demonstrates the possibility for practical integration of PhC microresonators with active electro-optic capability into large-scale silicon photonic systems.United States. Defense Advanced Research Projects Agency. Photonically Optimized Embedded MicroprocessorsUnited States. Dept. of Energy (Science Graduate Fellowship

Collective potential for large N hamiltonian matrix models and free Fisher information

We formulate the planar `large N limit' of matrix models with a continuously infinite number of matrices directly in terms of U(N) invariant variables. Non-commutative probability theory, is found to be a good language to describe this formulation. The change of variables from matrix elements to invariants induces an extra term in the hamiltonian,which is crucual in determining the ground state. We find that this collective potential has a natural meaning in terms of non-commutative probability theory:it is the `free Fisher information' discovered by Voiculescu. This formulation allows us to find a variational principle for the classical theory described by such large N limits. We then use the variational principle to study models more complex than the one describing the quantum mechanics of a single hermitian matrix (i.e., go beyond the so called D=1 barrier). We carry out approximate variational calculations for a few models and find excellent agreement with known results where such comparisons are possible. We also discover a lower bound for the ground state by using the non-commutative analogue of the Cramer-Rao inequality.Comment: 25 pages, late

Determinants of institutional birth among women in rural Nepal: a mixed-methods cross-sectional study

Background: Encouraging institutional birth is an important component of reducing maternal mortality in low-resource settings. This study aims to identify and understand the determinants of persistently low institutional birth in rural Nepal, with the goal of informing future interventions to reduce high rates of maternal mortality. Methods: Postpartum women giving birth in the catchment area population of a district-level hospital in the Far-Western Development Region of Nepal were invited to complete a cross-sectional survey in 2012 about their recent birth experience. Quantitative and qualitative methods were used to determine the institutional birth rate, social and demographic predictors of institutional birth, and barriers to institutional birth. Results: The institutional birth rate for the hospital's catchment area population was calculated to be 0.30 (54 home births, 23 facility births). Institutional birth was more likely as age decreased (ORs in the range of 0.20-0.28) and as income increased (ORs in the range of 1.38-1.45). Institutional birth among women who owned land was less likely (OR = 0.82 [0.71, 0.92]). Ninety percent of participants in the institutional birth group identified safety and good care as the most important factors determining location of birth, whereas 60 % of participants in the home birth group reported distance from hospital as a key determinant of location of birth. Qualitative analysis elucidated the importance of social support, financial resources, birth planning, awareness of services, perception of safety, and referral capacity in achieving an institutional birth. Conclusion: Age, income, and land ownership, but not patient preference, were key predictors of institutional birth. Most women believed that birth at the hospital was safer regardless of where they gave birth. Future interventions to increase rates of institutional birth should address structural barriers including differences in socioeconomic status, social support, transportation resources, and birth preparedness