Longer Delay Times Research Articles

Correlation of substorm injections, auroral modulations, and ground Pi2

In this case study we report a substorm, 23 March 2007, which exhibited oscillations with a period of ∼135 s in three substorm phenomena all of which were one‐to‐one correlated. The in‐situ observations are from one THEMIS spacecraft (8.3 RE geocentric distance) and the geosynchronous LANL‐97A spacecraft. The focus here is on the intensification phase during which THEMIS was conjugate to the region of auroral brightening and its foot point was near the high‐latitude ground station Kiana. The following results will be demonstrated: (1) THEMIS and LANL‐97A (time‐delayed) recorded periodic ion injections (>100 keV). (2) Near‐conjugate high‐latitude ground magnetometer data show very large Pi2 (δH∼150 nT) with a 6‐s time delay compared to the THEMIS ion injections. (3) Low‐latitude ground magnetometer data also show Pi2 with the same waveform as the high‐latitude Pi2 but with longer time delays (20–31 s). (4) Auroral luminosity was periodically modulated during the intensification phase. (5) All three signatures (ion injections, ground Pi2, optical modulation) had the same periodicity of ∼135 s but with various time delays with respect to the THEMIS ion injections. These observations demonstrate that the three substorm phenomena had a common source which controlled the periodicity.

Low power multipliers based on new hybrid full adders

Five hybrid full adder designs are proposed for low power parallel multipliers. The new adders allow NAND gates to generate most of the multiplier partial product bits instead of AND gates, thereby lowering the power consumption and the total number of needed transistors. For an 8×8 implementation, the ALL-NAND array multiplier achieves 15.7% and 7.8% reduction in power consumption and transistor count at the cost of a 6.9% increase in time delay compared to standard array multiplier. The ALL-NAND tree multiplier exhibits lower power consumption and transistor count by 12.5% and 7.3%, respectively, with a 4.4% longer time delay, compared to conventional tree multiplier.

Factors associated with longer time from symptom onset to hospital presentation for patients with ST-elevation myocardial infarction.

Previous studies have demonstrated the effects of single factors, such as age, sex, and race, with longer delays from symptom onset to hospital presentation in patients with ST-elevation myocardial infarction. We studied risk factors individually and in combination to determine the cumulative effect on delay times in 482,327 patients with ST-elevation myocardial infarction enrolled in the National Registry of Myocardial Infarction between January 1, 1995, and December 31, 2004. We analyzed patient subgroups with the following risk factors in combination: younger than 70 years vs 70 years and older, race/ethnicity, men vs women, and nondiabetic vs diabetic. The geometric mean for delay time was 114 minutes, with a decreasing trend from 123 minutes in 1995 to 113 minutes in 2004 (P < .001). Nearly half of the patients (45.5%) presented more than 2 hours and 8.7% presented more than 12 hours after the onset of symptoms. Compared with the reference group (those < 70 years, men, white, and did not have diabetes mellitus [DM]), subgroups with longer delay times (P < .01 for all) included those younger than 70 years, men, black, and had DM (+43 minutes); those younger than 70 years, women, black, and had DM (+55 minutes); those 70 years and older, men, black, and had DM (+60 minutes); and those 70 years and older, women, black, and had DM (+63 minutes). Patient subgroups with a combination of factors (older age, women, Hispanic or black race, and DM) have particularly long delay times that may be 60 minutes longer than subgroups without those characteristics. Improving patient responsiveness in these subgroups represents an important opportunity to improve quality of care and minimize disparities in care.

A Novel Scheme to Identify Symmetrical Faults Occurring During Power Swings

A novel, fast unblocking scheme for distance protection to identify symmetrical faults occurring during power swings has been proposed in this paper. First of all, the change rate of three-phase active power and reactive power being the cosine function and the sine function with respect to the phase difference between the two power systems during power swings has been demonstrated. In this case, they cannot be lower than the threshold of 0.7 after they are normalized. However, they will level off to 0 when a three-phase fault occurs during power swings. Thereafter, the cross-blocking scheme is conceived on the basis of this analysis. By virtue of the algorithm based on instantaneous electrical quantities, the calculation of the active and reactive power is immune to the variation of the system power frequency. As the integration-based criterion, it has high stability. Finally, simulation results show that this scheme is of high reliability and fast time response. The longest time delay is up to 30 ms.

Outcomes after primary coronary intervention with drug-eluting stent implantation in diabetic patients with acute ST elevation myocardial infarction

Drug-eluting stent (DES) has been used widely for the treatment of patients with acute coronary syndrome with or without diabetes mellitus during percutaneous coronary intervention (PCI), but its long-term safety and efficacy in diabetic patients with acute ST elevation myocardial infarction (STEMI) remain uncertain. This study aimed to investigate the clinical outcomes after primary coronary intervention with DES implantation for diabetic patients with acute STEMI, compared with non-diabetic counterparts. From December 2004 to March 2006, 56 consecutive diabetic patients (diabetic group) and 170 non-diabetic patients (non-diabetic group) with acute STEMI who underwent primary PCI with DES implantation in 3 hospitals were enrolled. Baseline clinical, angiographic, and procedural characteristics, as well as occurrence of major adverse cardiac event (MACE) including cardiac death, non-fatal recurrent myocardial infarction (re-MI) and target vessel revascularization (TVR) during hospitalization and one-year clinical follow-up were compared between the two groups. Patients in diabetic group were more hyperlipidemic (69.6% and 51.8%, P = 0.03) and had longer time delay from symptom onset to admission ((364 +/- 219) minutes and (309 +/- 223) minutes, P = 0.02) than those in non-diabetic group. The culprit vessel distribution, reference vessel diameter, and baseline TIMI flow grade were similar between the two groups, but multi-vessel disease was more common in diabetic than in non-diabetic group (82.1% and 51.2%, P < 0.001). Despite similar TIMI flow grades between the two groups after stenting, the occurrence of TIMI myocardial perfusion grade (TMPG) = 2 was lower in diabetic group (75.0% vs 88.8% in non-diabetic groups, P = 0.02). The MACE rate was similar during hospitalization between the two groups (5.4% vs 3.5%, P = 0.72), but it was significantly higher in diabetic group (16.1%) during one-year follow-up, as compared with non-diabetic group (6.5%, P = 0.03). The cumulative one-year MACE-free survival rate was significantly lower in diabetic than in non-diabetic group (78.6% vs 90.0%, P = 0.02). Angiographic stent thrombosis occurred in 5.4% and 1.2% of the patients in diabetic and non-diabetic group, respectively (P = 0.19). All of these patients experienced non-fatal myocardial infarction. Although the early clinical outcomes were similar in diabetic and non-diabetic patients with acute STEMI treated with DES implantation, the cumulative MACE-free survival at one-year follow-up was worse in diabetic than in non-diabetic patients. More effective diabetes-related managements may further improve the clinical outcomes of diabetic cohort suffering STEMI.

Measurement of electron density utilizing the H α-line from laser produced plasma in air

The electron density in a laser produced plasma experiment was measured utilizing the Stark broadening of the H α-line at 656.27 nm. This line results from the interaction of the Nd:YAG laser at the fundamental wavelength of 1.06 μm with a plane solid aluminum target in a humid air. The measurements were repeated at several delay times (0–10 μs) and at a fixed gate time of 1 μs. The electron density from the optically thin Al II-line at 281.62 nm was measured in parallel from the same spectra. The electron density was found in the range from 10 18 cm − 3 down to 6 × 10 16 cm − 3 at longer delay time. The electron density from the H α-line using the Griem's standard theory was compared with the predictions of other model due to Gigosos et al. The agreement between the measured electron density from both the H α-line and the Al II-line would confirm the reliability of utilizing the H α-line as an electron density standard reference line in LIBS experiments. Several important features characterize the H α-line: it is a well isolated line, it gives large signal to background ratio, it lasts a long time after the termination of the laser (up to 10 μs), its Stark width is relatively large and does not exhibit self-absorption.

Time Delays for the Giant Quadruple Lensed Quasar SDSS J1004+4112: Prospects for Determining the Density Profile of the Lensing Cluster

Abstract We investigated the dependence of the time delays for the large-separation gravitationally lensed quasar SDSS J1004$+$4112 on the inner mass profile of the lensing cluster. Adopting a mass model whose innermost density profile was parameterized as $\rho \propto r^{-\alpha}$, we derived a series of mass models that can fit the observational data, and then compute the probability distribution functions of time delays. We find that larger $\alpha$ has longer time delays, longer tails at the higher end of the probability distribution, and larger model uncertainties. The ratios of the time delays slightly depend on the slope, $\alpha$. Among others, time delays between images C and A (or B) have little dependence on the inner slope, particularly when the time delays are short. The dependence of time delays on $\alpha$ is well fitted by a linear form, which reflects the well-known degeneracy between the mass profile and time delays. We performed a Monte Carlo simulation to illustrate how well the inner slope can be constrained from measurements of time delays. We found that measurements of more than one time delay resulted in reasonably tight constraints on the inner slope ($\sigma_{\alpha} \lesssim 0.25$), while only one time delay could not determine the inner slope very well. Our result indicates that time delays indeed serve as a powerful tool to determine the mass profile, despite the complexity of the lensing cluster.

Factors Associated With Prolonged Prehospital Delay of African Americans With Acute Myocardial Infarction

Delays in seeking treatment for signs and symptoms of acute myocardial infarction are longer for African Americans than for whites. To determine factors associated with prolonged delay and the extent to which perceived racism influences prehospital delay in African Americans with acute myocardial infarction. Sixty-one African Americans with acute myocardial infarction were interviewed within 1 month of hospital admission. Delay times were calculated on the basis of the interviews. Independent t tests and chi(2) tests were used to determine factors associated with prolonged delays. Median delay was 4.25 hours and did not differ significantly between women and men (4.42 vs 3.50 hours). Most patients (69%) experienced their initial signs and symptoms at home, often witnessed by family members or friends (70%). Delay was longer for insured patients than for uninsured patients (4.45 vs 0.50 hours). Single, widowed, or divorced patients had longer delay times than did married patients (5.33 vs 2.50 hours), and patients with diabetes delayed longer than did those without diabetes (7.29 vs 3.50 hours). Perceived racism did not differ significantly between patients who delayed seeking treatment and those who did not. Median delay times were substantially longer than the recommended time of less than 1 hour, reducing the benefit from reperfusion therapies. Education and counseling of patients and their families should be a major strategy in optimizing patients' outcomes and decreasing the time to definitive treatment.

Thermal coupling in multishot laser microvia drilling for interconnection application

Microvia for interconnect application was drilled using multishot laser pulses of nanosecond duration. It is observed that time delay between successive pulses have an effect on the shape of the drilled microvias. There is a thresholdlike time delay at which microvia suffers an abrupt deformation which creates voids and complication in the subsequent metallization process. Thermal coupling between successive pulses could be used to explain this phenomenon. To avoid deformation, a longer time delay between subsequent pulses is preferred.

Haemodialysis vascular access problems in Canada: results from the Dialysis Outcomes and Practice Patterns Study (DOPPS II)

The optimal vascular access for chronic maintenance haemodialysis (HD) is the native arteriovenous fistula (AVF). Vascular access practice patterns are reported for a Canadian cohort of patients from the Dialysis Outcomes and Practice Patterns Study (DOPPS II). DOPPS II is a prospective, observational study in 12 countries, including Canada. A representative random sample of 20 Canadian HD facilities and patients within those units were studied during 2002-2004. Canadian results were compared with those found in Europe and the USA. AVF use in Canadian prevalent (53%) and incident (26%) patients was lower than Canadian guidelines recommend (60%), and lower than in Europe [prevalent (74%), incident (50%)]. Despite 85% of Canadian HD patients having seen a nephrologist for > 1 month prior to starting dialysis, central venous catheter use in Canada (33% in prevalent patients, 70% in incident patients) was much higher than in Europe (prevalent 18%, incident 46%) and slightly higher than in the USA (prevalent 25%, incident 66%). This pattern is contrary to the preferences of Canadian medical directors and vascular access surgeons. The typical time from referral until permanent vascular access creation is substantially longer in Canada (61.7 days) than in Europe (29.4 days) or the USA (16 days). This longer delay time and higher catheter use in Canada may be a consequence of the significantly lower number of access surgeons per 100 HD patients in Canada (2.9) compared with the USA (8.1) and Europe (4.6). Furthermore, the median hours per week devoted to vascular access-related surgery per 100 patients is substantially lower in Canada (0.027 h) compared with the USA (0.082 h) and Europe (0.059 h). These findings suggest that Canadian chronic HD patients often rely on central venous catheters for vascular access, despite their known association with numerous detrimental outcomes in HD. Nephrologists, vascular access surgeons, interventional radiologists, other physicians and health care funding bodies must be more broadly educated about the priority of AVF creation as the preferred vascular access for chronic HD patients. They must work together to secure both the human and financial resources and other health care system enhancements to increase AVF creation rates in a timely manner.

Enhancing echo cancellation via estimation of delay

The advent of packetized audio transmission, such as voice over IP (VoIP), has resulted in challenging requirements for echo cancellation technology. One key aspect of this technology is the need to characterize, quickly and accurately, the echo paths in the transmission media. Echo paths consist of a constant time delay with no echo signal and active regions in which the echo signal is present. When an adaptive filter echo cancellation algorithm is used, its performance can be greatly increased, and its complexity can be reduced if it is only applied to the active regions. This requires an algorithm to estimate the constant delay and locate the active regions. Traditionally, delay estimation has been based on direct application of cross-correlation. This method has poor performance because the input signals are highly correlated and has a high implementation cost because many cross-correlation lags have to be computed for longer time delays. The delay estimation addressed in this paper has two major advantages over the traditional methods. The first is that it has improved performance because the input signals are processed to have less correlation. The second is that the implementation cost is significantly reduced because fewer cross-correlation lags are computed, and an efficient method to estimate lags is created.

New observations on the luminescence decay lifetime of Mn2+ in ZnS:Mn2+ nanoparticles

A fast decay emission peaking at 645 nm with a decay lifetime within the experimental resolution of 0.14 micros is observed in ZnS:Mn2+ nanoparticles. This short-lived signal is also observed in pure ZnS and MgS: Eu3+ nanoparticles, which has nothing to do with Mn(2+)-doped ions but is from the deep trap states of the host materials. The short-lived component decreases in intensity relative to the Mn2+ emission at higher excitation powers, while it increases in intensity at low temperatures and shifts to longer wavelengths at longer time delays. Our observations demonstrated further that the emission of Mn2+ in ZnS: Mn2+ nanoparticles behaves basically the same as in bulk ZnS: Mn2+; the fast decay component is actually from the intrinsic and defect-related emission in sulfide compounds.

The 4051-Å band of C3 (ÃΠu1−X̃Σg+1, 000-000): Perturbed low-J lines and lifetime measurements

Rotational analyses have been carried out at high resolution for the 000-000 and 000-100 bands of the A (1)Pi(u)-X (1)Sigma(g) (+) transition of supersonic jet-cooled C(3). Two different spectra have been recorded for each band, using time gatings of 20-150 and 800-2300 ns. At the shorter time delay the spectra show only the lines observed by many previous workers. At the longer time delay many extra lines appear, some of which have been observed previously by [McCall et al.Chem. Phys. Lett. 374, 583 (2003)] in cavity ring-down spectra of jet-cooled C(3). Detailed analysis of these extra lines shows that at least two long-lived states perturb the A (1)Pi(u), 000 state. One of these appears to be a (3)Sigma(u) (-) vibronic state, which may possibly be a high vibrational level of the b (3)Pi(g) state, and the other appears to be a P = 1 state with a low rotational constant B. Our spectra also confirm the reassignment by McCall et al. of the R(0) line of the 000-000 band, which is consistent with the spectra recorded towards a number of stars that indicate the presence of C(3) in the interstellar medium. Fluorescence lifetimes have been measured for a number of upper-state rotational levels. The rotational levels of the A (1)Pi(u) state have lifetimes in the range of 230-190 ns, decreasing slightly with J; the levels of the perturbing states have much longer lifetimes, with some of them showing biexponential decays. An improved value has been obtained for the nu(1) vibrational frequency of the ground state, nu(1) = 1224.4933 +/- 0.0029 cm(-1).

Women's perceptions, expectations and satisfaction with induced labour—A questionnaire-based study

Objectives To evaluate the understanding and expectations of women undergoing labour induction, to assess their actual experience of the process and to compare their satisfaction with labour to those labouring spontaneously. Study design Four hundred and fifty women at term undergoing induction of labour and cervical ripening with prostaglandinE2 vaginal tablets and 450 women labouring spontaneously were recruited into the study. The induction group were requested to complete a questionnaire prior to the start of their induction process and another questionnaire post-delivery. The post-delivery questionnaire contained two sections, one pertaining to issues to do with the induction and the second with the actual labour process. The spontaneously labouring group was requested to complete a questionnaire post-delivery, which only contained the section pertaining to the actual labour process. The main outcome measures were satisfaction with labour, perception of pain and length of labour between the induced and spontaneous labour groups, and issues that the women might wish changed about their induction. Results In the induction group, 34.7% were not satisfied with the information they received about the induction prior to the procedure and 27.2% expected to deliver within 12 h of the administration of the inducing agent. Post-induction, 40% of the women felt the most important aspect they would like to change about their induction were they to have another one, would be the speed of the induction, 13.6% felt they might wish to take the inducing agent orally, 7% to have fewer vaginal examinations and 9% to have fewer complications. Among the women who returned questionnaires, 26.3% had a caesarean delivery in the induction group and 21.4% in the spontaneous labour group. Significantly more women were satisfied with their labour in the spontaneous labour group 79.5% versus 70.4%, RR 0.89, 95% CI 0.8–0.96, P = 0.006). Conclusions Labour that is artificially induced does result in lower satisfaction rates as compared to that following spontaneous onset. The longer time delay between the start of the induction and the delivery plays a significant part in this, with the mode of administration of the inducing agent, more vaginal examinations and the increase in caesarean deliveries being perceived as secondary issues. There is a need to improve the information provided to women undergoing labour induction, to counter unrealistic expectations and thereby improve satisfaction.

Measuring the Change in the Intermolecular Raman Spectrum during Dipolar Solvation

We demonstrate a method to directly measure the change in the spectrum of intermolecular solvent fluctuations as a function of time after electronic excitation of a solute, and this method is applied to the dye Coumarin 102 (C102) in acetonitrile. The complete intermolecular response is captured following resonant excitation with time domain third-order Raman spectroscopy. In a previous report, we introduced this method and used it to probe one point in the intermolecular response as a function of time after solute excitation (Underwood, D. F., Blank, D. A. J. Phys. Chem. A 2003, 107 (7), 956). Here we extend this approach to recover the change in the entire intermolecular response as a function of time. To our knowledge the results provide the first direct measurement of the difference in the equilibrated intermolecular response after excitation of a solute and its evolution during a dipolar solvation event. Excitation of C102 results in a significant increase in the solvent-solute interaction due to a large increase in the dipole moment. The observed change in the intermolecular response is consistent with a rapid change in local solvent density, with intermolecular kinetic energy transfer changing the response on longer time scales. Evolution of the response exhibits a strong frequency dependence and suggests changes over longer distances at longer delay times. The measured change in the spectrum of solvent fluctuations represents a direct experimental confirmation of the breakdown of linear response and confirms predictions from molecular dynamics simulations.

Excited-state decay of hydrocarbon radicals, investigated by femtosecond time-resolved photoionization: Ethyl, propargyl, and benzyl

The excited state decay of the hydrocarbon radicals ethyl, C(2)H(5); propargyl, C(3)H(3); and benzyl, C(7)H(7) was investigated by femtosecond time-resolved photoionization. Radicals were generated by flash pyrolysis of n-propyl nitrite, propargyl bromide, and toluene, respectively. It is shown that the 2 (2)A(') (3s) Rydberg state of ethyl excited at 250 nm decays with a time constant of 20 fs. No residual signal was observed at longer delay times. For the 3 (2)B(1) state of propargyl excited at 255 nm a slower decay with a time constant 50+/-10 fs was determined. The 4 (2)B(2) state of benzyl excited at 255 nm decays within 150+/-30 fs.

Time-of-Flight Mass Spectroscopy of Carbon Clusters and Hydrocarbons Produced by Laser Ablation of Graphite under H2 and He Buffer Gas-Formation and Stability of C10 and C2nH2 (n=2-5)-

The products from laser ablated graphite under the flow of H2 and He buffer gases were analyzed by time-of-flight (TOF) mass spectroscopy in combination with one-photon ionization of an energy of 10.5 eV/photon. By changing the time interval between the ablation laser pulse and the photoionization laser pulse it was found that the neutral clusters ablated from the graphite have three distinctly different velocities for one and the same value of m/z, which was detected as three separate bunches of TOF mass peaks. The effect of changing the time interval was examined extensively. As a result, it was found that the first component that appeared earlier in the ionization region consisted of various bared carbon clusters Cn with n≥6 and hydrocarbons CnHm with n≥4 and m=1 through 4 while the second and third components that arrived later were C10 and C2nH2 (n=2 through 5) only. This persistence of C10 and C2nH2 at longer delay times was attributed to the robustness of these clusters against collisions occurring in ablated plumes. It was inferred that the robustness is due to the chemical inertness of a monocyclic form for C10 and of a linear polyynic form, H(-C≡C)n-H, for C2nH2. In the He buffer gas heated to 600 K the yield of the third (slowest) component of C10 enhanced drastically, which indicates that thermal collisions in plumes favor the production of this monocycle, which further suggests that the monocycle may play a crucial role in the formation of C60, known as a favored product in hot plumes of ablated graphite.

Efficient method to obtain the entire active area against circuit delay time trade-off curve in gate sizing

The authors are concerned with the optimisation of combinational logic circuits. The competing factors, active area and delay time, are considered in the optimisation. The total active area is assumed to be a linear function of the gate sizes. There is a critical path whose delay time, the longest delay time of the circuit, depends on the sizes of the individual gates. This path will change many times during the optimisation. The optimisation process is used to produce the trade-off curve. The proposed methodology is based on the optimisation of the circuit critical path. This is a gate sizing problem on those paths that define the delay time of a circuit. Given a drive size for all the gates of the circuit, the trade-off curve contains design space points of minimum delay time and active area. A variable-sized subset of the Boolean network is optimised. Only the gates in the circuit critical path are optimised. The gates in the Boolean network which are not in the critical path do not need to be optimised. An efficient method is proposed for updating the critical path as the trade-off curve is obtained. Performance comparison and results were obtained over the set of MCNC two-level and combinational multilevel benchmark circuits. The proposed methodology produces trade-off curves, in relatively large circuits, with a great reduction in number of variables and run-time compared with the original full problem. In the proposed method, the number of variables is reduced by a factor of up to 7.3 times relative to the original full problem. The run-time behaviour is excellent, with an improvement between 1.5 and 32.5 times less CPU time compared with computation of the full Boolean network. With a higher gate count of the circuit, there are greater improvements in both run-time and number of variables.

Effect of temperature on the luminescence processes of SrAl2O4:Eu2+

The UV excited and persistent luminescence properties as well as thermoluminescence (TL) of Eu2+ doped strontium aluminates, SrAl2O4:Eu2+ were studied at different temperatures. Two luminescence bands peaking at 445 and 520nm were observed at 20K but only the latter at 295K. Both Sr-sites in the lattice are thus occupied by Eu2+ but at room temperature efficient energy transfer occurs between the two sites. The UV excited and persistent luminescence spectra were similar at 295K but the excitation spectra were different. Thus the luminescent centre is the same in both phenomena but excitation processes are different. Two TL peaks were observed between 50 and 250°C in the glow curve. Multiple traps were, however, observed by preheating and initial rise methods. With longer delay times only the high temperature TL peak was observed. The persistent luminescence is mainly due to slow fading of the low temperature TL peak but the step-wise feeding process from high temperature traps is also probable.

A mass spectroscopic study of laser vaporized graphite in H 2 and D 2 gases: the stability of C 2 nH 2 ( n=2–5) and C 10

Carbon clusters and hydrocarbon molecules and radicals produced by laser vaporization of graphite in a hydrogen (H 2 or D 2) gas expansion source were studied using 10.5 eV one-photon ionization followed by time-of-flight mass spectroscopy. By changing the delay time of the ionization pulse relative to the vaporization pulse, we found two distinctly different mass patterns: rather non-selective signals of C n ( n=6–20) and C n H m ( n=3–20 and m=1–4) at shorter delay times, while selective signals of C 2 n H 2 ( n=2–5) and C 10 at longer delay times. The selective formation of the carbon cluster and hydrocarbon molecules at longer delay times is attributed to the relatively inert nature of polyynes H(–CC–) n H ( n=2–5) and monocyclic C 10. The formation mechanism of these hydrocarbons and carbon clusters by laser ablation under hydrogen gas is discussed.