2012. Vol.3, No.12A, 1259-1263
Published Online December 2012 in SciRes (
Copyright © 2012 SciRes. 1259
Protective Factors for Violence Risk: The Value for
Clinical Practice
Michiel de Vries Robbé, Vivienne de Vogel, Jeantine Stam
Van der Hoeven Kliniek, Utrecht, The Netherlands
Received October 11th, 2012; revised November 9th, 2012; accepted December 5th, 2012
Violence risk assessment tools in forensic psychiatry have traditionally solely been focused on risk factors.
Recently, positive psychology inspired a more strengths-based approach to treatment and sparked an in-
novation in the assessment of violence risk: the introduction of protective factors. The Structured Assess-
ment of Protective Factors for Violence Risk (SAPROF) was developed to complement violence risk as-
sessment with an assessment of protective factors. In this article, clinical experiences with the use of pro-
tective factors in forensic practice are described and empirical findings on incorporating protective factors
in the risk assessment procedure are discussed. The results of this study underline the value of protective
factors for a balanced and more accurate violence risk assessment and exemplify their potential in guiding
treatment planning, evaluating treatment progress and improving positive risk management strategies.
Keywords: Protective Factors; Violence Risk Assessment; SAPROF; Strengths-Based; Positive
Positive psychology has inspired an innovative direction for
treatment not only in general psychiatry but also in forensic
psychiatry. Encouragement of the healthy aspects of mentally
disordered patients and their environment can provide a valu-
able contribution to the treatment and reintegration process.
Therefore, treatment aimed at reducing violent recidivism
should not only be focused on diminishing risk factors, but also
on reinforcing protective factors (De Ruiter & Nicholls, 2011;
Ullrich & Coid, 2009). Strengths-based approaches are eagerly
being adopted by clinicians seeking hopeful and positive alter-
natives for the gloomy vision of the risk-only approach. In-
spired by this new direction in (forensic) psychology, over the
past decade clinicians and researchers in forensic psychiatry
have increasingly focused on positive and changeable treatment
related issues. As such, treatment approaches have more and
more adopted positive strategies and strengths-based interven-
tions (see for example the Good Lives Model; Ward & Brown,
2004). Although positive factors have traditionally been ad-
dressed in most treatment efforts, the notion that these positive
factors can indeed act as protective factors for violence risk in
forensic psychiatric patients is relatively new. Moreover, link-
ing this positive preventive approach to a structured evaluation
of personal and situational strengths in risk assessment was
virtually non-existing before the turn of the century. Rogers
(2000) stated that most assessments were risk-only evaluations,
which were inherently inaccurate and implicitly biased. Ac-
cording to Miller (2006), the mere focus on risk factors in most
risk assessment instruments likely results in pessimism among
therapists and over-prediction of recidivism, possibly leading to
the wrongful, lengthy detention of forensic psychiatric patients,
which is costly both for the patients, in terms of loss of personal
liberties, and for society, in terms of financial burden.
Many researchers now agree that by focusing solely on risk
factors, important information concerning the other side of the
violence risk equation, the possible risk reducing effect of pro-
tective factors, is wrongfully ignored and that a balanced risk
assessments including both risk- and protective factors is vital
for an accurate appraisal of the risk of relapse into violence
(e.g., DeMatteo, Heilbrun, & Marczyk, 2005; Gagliardi, Lovell,
Peterson, & Jemelka, 2004; Haggård-Grann, 2005; Salekin &
Lochman, 2008). However, as of yet the specific assessment of
protective factors remains understudied and the concept of pro-
tective factors is still ambiguous (Braithwaite, Charrette,
Crocker, & Reyes, 2010; De Vogel, De Ruiter, Bouman, & De
Vries Robbé, 2011). Protective factors can be personal factors
or situational factors. They are defined as: any characteristic of
a person, his or her environment or situation which reduces the
risk of future violent behavior (De Vogel, De Ruiter, Bouman,
& De Vries Robbé, 2009, 2012). If protective factors are dy-
namic in nature, they make for promising positive targets for
violence risk reduction by providing positive goals for treat-
ment programming and risk management planning (Douglas &
Skeem, 2005). In recent years, many researchers and clinicians
in forensic treatment have started to acknowledge the value of
protective factors for accurate risk assessment and effective
violence prevention (Fougere & Daffern, 2011; Lösel & Far-
rington, 2012; Ullrich & Coid, 2009; Webster, Martin, Brink,
Nicholls, & Desmarais, 2009). In this article protective factors
for violence risk will be investigated and a tool for the struc-
tured assessment of protective factors will be introduced. The
benefits of protective factors for the risk assessment and treat-
ment of forensic psychiatric patients will be described.
Assessment Tools for Protective Factors
Many risk assessment tools in forensic clinical practice fol-
low the Structured Professional Judgment (SPJ; see Douglas,
2009) approach. SPJ tools are checklists containing empirically
derived risk related factors. After coding the items in the tool,
the assessor interprets and integrates the evidence to come to an
overall final judgment on the level of risk or protection present.
Integrating empirical knowledge with clinical expertise ensures
a well-informed risk judgment. Moreover, the SPJ approach
provides valuable insights into possible risk scenarios and is
able to guide treatment planning and risk management. Very
few structured violence risk assessment tools include a specific
focus on strengths. Only three SPJ tools have been developed
which include protective factors. The Structured Assessment for
Violence Risk in Youth (SAVRY; Borum, Bartel, & Forth, 2006)
is a checklist for violence risk assessment in youth containing
six protective factors in addition to 24 risk factors (e.g., Proso-
cial involvement, Resilient personality traits). Several studies
on the SAVRY found that the protective factors in the SAVRY
are good predictors of reduced violence and that they have ad-
ditional value to risk factors (Lodewijks, De Ruiter, & Dorelei-
jers, 2010; Rennie & Dolan, 2010). The Short-Term Assessment
of Risk and Treatability (START; Webster et al., 2009) is a
clinical guideline for the dynamic assessment of short-term
risks. The 20 dynamic items have to be simultaneously coded
on two three-point scales: first as strength, then as risk. In other
words, risks and strengths are regarded as opposing ends of the
same variable rather than being unique concepts. The START is
intended to be used for short-term assessments of acute risk and
is repeated bimonthly. In recent studies the START strengths-
scale (the total score of the strength side of all items) showed to
be predictive of less violence in the short-term and of success-
ful community reintegration (Braithwaite et al., 2010; Nonstad
et al., 2010; Viljoen, Nicholls, Greaves, De Ruiter, & Brink,
2011; Wilson, Desmarais, Nicholls, & Brink, 2010).
Given the lack of a suitable protective factors assessment
tool which could be used in accordance with the most com-
monly used forensic assessment tools for risk factors with a
medium-term time-frame (i.e., the Historical Clinical Risk
management-20 (HCR-20); Webster, Douglas, Eaves, & Hart,
1997), the SAPROF was developed. The tool was inspired by
findings from positive treatment aspects in clinical practice and
by a strong whish from clinicians for a more strengths-based
yet empirically sound approach. Through extensive literature
reviews on protective and contextual factors, qualitative studies
on the working positive aspects of forensic clinical treatment
and pilot studies among several Dutch forensic psychiatric in-
stitutions, in 2007 the Structured Assessment of Protective
Factors for violence risk (SAPROF; De Vogel, De Ruiter,
Bouman, & De Vries Robbé, 2007; English version 2009) was
developed in the Netherlands. The SAPROF was designed as a
SPJ checklist. It was intended as a positive dynamic addition to
structured risk assessment in forensic clinical practice and thus
to be used in combination with a SPJ risk evaluation instrument,
like the HCR-20 or the Historical Clinical Risk management:
Version 3 (HCR:V3; Douglas, Hart, Webster, Belfrage, &
Eaves, in preparation). Since the publication of the English
manual in 2009, the SAPROF was subsequently translated in
10 different languages and was quickly adopted by forensic
psychiatric institutions in various countries.
The SAPROF consists of two static and fifteen dynamic pro-
tective factors organized within three scales according to their
general background: the Internal factors (e.g., Coping, Self-
control), the Motivational factors (e.g., Work, Attitudes towards
authority) and the External factors (e.g., Social network, Pro-
fessional care). Appendix 1 shows the coding sheet with an
overview of all protective factors in the SAPROF. The factors
are rated on a three-point scale (0-2), reflecting the extent to
which they are present as a protective factor for violence risk
for a given patient in a specific situation. Additionally, factors
can be indicated as particularly important for the individual in
two ways. Factors that provide much protection at the time of
assessment can be marked as key factors, while factors that are
seen as potential targets for treatment intervention can be
marked as goal factors. In clinical practice, the indication of
key factors and goal factors sharpens the view on the impor-
tance of specific protective factors for the individual, which can
be useful for the development of risk management plans and
treatment intervention strategies. Following the SPJ approach,
the SAPROF concludes with a final judgment on the overall
protection that is present to counterbalance violence risk in the
assessed situation (low, moderate, or high). Like with all SPJ
tools, the final judgment is composed by interpreting, weighing
and integrating the factors that are present. Finally, this Final
Protection Judgment is combined with the risk factors from a
SPJ risk tool to come to an integrative and balanced Final Risk
Judgment for future violent behavior. In De Vogel et al. (2011)
the background and content of the SAPROF is explained fur-
ther and its protective factors are discussed in more detail.
The Benefits of a Positive Approach Clinical
The predominantly dynamic protective factors in the SAP-
ROF aim to inform treatment with positive and attainable goals
for interventions. By doing so, the assessment of protective
factors can offer valuable guidance in narrowing the gap be-
tween risk assessment and risk management. In 2007, the
SAPROF was implemented into general risk assessment prac-
tice for violent and sexually violent offenders in the Van der
Hoeven Kliniek, a forensic psychiatric hospital in The Nether-
lands, to complement traditional risk assessment with risk-only
tools like the HCR-20 and the Sexual Violence Risk-20
(SVR-20; Boer, Hart, Kropp, & Webster, 1997). Mental health
professionals, clinical psychologists and researchers in Dutch
forensic psychiatry state that they appreciate the usefulness of
the assessment of protective factors for the atonement of treat-
ment plans and implementation of feasible and effective risk
management strategies (Van den Broek & De Vries Robbé,
2008). For example, clinicians value the use of key-factors and
goal-factors when assessing and reporting patient strengths in
relation to treatment progress. In turn, this supports well-in-
formed decision making regarding treatment phasing. More-
over, the use of a positive tool with a focus on the healthy as-
pects and strengths of a patient and his or her environment en-
courages positive communication between staff and patients
and enhances treatment motivation in both patients and clini-
cians. The value of these positive changes for treatment pro-
gress has also been recognized in the therapeutic assessment
approach by Finn and colleagues (see Finn, 2007). Although
this collaborative assessment procedure revolves much more
around patient involvement, the primary goals is very similar:
facilitating positive change in people.
In order to provide more insight into the nature of the rela-
tionship between positive factors and a reduced likelihood of
Copyright © 2012 SciRes.
recidivism, several validation studies were carried out on the
SAPROF protective factors. Although the greatest supplemen-
tal value of the SAPROF is its importance for guiding treatment
evaluation and planning, proper examination of its predictive
validity for violent recidivism, both retrospectively and pro-
spectively, is essential.
Two retrospective file studies were carried out in order to
assess the psychometric qualities of the SAPROF and evaluate
the additional value of using the SAPROF alongside traditional
risk only evaluations in clinical practice with: 1) violent of-
fenders; and 2) sexually violent offenders. The first validation
study (De Vries Robbé & De Vogel, 2012; De Vries Robbé, De
Vogel, & De Spa, 2011) included 105 male violent offenders
discharged from forensic psychiatric treatment after intensive
clinical and outpatient treatment (mean treatment duration 5.5
years). Interrater reliability was good for the total SAPROF
item scores (intraclass correlation coefficient (ICC) = .88).
Predictive validities for non-recidivism with violent offenses
after treatment within three different follow-up periods, one
year, three year and long-term (M = 8 year), after treatment
were excellent. Patients with more protective factors at dis-
charge recidivated significantly less often and less quickly than
patients with lower protective factors scores (area under curve
value (AUC) = .85 at one year; .74 at three year; and .71 at
long-term follow-up). The predictive validity of the protective
factors in the SAPROF and the risk factors in the HCR-20
combined significantly outperformed the risk-only evaluation.
In addition to ratings at the time of discharge, for part of the
sample data were also collected on ratings at the time of admis-
sion to assess the progress made by patients during their foren-
sic psychiatric treatment. A comparison between the pre- and
post-treatment ratings showed significant improvements in
protective factors scores during treatment, providing evidence
for the changeability of the dynamic protective factors in the
SAPROF and their potential usefulness for positive treatment
progress evaluation and risk management planning.
A subsequent study (De Vries Robbé & De Vogel, 2012; De
Vries Robbé, De Vogel, Koster, & Bogaerts, submitted for
publication) investigated the value of the SAPROF protective
factors for sexual offenders. The study included 83 discharged
sexually violent male offenders (mean treatment duration 5.4
years). As was found for the violent offender sample, the inter-
rater reliability of the SAPROF protective factors was good for
the sexual offenders (ICC = .85). Predictive validity results
were high as well for the sexual offender sample: the SAPROF
showed good predictive validity at different follow-up times of
1 year, 3 year and long-term (M = 15 year) both for non-re-
cidivism in sexual violence (AUC = .83; .77; .74, respectively)
and for non-recidivism in general violence (AUC = .93; .76; .71,
respectively). Again, adding the SAPROF protective factors
produced significantly more accurate assessments than assess-
ments with the risk-only HCR-20 or SVR-20 alone. Compari-
son of pre- and post-treatment ratings showed very similar ef-
fects for the sexual offender sample as for the violent offender
sample: significant positive changes on the SAPROF factors
during treatment. These treatment changes in themselves were
predictive of less recidivism, meaning that those patients who
showed the most progress on their protective factors during
treatment, also recidivated the least after treatment. Although
the results from these studies were equally good for violent and
sexual offenders, analyses revealed different protective factors
that were most predictive of no future (sexual) violence for the
two offender groups: Self-control, Work and Financial man-
agement for the violent offenders; Coping, Self-control, Moti-
vation for treatment and Attitudes towards authority for the
sexual offenders (De Vries Robbé & De Vogel, 2012).
In order to assess the usefulness of protective factors for the
assessment of inpatient aggression, a prospective study was
carried out within clinical practice (De Vries Robbé, De Vogel,
Wever, Douglas, & Nijman, submitted for publication). The
study included data on 315 assessments, which had been carried
out during different stages of clinical treatment at a Dutch fo-
rensic psychiatric hospital. Predictive validity analyses for no
inpatient aggression within the year following the assessment
showed good results for the protective factors in the SAPROF
for different groups of patients including male violent offenders
(AUC = .77), male sexual offenders (AUC = .81) and female
offenders (AUC = .70). Overall, similar to the findings in the
retrospective file studies, combining the protective factors with
the risk factors showed to provide the most accurate predictions.
When patients at different stages during their treatment were
compared, the presence of dynamic protective factors showed
to increase as treatment progressed, while the presence of dy-
namic risk factors showed to decrease over time. Together the
improved protective factors and the diminished risk factors
resulted in an overall reduction in violence risk and conse-
quently less inpatient aggression. It was found that there were
far fewer incidents of violence at the later stages in treatment
and that protective factors were particularly useful later on in
treatment, when patients had been able to use their increased
protective factors to their advantage outside the hospital walls.
Although protective factors inevitably have always been part
of clinical practice, their true potential for positive treatment
outcome has long been underestimated and wrongfully received
little acknowledgement. In order for treatment programs aimed
at increasing protective factors to be meaningful it is essential
to be able to evaluate the presence of protective factors that are
empirically related to reductions in violence risk. Structurally
assessing the positive characteristics of offenders and their
environment offers a valuable additional starting point for ef-
fective and achievable positive treatment interventions. Com-
plementing the risk-only focus with protective factors brings
forth a more balanced assessment of future violence risk and
consequently leads to better informed risk management. Vali-
dation studies to date on the SAPROF as a tool for the struc-
tured assessment of protective factors have provided support for
a strong relationship between the presence of protective factors
and the reduced likelihood of future violence. Moreover, the
changeability of dynamic protective factors makes them valu-
able positive treatment targets and provides clinicians with a
tool to evaluate treatment progress and guide interventions.
Focusing on strengthening these dynamic protective factors
provides clinicians in forensic psychiatry with a promising
improvement in the prevention of violent recidivism.
Boer, D. P., Hart, S. D., Kropp, P. R., & Webster, C. D. (1997). Manual
for the Sexual Violence Risk-20. Professional guidelines for assess-
ing risk of sexual violence. Vancouver: Institute against Family Vio-
Copyright © 2012 SciRes. 1261
Copyright © 2012 SciRes.
Borum, R., Bartel, P., & Forth, A. (2006). Manual for the Structured
Assessment for Violence Risk in Youth (SAVRY). Odessa, FL: Psy-
chological Assessment Resources.
Braithwaite, E., Charrette, Y., Crocker, A., & Reyes, A. (2010). The
predictive validity of clinical ratings of the Short-Term Assessment
of Risk and Treatability (START). International Journal of Forensic
Mental Health, 9, 271-281. doi:10.1080/14999013.2010.534378
De Ruiter, C., & Nicholls, T. L. (2011). Protective factors in forensic
mental health: A new frontier. International Journal of Forensic
Mental Health, 10, 160-170. doi:10.1080/14999013.2011.600602
De Vogel, V., de Ruiter, C., Bouman, Y., & de Vries Robbé, M. (2007).
SAPROF manual. Structured assessment of protective factors for
violence risk. Version 1. Utrecht: Forum Educatief.
De Vogel, V., de Ruiter, C., Bouman, Y., & de Vries Robbé, M. (2009).
SAPROF. Guidelines for the assessment of protective factors for vio-
lence risk. English version. Utrecht: Forum Educatief.
De Vogel, V., de Ruiter, C., Bouman, Y., & de Vries Robbé, M. (2012).
SAPROF. Guidelines for the assessment of protective factors for vio-
lence risk (2nd ed.). Utrecht: De Forensische Zorgspecialisten.
De Vogel, V., de Vries Robbé, M., de Ruiter, C., & Bouman, Y. H. A.
(2011). Assessing protective factors in forensic psychiatric practice.
Introducing the SAPROF. International Journal of Forensic Mental
Health, 10, 171-177. doi:10.1080/14999013.2011.600230
De Vries Robbé, M., & de Vogel, V. (2012). SAPROF 2nd edition
manual updated Research chapter. Utrecht: Van der Hoeven Kliniek.
De Vries Robbé, M., de Vogel, V., & de Spa, E. (2011). Protective
factors for violence risk in forensic psychiatric patients. A retrospec-
tive validation study of the SAPROF. International Journal of Fo-
rensic Mental Health, 10, 178-186.
De Vries Robbé, M., de Vogel, V., Koster, K., & Bogaerts, S.
(submitted for publication). Protective factors for sexually violent
offenders: A retrospective validation study of the SAPROF.
De Vries Robbé, M., de Vogel, V., Wever, E. C., Douglas, K. S., &
Nijman, H. L. I. (submitted for publication). Risk and protective fac-
tors in clinical practic e : Measuring change in high-risk offenders.
DeMatteo, D., Heilbrun, K., & Marczyk, G. (2005). Psychopathy, risk
of violence, and protective factors in a noninstitutionalized and non-
criminal sample. International Journal of Forensic Mental Health, 4,
147-157. doi:10.1080/14999013.2005.10471220
Douglas, K. S. (2009). Expert opinion. Assessing risk for violence
using structured professional judgment. American Psychology-Law
Society News, 29, 12-15.
Douglas, K. S., Hart, S. D., Webster, C. D., Belfrage, H., & Eaves, D.
(in preparation). HCR:V3 historical, clinical, risk management (Ver-
sion 3): Assessing risk for violence. Vancouver: Mental Health, Law,
and Policy Institute, Simon Fraser University.
Douglas, K. S., & Skeem, J. L. (2005). Violence risk assessment: Get-
ting specific about being dynamic. Psychology, Public Policy, and
Law, 11, 347-383. doi:10.1037/1076-8971.11.3.347
Finn, S. E. (2007). In our clients’ shoes: Theory and techniques of
Therapeutic Assessment. Mahwah, NJ: Erlbaum.
Fougere, A., & Daffern, M. (2011). Resilience in youth offenders.
International Journa l of Forensic Mental Health, 10, 244-253.
Gagliardi, G. J., Lovell, D., Peterson, P. D., & Jemelka, R. (2004).
Forecasting recidivism in mentally ill offenders released from prison.
Law and Human Behavior, 28, 133-155.
Haggård-Grann, U. (2005). Violence among mentally disordered of-
fenders: Risk and protective factors. Stockholm: Edita Norstedts
Lodewijks, H. P. B., de Ruiter, C., & Doreleijers, Th. A. H. (2010). The
impact of protective factors in desistance from violent reoffending: A
study in three samples of adolescent offenders. Journal of Interper-
sonal Violence, 25, 568-587. doi:10.1177/0886260509334403
Lösel, F., & Farrington, D. P. (2012). Direct protective and buffering
protective factors in the development of youth violence. American
Journal of Preventive Medicine, 43, 8-23.
Miller, H. A. (2006). A dynamic assessment of offender risk, needs,
and strengths in a sample of general offenders. Behavioral Sciences
and the Law, 24, 767-782. doi:10.1002/bsl.728
Nonstad, K., Nesset, M. B., Kroppan, E., Pedersen, T. W., Nøttestad, J.
A., Almvik, R., & Palmstierna, T. (2010). Predictive validity and
other psychometric properties of the Short-Term Assessment of Risk
and Treatability (START) in a Norwegian high secure hospital. In-
ternational Journal of Forensic Mental Health, 9, 294-299.
Rennie, C. E., & Dolan, M. C. (2010). The significance of protective
factors in the assessment of risk. Criminal Behaviour and Mental
Health, 20, 8-22. doi:10.1002/cbm.750
Rogers, R. (2000). The uncritical acceptance of risk assessment in
forensic practice. Law and Human Behavior, 24, 595-605.
Salekin, R. T., & Lochman, J. E. (2008). Child and adolescent psy-
chopathy. The search for protective factors. Criminal Justice and
Behavior, 35, 159-172. doi:10.1177/0093854807311330
Ullrich, S., & Coid, J, (2011). Protective factors for violence among
released prisoners—Effects over time and interactions with static risk.
Journal of Consulting and Clin ic al Psychology, 79, 381-390.
van den Broek, E., & de Vries Robbé, M. (2008). The supplemental
value of the SAPROF from a treatment perspective: A counterbal-
ance to risk? 8th Conference of the International Association of Fo-
rensic Mental Health Services, Vienna, 14-16 July 2008.
Viljoen, S., Nicholls, T., Greaves, C., de Ruiter, C., & Brink, J. (2011).
Resilience and successful community reintegration among female
forensic psychiatric patients: A preliminary investigation. Behavioral
Sciences and the Law, 29, 752-770. doi:10.1002/bsl.1001
Ward, T., & Brown, M. (2004). The good lives model and conceptual
issues in offender rehabilitation. Psychology, Crime & Law, 10, 243-
257. doi:10.1080/10683160410001662744
Webster, C. D., Douglas, K. S., Eaves, D., & Hart, S. D. (1997).
HCR-20. Assessing the risk of violence. Version 2. Burnaby: Simon
Fraser University and Forensic Psychiatric Services Commission of
British Columbia.
Webster, C. D., Martin, M., Brink, J., Nicholls, T. L., & Desmarais, S.
L. (2009). Short-Term Assessment of Risk and Treatability (START).
Clinical guide for evaluation risk and recovery. Version 1.1. Ontario:
St. Joseph’s Healthcare Hamilton.
Wilson, C., Desmarais, S. L., Nicholls, T. L., & Brink, J. (2010). The
role of client strengths in assessments of violence risk using the
Short-Term Assessment of Risk and Treatability (START). Inter-
national Journal of Foren si c M en ta l Health, 9, 282-293.
Appendix 1
SAPROF coding sheet.
Coding sheet SAPROF
Protective factors for violence risk
To be used only in combination with the HCR-20
or related structur ed risk assessment tools
Name: Number: Date:
Age: Gender:
Context risk assessment:
Internal factors Score Key Goal
1. Intelligence
2. Secure attachment in childhood
3. Empathy
4. Coping
5. Self-control
Motivational fac tors Score Key Goal
6. Work
7. Leisure activities
8. Financial management
9. Motivation for treatment
10. Attitudes towards authority
11. Life goals
12. Medication n/a
External factors Score Key Goal
13. Social network
14. Intimate relationship
15. Professional care
16. Living circumstances
17. External control
Other considerations:
Final Prote ction Judgment and
Integrative Final Risk Judgment
Name(s) assessor(s):
© Copyright January 2012, Forum Educatief; Vivienne de Vogel, Corine de Ruiter, Yvonne Bouman and Michiel de Vries Robbé.
Copyright © 2012 SciRes. 1263