Empirical justifications for the lognormal, Rayleigh and Suzuki (1977) probability density functions in multipath fading channels are examined by quantifying the rates of convergence of the central ...limit theorem (CLT) for the addition and multiplication of random variables. The accuracy of modeling the distribution of rays which experience multiple reflections/diffractions between transmitter and receiver as lognormal is quantified. In addition, it is shown that the vector sum of lognormal rays, such as in a narrow-band signal envelope, may best be approximated as being either Rayleigh, lognormal or Suzuki distributed depending on the fading channel conditions. These conditions are defined statistically.
The switching behavior of the novel hybrid material (FA)NaFe(CN)5(NO).H2O (1) in response to temperature (T), light irradiation and electric field (E) is studied using in situ X‐ray diffraction ...(XRD). Crystals of 1 display piezoelectricity, pyroelectricity, second and third harmonic generation. XRD shows that the FA+ are disordered at room‐temperature, but stepwise cooling from 273–100 K induces gradual ordering, while cooling under an applied field (E=+40 kVcm−1) induces a sudden phase change at 140 K. Structural‐dynamics calculations suggest the field pushes the system into a region of the structural potential‐energy surface that is otherwise inaccessible, demonstrating that application of T and E offers an effective route to manipulating the crystal chemistry of these materials. Photocrystallography also reveals photoinduced linkage isomerism, which coexists with but is not correlated to other switching behaviors. These experiments highlight a new approach to in situ studies of hybrid materials, providing insight into the structure–property relationships that underpin their functionality.
Hybrid materials based on known molecular photoswitches show great potential for the rational design of new pyro‐ and ferroelectric photoswitches. This article shows how in situ X‐ray diffraction using thermal, photochemical and electrical stimuli can explore structure–property relationships in the novel pyroelectric (FA)NaFe(CN)6(NO).H2O, enabling a deeper understanding of its complex energy landscape via structural‐dynamics calculations.
The effect of narrowband interference on OFDM systems is considered, with particular regard to the receiver post-detection bit error rate performance. It is shown both by analysis and by computer ...simulation that the ensemble average bit error rate is severely affected by narrowband interference and that particular values of interferer carrier frequency and phase can produce bit error rates significantly higher than the ensemble average. An interference suppression technique based on excision (notch) filtering is proposed and is shown by computer simulation to improve ensemble average bit error rates to about 0.001 for BPSK modulated OFDM with signal-to-interference ratios as low as -30 dB
Purpose: To study surgically excised vascular tissue from lower extremities for the presence of
Chlamydia pneumoniae, to extend the previously described association of the organism with ...atherosclerosis.
Methods: Arterial biopsy specimens obtained from femoral and popliteal arteries during bypass operation for claudication were examined by immunocytochemical analysis and polymerase chain reaction for the presence of organisms.
Results: C. pneumoniae was detected in atherosclerotic plaques by either method in either artery of 11 of 23 patients (48%). Eight of 21 popliteal and three of 18 femoral arteries had positive results.
Conclusions: Detection of
C. pneumoniae in peripheral arteries indicates that the organism is widespread in atherosclerosis of the vascular system. (J Vasc Surg 1997;26:29-31.)
This study examined a wide array of clinical factors to evaluate their influence on fracture risk and T scores in women with rheumatoid arthritis (RA) and determine if women with RA who are at risk ...for osteoporosis (OP) are adequately treated with OP medications.
Data from 8419 female RA patients participating in the Consortium of Rheumatology Researchers of North America registry from March 02, 2006 to August 15, 2006 was evaluated. Covariates included medication subgroups, demographic, and clinical parameters. Lumbar spine and hip T scores and fracture rates were studied in relation to the variables. Use of OP medications in patients with OP risk factors was also evaluated.
Postmenopausal status and higher modified health assessment questionnaire score (mHAQ) had a negative effect on lumbar spine score,while marriage, education, and body mass index had a positive effect. A similar trend was found with hip T scores. Increase in overall fracture risk correlated with postmenopausal status, mHAQ, and prednisone use, while tumor necrosis factor monotherapy was associated with decreased overall fracture risk. mHAQ was also associated with nonhip/nonspine fractures. Eighty percent of patients had at least 1 risk factor for OP, but only 32% were on OP medications. Only 54% of patients with 3 risk factors were on OP medication.
In RA, postmenopausal status, mHAQ, and prednisone use were associated with a higher overall fracture risk. Women with RA who were at risk for OP may have been inadequately treated with OP medications.
Abstract Objectives: To explore general practitioners' attitudes towards and use of a computer program for assessing genetic risk of cancer in primary care. Design: Qualitative analysis of ...semistructured interviews and video recordings of simulated consultations. Participants: Purposive sample of 15 general practitioners covering a range of computer literacy, interest in genetics, age, and sex. Interventions: Each doctor used the program in two consultations in which an actor played a woman concerned about her family history of cancer. Consultations were videotaped and followed by interviews with the video as a prompt to questioning. Main outcome measures: Use of computer program in the consultation. Results: The program was viewed as an appropriate application of information technology because of the complexity of cancer genetics and a sense of “guideline chaos” in primary care. Doctors found the program easy to use, but it often affected their control of the consultation. They needed to balance their desire to share the computer screen with the patient, driven by their concerns about the effect of the computer on doctor-patient communication, against the risk of premature disclosure of bad news. Conclusions: This computer program could provide the necessary support to assist assessment of genetic risk of cancer in primary care. The potential impact of computer software on the consultation should not be underestimated. This study highlights the need for careful evaluation when developing medical information systems. Key messages General practitioners are under increasing pressure to advise their patients about genetic predisposition to various diseases Computers could help doctors to give genetic advice by simplifying the construction and assessment of family trees and implementing referral guidelines This qualitative evaluation explored the context in which a computer program for assessing genetic risk of cancer would be used in general practice and issues surrounding its integration into a consultation Most of the doctors found the program easy to use, but it affected their control of the consultation—because of their desire to share the computer screen with the patient and their inability to anticipate the information that would be displayed The study identified important issues relating to the use of computers in consultations which may be of use in testing software for primary care in the future
We compared the ProSeal (PLMA) and Classic (LMA) laryngeal mask airway for airway management by inexperienced personnel. Nine nurses from the post-anaesthesia care unit, with no prior experience of ...LMA or PLMA insertion, were observed inserting the LMA and PLMA in 60 ASA 1 to 2 anaesthetized, paralyzed adults following manikin-only training. The time to achieve an effective airway (2 consecutive expired tidal volumes (6 ml/kg; maximum 2 minutes allowed), the number of insertion attempts and the reasons for failure (inability to insert into pharynx or inadequate ventilation) were determined by analysis of digital video recordings. The first attempt success rate (LMA, 85%; PLMA, 83%), overall success rate (LMA, 88%; PLMA, 90%) and effective airway time (LMA, 39 +/- 13 s; PLMA, 43 +/- 19 s) were similar. Failure was from an inability to insert into the pharynx in five with the LMA and three with the PLMA, and inadequate ventilation with two from the LMA and three from the PLMA. Effective airway time and the number of failures were similar for the first and second device. Failure of both devices occurred in four patients. We conclude that airway management in anaesthetized, paralyzed adults is equally successful for the LMA and PLMA by inexperienced personnel following manikin-only training. The PLMA is worthy of consideration as a tool for emergency airway management by inexperienced personnel.
The long-term goal of this project is the elucidation of the complete sequence of the Caenorhabditis elegans genome. During the first year methods have been developed and a strategy implemented that ...is amenable to large-scale sequencing. The three cosmids sequenced in this initial phase are surprisingly rich in genes, many of which have mammalian homologues.
Nth-order nonuniform sampling is described for generalized bandpass signal frequency position, bandwidth, sampling rate, frequency-shift and phase-shift. A bandpass extension to the Nyquist criterion ...is derived, showing that restrictions on bandpass frequency position for odd orders of nonuniform sampling tend to zero as N tends to infinity. Bandpass interpolants based on the sinc function are derived for the generalized Nth-order sampled bandpass signals. It is shown that, for minimum (Nyquist) rate sampling, these interpolants are comprised of N bandpass filters, each with independent phase. The number of bandpass filters comprising the interpolant is found to decrease as the sample rate increases. The advantage of describing Nth-order sampling as the Nth replication and uniform sampling of a signal is demonstrated. Finally, digital implementation of the Nth-order bandpass sampling interpolants is discussed. It is established that it is not practicable to attempt to perform nonuniform bandpass sampling at the theoretical minimum rate, where the interpolation is to be performed digitally.< >
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