Scheduling control for a single-server queue with
I
customer classes and reneging is considered, with linear holding or reneging cost. An asymptotically optimal (AO) policy in heavy traffic is ...identified where classes are prioritized according to a workload-dependent dynamic index rule. Denote by
c
i
,
μ
i
, and
θ
i
,
i
∈ ℐ := {1, …,
I
} the queue length cost, service rate, and reneging rate, for class-
i
customers. Then, a relabeling of the classes and a partition 0 =
w
0
<
w
1
< ⋯ <
w
K
= ∞,
K
≤
I
are identified such that the policy acts to always assign least priority to the class
i
when the rescaled workload is in the interval
w
i
−1
,
w
i
). The relabeling is such that when workload is withing the lowest resp., highest interval
w
i
−1
,
w
i
), the least priority class is the one with smallest
cμ
resp., greatest
θ
value. This result stands in sharp contrast to known fluid-scale results where it is AO to prioritize by the fixed
cμ/θ
index. One of the technical challenges is the discontinuity of the limiting queue length process under optimality. Discontinuities occur whenever the workload reaches one of the levels
w
i
.
Mean platelet volume (MPV), an essential component of the complete blood count (CBC) indices, is underutilized in common practice. In recent years, MPV has drawn strong interest, especially in ...clinical research. During inflammation, the MPV has a higher value because of platelet activation.
To verify whether high MPV values discovered incidentally in healthy naïve patients indicates the development or the presence of cardiovascular risk factors, particularly metabolic syndrome and pre-diabetes.
A cohort study was used to assess the diagnostic value of high MPV discovered incidentally, in naïve patients (without any known cause of an abnormal high MPV, greater than upper limit of the normal range, such as active cardiovascular diseases and metabolic syndrome).
The mean MPV value in the patient group was 12.3 femtoliter. There was a higher incidence of metabolic syndrome in our research group than in the general population and a non-significant tendency of pre-diabetes. Family doctors more frequently meet naïve patients with high MPV than a hospital doctor. The results of our study are more relevant for him, who should know the relevance of such a finding and search for a hidden pre-diabetes or metabolic syndrome.
High MPV values discovered incidentally in healthy naïve subjects suggest the development or the presence of cardiovascular risk factors, particularly metabolic syndrome and pre-diabetes. No statistically significant association was found between MPV and the presence of cardiovascular disease.
BACKGROUNDAmong dialysis patients, occlusive mesenteric vascular disease has rarely been reported. OBJECTIVESTo report on the experience of one center with regard to diagnosing and treating this ...complication. METHODSThe retrospective case-series involved six patients (3 females, 3 males; age 52-88 years; 5/6 were smokers) on chronic hemodialysis at a single center. All patients with symptoms suggestive of occlusive mesenteric disease and a subsequent angiographic intervention were included. Demographic, clinical, and laboratory data were collected from patient charts for the period before and after angioplasty and stenting of the mesenteric vessels. A Wilcoxon signed-rank test was used to compare the relevant data before and after the intervention. RESULTSAll participants had variable co-morbidities and postprandial abdominal pain, food aversion, and weight loss. CT angiography was limited due to heavy vascular calcifications. All underwent angioplasty with stenting of the superior mesenteric artery (4 patients) or the celiac artery (2 patients). All procedures were successful in resolving abdominal pain, malnutrition, and inflammation. Weight loss before was 15 ± 2 kg and weight gain after was 6 ± 2 kg. C-reactive protein decreased from 13.4 ± 5.2 mg/dl to 2.2 ± 0.4 mg/dl (P < 0.05). Serum albumin increased from 3.0 ± 0.2 g/dl to 3.9 ± 0.1 g/dl (P < 0.05). Two patients underwent a repeat procedure (4 years, 5 months, respectively). Follow-up ranged from 0.5-7 years. CONCLUSIONSOcclusive mesenteric ischemia occurs among dialysis patients. The diagnosis requires a high degree of suspicion, and it is manageable by angiography and stenting of the most involved mesenteric artery.
Abstract
We present the design, prototype developments and test results of the new time-of-flight detector (ToFD) which is part of the R
$$^3$$
3
B experimental setup at GSI and FAIR, Darmstadt, ...Germany. The ToFD detector is able to detect heavy-ion residues of all charges at relativistic energies with a relative energy precision
$$\sigma _{\varDelta E}/{\varDelta E}$$
σ
Δ
E
/
Δ
E
of up to 1% and a time precision of up to 14 ps (sigma). Together with an elaborate particle-tracking system, the full identification of relativistic ions from hydrogen up to uranium in mass and nuclear charge is possible.
Early and mid-term results of repeat percutaneous balloon mitral commissurotomy (PBMC) were analyzed in 35 patients with symptomatic valvular restenosis: 12 patients (34%) after first successful PBMC ...and 23 patients (66%) after successful surgical closed mitral commissurotomy. Twenty-one patients had bilateral fused commissures, and 14 patients had unilateral or bilateral split commissures. Mitral valve area gain was significantly greater in the group with fused commissures compared with the group with split commissures (0.6 ± 0.2 vs 0.3 ± 0.2 cm
2, respectively, p = 0.04).
An unusual case of hemoptysis following subclavian vein puncture is reported: the amount of blood was small and self terminating. We suggest that it was caused by an inadvertent lung puncture.
The incidence and clinical significance of immobile and 'frozen' posterior mitral leaflet (FPML) were evaluated in the pathophysiology and immediate outcome of patients with severe pliable mitral ...stenosis (MS) undergoing percutaneous balloon mitral commissurotomy (PBMC).
During the past four years, 30 'ideal' patients (mean age 46 +/- 8 years) with Wilkins' score <8, bilateral commissural fusion and absence of commissural calcification underwent peri-procedural echocardiographic analysis. Anterior mitral leaflet (AML) mobility index (MI), chordae tendineae (CT) length, and mitral valve area (MVA) were evaluated.
Pre-procedure FPML was noted in 28 patients (93%). All patients achieved MVA > or = 1.5 cm2. Post-procedure MVA in patients with bilateral commissural splitting was 1.9 +/- 0.2 cm2 versus 1.6 +/- 0.1 cm2 in patients with unilateral commissural splitting (p < 0.05). CT lengths directed to the AML and PML were 15 +/- 2 mm and 8 +/- 2 mm, respectively (p < 0.05). MI of the AML before and immediately after PBMC was 0.4 and 0.6, respectively (p < 0.05). None of the patients with FPML showed improved mobility following successful PBMC.
FPML may be found in most patients with pliable MS. It is mainly a result of short, rigid and fused CT directed to the PML. A 'single-wing door' or a unicuspid valve may be used as a model for rheumatic pliable MS. It is suggested that pre-procedure leaflet morphology and functional assessment should focus on the AML.
Current clinical guidelines restrict catheterization laboratory activity without on-site surgical backup. Recent improvements in technical equipment and pharmacologic adjunctive therapy increase the ...safety margins of diagnostic and therapeutic cardiac catheterization.
To analyze the reasons for urgent cardiac surgery and mortality in the different phases of our laboratory's activity in the last 11 years, and examine the impact of the new interventional and therapeutic modalities on the current need for on-site cardiac surgical backup.
We retrospectively reviewed the mortality and need for urgent cardiac surgery (up to 12 hours post-catheterization) through five phases of our laboratory's activity: a) diagnostic (years 1989-2000), b) valvuloplasties and other non-coronary interventions (1990-2000), c) percutaneous-only balloon angioplasty (1992-1994), d) coronary stenting (1994-2000), and e) use of IIb/IIIa antagonists and thienopiridine drugs (1996-2000).
Forty-eight patients (0.45%) required urgent cardiac surgery during phase 1, of whom 40 (83%) had acute coronary syndromes with left main coronary artery stenosis or the equivalent, and 8 (17%) had mechanical complications of acute myocardial infarction. Two patients died (0.02%) during diagnostic procedures. In phase 2, eight patients (2.9%) were referred for urgent cardiac surgery due to either cardiac tamponade or severe mitral regurgitation, and two patients (0.7%) died. The combined need for urgent surgery and mortality was significantly lower in phase 4 plus 5 as compared to phase 3 (3% vs. 0.85%, P = 0.006).
In the current era using coronary stents and potent antithrombotic drugs, after gaining experience and crossing the learning curve limits, complex cardiac therapeutic interventions can safely be performed without on-site surgical backup.
An elevated left atrial pressure and high diastolic pressure gradient (DPG) across the mitral valve are the major hemodynamic abnormalities in mitral stenosis (MS). However, a subgroup of patients ...with severe MS is characterized by low initial DPG. The authors reviewed the clinical, echocardiographic and hemodynamic data as well as procedural results in 180 patients who underwent percutaneous balloon mitral valvuloplasty (PBMV). An initial mean DPG > 10 mmHg was found in 144 patients (80%) (group A) and mean DPG ≤ 10 mmHg in 36 patients (20%) (group B). Patients in group A had higher left ventricular ejection fraction (LVEF) than in group B (61 ± 5% versus 42 ± 6%, respectively) and higher cardiac index (2.8 ± 0.4 versus 2.0 ± 0.3 l/min/m
2
). In group B 12 patients (33%) had normal LVEF, whereas 24/36 (67%) had reduced LVEF. All the latter had wall motion abnormalities on ventriculography. Unlike group A, intraprocedural echocardiography was essential for monitoring and evaluating immediate results of PBMV in group B. On follow-up of three years, 75% of group A patients and 55% in group B were in functional class I (p < 0.05). PBMV did not significantly improve symptoms in patients in group B who had preprocedure LVEF ≤ 35%. (Int J Cardiac Intervent 2003; 5: 200-205)
