电子邮件营销:因资源与投资回报失衡而被低估

博客和业内专家认为,电子邮件营销面临的最大挑战非常复杂,如收件箱传输能力或渲染。这是真的吗?一名博学的市场人员、设计师或程序员都可以轻易解决上述两个问题,而对于其他大多数人来说,问题就不是那么简单了。这才是真正的问题。大多数公司并不知道电子邮件营销的最佳实践,同时他们内部也缺少相关的专业资源。然而,却很少有公司意识到这个问题,因为即使是写得很糟糕的电子邮件似乎仍表现不错。未造成伤害,也没有犯错,不是吗?     

Optimisation of design and operation of generators for offshore vertical axis wind turbines

A process for optimizing both the design and operation of the generator for a large offshore vertical axis wind turbine (VAWT) is developed. The objectives of the optimization process are to minimize additional costs and losses in the generator to allow for a fair evaluation of the impact of the VAWT environment on the powertrain. A spectrum of torque control strategies was tested based on the ratio, q, of the allowed electrical torque variation to the inherent mechanical torque variation. Equations relating q to the generator losses were established. The effect of q on the energy extracted by the rotor was also investigated and incorporated into the optimization process. This work shows that a variable q strategy with respect to wind speed can improve turbine performance across the range of operational wind speeds depending on the torque loading from the rotor blades. In turn, this also allows for the torque rating of the generator to be reduced from the peak torque rating that would otherwise be expected, creating an opportunity to downscale the generator size, reducing costs. The optimization of powertrain design and operation should be carried out at as high level as is possible, ideally using the fully factored cost of energy (COE) to guard against unexpected losses because of excessive focus in one COE factor (for example reducing upfront cost but in turn reducing availability).     

Hemodynamic and norepinephrine responses to pacing-induced heart failure in conscious sinoaortic-denervated dogs

The present study was undertaken to determine the effects of chronic sinoaortic (baroreceptor) denervation (SAD) on the hemodynamic and sympathetic alterations that occur in the pacing-induced model of congestive heart failure. Two groups of dogs were examined: intact (n = 9) and SAD (n = 9). Both groups of dogs were studied in the control (prepace) state and each week after the initiation of ventricular pacing at 250 beats/min. After the pacemaker was turned off, hemodynamic and plasma norepinephrine levels returned toward control levels in the prepaced state and after 1 and 2 wk of pacing. However, by 3 wk all hemodynamic and norepinephrine levels remained relatively constant over the 10-min observation period with the pacemaker off. With the pacemaker off, left ventricular end-diastolic pressure went from 2.7 +/- 1.4 (SE) mmHg during the prepace state to 23.2 +/- 2.9 mmHg in the heart failure state in intact dogs (P < 0.01). Left ventricular end-diastolic pressure increased to 27.1 +/- 2.2 mmHg from a control level of 4.2 +/- 1.9 mmHg i SAD dogs (P < 0.0003). Mean arterial pressure significantly decreased in intact and SAD dogs. Resting heart rate was significantly higher in SAD dogs and increased to 135.8 +/- 8.9 beats/min in intact dogs and 136.1 +/- 6.5 beats/min in SAD dogs. There were no significant differences in the hemodynamic parameters between intact and SAD dogs after pacing. Plasma norepinephrine was significantly lower in intact than in SAD dogs before pacing (197.7 +/- 21.6 vs. 320.6 +/- 26.6 pg/ml; P < 0.005). In the heart failure state, plasma norepinephrine increased significantly in both intact (598.3 +/- 44.2 pg/ml) and SAD (644.0 +/- 64.6 pg/ml) groups. There were no differences in the severity or the magnitude of the developed heart failure state in SAD vs. intact dogs. We conclude from these date that the arterial baroreflex is not the sole mechanism for the increase in sympathetic drive in heart failure.     

Bacterial attachment to oropharyngeal epithelial cells in breastfed newborns

Dopaminergic agents and carbidopa/levodopa have become the preferred treatment for both the restless legs (RL) syndrome and for periodic limb movements in sleep (PLMS). For once-nightly treatments with carbidopa/ levodopa, a problem with morning end-of-dose rebound increases in leg movements has been reported to occur in the about one-fourth of the patients. In our clinical studies a previously unreported but far more significant problem of markedly augmented RL symptoms occurred in the afternoon and the evening prior to taking the next nightly dose. A systematic prospective evaluation of this augmentation in 46 consecutive patients treated with carbidopa/ levodopa for RL syndrome or PLMS disorder found this augmentation to be the major adverse effect of treatment. Augmentation occurred for 31% of PLMS patients and 82% of all RL patients. It was greater for subjects with more severe RL symptoms and for patients on higher doses (> or = 50/200 mg carbidopa/levodopa) but was unrelated to gender, age or baseline severity of PLMS. This augmentation was severe enough to require medication change for 50% of the RL patients and 13% of PLMS patients. Augmentation resolved with cessation of the medication and could be minimized by keeping the dose low.     

The potential of subtype-selective neuronal nicotinic acetylcholine receptor agonists as therapeutic agents

Neuronal nicotinic acetylcholine receptors (NAChRs) are pentameric ligand-gated ion channel receptors which exist as different functional subunit combinations which apparently subserve different physiological functions as indicated by molecular biological and pharmacological techniques. It is possible to design and synthesize novel compounds that have greater selective affinities and efficacies than nicotine for different NAChRs, which should translate into different behavioral profiles and therapeutic potentials. Examples of NAChR agonists studied are nicotine, SIB-1508Y, SIB-1553A and epibatidine. These compounds have different degrees of selectivity for human recombinant NAChRs, different neurotransmitter release profiles in vitro and in vivo and differential behavioral profiles. Preclinical studies suggest that SIB-1508Y is a candidate for the treatment of the motor and cognitive deficits of Parkinson's disease, whereas SIB-1553A appears to have potential as a candidate for the treatment of Alzheimer's disease. Epibatidine has a strong analgesic profile, however the ratio between pharmacological activity and undesirable effects is so low that it is difficult to envisage the use of this compound therapeutically. Nicotine has a broad profile of pharmacological activity, for instance demonstrating activity in models for cognition and analgesia. As for epibatidine, the adverse effects of nicotine severely limits its therapeutic use in humans. The discovery of subtype-selective NAChR agonists such as SIB-1508Y and SIB-1553A provides a new class of neuropsychopharmacological agents with better therapeutic ratios than nonspecific agents such as nicotine.     

Single- versus multiple-dose antimicrobial prophylaxis for major surgery: a systematic review

BACKGROUND: Single-dose antimicrobial prophylaxis for major surgery is a widely accepted principle; recommendations have been based on laboratory studies and numerous clinical trials published in the last 25 years. In practice, single-dose prophylaxis has not been universally accepted and multiple-dose regimens are still used in some centres. Moreover, the principle has recently been challenged by the results of an Australian study of vascular surgery. The aim of this current systematic review is to determine the overall efficacy of single versus multiple-dose antimicrobial prophylaxis for major surgery and across surgical disciplines. METHODS: Relevant studies were identified in the medical literature using the MEDLINE database and other search strategies. Trials included in the review were prospective and randomized, had the same antimicrobial in each treatment arm and were published in English. Rates of postoperative surgical site infections (SSI) were extracted, 2 x 2 tables prepared and odds ratios (OR) [with 95% confidence intervals (95% CI)] calculated. Data were then combined using fixed and random effects models to provide an overall figure. In this context, a high value for the combined OR, with 95% CI > 1.0, indicates superiority of multiple-dose regimens and a low OR, with 95% CI < 1.0, suggests the opposite. A combined OR close to 1.0, with narrow 95% CI straddling 1.0, indicates no clear advantage of one regimen over another. Further subgroup analyses were also performed. RESULTS: Combined OR by both fixed (1.06, 95% CI, 0.89-1.25) and random effects (1.04, 95% CI, 0.86-1.25) models indicated no clear advantage of either single or multiple-dose regimens in preventing SSI. Likewise, subgroup analysis showed no statistically significant differences associated with type of antimicrobial used (beta-lactam vs other), blinded wound assessment, length of the multiple-dose arm (> 24 h vs 24 h or less) or type of surgery (obstetric and gynaecological vs other). CONCLUSIONS: Continued use of single-dose antimicrobial prophylaxis for major surgery is recommended. Further studies are required, especially in previously neglected surgical disciplines.     

Impaired interleukin-12 production is associated with a defective anti-tumor response in colorectal cancer

OBJECTIVE: Spontaneous spinal epidural hematoma (SSEH) is an idiopathic accumulation of blood in the vertebral epidural space without identifiable predisposing factors. First reported in 1869, the clinical outcome in children younger than 18 years old has not been clearly delineated. DESIGN: A comprehensive review of the English language literature revealed 26 patients younger than 18 years old with reported clinical outcomes. The 27th case is presented. RESULTS: Complete neurologic recovery occurred in 14 of 27 (52%) patients, partial recovery in 12 of 27 (44%) patients, and death in 1 of 27 (4%) patients. CONCLUSION: There is an overall good prognosis for neurologic recovery in children who experience SSEH.     

Pressure acid leaching of arid-region nickel laterite ore: Part I: effect of water quality

The effect of water salinity on the reactions occurring during pressure acid leaching of an arid-region laterite ore, using hypersaline water, seawater, sub-potable water and tap water, is examined. Particular emphasis is placed on the mineralogy of the residue and its implications with regard to residue volume/mass, overall acid consumption and nickel extraction. Analysis of a pressure acid leach residue by electron microprobe indicates that the residual nickel is present in phases that contain silicon and varying concentrations of aluminium, but are deficient in sulphur. Incomplete extraction of nickel from the ore may not be attributed to any one mineral phase.     

A multilevel model of the effects of equal opportunity climate on job satisfaction in the military.

To date, minimal work has explored associations between equal opportunity (EO) climate and employee work attitudes, and no known research has investigated the effects of EO climate beyond the individual level. We address these gaps in the literature by testing a multilevel structural equation model in which effects of EO climate are considered at both the individual and unit levels. At the individual level, we predicted that psychological EO climate would be directly associated with job stress and job satisfaction, as well as indirectly related to job satisfaction via stress. In addition, cross-level associations between unit EO climate and job stress and job satisfaction were hypothesized to be mediated by cohesion. Findings supported the proposed model; hypothesized relations were supported at both levels of analysis. We conclude with a discussion of the findings, study limitations, and directions for future EO climate research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)