Phenomenon Of Skipping Research Articles

Genome editing through large insertion leads to the skipping of targeted exon.

BackgroundHighly efficient genome editing can be achieved through targeting an endonuclease to specific locus of interest. Engineered zinc-finger nuclease (ZFN) and CRISPR-associated protein-9 nuclease (Cas9) offer such an elegant approach for genome editing in vertebrate cells. In this study, we have utilized ZFN and Cas9-catalyzed double strand break followed by homologous recombination-mediated incorporation of premature stop codon and selection marker to target human cell division cycle 14A (hCDC14A) and cell division cycle 14B (hCDC14B) genes.ResultsTargeting of the hCDC14A and hCDC14B loci in telomerase immortalized human retinal pigment epithelium (hTERT-RPE1) and human colon cancer (HCT116) cells were confirmed by Southern blot hybridization. Nevertheless, DNA sequence analysis of reverse transcription polymerase chain reaction (RT-PCR) products confirmed that in all the single/double allele ablations, the targeted exon was spliced out. The phenomenon of exon skipping was independent of the genome editing approaches exploited, Cas9 or ZFN. Because the exons had a nucleotide number that could be divided by 3, the reading frame of the exon deletion was maintained. This indicates an exon-skipping event possibly due to the insertion of large DNA fragment (1.7 to 2.5 Kb) within the targeted exons. As a proof-of-principle, we have used gene disruption followed by non-homologous end joining (NHEJ) approach. Small alterations in the exon (one to fifteen bases) were transcribed to mRNA without exon skipping. Furthermore, loxP site-mediated removal of selection markers left a 45 bp scar within the targeted exon that can be traced in mRNA without exon skipping.ConclusionFrom this study, we conclude that insertion of a large DNA fragment into an exon by genome editing can lead to its skipping from the final transcript. Hence, more cautious approach needs to be taken while designing target sites in such that the possible skipping of targeted exon causes a frame-shift mediated incorporation of pre-mature stop codon. On the other hand, exon skipping may be a useful strategy for the introduction of protein deletions.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-2284-8) contains supplementary material, which is available to authorized users.

성공적인 확인응답이 필요한 비디오 정보 파일에 의한 토큰버킷 자동 파라메타 설정 기법을 가진 비디오 스트리밍 수신기

비디오 스트리밍 수신기의 재생 버퍼에 있는 패킷량은 네트워크 상태에 따라 변화되며 지연 및 지터의 영향으로 인해 포화 및 고갈 현상이 일어날 수 있다. 특히, 유입되는 비디오 트래픽의 양이 재생 버퍼의 최대 양을 넘으면 버퍼 오버플로우(buffer overflow)문제가 발생된다. 버퍼 오버플로우는 화질의 열화를 발생시키고 스킵(skip) 현상으로 인해 재생의 불연속성을 발생시킨다. 또한 네트워크 혼잡으로 인하여 패킷의 유입이 늦어지면 버퍼 언더플로우(buffer underflow) 문제에 의한 버퍼링에 의해 영상의 멈춤 현상이 일어날 수 있다. 상기 문제들을 해결하기 위하여 본 논문에서는 토큰버킷(Token Bucket)의 주요 파라미터인 토큰 발생률 파라메타와 버킷의 최대 용량 파라미터를 각각의 비디오 패킷들의 패턴에 따라서 자동적으로 설정하는 토큰버킷 기법을 장착한 비디오 스트리밍 수신기를 제안한다. NS-2(Network Simulator-2)와 JSVM(Joint Scalable Video Model)을 이용하는 시뮬레이션 결과는 제안하는 토큰버킷 파라메타 자동설정 기법이 기존의 수동설정 기법보다 3개의 시험 비디오 시퀀스들에 대해 오버플로우/언더플로우 횟수와 패킷 손실 비율 및 PSNR(Peak Signal to Noise Ratio)측면에서 우수한 성능을 제공함을 확인 할 수 있었다. The amount of packets in palyout buffer of video streaming receiver can be changed by network condition, and saturated and exhausted by the delay and jitter. Especially, if the amount of incoming video traffic exceeds the maximum allowed playout buffer, buffer overflow problem can be generated. It makes the deterioration of video image and the discontinuity of playout by skip phenomenon. Also, if the incoming packets are delayed by network confusion, the stop phenomenon of video image is made by buffering due to buffer underflow problem. To solve these problems, this paper proposes the video streaming receiver with token bucket scheme which automatically establishes the important parameters like token generation rate r and bucket maximum capacity c adapting to the pattern of video packets. The simulation results using network simulator-2 (NS-2) and joint scalable video model (JSVM) show that the proposed token bucket scheme with automatic establishment parameter provides better performance than the existing token bucket scheme with manual establishment parameter in terms of the generation number of overflow and underflow, packer loss rate, and peak signal to noise ratio (PSNR) in three test video sequences.

Efficient pseudo-Gauss-Newton full-waveform inversion in the τ-p domain

Full-waveform inversion (FWI) seeks to estimate subsurface elastic properties by iterative minimization of the difference between synthetic and observed data. Its industrial application suffers from several well-defined obstacles, including high computational cost, slow convergence rate, and the phenomenon of cycle skipping. We have developed an efficient [Formula: see text] domain waveform inversion aimed at reducing the computational burden of FWI with a phase-encoding technique. The gradient is constructed in the [Formula: see text] domain using linear phase-encoding, and a slant update strategy further reduces the computational burden. Poorly scaled and blurred gradient updates can be enhanced using exact or approximate versions of the inverse Hessian, which leads to a faster convergence rate. We developed a new chirp phase-encoding strategy for diagonal Hessian construction. Preconditioning the gradient using the diagonal phase-encoded approximate Hessian forms what we refer to as a pseudo-Gauss-Newton (PGN) step. To test the effectiveness of the [Formula: see text]-domain FWI, the strategies were enacted on a modified Marmousi model. We compared the computational cost of the PGN method with traditional methods, and we evaluated the quality of the inversion results. The PGN method can get a better inversion result with the same computational cost. We have also analyzed the effects of different ray parameter settings and the influence of source spacing, and we compared different preconditioning methods for [Formula: see text]-domain FWI.

Theory of Charge Kondo Effect on Pair Hopping Mechanism

A new microscopic model of the charge Kondo effect is proposed and is studied on the basis of numerical renormalization group calculations. It is shown that the charge Kondo effect is caused by the pair hopping interaction between the conduction band and the localized band. It is found that the formation of a charge Kondo–Yosida singlet due to its mechanism corresponds to the appearance of a valence skipping phenomenon, and that the charge Kondo–Yosida singlet and the spin Kondo–Yosida singlet state coexist for a tuned parameter set, because the charge and spin degrees of freedom are separated in this model. It is also found that the Sommerfeld coefficient is enhanced by the competition between these two singlet states.

Calculation of Turn Skipping Losses in Helical Flux Compression Generators

In helical flux compression generators, the ohmic and intrinsic flux losses limit severely the performance of them. One of the sources of intrinsic flux losses is the turn skipping flux loss. This paper first introduces an accurate criterion for the prevention of the turn skipping phenomenon in these generators. Then, a novel method is presented to calculate the flux loss due to this phenomenon. In addition, an equivalent resistance is introduced to consider the effect of turn skipping flux loss on the generator performance. The calculation results show that, as soon as the turn skipping occurs, about 30% of a turn flux is lost and this value is increased rapidly with eccentricity increasing. Therefore, it is necessary to prevent this phenomenon as far as possible. The calculated output current of the simulated generator also shows that the maximum current when considering the turn skipping loss is about 15% of the maximum current in the case of ignoring it. Based on the authors' knowledge, quantification of the turn skipping flux losses has not been presented previously in the open literature.

Chronic traumatic encephalopathy in an Iraqi war veteran with posttraumatic stress disorder who committed suicide

Following his discovery of chronic traumatic encephalopathy (CTE) in football players in 2002, Dr. Bennet Omalu hypothesized that posttraumatic stress disorder (PTSD) in military veterans may belong to the CTE spectrum of diseases. The CTE surveillance at the Brain Injury Research Institute was therefore expanded to include deceased military veterans diagnosed with PTSD. The authors report the case of a 27-year-old United States Marine Corps (USMC) Iraqi war veteran, an amphibious assault vehicle crewman, who committed suicide by hanging after two deployments to Fallujah and Ramadi. He experienced combat and was exposed to mortar blasts and improvised explosive device blasts less than 50 m away. Following his second deployment he developed a progressive history of cognitive impairment, impaired memory, behavioral and mood disorders, and alcohol abuse. Neuropsychiatric assessment revealed a diagnosis of PTSD with hyperarousal (irritability and insomnia) and numbing. He committed suicide approximately 8 months after his honorable discharge from the USMC. His brain at autopsy appeared grossly unremarkable except for congestive brain swelling. There was no atrophy or remote focal traumatic brain injury such as contusional necrosis or hemorrhage. Histochemical and immunohistochemical brain tissue analysis revealed CTE changes comprising multifocal, neocortical, and subcortical neurofibrillary tangles and neuritic threads (ranging from none, to sparse, to frequent) with the skip phenomenon, accentuated in the depths of sulci and in the frontal cortex. The subcortical white matter showed mild rarefaction, sparse perivascular and neuropil infiltration by histiocytes, and mild fibrillary astrogliosis. Apolipoprotein E genotype was 3/4. The authors report this case as a sentinel case of CTE in an Iraqi war veteran diagnosed with PTSD to possibly stimulate new lines of thought and research in the possible pathoetiology and pathogenesis of PTSD in military veterans as part of the CTE spectrum of diseases, and as chronic sequelae and outcomes of repetitive traumatic brain injuries.

Basement configuration of on-land Kutch basin from seismic refraction studies and modeling of first arrival travel time skips

The Kutch basin is one of the three (Narmada, Cambay and Kutch) major marginal rift basins that are close to each other in mid-western part of the Indian subcontinent. The seismic refraction and wide-angle reflection data were acquired and a first order velocity structure of the Kutch sedimentary basin along Jakhau–Mandvi, Mandvi–Mundra, Mundra–Adesar and Hamirpur–Halvad profiles is derived. The travel time skip phenomenon has been noticed in the travel time plots and record sections indicating presence of low velocity sediments. Derived two-dimensional velocity–depth models revealed a Mesozoic sedimentary sequence sandwiched between Trap and Limestone layers, in some of the profiles. Two thick low velocity layers (that corresponds early to late Mesozoic era) have been identified. These are dipping towards Mandvi along Jakhau–Mandvi profile. The early Mesozoic layer that is thinning towards southeast is completely missing in Mandvi–Mundra profile. It is also noticed that the early Mesozoic Bhuj formation exists in the northern parts of the Mundra–Adesar and Hamirpur–Halvad profiles, where it directly overlies the granitic basement. The derived velocity–depth model suggests that the basement is about 3 km deep near Jakhau and reaches a depth of about 6 km near Mandvi. The layered structure may correspond to the Tertiary, Trap, Late Mesozoic sediments and Mesozoic limestone. The velocity–depth model obtained in Kutch is very similar to earlier derived model for Jamnagar and Dwarka sub-basins of northwestern Saurashtra peninsula suggesting probable continuity/linkage between southern on-land Kutch and, across the Gulf of Kutch to Saurashtra peninunsula. We also conclude that the evolution of Kutch basin, as a peri-cratonic rift basin, is essentially controlled by the four (F1–F4) faults inferred from obvious abrupt changes in layer thickness/velocity along the seismic refraction profiles.

Surgical Management of Non-small Cell Lung Cancer with Mediastinal Lymphadenopathy

Several issues regarding the surgical management of N2 disease remain unresolved. First, the anatomical attribution of a mediastinal nodal station, especially in certain areas (i.e., azygos recess), is a source of continuous debate. Second, the presence of occult N2, single or multilevel N2, bulky N2, the skip phenomenon and the observation of a different prognostic outlook for specific mediastinal nodal stations are all elements of discussion that cannot clarify whether stage IIIA-N2 non-small cell lung cancer is indeed a locally, albeit advanced, manifestation of the disease or the prodrome of an actual systemic dissemination. In this subset of patients lies the challenge for multidisciplinary treatment modalities, where the surgical role needs to be further defined in the context of an integrated collaborative effort with the medical oncologist and the radiotherapist.

The Skip-resistant Sprinkler Concept -- Theoretical Evaluation

This article presents a model for the response time of a sprinkler designed to reduce the skipping phenomenon experienced during large-scale fires. The model guides the design of a cylindrical shield intended to reduce drop impingement from nearby operating sprinklers. Several designs are experimentally tested and shown to reduce likely skipping when compared to the same sprinkler without a shield. The model is validated using a laboratory Plunge Tunnel apparatus to measure the effect of the shield on the thermal sensitivity of the sprinkler and its ability to intercept water drops. This work successfully demonstrates that shielding can decrease the response time of a sprinkler in drop-laden gas flow without causing a substantial increase in response time when exposed to a dry-gas flow. This is the first of two articles on the skip-resistant sprinkler concept. The following article evaluates the performance of the shield in actual fires.

Dynamical Behaviors of Periodically Forced Hindmarsh-Rose Neural Model: The Role of Excitability and `Intrinsic' Stochastic Resonance

In the presence/absence of external noise, dynamical behaviors of periodically forced neural systems and firing modes of interspike interval (ISI) are investigated by employing the Hindmarsh-Rose model. In the biologically relevant range of the forcing frequency, the interplay among the intrinsic oscillation, the forcing oscillation, and the noise leads to three kinds of firing modes: multi-modal firing, bi-modal firing, and intrinsic oscillation, in terms of which we can roughly classify the relevant experimental observations on the periodically forced sensory neural systems through their dynamical status. The resonant feature of subthreshold intrinsic oscillations shown in the ISI, the output signal-to-noise ratio, and the mean firing rate, appears to be an indication of stochastic resonance (SR) without external noise, or the `intrinsic' SR. In the multi-modal firing region where SR leads to the skipping phenomenon, based on the `intrinsic' SR, a possible explanation of a specific ISIH observed in experiments is given. Moreover, a neural system can tune itself to be chaotic to encode the weak signal, rather than relying only on the external noise.

Three-field lymphadenectomy and pattern of lymph node spread in T3 adenocarcinoma of the distal esophagus and the gastro-esophageal junction.

Lymph node metastasis in carcinoma of the esophagus and the gastro-esophageal junction is often underestimated by clinical staging. It is the aim of this study to provide support to the fact that three-field lymphadenectomy leads to a better pathological staging also in adenocarcinoma. The pattern of lymph node metastasis in adenocarcinoma of the gastro-esophageal junction (GEJ) and the distal esophagus was charted in a prospective way by using a database. An analysis was performed with regard to lymphatic spread in T3, N+ adenocarcinomas of the distal esophagus and the GEJ junction, which were treated with a radical resection including a three-field lymphadenectomy. Out of 324 patients with adenocarcinoma of the esophagus and GEJ, we selected a group of 37 patients with an adenocarcinoma T3, N+ of the distal (n = 17) or GEJ junction (n = 20), treated with a radical resection and three-field lymphadenectomy ( > 25 lymph nodes resected). In total, 2240 lymph nodes were removed, with a mean of 59.5 per patient. In the GEJ group the ratio of positive nodes was 15.9, in the distal 1/3 group this ratio was 12.7%. Abdominal lymph nodes were positive in all GEJ tumors and in 70% of the distal third carcinomas. Thoracic lymph nodes were positive in 40% of GEJ tumors, and 70.6% of the distal group. Cervical lymph nodes were positive in 20% of the GEJ tumors and in 35.3% of the distal tumors. In six patients only right-sided cervical nodes were affected. Three patients in the GEJ group had positive lymph nodes in the neck without any involvement of thoracic lymph nodes. (1) Three-field lymphadenectomy improves accuracy of staging. (2) Cervical nodes are frequently involved. (3) Especially in tumors of the GEJ there is an important skipping phenomenon, i.e. positive lymph nodes in the neck in the absence of involvement of thoracic nodes. (4) Clinical staging remains deficient in regard to lymph node metastasis, especially cervical nodes. (5) The frequent unforeseen involvement of cervical lymph nodes in adenocarcinoma of the distal esophagus and GEJ tumors makes the interpretation of results of induction chemoradiotherapy questionable. (6) For the same reason, cervical lymph nodes should be included in the radiation field in case of induction chemoradiotherapy. (7) The similar pattern of lymph node involvement suggests similar oncological behavior of adenocarcinoma of the distal esophagus and the GEJ, questioning the actual TNM classification of these tumors as gastric carcinomas.

Nearby Stop Codons in Exons of the Neurofibromatosis Type 1 Gene Are Disparate Splice Effectors

Stop mutations are known to disrupt gene function in different ways. They both give rise to truncated polypeptides because of the premature-termination codons (PTCs) and frequently affect the metabolism of the corresponding mRNAs. The analysis of neurofibromin transcripts from different neurofibromatosis type 1 (NF1) patients revealed the skipping of exons containing PTCs. The phenomenon of exon skipping induced by nonsense mutations has been described for other disease genes, including the CFTR (cystic fibrosis transmembrance conductance regulator) gene and the fibrillin gene. We characterized several stop mutations localized within a few base pairs in exons 7 and 37 and noticed complete skipping of either exon in some cases. Because skipping of exon 7 and of exon 37 does not lead to a frameshift, PTCs are avoided in that way. Nuclear-scanning mechanisms for PTCs have been postulated to trigger the removal of the affected exons from the transcript. However, other stop mutations that we found in either NF1 exon did not lead to a skip, although they were localized within the same region. Calculations of minimum-free-energy structures of the respective regions suggest that both changes in the secondary structure of the mRNA and creation or disruption of exonic sequences relevant for the splicing process might in fact cause these different splice phenomena observed in the NF1 gene.

Computer simulation of solder paste flow Part II: Flow out of a stencil aperture

Journal of Electronics ManufacturingVol. 04, No. 03, pp. 149-154 (1994) No AccessComputer simulation of solder paste flow Part II: Flow out of a stencil apertureS.H. MANNAN, N.N. EKERE, I. ISMAIL, and M.A. CURRIES.H. MANNANDepartment of Aeronautical, Mechanical and Manufacturing Engineering, University of Salford, Salford M5 4WT, UK Search for more papers by this author , N.N. EKEREDepartment of Aeronautical, Mechanical and Manufacturing Engineering, University of Salford, Salford M5 4WT, UK Search for more papers by this author , I. ISMAILDepartment of Aeronautical, Mechanical and Manufacturing Engineering, University of Salford, Salford M5 4WT, UK Search for more papers by this author , and M.A. CURRIEDepartment of Aeronautical, Mechanical and Manufacturing Engineering, University of Salford, Salford M5 4WT, UK Search for more papers by this author https://doi.org/10.1142/S096031319400016XCited by:17 PreviousNext AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsRecommend to Library ShareShare onFacebookTwitterLinked InRedditEmail AbstractIn this paper we use the computer simulation of dense suspensions introduced in Part I to simulate the flow of solder paste during stencil printing for reflow soldering in surface-mount technology (SMT). In order to understand the results of the simulation better, we first simulate the flow of solder paste between two parallel plates, in an arrangement similar to that found in a parallel plate viscometer. We then proceed to examine the results for flow of paste out of a stencil aperture. The aperture width, height, angle of wall inclination, particle size and concentration of the suspension are all varied to see the effect on tensile stress in the paste, and flow patterns. The most significant effect occurs when the angle of wall inclination is changed, and it is argued that walls should be inclined to reduce paste skipping (i.e. shorts on the reflowed PCB). Insight is gained into the phenomenon of skipping in general.Keywords:Solder pasteSMTdense suspensionscomputer simulation FiguresReferencesRelatedDetailsCited By 17Particle Level Modelling of Solder Pastes Rheological Behaviour in Viscosity MeasurementTareq Al-Ma'aiteh and Oliver Krammer1 May 2019Rheological Characterisation and Empirical Modelling of Lead-Free Solder Pastes and Isotropic Conductive Adhesive PastesR. Durairaj, Lam Wai Man, S. Ramesh and S. W. Dean1 Jan 2010 | Journal of ASTM International, Vol. 7, No. 7Rheological characterisation and printing performance of Sn/Ag/Cu solder pastesR. Durairaj, S. Ramesh, S. Mallik, A. Seman and N. Ekere1 Oct 2009 | Materials & Design, Vol. 30, No. 9Rheological characterisation of solder pastes and isotropic conductive adhesives used for flip-chip assemblyR. Durairaj, S. Mallik, A. Seman, A. Marks and N.N. Ekere1 Apr 2009 | Journal of Materials Processing Technology, Vol. 209, No. 8Viscoelastic properties of solder pastes and isotropic conductive adhesives used for flip-chip assemblyR. Durairaj, S. Mallik, A. Seman, A. Marks and N.N. Ekere1 Nov 2008Solder paste characterisation: towards the development of quality control (QC) toolR. Durairaj, S. Mallik and N.N. Ekere27 Jun 2008 | Soldering & Surface Mount Technology, Vol. 20, No. 3Analysis of jamming networks in sheared suspensionsSimon R. Hillman and Samjid H. Mannan1 May 2006 | Journal of Rheology, Vol. 50, No. 3Understanding the process window for printing lead-free solder pastesT.A. Nguty, B. Salam, R. Durairaj and N.N. Ekere1 Oct 2001 | IEEE Transactions on Electronics Packaging Manufacturing, Vol. 24, No. 4Critical factors affecting paste flow during the stencil printing of solder pasteR. Durairaj, T.A. Nguty and N.N. Ekere1 Aug 2001 | Soldering & Surface Mount Technology, Vol. 13, No. 2Analysis of Solder Paste Release in Fine Pitch Stencil Printing ProcessesG. Rodriguez and D. F. Baldwin1 September 1999 | Journal of Electronic Packaging, Vol. 121, No. 3Effective modeling of the reflow soldering process: use of a modeling tool for product and process designF. Sarvar and P.P. Conway1 Jul 1998 | IEEE Transactions on Components, Packaging, and Manufacturing Technology: Part C, Vol. 21, No. 3Understanding the process window for printing lead-free solder pastesT.A. Nguty, S. Budiman, D. Rajkumar, R. Solomon and N.N. Ekere et al.Simulation of the stencil printing process [solder pastes]G.P. Glinski, C. Bailey and K. PericleousSolder paste printing process modelling mapN.N. Ekere, S.H. Mannan and M.A. CurrieThe study of the response of solder pastes under sinusoidal vibrationD. He, N.N. Ekere and M.A. CurrieAn investigation into the printing characteristics and mechanical dynamics of advanced squeegee mechanismsM. Howarth, S.A. Silvester, M. Lacey and K. SivaygonathanCorrelating solder paste composition with stencil printing performanceT.A. Nguty, N.N. Ekere and A. Adebayo Recommended Vol. 04, No. 03 Metrics History Received 1 August 1994 Accepted 1 August 1994 KeywordsSolder pasteSMTdense suspensionscomputer simulationPDF download

Multiple forms of chicken alpha 3(VI) collagen chain generated by alternative splicing in type A repeated domains.

Type VI collagen is a structurally unique component widely distributed in connective tissues. Its molecular structure consists of monomers that have the potential to assemble intracellularly into dimers and tetramers which, once secreted, can form microfilaments by end-to-end association. Individual monomers are composed of chains of Mr = approximately 140,000 (alpha 1 and alpha 2) and greater than 300,000 (alpha 3). Type VI collagen molecules contain a short triple helix with large globular domains at both ends. These domains are made for their greatest part of repetitive units similar to type A repeats of von Willebrand Factor. The alpha 3(VI) chain, contributing most of the mass of the NH2-terminal globule, appeared heterogenous both at the mRNA and protein level. Several alpha 3(VI)-specific clones that lack the sequences corresponding to repeats A8 and A6 were isolated from a chicken aorta cDNA library. Northern blot hybridization of poly (A+)-enriched RNA from chicken gizzard with cDNA fragments corresponding to several individual type A repeats showed that A8- and A6-specific probes did not hybridize to the lower Mr transcripts. Clones spanning approximately 20 kb of the 5'-end of the alpha 3(VI) gene were isolated from a chicken genomic library and subjected to analysis by restriction mapping, Southern blotting, and selective sequencing of the intron-exon boundaries. At the most 5'-end of the gene an additional type A repeat (A9), previously undetected in cDNA clones, was identified. Furthermore, it was determined that the presumed signal peptide and repeats A9 through A6 are encoded within individual exons. Reverse transcription and polymerase chain reaction of aorta RNA suggested that a mechanism of alternative mRNA splicing by a phenomenon of exon skipping generates alpha 3(VI) isoform variants that contain different numbers of type A repeats. Immunohistochemistry of frozen sections of chicken embryo tissues with repeat-specific mAbs showed that an antibody directed against a conditional exon has a more restricted tissue distribution compared to an antibody against a constitutive exon.

Occurrence and reproducibility of the “skip” phenomenon in bactericidal testing of Staphylococcus aureus

A “skip” phenomenon, in which subcultures to determine bactericidal endpoints show discordant results, can make bactericidal testing of Staphylococcus aureus difficult to interpret. Either a single or several consecutive concentrations may be skipped, with insignificant growth from these concentrations, but heavy growth from higher antimicrobic concentrations. Replicate macrodilution minimum bactericidal concentration testing of cephalothin against S . aureus was investigated to determine the frequency and reproducibility of the skip phenomenon in this test. In preliminary testing, the skip phenomenon occurred at 24 hr in 11 of the 30 tests performed on ten S . aureus strains. Incubation of tubes for 48 hr before subculture markedly reduced the number of tests containing a skip tube (four of 30). The skip phenomenon was not reproducible either within concurrent replicate testing or on repeat testing of the same isolate on subsequent days. The ten strains were retested in replicative trials using the macrodilution test comparing Mueller-Hinton broth (MHB) and MHB supplemented with Tween 80. The number of skips occurring in the supplemented broth test was the same (two of 22) at 24 hr as nonsupplemented broth. For reproducible results, macrodilution minimum bactericidal testing requires performance of the test in duplicate, with repeat subculture at 48 hr if the skip phenomenon occurs in both trials at the 24-hr subculture. Killing curves performed on these isolates did not appear to demonstrate any relationship between the skip phenomenon and the paradoxical effect described by Eagle.

Extraordinary Oscillation in Nonlinear Polyphase Circuit

Polyphase circuit phenomena are discussed from the standpoint of improving reliability of conversion detection devices used in measuring equipment. A nonlinear three-phase circuit was analyzed by the harmonic balance method. It was found that the line impedance Z L and line resistance R L have a very large effect on the zero phase voltage and extraordinary oscillation region, and that the line and protective relay load capacitances C L and C O are closely related to the skip phenomenon.

A Dynamic and Static Analysis of a Solenoid Actuated Stepping Motor

When the law of conservation of energy is applied to a solenoid actuated stepping motor, it becomes possible to derive an expression for the maximum stepping rate and to explain the phenomenon of skipping. If a sinusoidal electric input and a simple harmonic motion for the plunger are assumed as a mathematical model, the phenomenon of overspin can be explained as a consequence of resonance between the electric input and the plunger motion.