Various microenvironmental cues determine monocyte fate which can

Various microenvironmental cues determine selleck chem Ruxolitinib monocyte fate which can lead to differentiation into macrophage and dendritic cells [10]. However monocytes are not simply macrophage and dendritic cell precursors but are also immune effector cells [11]. Under inflammatory conditions, circulating monocytes can be recruited to the site of infection or injury, and once there, differentiate. However under steady state conditions, local proliferation maintains resident macrophages Inhibitors,research,lifescience,medical in sites such as the lungs and liver. Macrophages (Ms) are central players in the development, progression, and resolution of inflammation [12]. They are polarized following activation into classic (or M1) and alternative (or M2) macrophages [13–15]. M1 macrophages

are activated in response to microbial products such as lipopolysaccharide (LPS) or cytokines like interferon-γ (IFN-γ) and tumour necrosis factor α (TNFα) and are characterized by a strong

propensity to present antigen. In a polarized response, M1 cells Inhibitors,research,lifescience,medical are thought to kill intracellular microorganisms and produce abundant proinflammatory cytokines such as TNF-α, interleukin (IL)-12, IL-23, and proinflammatory mediators like nitric oxide (NO) and reactive oxygen intermediates (ROI). On the other hand, M2 macrophages are promoted by various signals such as IL-4, IL-13, Inhibitors,research,lifescience,medical glucocorticoids, IL-10, immune complexes and some pathogen-associated molecular patterns (PAMPs) that elicit different M2 forms (M2a, b and c). They function in inflammation resolution and tissue remodelling. Pathogen Recognition Receptors (PRRs) have evolved to recognise conserved molecular-associated molecular patterns (PAMPS) from pathogens, such as lipopolysaccharide or bacterial Inhibitors,research,lifescience,medical DNA motifs. The Toll-like receptors (TLRs) are one such family whose ligands have generated much excitement over the last decade as immunostimulatory adjuvants Inhibitors,research,lifescience,medical in vaccine selleck chemical Trichostatin A development [16]. Engagement of TLRs by their cognate

ligands will activate antigen presenting cells, stimulate cytokine secretion that regulates the adaptive immune response, and promote up regulation of costimulatory molecules in order to improve antigen Dacomitinib presentation to T cells. Thus incorporation of TLR ligands or immunomodulatory moieties into liposomes has been a strategy for improving efficacy of both vaccine development and drug targeting [17]. For example, as TLR ligands have been shown to activate macrophages and dendritic cells and enhance antigen-specific T cell responses, then enhanced uptake of PAMP-coated liposomes into these cells would be expected. However, whilst TLR ligands and PAMPs in general can increase liposome uptake, their ability to stimulate and activate macrophages and enhance antigen-specific T cell activation and immune reactivity would suggest that their potential inflammatory properties may be an issue for general use in targeting strategies [18]. In this respect other target receptors such as the scavenger receptors and mannose receptors may prove more appropriate.

As a consequence of this pairing, the CS acquire the ability to e

As a consequence of this pairing, the CS acquire the inhibitor Brefeldin A ability to elicit a spectrum of behavioral,

autonomic, and endocrine responses that normally would only occur in the context of danger. Fear conditioning can be adaptive and enable efficient behavior in dangerous situations. The individual who can accurately predict threat can engage in the appropriate behaviors in the face of danger. However, in patients with anxiety disorders, specific environmental features (CS) may be linked to the traumatic Inhibitors,research,lifescience,medical event (US), such that reexposure to a similar environment produces a recurrence of symptoms of anxiety and fear. Patients with anxiety disorders often generalize these cues and experience a continuous perception of threat to the point that they become conditioned to context. A chronic state

of anxiety ensues. The neural circuitry that mediates fear-conditioning phenomena has been well worked out. Cue-specific CS are transmitted Inhibitors,research,lifescience,medical to the thalamus by external and visceral pathways. Afferents then reach the lateral amygdala via two parallel circuits. A rapid subcortical Inhibitors,research,lifescience,medical path directly from the dorsal (sensory) thalamus and a slower regulatory cortical pathway encompassing primary somatosensory cortices, the insula, and anterior cingulate/PFC. Contextual CS are projected to the lateral amygdala from the hippocampus and perhaps the BNST. The long loop pathway indicates that sensory information relayed to the amygdala undergoes substantial higher level processing, thereby enabling assignment of significance, based upon prior experience, to complex stimuli. A Inhibitors,research,lifescience,medical variety of behavioral and electrophysological data has led LeDoux and colleagues to propose a model to explain how neural

responses to the CS and US in the lateral amygdala could influence long-term potentiation (LPT)-like changes that store memories during fear conditioning. This model proposes that calcium entry through NMDA receptors and voltage-gated calcium channels (VGCCs) initiates the molecular processes to consolidate synaptic changes into long-term memory.116 Carfilzomib Inhibitors,research,lifescience,medical Short-term memory requires calcium entry only through NMDA receptors and not VGCCs. This hypothesis leads to several predictions that may have relevance to psychological responses to stress and vulnerability to anxiety disorders. It suggests that blocking NMDA receptors in the amygdala during learning should impair short- and long-term fear memory. This has been demonstrated in rodents.117-119 Valid human models of fear conditioning and the availability of the NMDA receptor antagonist, memantine, should permit this hypothesis to be tested clinically. If memantine impairs the acquisition of fear in humans, it may have utility in the prevention and treatment of anxiety disorders such as PTSD. Blockade of VGCCs appear to block long-term but not short-term memory.

The success of NIV was defined as the recovery from acute respira

The success of NIV was defined as the recovery from acute respiratory without endotracheal intubation among patients with full code (without limitation of therapy). Outcomes The primary outcome was to identify the incidence of use of NIV in patients with ARF and to identify the factors associated with the failure of the NIV among the same. The secondary outcome was to identify

the long term survival among the patients with ARF who were on palliative NIV. The survivors after the hospital discharge were followed till the end of 2010. The death date was identified from the EMR or death registration record Inhibitors,research,lifescience,medical of Minnesota, in case of out-of-hospital deaths. Statistical analysis All the continuous data was summarized as median

(interquartile range [IQR]). Categorical data was summarized as counts and percentages. Inhibitors,research,lifescience,medical Age and gender-specific incidence rate (95% confidence interval [CI]) for NIV use in the ICU was calculated assuming that the sellectchem entire selleck catalog population of Olmsted County (≥18years) was at risk. The incidence rate was adjusted to the projected 2006 United States population (utilizing the data from the 2000 U.S. population census and calculating an expected 1.9% population growth per year). Kaplan-Meier survival analysis with log-rank test was used to assess the long term survival among the ARF patients who were initiated Inhibitors,research,lifescience,medical on palliative NIV. A univariate and multivariate logistic regression analysis was used to identify the factors associated with failure

of NIV in full Inhibitors,research,lifescience,medical code patients. Significant variables on the univariate analysis (p < 0.2) were included in the multivariate logistic regression model. Stepwise forward and backward procedure was used to select variables included in the final analysis. Non-significant factors (p > 0.05) were eliminated (one at a time) Inhibitors,research,lifescience,medical until all remaining factors had a significant association with NIV failure. JMP statistical software (version 8.0, SAS, Cary, NC) was used Cilengitide for all the data analyses. The level of significance for all statistical tests was 2-sided, with P <0.05. Results In 2006, out of 1707 ICU admissions, a total of 1461 unique Olmsted County adult residents were identified. The study flowchart was shown in detail in Figure1. Three hundred and sixty four patients developed ARF and were ventilated in ICU, among which 146 (40%) were initiated on the NIV yielding a cumulative incidence of 180 episodes per 100,000 person-years (95% CI 154~206/100,000) (Figure1). The median age in years was 75 (IQR, 60–84), 48% were females and 88.7% were Caucasians. Eighteen patients (12%) were on CPAP mode and 128 (88%) were on NIPPV mode. Figure 1 Study outline of noninvasive mechanical ventilation use in the acute respiratory failure patients.

2003, 2009] A reason for this discrepancy might derive from the

2003, 2009]. A reason for this discrepancy might derive from the treatment cultures of the countries of study origin, i.e. Germany and Switzerland where negative attitudes were found and the United

Kingdom with positive attitudes of psychiatrists towards LAIs in the treatment of FEPs [Heres et al. 2011; Jaeger and Rossler, 2010; Patel et al. 2003, 2009]. The UK traditionally has a more assertive community mental health system available [Burns et al. 2001]. Nevertheless the UK studies reported 69% [Patel et al. 2003] and 52% [Patel et al. 2009] of clinicians believed that patients were less likely to accept depot than oral medication. Inhibitors,research,lifescience,medical There are only few hints that depots are really perceived as more selleck products coercive by patients [Patel et al. 2010], while other results indicate that acceptation rates of LAIs in FEPs are rather high [Weiden et al. 2009]. In summary, several studies found a strong Inhibitors,research,lifescience,medical emphasis by psychiatrists on patients’ assumed objection to depot antipsychotics while data on the actual attitude on depot antipsychotics

Inhibitors,research,lifescience,medical of FEP is scarce. There might be two main reasons for this presumption on the part of clinicians. First, owing to the long-established association of depot treatment as a coercive, stigmatizing therapy [Patel et al. 2003, 2009, 2010; Walburn et al. 2001], clinicians would be more sensitive in their approach to patients experiencing psychosis and receiving antipsychotic treatment for the first time. Second, former treatment guidelines and expert opinions suggested oral SGA drugs as first-line treatment [Emsley, 2009; Lehman et al. 2004]. Furthermore, until

now a clear statement towards the role of depot antipsychotics Inhibitors,research,lifescience,medical in FEPs is still missing [Barnes et al. 2009; Barnes, 2011]. Inhibitors,research,lifescience,medical Taking into account that in recent years many studies have focused on the clinical effectiveness of depot medications in FEPs [Emsley et al. 2008; Kim et al. 2008; Weiden et al. 2009], the lack of evidence about patient’s attitude towards LAIs is particularly worrisome. So why do the majority of psychiatrists presume that patients would dislike depot treatment instead of asking them what way of administration they would choose? One reason might be found in the therapeutic relationship that still might Cilengitide be distinguished by traditionally paternalistic self-conceptions of psychiatrists. This might lead to recommendations by the psychiatrist on the best possible treatment according to his or her beliefs instead of providing full information about actual treatment options to the patient and making a treatment decision conjointly. Until now psychiatrist-stated noncompliance and a history of multiple relapses have been used as patients’ attributes that would qualify them for depot treatment. This long-standing stereotype was confirmed in a cluster analysis by Heres and colleagues [Heres et al. 2008].

We imported the transcripts into NVivo qualitative data analysis

We imported the transcripts into NVivo qualitative data analysis software (version 8) to facilitate coding. A preliminary set of three categories (e.g. access to end-of-life care, community partnerships, and education and training) was extracted from lead author’s field notes and used to provide an initial framework for the analysis. Two of us (RM & LBD) independently coded the data by drawing on constant comparison methods, wherein preliminary categories were revised and emerging categories were identified and expanded Inhibitors,research,lifescience,medical through constant comparison to the data [42,43]. We regularly met to discuss

emerging categories, with any revisions to the coding framework made by consensus. Inhibitors,research,lifescience,medical All authors discussed emerging themes to aid in framing the findings in relation to existing literature. Once the final categories were established, one of us (RM) re-coded sections of the data to ensure the credibility of these categories. Ethics This study was approved by the research ethics committees at the University of British Columbia and Saint Paul University. Informed consent was obtained prior to interviews and

participants retained a duplicate copy of the informed consent protocol. Results Participants identified key barriers to end-of-life Inhibitors,research,lifescience,medical care services for homeless persons and recommendations for improving the end-of-life care system for this population. Five themes are organized

into two domains: first, barriers to end-of-life care services; and, second, recommendations to improve the end-of-life care system. Barriers to and recommendations for improving the Inhibitors,research,lifescience,medical end-of-life care system were consistent across the cities included in this study, although the availability of low threshold services in two cities (Ottawa and Toronto) was perceived to minimize some barriers to care. Where participants are quoted directly, they are identified by profession to provide insight into the type of support they provide. Organizations named by participants have been replaced with generic descriptions Cilengitide Inhibitors,research,lifescience,medical to preserve their anonymity. Perceived barriers to the end-of-life care system Availability of end-of-life services and supports Participants noted that, although end-of-life care services struggled to meet local demand, what services were available were generally inaccessible to homeless populations. Participants noted that homeless populations were unable to access end-of-life care services as a result of a lack of caregiver support and/or financial resources. Participants reported that end-of-life care services in their communities assumed that clients were stably housed and supported by caregivers or had the financial resources to pay for care (e.g. assisted living facilities). As a consequence, they felt that their clients were unable to access these services.

19,36 For instance, the brain has a higher metabolism level

19,36 For instance, the brain has a higher metabolism level than the rest of the body and utilizes

a large proportion of consumed oxygen, hence increasing the potential for producing reactive oxygen species and subsequent oxidative stress. Oxidative stress mediates specific neuronal damage, including modifications to lipids, protein, and DNA, resulting in inflammation, Inhibitors,research,lifescience,medical an increase in reactive astrocytes, and altered Ca2+- and mitochondria-mediated neuronal functions, which together may contribute to the deterioration of mental capacities with age.37,38 Further, with rare exceptions, neurons do not divide,39 and thus cellular damage tends to accumulate with increasing age. This is paralleled by a decrease in the capacity for cellular repair.36 Structurally, studies reveal a decrease in neuron volumes, a small loss or no change in cell numbers,40,41 and a progressive thinning of cortical thickness, Inhibitors,research,lifescience,medical affecting

both gray and white matter.42,43 Functionally, studies Inhibitors,research,lifescience,medical indicate a continuous decline with age in certain aspects of cognitive functions (speed of processing, working memory, and long-term memory) beginning in the 20s.44 In contrast, verbal knowledge selleck chemical increases throughout the lifetime.32 This latter observation highlights the point that, while studies often demonstrate a negative conceptual bias towards aging, age-related nearly changes can also be positive, and may represent Inhibitors,research,lifescience,medical the recruitment of protective mechanisms against known deleterious effects of aging (ie, oxidative stress) or uncharacterized and beneficial late Inhibitors,research,lifescience,medical brain-maturation processes. Based on the above observations, and supported by developments in gene array technology, our group7,8 and others45-48 have investigated the presence of age-dependent gene expression changes in the human brain, as molecular correlates of affected cellular functions. “Molecular aging” of the human brain

It has been known for some time that robust changes in gene expression occur with aging in peripheral tissues.49 The fact that age-related changes in gene expression extend to the brain may not be surprising, given the body of knowledge about changes in structure and function of the Brefeldin_A brain with age (described briefly above). Indeed, one might hypothesize that age-related changes in gene expression reflect a general deterioration of the brain and that a preponderance of genes would be affected. This, however, does not appear to be the case. Recent genome-wide studies demonstrate that a relatively small number of genes exhibit age-dependent gene expression changes.

This is in stark contrast to the male, who can produce upwards of

This is in stark contrast to the male, who can produce upwards of 100 million sperm a day. Changes in Sexual Function in the Aging Male Studies have consistently shown that increasing male age is associated with an increased time to pregnancy and scientific assays Decreased pregnancy rates. However, only a few studies have examined these outcomes while adjusting for female

Inhibitors,research,lifescience,medical age. Ford and colleagues performed a secondary data analysis of the Avon Longitudinal Study of Pregnancy and Childhood, a large population-based study in the United Kingdom. Surveys from 8559 pregnancies were used to determine the effect of age on time to pregnancy. After adjusting for female age, conception during a 12-month period was 30% less likely for men over age 40 years as compared with men younger than age 30 years.9 In addition to female age, coital frequency and sexual Inhibitors,research,lifescience,medical functioning are variables that affect time to conception and pregnancy rates. Decreased sexual activity can decrease the chances of conception,10 and erectile dysfunction Inhibitors,research,lifescience,medical (ED) increases with age.11 Decreased coital frequency with age is due in part to diminished sexual functioning; however, sexual dysfunction itself has no known influence on germ cells and its impact on infertility

can be overcome by measures of assisted reproductive technology.12 In a study of 1290 men aged 40 to 70 years who enrolled in the Massachusetts Male Aging Study (MMAS), sexual functioning and coital frequency were assessed. Between ages 40 and 70, the probability of having severe ED increased threefold and the probability of moderate ED increased twofold.13 In the same

cohort followed for an average of 9 years, coital frequency was assessed in 1085 men. After adjusting for JAK1/2 inhibito baseline sexual Inhibitors,research,lifescience,medical Inhibitors,research,lifescience,medical function, men engaged in sexual activity an average of 6.5 times per month prior to age 40. This frequency decreased by one to two times per month after age 50 and by another one to two times per month after age 60.14 In a survey study of 1976 British women controlled for female age, coital frequency, social history, and weight, an even stronger age effect on pregnancy rate was found than in the study by Ford and colleagues. This study reported a five times greater increase Dacomitinib in time to pregnancy in men aged 45 years and older compared with men aged < 25 years. The increased time to pregnancy was similar even when restricting the analysis to men whose female partners were aged < 25 years.15 To evaluate pregnancy rates in different age groups, a French study examined 901 cycles of intrauterine artificial insemination. They found that the most significant factor contributing to probability of pregnancy was the age of the male partner. After six cycles, men aged ≥ 35 years had fertility rates of 25% compared with fertility rates of 52% in men aged < 35 years, representing a 52% decrease in fertility rate.

Overall, although all studies agree that significant miRNA expres

Overall, although all studies agree that significant miRNA expression changes purchase Everolimus occur in HF, the fine details thereof remain unclear and, in some cases, even contradictory. These discrepancies may reflect the existence of distinct miRNA signatures in the failing hearts of different etiologies, or to different stages of disease progression. More recently, next generation sequencing has also been used for the analysis of human failing left ventricles of HCM or DCM etiology, and demonstrated significant changes in more than 250 of the 800 known human miRNAs, 33 with approximately twice as many annotated miRNAs expressed in HF than unaffected cardiac tissue. Amongst the ten most abundant

miRNAs in the HF samples that have been previously described in CVD studies, four have been shown to promote (miR-23a) or inhibit cardiac hypertrophy (miR-1 71–76 ), or negatively regulate fibrosis (miR-24, 82 -133a 83 ). Importantly, amongst the top ten overexpressed miRNAs that have not been described

in previous profiling studies in HF (miR-23b,-30d, -125a, -143, -145,-193, -197, -342, -365, -455), miR-145 emerges as an important new player in cardiovascular disease, and in left ventricle pathological remodeling, in specific. 33 With regards to the precise miRNA mechanisms impaired in HF, Thum et al demonstrated that 87% of the over-expressed miRNAs and 84% of the under-expressed miRNAs were similar to the miRNA expression profiles of fetal cardiac tissue (e.g. miR-21, -29, -30, -129, -212), suggesting the activation of the “fetal gene expression program”. 79 The reactivation of the “fetal gene expression program” is a hallmark of the hypertrophic and failing myocardium, often accompanying pathological

left ventricular remodeling. In order to prove this concept, Thum et al showed that simultaneous re-expression of three of the miRNAs overexpressed in both HF and fetal tissue (miR-21, -129, -212) resulted in activation of fetal gene program and HF-related changes, like hypertrophy, in neonatal and adult CMCs. In specific, the miRNA-regulated fetal genes included ANP, BNP, β-MHC, α-skeletal actin and MEF2a, amongst others. 79 This study shed light to significant aspects of the reactivation of the cardiac fetal gene program Carfilzomib during HF, and revealed possible molecular players of left ventricular pathological remodeling. MiR-21, miR-29 and miR-30 are some of the miRNAs whose HF expression parallels this of fetal hearts, and have been studied extensively in the context of HF. miR-21 appears upregulated in cardiac fibroblasts of DCM-related HF, likely following activation of the STAT3 and NfkB transcription regulators. 84–85 This is consistent with the emerging topic of miRNA participation in a feedback loop with TFs that regulate their transcription.

To determine if there is a network of structures for which neural

To determine if there is a network of structures for which neural activity correlates with the intensity of WIC we conducted a correlation analysis to identify areas where the strength of rsFC (abstinent condition vs. satiated condition) correlated with the strength of WIC (craving score for

the abstinent condition minus that for the Inhibitors,research,lifescience,medical satiated condition). Statistical analysis Statistical analyses were done using SPM8, with threshold levels for significant differences set at P < 0.001, uncorrected at a voxel level, and P < 0.05, uncorrected for multiple comparisons at a cluster level. Results Table ​Table11 lists demographics and measures of nicotine dependence for smokers and nonsmokers. There was no significant age difference between smokers and nonsmokers. A comparison of rsFC between the first and second imaging sessions for the nonsmokers revealed no significant differences, Inhibitors,research,lifescience,medical indicating the stability of measurement and an absence of any order effects (Table ​(Table22A). Table 1 Demographics and measures of nicotine dependence Table 2 Summary of results showing peak clusters After excluding components of noise and motion, 13 components were identified from ICA output corresponding to the following networks: cerebellum-hippocampal-precuneus, inferior frontal gyrus-mid temporal, posterior DMN, motor, visual

(two), right executive, anterior DMN, supplementary motor, auditory, left executive, parietal, and salience Inhibitors,research,lifescience,medical network. The DMN, comprising the anterior and posterior DMN (Fig. ​(Fig.1A)1A) was further examined for group comparisons. Compared to nonsmokers, a two-sample t test showed enhanced connectivity in the DMN of smokers in the abstinent condition to areas of ACC, caudate, putamen, middle frontal area, precentral gyrus, and the medial frontal gyrus (Fig. ​(Fig.1B).1B). Inhibitors,research,lifescience,medical When compared to the Inhibitors,research,lifescience,medical satiated condition, DMN of smokers in the abstinent

condition had enhanced connectivity to areas of the ACC, precuneus, medial orbital frontal area, insula, superior medial frontal area, middle temporal gyrus, and superior frontal area (Fig. ​(Fig.11C). Figure 1 Results from ZD6474 independent component analysis (ICA), particularly in the default mode network (DMN). (A) Components that formed the DMN, including the posterior DMN and the anterior DMN. (B) Difference selleck chem Ponatinib within the DMN between nonsmokers and smokers during … Smokers in the abstinent state showed stronger ACC-seeded rsFC than nonsmoking controls in the precuneus, caudate, putamen, Dacomitinib frontal cortex, temporal cortex, and inferior parietal lobe (P < 0.05, Table ​Table2B,2B, and Fig. ​Fig.2).2). The comparison of smokers in the satiated and abstinent conditions revealed that withdrawal from nicotine for 11 h was associated with increased rsFC between the ACC and the precuneus, insula, orbital frontal gyrus, superior frontal gyrus, posterior cingulate cortex, superior temporal lobe, and the inferior temporal lobe (P < 0.02, Table ​Table2C,2C, Fig. ​Fig.3).


Ultrasonic sensors were originally designed to measure distances in industrial environments, where objects are rigid, and the reflection surface is perpendicular to the direction of the ultrasonic wave; therefore, some authors question their usefulness in orchards [6]. Despite these shortcomings, ultrasound sensors are currently being used for the characterization of plant mass and provide good results in certain scenarios. The main advantages of ultrasonic sensors are their robustness and low price. Contrary to the expensive radar system, Gil et al. [7] suggested the use of ultrasonic sensors and proportional electro-valves with the corresponding software and automation, which allowed real time modification of the sprayed flow rate adapted to the crop structure of the vineyard.McConnell et al. [8] estimated canopy volume by using several ultrasonic sensors mounted on a vertical mast or on a sprayer things driven by a tractor, but the application technologies did not allow this information to be used in real time. Gil et al. [7] evaluated a modified orchard air-blast sprayer equipped with three ultrasonic transducers and concluded that savings in pesticide application when using the electronic control system were strongly related to target crop architecture. The same authors found that sprayer control based on target measurement resulted in substantial increases in savings on applied spray liquid.Molt�� et al. [9] also applied three ultrasonic sensors for the detection and ranging of geometric information from citrus fruit tree canopies; this enables the application of pesticides in fruit orchards by three different flow rates according to a canopy width estimation made with an ultrasonic sensor. In response to changes in the shape and size of the vines during the growing season Gil et al. [7] reported a reduction in spray volume and use of pesticides by up to 57%, while coverage and penetration rates were similar to those from conventional spraying methods. Llorens et al. [10] achieved a 58% saving in application volume with the variable rate method, obtaining similar or even better leaf deposits in comparison to the control with an air-blast orchard sprayer. Tumbo et al. [11] used ultrasonic sensors to estimate the most relevant geometrical parameters of trees and tree crops i.e., height, width, volume and leaf area and compared these with manual measurements. In [12] the variability in distance estimations in an apple orchard proved to cause interference by sensors whenever these were mounted too close each other; thus it was suggested that sensors be separated more than 60 cm apart in order to avoid high interference effects. In [13] the effect of foliage density and tractor speed on ultrasound measurements was investigated. The software developed to create maps of volume in real time showed the influence of row spacing and age on the accuracy of tree volume measurements.