Qualitative research can provide a unique insight into individual

Qualitative research can provide a unique insight into individual’s perspective and attitudes towards physical activity that cannot be elicited through quantitative methods. Frequently reported reasons to be physically active in the general elderly

population are: health concerns, socialisation, facilities, physician encouragement and purposeful activity. Frequently reported reasons to be sedentary are: lack of time, fear of injury, tiredness, lack of discipline, inadequate motivation, boredom, intimidation (afraid to slow others down), poor health, the physical environment, and lack of knowledge and understanding of the relationship between physical activity and health (Costello et al 2011, Reichert et al 2007, Schutzer Ku-0059436 nmr and Graves 2004). However, to be able to increase the physical activity level in people with COPD particularly, we believe it is necessary to identify COPD-specific reasons to be physically active or sedentary. In the pulmonary rehabilitation setting, some qualitative studies have been performed concerning physical activity maintenance. For example, Hogg et al (2012) identified social support from peers and professionals and confidence as important reasons influencing maintenance after pulmonary

rehabilitation. As pulmonary rehabilitation is not accessible for all people with COPD, it would be interesting to also investigate AUY-922 the reasons relevant to physical activity in daily life. Williams et al (2007) found that social integration, independence, and enjoyment were related to walking and other Libraries functional physical activities in daily life, but the sample size of this study was small. Furthermore, enough it would be interesting to investigate whether these personal reasons relate to

the individual’s physical activity level. If barriers are identified that are amenable to change, then this might provide useful information about how physical activity participation could be enhanced in people with COPD. The research questions addressed in this study were: 1. Among people with COPD, what reasons are perceived as influencing whether they are physically active or sedentary? This observational study combined a qualitative and quantitative approach. People with mild to very severe COPD were invited to participate in this study via a letter from their general practitioner or respiratory physician at outpatient clinics of general hospitals in the northern part of The Netherlands. This study was part of a larger study on physical activity in people with COPD. Participants were enrolled in this cross-sectional study between February 2009 and February 2012 if they had COPD according to the GOLD criteria (Vestbo et al 2012). Comorbidities were allowed, but people were excluded if they had serious active disease that needed medical treatment (eg, recent myocardial infarct, carcinoma), or if they were treated for an exacerbation of their COPD during the previous two months.

Selection of the Chair is based on expertise and knowledge in the

Selection of the Chair is based on expertise and knowledge in the field of immunization

practices, public health, and use of vaccines and prophylaxis agents for the prevention of vaccine-preventable diseases. A Vice-Chair selected from existing membership is also appointed for a four-year term. The Vice-Chair becomes the NACI Chair when the Chair’s term is complete. The Director of the Immunization and Respiratory Infectious Disease Division designates an Executive Secretary who provides leadership and strategic advice for the Committee and works selleck chemicals llc closely with the Chair and the NACI Secretariat (currently comprised of two project managers/assistants and one nurse epidemiologist). Secretariat functions to NACI are provided for or funded by the federal public health agency. Liaison members of NACI are representatives from groups identified by the Chief Public Health Officer to provide expertise on vaccine safety and effectiveness, and/or provide input to ensure appropriate interpretation of NACI’s advice, and/or have access to relevant research on specific issues. Liaison members are selected by their organizations, and are expected to bring knowledge and input into the NACI discussions, express the

views of the organization, and communicate NACI’s advice to the organization as permitted. Ex officio representatives selleck kinase inhibitor on NACI are assigned by the Director General of the Centre for Immunization & Respiratory Infectious Diseases of the Public Health inhibitors Agency of Canada. The role of the ex officio members is to support the work of NACI and the agency by providing additional knowledge and expertise, communicating the views of the Department/Agency/Division they represent (e.g. First Nations and Inuit Health Branch), and communicating NACI’s advice as permitted by the PHAC. Vaccine industry representatives cannot be members of NACI, and do not participate in group discussions. Industry experts do provide information about vaccines to the Committee, and may be invited to make presentations to the full committee

or its working groups. NACI is not funded in any way by the vaccine industry. NACI Working Groups are established to address specific vaccine and immunization issues. These groups review evidence and draft Rolziracetam Advisory Committee Statements on specific vaccines, including options for vaccine recommendations for the full committee to consider. Working groups may prepare guidance in response to specific inquiries or other issues as they arise, and are also asked to contribute to and revise relevant chapters of the Canadian Immunization Guide. Working Groups are comprised of voting and liaison members, PHAC staff and external experts as necessary. Working group chairs are members of NACI or others who are appointed as deemed appropriate by the Committee Chair.

2 The study was designed and performed in accordance with the pr

The study was designed and performed in accordance with the principles of the Declaration of Helsinki and with Good Clinical Practice Selleck SCR7 Guidelines

established by the International Conference on Harmonization. The study was approved by the Committee for the protection of persons in France (St. Germain en Laye) and discussed at Chad’s National Vaccination Technical Committee before approval by the Ministry of Health in Chad. The head of each participating village provided permission for their village to participate and written informed consent was obtained before enrollment from all participants. All participation was voluntary and no identifying information encoded. The trial was registered at clinicaltrials.org with registry number NCT01559597. A total of 2128 participants residing in 42 villages grouped in 34 clusters

were enrolled in this study (1068 in CTC; 1060 in SCC) (Fig. 1). A total of 952 participants completed the study in each group. The primary ITV analysis included 1830 participants with pre- and post-vaccination antibody level results (913 in CTC; 917 in SCC). The PP population (n = 1563) Modulators includes all participants who received VE 822 2 TT doses 21 to 42 days apart according to the allocated strategy, had blood sampling 21 to 42 days post TT2 and had pre- and post-vaccination serological results. The reasons for exclusion from the PP analysis were an incorrect interval between TT doses and/or blood sampling (n = 240) and receiving TT doses kept in different strategies (n = 27). Baseline

demographics were similar in both arms ( Table 2). Administered CTC vaccines were exposed to temperatures between 21.4 and 38.3 °C (25 ≤ 30 °C during 71.4% of time and ≥30 °C for 20%) for 5 to 27 days with a median of 16 and 14 days for first and second dose (Table 3). Cold chain vaccines were kept between 1.5 and 11.2 °C (<2 or >8 °C for 0.2% of the time). At the time of use, all VVMs indicated that vaccine could be used. At baseline, 272 participants (14.9%), had anti-tetanus IgG levels of <0.16 IU/ml (142 in CTC; 130 in SCC). Among susceptible participants, 95.77% (95%CI = 91.09–98.05) in CTC and 96.15% (95%CI = 91.31–98.35) in SCC had protective antibody levels following two doses of TT (Table mafosfamide 4). The upper limit of the 95%CI for the difference in seroconversion was 5.6 in the ITV analysis and 4.4 in the PP analysis. If a protection cutoff of 0.20 IU/ml is used, there were 512 susceptible participants at baseline (259 in CTC; 253 in SCC); the difference in seroconversion was 1.48 (95%CI = −2.8 to 5.7). Following vaccination, overall seroprotection was equal in both groups: 99.34% in the CTC and 99.45% in the SCC groups (Table 4). Pre-vaccination GMC was 0.35 IU/ml in both groups (p = 0.82). After vaccination, GMCs were 1.47 IU/ml (95%CI = 1.40–1.54) in the CTC group and 1.55 IU/ml (95%CI = 1.48–1.62) in the SCC. Inverse cumulative distribution curves of GMCs pre and post-vaccination by group are presented in Fig.

The numbers of entries into the open and

closed arms were

An entry was defined as having all four paws within the arms. 7 Data obtained from the experiment was expressed as Mean ± S.E.M. Mice were treated with A. paeoniifolius (100, 150 & 200 mg/kg; oral), diazepam (0.5 mg/kg; IP), vehicle based on respective group. After 30 min, they were placed individually in one of the corner squares. The number of rearings (two paws touching the walls of the apparatus) and the PI3K inhibitor number of squares crossed were counted for 5 min. 8 Data obtained from the experiment was expressed as Mean ± S.E.M. The mice were placed individually in the centre of the light box and observed for the next 5 min for time spent in the light and dark boxes. The mice were treated with A. paeoniifolius (100, 150 & 200 mg/kg; oral), diazepam (0.5 mg/kg, IP), and vehicle based on their respective group 30 min

before being placed in the light box. 9 Data obtained from the experiment was expressed as Mean ± S.E.M. The petroleum ether extracts of A. paeoniifolius was found to be non-toxic up to 1.5 g/kg. Hence 1/15th, 1/10th & 1/7.5th of the toxic dose 10 that is, 100 mg/kg, 150 mg/kg, 200 mg/kg were used for Libraries further studies. A. paeoniifolius showed a significant increase in the number of entries into the open arm of elevated plus maze at a dose dependent manner. At 100 mg/kg the number of entries into the open arm was not significantly higher than control animals. However at 150 mg/kg the MK1775 number of entries was significantly higher (p < 0.05 n = 6) than the control group. This significance increased further at 200 mg/kg (p < 0.01 n = 6). However diazepam was found to be a more potent anxiolytic (p < 0.001 n = 6) than A. paeoniifolius

as shown in Fig. 1A. A. paeoniifolius also significantly increased the time spent in open arm of elevated plus maze at the maximal dose of 200 mg/kg (p < 0.05 n = 6) and this response was comparable with the effects of diazepam (p < 0.05 n = 6). There was a subsequent decrease in the number of entries in closed arm and decreased time spent in closed arm after application of test drug and diazepam Fig. 1B. Hence we can conclude that A. paeoniifolius showed anxiolytic activity in mice using the elevated plus maze model. A. paeoniifolius showed significant increase in the number of squares crossed in open field PD184352 (CI-1040) model in a dose dependent manner. At 100 mg/kg the number of squares crossed was not significantly higher than control group. However at 150 mg/kg and 200 mg/kg the number of squares crossed was significantly higher (p < 0.05 n = 6) than control. Diazepam a potent anxiolytic showed a similar effect as A. paeoniifolius in open field test model (p < 0.05 n = 6) as shown in Fig. 2A. A. paeoniifolius also significantly increased the number of rearing in open field apparatus at doses 150 mg/kg & 200 mg/kg (p < 0.05 n = 6). Diazepam also showed marked increase the number of rearing (p < 0.001 n = 6) Fig. 2B.

As seen in Trial #1, the vaccine improved the clinical symptoms o

As seen in Trial #1, the vaccine improved the clinical symptoms of CVL dogs, whereas untreated dogs did not show improvement (Fig. 2). It is intriguing that the effectiveness of the vaccine depended on disease severity at the time of inclusion in the study. Severely sick dogs did not respond to the vaccine either clinically or immunologically (Fig. 2 and Fig. 3). The immunological hypo-responsiveness of the dogs may be due to an antigen-specific immunosuppressive status in severe CVL. It is accepted for dogs as well as for other mammalian hosts that a Th1 response is responsible for protection [34]. Production of Th1 cytokines such as IFN-γ, TNF, and IL-2 is associated

PI3K inhibitor with protection against CVL [35] and [36]. For this reason we stimulated whole blood from the Study #2 dogs with inhibitors antigen and attempted to measure IFN-γ production by ELISA. Unfortunately, the assay failed, and we were unable to detect IFN-γ production

with even con A stimulation on many samples. This was likely a technical issue because in a previous study the vaccine induced cell-mediated immune responses in dogs [26]. The disease severity-related hypo-responsiveness of these dogs to the vaccine may be related to an IL-10 down-regulation of the Th1 response. Because IL-10 levels increase in the spleen as CVL progresses [37], some dogs with advanced disease may be rendered less responsive to such an extent that the immune system http://www.selleckchem.com/products/PF-2341066.html is refractory to the Leish-111f + MPL-SE vaccine. Other strategies, such as giving a vaccine along with anti-IL-10 antibody, should be considered for immunotherapy of dogs with too advanced CVL. The use of adjuvant alone also improved clinical outcomes in Study #2, and the efficacy was comparable to the vaccine (Fig. 2). Unlike with the Vaccine group, the single Adjuvant dog with a Day 0 CS ≥8 (whose CS changed by −2 vs. 0

for Vaccine) showed clinical improvement (Fig. 2) even though this dog exhibited no increased antibody titer to any of the antigens tested (Fig. 3A and data not shown). The clinical improvements observed in the Adjuvant group might be due to the immunostimulatory activity of MPL as a TLR4 ligand that directly activates cells within innate immune response pathways and, in conjunction with antigens present due to the existing parasite burden, may stimulate an effective anti-parasite, adaptive immune response. Such responses have previously been observed in immunotherapy settings; for example, in some cases the TLR ligands CpG oligonucleotides and imiquimod do not require exogenous antigens to improve clinical outcomes of leishmaniasis or to reduce parasite burdens [38], [39] and [40]. Similar results have been obtained in our human clinical trials of the Leish-111f + MPL-SE vaccine: Injection of adjuvant without antigen accelerated the cure of CL by chemotherapy (Piazza F et al.

, 1995), demonstrated that

, 1995), demonstrated that Selleck SCH-900776 NRP1-positive axons emerged from the RGC layer (Figure S1 available online). We conclude that NRP1, but not NRP2, is expressed in the developing mouse visual system at the correct time and in the right place to play a role in RGC axon growth. To determine if NRP1 is essential for RGC pathfinding at the optic chiasm, we studied

mice carrying a Nrp1 null mutation on a mixed CD1/JF1 genetic background, which ameliorates the severe cardiovascular defects seen in mutants on the C57 BL/6J background and enables embryo survival until E14.5 ( Schwarz et al., 2004). We performed anterograde DiI labeling of RGC axons from one eye at E14.0, when axons have just entered the optic tracts, and at E14.5, when both contralateral and ipsilateral tracts are established ( Figure S2A). Wholemount views of the chiasm revealed striking and consistent differences in RGC organization between homozygous mutants and their wild-type littermates ( Figures 2A and 2B; n = 10 each). First, all mutants showed defasciculation of both the ipsilateral and contralateral optic tracts, with axons being organized into two discrete bundles. Consequently, the normal asymmetry in the width of the contralateral and ipsilateral tracts was lost

in the mutants. Second, the proportion Dolutegravir mouse of axons projecting ipsilaterally appeared increased in the mutants. Sections through the DiI-labeled brains showed that the optic tracts were thinner in mutants than in wild-types, due to their defasciculation (Figure 2C). However, the path taken by the mutant axons appeared normal, both at the level of the optic chiasm (Figure 2C, top panels) and at the site where the optic tracts began to diverge (Figure 2C, bottom panels). Thus, axons did not stray from the pial surface or project aberrantly at the midline, as seen in mutants lacking SLITs (Plump et al., 2002). Gross disturbances in axon guidance at the midline are therefore not the likely cause of the increased ipsilateral projection in Nrp1 null

mutants. Owing to the lethality of Nrp1 null mutants at E15.5, we could not quantify the number and distribution of ipsilaterally projecting RGCs by conventional retrograde DiI labeling from the optic tract to until the retina; this method only works reliably from E15.5 onward, when many axons have reached the dorsal thalamus ( Godement et al., 1987 and Manuel et al., 2008). We therefore analyzed Nrp1 null mice at E14.5, the latest time point at which mutants were perfectly viable, using a semiquantitative method that measures the relative fluorescence in the ipsilateral optic tract and compares it to the sum of fluorescence intensity in both optic tracts ( Figure 2D; adapted from Herrera et al., 2003). This so-called ipsilateral index was increased 5-fold in mutants compared to wild-type littermates (wild-types: 0.08 ± 0.02; mutants: 0.38 ± 0.06; n = 10 each; p < 0.001; Figure 2D).

Further, these regions respond during mental imagery of big and s

Further, these regions respond during mental imagery of big and small objects, which is a characteristic property of other nearby category-selective regions. Finally,

we find that these regions reflect information about the category of the object rather than how big the object was conceived. Broadly, these results show that real-world size R428 supplier is a large-scale dimension that differentiates distributed object representations in occipitotemporal cortex. We propose a potential account of this organization, in which the size of objects in the world naturally give rise to systematic biases in visual experience which are extracted in early visual areas and ultimately dictate where high-level object representations will be in anterior occipitotemporal cortex. In Experiment 1a, observers were presented with images selleck chemical of isolated big objects (e.g., car, piano) and isolated small objects (e.g., strawberry, safety pin), presented at the same retinal size on the screen (Figure 1A; for all stimuli see Figure S1 available online; see Experimental Procedures). The experiment consisted of one run of 8.8 min

of scanning, during which 200 distinct big objects and 200 distinct small objects were presented in a standard blocked design (see Experimental Procedures). To compare the neural response of big and small objects, we conducted a size-preference map analysis and a whole-brain contrast analysis. In the first analysis, we visualized the spatial distribution

of small and big object preferences across occipitotemporal cortex. Size-preference maps were computed reflecting whether the voxels had a preference for big objects (blue) or small objects (orange) within an object-responsive mask (see Experimental Procedures), and these are shown on an inflated cortical surface in Figure 1. We observed a striking large-scale organization along the ventral surface, evident at the group level and at the single-subject level, with big and small object preferences arranged in a medial to lateral organization across both hemispheres. Further, also this organization was mirrored along the lateral surface of the cortex, with small to big object preferences arranged from inferior to superior (Figures 1B and 1C). Importantly, these data should not be interpreted as evidence that big and small objects are represented in separate swaths of cortex. Both big and small objects activate most of this object-responsive cortex to varying degrees, illustrated in Figures 2, consistent with accounts of distributed activation profiles of these objects (e.g., Haxby et al., 2001). However, voxels with a big-object preference are consistently found along medial ventral temporal cortex, while voxels with a small-object preference were consistently found along lateral temporal cortex (Figures 2C and 2D).

There were three main sub-themes that were

brought up by

There were three main sub-themes that were

brought up by participants around CM pertaining to the relative importance of effectiveness of CM as an intervention. These were as follows (see Table 2.4 for examples): 1. A pragmatic approach that linked in with the discussions around having CM as part of a ‘tool kit’ of interventions. This could be summarised as ‘if it works, use it.’ This stance was primarily taken by the more experienced clinicians. The aims of this study were to explore systematically the attitudes, concerns and opinions Tyrosine Kinase Inhibitor Library supplier of staff and service users about the use of CM in publicly funded substance misuse services and to identify the key areas that may be influential in terms of implementation and outcome. Below we summarise the findings and examine specifically what this study adds to the literature in terms of: 1. How CM may fit within the context of substance misuse programmes.

The causes of addictions are well recognised to be a complex interaction of biological, social and psychological factors and from a health perspective can be considered within a chronic disease model (McLellan et al., 2000), requiring a collaborative approach between professional and patient if long-term, sustained positive outcomes are to be achieved. Many substance misuse services in developed countries work within a multi-disciplinary, community treatment model. Consequently, the way that new interventions Selleck DAPT are viewed by clinicians (in their role as individual citizen as well as practitioner), and the collective philosophy of a treatment service will have a substantial impact on the effectiveness and cost-effectiveness of their implementation and uptake (Benishek et al., 2010, Cameron and Ritter, 2007, Kirby et al., 2006 and McGovern et al., 2004). This study highlighted the issues most consistently discussed about the use of CM by service users (both current and past) and health professionals. The 15 different themes are concerns that will need to be considered Bay 11-7085 in any evaluation of effectiveness of CM implementation

within different clinical settings, and across different health care systems. Whilst the evidence base from randomised controlled trials (RCTs) for the role of CM in substance misuse programmes is compelling (Dutra et al., 2008, NIHCE, 2007 and Pilling et al., 2007) the uptake into clinical practice has been less good (Kirby et al., 2006 and Petry, 2006). The results of this study suggest that the overall aims of a treatment programme (e.g., whether the aim is for harm minimisation or abstinence) may be a significant factor in how a single intervention is viewed and the likelihood of its implementation. The methodology of an RCT, even of a complex intervention, specifically attempts to insulate the intervention under examination, from such contextual factors.

, 2008; B N L , unpublished data) We favor the idea that multipl

, 2008; B.N.L., unpublished data). We favor the idea that multiple,

redundant kinases perform SAD ALT phosphorylation in DRG neurons, but their ability to access the SAD ALT is dependent upon SAD CTD dephosphorylation. In this scenario, ALT phosphorylation is regulated not by limited availability of an ALT kinase but by CTD-dependent accessibility of the ALT site. In addition to regulating the activation state of SAD kinases, phosphorylation of the CTD may also play a role in stabilizing the protein: removing the 18 sites of CTD phosphorylation around the D box consistently decreased protein levels in cell lines and in neurons (Figure 6 and data not shown). Phosphorylation of the SAD CTD around the D box could stabilize the protein by inhibiting interaction with the APC/C, a mechanism similar to that learn more described for the control of securin ubiqutination during anaphase (Holt et al., 2008). Dephosphorylation of the CTD in response to NT-3 could then result in targeting

of SADs for degradation, thus extinguishing signals Compound C cost from SADs in the activated, dephospho-CTD form (Figure 8G). In the telencephalon, LKB1 and SADs control early axon-dendrite polarization and axon formation (Kishi et al., 2005, Barnes et al., 2007 and Shelly et al., 2007). Here, we have shown that SADs affect axonal arborization in some sensory neurons. Initial studies of the C. elegans SAD ortholog, SAD-1, demonstrated a role for this kinase in presynaptic differentiation ( Crump et al., 2001), and we found recently that SADs are required for maturation of multiple synaptic types in mouse central and peripheral nervous systems (B.N.L. STK38 and J.R.S., unpublished data). Finally, Inoue et al. (2006) have reported that SADs modulate presynaptic function in adults. Together, these

studies establish SAD kinases as essential regulators of multiple phases of axonal development and function. A major outstanding question is how SAD kinases activate programs that influence multiple processes of axonal development. While we cannot rule out possible kinase-independent roles of SAD kinases, at least in C. elegans, kinase activity is essential for SAD function in vivo ( Crump et al., 2001 and Kim et al., 2008), suggesting that substrate phosphorylation is the key functional output. However, only a few SAD substrates have been identified so far, including the microtubule-associated proteins Tau, the cell cycle regulators Wee1 and Cdc25, gamma-tubulin and the nerve terminal component RIM ( Barnes et al., 2007, Inoue et al., 2006, Lu et al., 2004, Müller et al., 2010 and Alvarado-Kristensson et al., 2009). Determining how SAD kinases shape neuronal form and connectivity will require examination of how these kinases process upstream signals in distinct developmental contexts and how downstream phosphorylation modifies the activity of yet-to-be-identified substrates.

, 2002, Dehmel et al , 2002 and Kulesza et al , 2003) This IPSP-

, 2002, Dehmel et al., 2002 and Kulesza et al., 2003). This IPSP-induced offset firing is mediated by glycine receptors (Kadner and Berrebi, 2008) and three mechanisms have been postulated to explain the offset firing: (1) Coincident excitation and inhibition suppress firing during the sound, but the excitation outlasts the inhibition (discussed in Kulesza et al., 2003). We demonstrate that offset firing is an intrinsic activity of SPN neurons

with the ionic mechanism requiring three crucial elements: sound-evoked IPSPs, a large electrochemical chloride gradient, and the combination of a hyperpolarization-activated cation current, IH, with a T-type calcium current, ITCa. Modeling has suggested that IH could contribute to stimulus duration encoding (Hooper et al., 2002); our results provide experimental evidence for this but also demonstrate the crucial importance of the IPSP high throughput screening Screening Library cost and enhanced chloride gradients, so that the inhibition can provide sufficient hyperpolarization to activate IH in response to physiological sensory

input. We have confirmed this interpretation using sound-evoked SPN single-unit recordings in vivo, characterized the conductances using voltage clamp in vitro, and demonstrated that these conductances are sufficient to explain the results by computational modeling. The result is a physiologically elegant solution to computation of sound termination: a cell-specific conversion of inhibition into excitatory AP firing, which enhances timing accuracy and provides crucial information for downstream duration encoding. The majority of SPN neurons showed AP firing as an offset response following sound stimulation in vivo (64%, extracellular single unit, n = 15, Figures 1E, 1F, and 1I) or following hyperpolarization in vitro (89%, whole-cell patch clamp, n = 70, Figures 1C, 1H, and 1I). A minority of neurons showed no offset firing upon 17-DMAG (Alvespimycin) HCl hyperpolarization

(Figure 1I), but instead showed sustained or onset firing in vivo, as seen in other species (Behrend et al., 2002 and Dehmel et al., 2002). The offset firing characteristically exhibited an intrinsic rhythm observed as multiple distinct peaks in the poststimulus time histogram (PSTH; Figure 1F, inset). The average number of APs in the offset response was 3.5 ± 0.4 (n = 65) with an interspike interval of 1.85 ms ± 0.19 ms (n = 26 cells) between the first two APs and increasing variability for the subsequent APs, as shown in the inset in Figure 1C. A subpopulation of cells (25%; Figure 1I, dotted line) fired only one offset AP; these neurons lacked the very negative ECl (see below) and possessed an IA type potassium current, suggesting that their role may differ. The differences were minor and we did not exclude these cells from the data set to avoid sample bias.