Quality of life measurement in teledermatology. Position statement of the European Academy of Dermatology and Venereology Task Forces on Quality of Life and Patient Oriented Outcomes and Teledermatology

Many events, including the COVID-19 pandemic, have accelerated the implementation of teledermatology pathways within dermatology departments and across healthcare organizations. Quality of Life (QoL) assessment in dermatology is also a rapidly developing field with a gradual shift from theory to practice. The purpose of this paper organized jointly by the European Academy of Dermatology and Venereology (EADV) Task Force (TF) on QoL and patient-oriented outcomes and the EADV TF on teledermatology is to present current knowledge about QoL assessment during the use of teledermatology approaches, including data on health-related (HR) QoL instruments used in teledermatology, comparison of influence of different treatment methods on HRQoL after face-to-face and teledermatology consultations and to make practical recommendations concerning the assessment of QoL in teledermatology. The EADV TFs made the following position statements: HRQoL assessment may be an important part in most of teledermatology activities; HRQoL assessment may be easily and effectively performed during teledermatology consultations. It is especially important to monitor HRQoL of patients with chronic skin diseases during lockdowns or in areas where it is difficult to reach a hospital for face-to-face consultation; regular assessment of HRQoL of patients with skin diseases during teledermatology consultations may help to monitor therapy efficacy and visualize individual patient's needs; we recommend the use of the DLQI in teledermatology, including the use of the DLQI app which is available in seven languages; it is important to develop apps for dermatology-specific HRQoL instruments for use in children (for example the CDLQI and InToDermQoL) and for disease-specific instruments.

Preferences of German and Swiss melanoma patients for toxicities versus melanoma recurrence during adjuvant treatment (GERMELATOX-A-trial)

PURPOSE

Adjuvant treatment with immune checkpoint inhibitors like PD1-antibodies (ICI) ± CTLA4-antibodies (cICI) or targeted therapy with BRAF/MEK inhibitors (TT) in high-risk melanoma patients demonstrate a significant improvement in disease-free survival (DFS). Due to specific side effects, the choice of treatment is very often driven by the risk for toxicity. This study addressed for the first time in a multicenter setting the attitudes and preferences of melanoma patients for adjuvant treatment with (c)ICI and TT.

METHODS

In this study ("GERMELATOX-A"), 136 low-risk melanoma patients from 11 skin cancer centers were asked to rate side effect scenarios typical for each (c)ICI and TT with mild-to-moderate or severe toxicity and melanoma recurrence leading to cancer death. We asked patients about the reduction in melanoma relapse and the survival increase at 5 years they would require to tolerate defined side-effects.

RESULTS

By VAS, patients on average valued melanoma relapse worse than all scenarios of side-effects during treatment with (c)ICI or TT. In case of severe side effects, patients required a 15% higher rate of DFS at 5 years for (c)ICI (80%) compared to TT (65%). For survival, patients required an increase of 5-10% for melanoma survival during (c)ICI (85%/80%) compared to TT (75%).

CONCLUSION

Our study demonstrated a pronounced variation of patient preferences for toxicity and outcomes and a clear preference for TT. As adjuvant melanoma treatment with (c)ICI and TT will be increasingly implemented in earlier stages, precise knowledge of the patient perspective can be helpful for decision making.

Quality of life measurement in alopecia areata. Position statement of the European Academy of Dermatology and Venereology Task Force on Quality of Life and Patient Oriented Outcomes

New treatment options may lead to an increased interest in using reliable and sensitive instruments to assess health-related quality of life in people with alopecia areata (AA). The purpose of this paper is to present current knowledge about quality of life assessment in AA. The dermatology-specific Dermatology Life Quality Index (DLQI) was the most widely reported health-related quality of life instrument used in AA. Three AA-specific (Alopecia Areata Symptom Impact Scale, Alopecia Areata Quality of Life Index and Alopecia Areata Patients' Quality of Life) and three hair disease-specific instruments (Hairdex, Scalpdex and 'hair-specific Skindex-29') were identified with a range of content and validation characteristics: there is little evidence yet of the actual use of these measures in AA. Scalpdex is the best-validated hair disease-specific instrument. Further extensive validation is needed for all of the AA-specific instruments. The European Academy of Dermatology and Venereology Task Force on Quality of Life and Patient Oriented Outcomes recommends the use of the dermatology-specific DLQI questionnaire, hair disease-specific Scalpdex and the alopecia areata-specific instruments the Alopecia Areata Symptom Impact Scale or Alopecia Areata Quality of Life Index, despite the limited experience of their use. We hope that new treatment methods will be able to improve both clinical signs and health-related quality of life in patients with AA. In order to assess the outcomes of trials on these new treatment methods, it would be helpful when further development and validation of AA-specific instruments is being encouraged and also conducted.

Pruritus Intensity Scales across Europe: a prospective validation study

BACKGROUND

Chronic pruritus (CP) is a subjective symptom, and it is necessary to assess its intensity with validated patient-reported outcome tools in order to allow determination of the treatment course.

OBJECTIVES

So far, the itch intensity scales were validated in small cohorts and in single languages. Here, we report the validation of the numerical rating scale, the verbal rating scale and the visual analogue scale for the worst and average pruritus intensity in the last 24h in several languages across Europe and across different pruritic dermatoses.

METHODS

After professional translation, the intensity scales were digitized for use as a tablet computer application. Validation was performed in clinics for Dermatology in Austria, France, Germany, Italy, Poland, Russia, Spain, Switzerland and Turkey.

RESULTS

A total of 547 patients with contact dermatitis, chronic nodular prurigo, psoriasis vulgaris, lichen planus or cutaneous T-cell lymphoma were included. The intensity scales showed a high level of reproducibility and inter-correlations with each other. The correlation with the Dermatology Life Quality Index was weak to strong in nearly all countries and dermatoses with the exception of France and patients with chronic nodular prurigo, for which no statistically significant correlations were found.

CONCLUSIONS

The numerical rating scale, the verbal rating scale und the visual analogue scales are valid instruments with good reproducibility and internal consistency in German (Germany, Austria, Switzerland), French, Italian, Polish, Russian, Spanish and Turkish for different pruritic dermatoses. VAS worst was the best reproducible and consistent measuring instrument in all countries.

Validation of the Spanish Wound-QoL Questionnaire

BACKGROUND AND AIMS

The Wound-QoL is a validated and feasible questionnaire for measuring disease-specific health-related quality of life in chronic wounds, originally developed for use in German. The objective of this study was to translate the Wound-QoL for use in clinical care and in clinical trials in Spain and to validate this version.

MATERIALS AND METHODS

Two independent fourth- and back translations of the Wound-QoL from the original German version were conducted, followed by an expert consensus of the resulting versions. After refinement, the final tool was piloted in N=10 patients and then used in the validation study.

RESULTS

A total of 115 patients were recruited. Mean age was 69.5 (SD 14.5) years, 60.0% were female. The Spanish version of Wound-QoL showed high internal consistency (Cronbach's alpha>0.8 in all scales). Factor analysis resulted in the same scales as the original version. There were satisfactory distribution characteristics of the global score and the subscales. Construct validity and convergent validity with other outcomes (generic QoL, healing rate) were satisfactory. The vast majority of patients considered the Wound-QoL a simple and feasible tool. Mean time needed for completing the questionnaire was 5minutes. Overall, 99.1% of the participants found it easy to understand the questions and 94.7% stated that the questionnaire suits the personal situation.

CONCLUSIONS

The Spanish version of the Wound-QoL shows good validity in clinical practice. It can be recommended for use in clinical routine and trials.

Position statement of the European Academy of Dermatology and Venereology Task Force on Quality of Life and Patient Oriented Outcomes on quality of life issues in dermatologic patients during the COVID-19 pandemic

The pandemic of COVID‐19 is a global challenge for health care, and dermatologists are not standing apart from trying to meet this challenge. The European Academy of Dermatology and Venereology (EADV) has collected recommendations from its Task Forces (TFs) related to COVID‐19. The Journal of the EADV has established a COVID‐19 Special Forum giving free access to related articles. The psychosocial effects of the pandemic, an increase in contact dermatitis and several other skin diseases because of stress, disinfectants and protective equipment use, especially in healthcare workers, the temporary limited access to dermatologic care, the dilemma whether or not to pause immunosuppressive therapy, and, finally, the occurrence of skin lesions in patients infected by COVID‐19 all contribute to significant quality of life (QoL) impairment. Here, we present detailed recommendations of the EADV TF on QoL and patient‐oriented outcomes on how to improve QoL in dermatologic patients during the COVID‐19 pandemic for several different groups of patients and for the general population.

Characterizing treatment-related patient needs in atopic eczema: insights for personalized goal orientation

BACKGROUND

Atopic eczema (AE) is a common and burdensome chronic skin disease. Clinical guidelines suggest an evidence-based, personalized and stepwise treatment approach. Only few studies have so far focused on the specific patient needs in treatment.

OBJECTIVES

To characterize therapeutic needs of patients with AE in routine care.

METHODS

Nationwide cross-sectional study in 91 dermatology practices and outpatient clinics. Descriptive statistics were used for valuation. Comparisons of HRQoL and general health status were performed including subgroups (age, gender and disease duration). Group comparisons of patient needs were performed for age groups, gender and disease duration. Correlations between patients' needs (PNQ) and HRQoL, generic health status and severity were tested. In addition, a hierarchical regression analysis was performed to determine which variables contribute to explain the variance in patient needs.

RESULTS

Analysis of 1678 patients (60.5% female, mean age 38.35 ± 15.92 years) revealed a high disease burden with mean SCORAD of 42.26 ± 18.63, mean DLQI of 8.49 ± 6.45 and mean EQ VAS of 63.62 ± 21.98. Among the patient needs that were most frequently rated as 'quite important'/'very important' were as follows: 'to be free of itching' (96.0%), 'to get better skin quickly' (87.7%) and 'to be healed of all skin defects' (85.7%). In general, older people, women and patients who had been diagnosed with AE for 1 year or less rated the treatment needs as more important than younger patients, men and patients who had been diagnosed with AE for more than 1 year. Major determinants of higher needs were skin-related quality of life impairments, higher disease severity and higher age.

CONCLUSIONS

Patients with AE show a high number and variety of therapeutic needs related to disease signs and symptoms, which are associated with individual disease burden. The patient needs vary substantially according to patient characteristics. Identification of patient-specific needs may support personalized, patient-centred care and shared decision-making.

Validation of a short-form of the Freiburg Life Quality Assessment for lymphoedema (FLQA-LS) instrument

BACKGROUND

Chronic lymphoedema (CLE) is a burdensome disease of multiple causes leading to significant reductions in health-related quality of life (HRQoL). A specific method to assess HRQoL is the Freiburg Life Quality Assessment for lymphoedema (FLQA-L), which consists of 92 items.

OBJECTIVES

To develop and validate a short form of the FLQA-L with improved psychometric properties and feasibility.

METHODS

The FLQA-L validation data were reanalysed by patients and experts. The application of factor analysis enabled the exclusion of lower-load items. An optimized short version of the questionnaire (FLQA-LS) with 33 items was generated and tested in a validation study on patients with different forms of CLE.

RESULTS

In total, 348 patients with CLE of the upper or lower extremities were included (mean age 57.3 years, range 24-89; 90.8% female), and data from 301 patients could be analysed. Overall, 42.8% of the patients had secondary lymphoedema, 23.6% had primary lymphoedema, 9.5% had lipoedema and 24.1% had lipolymphoedema. The lower extremities were mostly affected (64.4% of the patients presented with leg involvement and 17.5% with both arm and leg impairment). The FLQA-LS showed good internal consistency, with high Cronbach's alpha in the subscales and in the global scale ranging between 0.79 and 0.94. Regarding convergent validity, a good correlation was found with the general HRQoL questionnaire EQ-5D (r = 0.72, P < 0.001).

CONCLUSIONS

FLQA-LS is an improved version of the FLQA-L questionnaire for chronic lymphoedema. It demonstrated validity and feasibility and can be easily used in clinical practice and research studies.

Cross-European validation of the ItchyQoL in pruritic dermatoses

BACKGROUND

Chronic pruritus (CP) is a frequently occurring symptom in inflammatory dermatoses, causing a high burden and limitations to health-related quality of life (HRQoL).

OBJECTIVE

The ItchyQoL was developed to assess the impairment to HRQoL in patients with CP. However, it has only been validated in English and German. Here, we report the validation in several languages across Europe.

METHODS

After professional translation, the versions of ItchyQoL were digitized for use as a tablet application. Validation was performed in clinics for dermatology in Austria, France, Germany, Italy, Poland, Russia, Spain, Switzerland and Turkey.

RESULTS

Five hundred and thirty-five patients with either contact dermatitis, chronic prurigo - nodular type, psoriasis vulgaris, lichen planus or mycosis fungoides/Sézary syndrome and with CP ≥ 3 on the numerical rating scale were included. ItchyQoL showed a high level of consistency (Cronbach's-α, all: 0.95) and test-retest reliability (intraclass correlation: 0.91). It strongly correlated with the Dermatology Life Quality Index (r = 0.72, P < 0.001) and moderately correlated with itch intensity scales in the study population (visual analogue scale r = 0.46; numerical rating scale r = 0.51; verbal rating scale r = 0.51, for all: P < 0.001).

CONCLUSION

ItchyQoL is now also validated in French, Italian, Polish, Russian, Spanish and Turkish and can be used in clinical trials in countries speaking these languages.

Quality of life and patient benefit following transition from methotrexate to ustekinumab in psoriasis

BACKGROUND

TRANSIT (NCT01059773) compared immediate and gradual transition from methotrexate to ustekinumab in psoriasis patients via multiple measures, including patient-reported outcomes.

OBJECTIVE

To evaluate patient perception of treatment benefits in TRANSIT.

METHODS

A total of 489 psoriasis patients received ustekinumab, with immediate cessation of methotrexate (Arm 1) or 4 weeks' overlap with decreasing methotrexate dose (Arm 2). Ustekinumab was administered at weeks 0, 4, 16, 28 and 40. Dermatology Life Quality Index (DLQI), EuroQol 5-item (EQ-5D), visual analogue scale (VAS) valuation technique and patient benefit index (PBI) were employed. Mean global PBI and sub-scores were calculated from the sum of the benefit items weighted by their respective relevance at baseline. Patient-relevant benefit was defined as PBI ≥1 (scale: 0 [no benefit] to 4 [maximum benefit]). Correlations of global PBI with Psoriasis Area and Severity Index (PASI) and DLQI were examined.

RESULTS

Relationships between PBI and clinical data were evaluable in 340 patients. The most important treatment goals at baseline included: 'be healed of all skin defects', 'have confidence in therapy', 'get better skin quickly' and 'regain control of the disease'. Benefit in PBI global score was achieved at week 4 by 93% of patients in Arm 1 and 91% in Arm 2. Global PBI scores increased in both Arms between weeks 4 and 52. Global PBI correlated weakly with PASI change from baseline (correlation coefficient range: -0.22 to -0.40), and moderately with DLQI (-0.29 to -0.54). Overall DLQI score was lower than baseline at all times; and the percentage of patients with an overall score of 0 or 1 increased with time. Correspondingly, EQ VAS scores increased with time. DLQI and EQ VAS results were similar between arms.

CONCLUSIONS

Regardless of the strategy for transitioning from methotrexate, ustekinumab was associated with rapid and sustained improvement in patient-reported outcomes. PBI appears a suitable tool for assessing patient-relevant treatment benefits in psoriasis patients.

Evaluation of patient-relevant outcomes of lymphedema and lipedema treatment: development and validation of a new benefit tool

OBJECTIVES

Patient-relevant treatment benefit is traditionally measured with health-related quality of life (HRQoL) instruments. The Patient Benefit Index (PBI) methodology allows for a more direct measurement, with the patients rating both importance and achievement of treatment goals. Here, we developed and validated a PBI version specific for the assessment of benefit in lymphedema and lipedema treatment (PBI-L).

METHODS

The development included five steps: (1) open item collection; (2) consensus of items in a multidisciplinary expert panel; (3) application of the German PBI-L in a cross-sectional study (n = 301); (4) translation into English; (5) application of the English PBI-L in a randomized clinical trial (n = 82). Subscales were developed using factor analysis. Construct validity was analyzed by correlating PBI-L and convergent criteria such as HRQoL and quality of care. To test for responsiveness, the association to change in HRQoL measures was computed.

RESULTS

Floor and ceiling effects were low. There were few missing values. Two well-interpretable subscales were found with Cronbach's alpha >0.8 each. Global and subscale scores correlated with convergent criteria and with change in disease-specific HRQoL, but not with change in generic HRQoL.

CONCLUSIONS

The PBI-L is an internally consistent, valid, and responsive instrument for the assessment of patient-relevant benefit of edema treatment.

[Assessment of pruritus - current standards and implications for clinical practice : consensus paper of the Action Group Pruritus Parameter of the International Working Group on Pruritus Research (AGP)]

With a prevalence of 20%, chronic pruritus is a symptom of many diseases with major impact on healthcare costs. The lack of specific therapeutic measures makes the development of new drugs and their testing in clinical trials urgent. It is not possible to measure pruritus in an objective way. For these reasons, it is necessary to have a series of standardized measures to characterize pruritus in a reliable way. Intensity scales such as the visual analog scale (VAS) are most frequently used to document the course of the symptoms. However, for assessing pruritus intensity, VAS is not an optimal instrument, although it cannot be dispensed with. The VAS should be combined with other scales in clinical studies in order to internally test the consistency of data. Other instruments for assessing intensity and course of pruritus are in the process of development. Presently scratch activity and scratch-associated lesions can be documented in a descriptive fashion. There are some studies that have employed devices to document scratch activity; however, methodological studies are not yet available. The patient-benefit index is an indispensable tool in clinical trials. A questionnaire for gathering data on the history and some pruritus-specific parameters has been developed and published. Questionnaires on patient quality of life, anxiety and depression are helpful in obtaining data on other cost-relevant parameters. A questionnaire on the quality of life, for instance, can provide important help in the assessment of the burden of the disease. The results of these questionnaires can be correlated with data on pruritus intensity scales. The relevant questionnaires have been partially digitalized so that they are available immediately as part of patient care. Additional methodological developments and studies are required in order to define a robust set of instruments for measuring pruritus in daily practice and in clinical studies.

A new instrument for the assessment of patient-defined benefit in the treatment of allergic rhinitis

BACKGROUND

Allergic rhinitis (AR) is a common disease that affects health-related quality of life (HRQoL). Current and future health policy demands the assessment of patient-relevant treatment benefit for evaluation of treatments.

METHODS

We developed, validated and tested a standardized instrument for the assessment of patient-relevant needs and benefits in AR. In an open survey of patients with AR, 100 need and benefit items were generated. The items were condensed to a 25-item list by an expert panel. On this list, patient rates the personal importance of 25 treatment needs on a scale ranging from 'not at all' to 'very' before treatment (Patient Needs Questionnaire, PNQ). At the end of the treatment, patient rates the extent, to which these needs were achieved by treatment from 'did not help at all' to 'helped a lot' (Patient Benefit Questionnaire). The patient benefit index (PBI) is computed to provide a global weighted benefit parameter. This disease-specific instrument was validated in n = 104 patients with AR.

RESULTS

The PBI-AR showed good acceptability and feasibility in clinical routine. Reduction in nose and eye symptoms was rated most important. The PBI amounted to 2.2 (PBI ranges from 0 = 'no benefit' to 4 = 'maximum benefit'). Reliability of the PNQ was high (Cronbach's alpha = 0.9).The PBI was significantly correlated with relevant external validation criteria, such as patient satisfaction (R = 0.54) and HRQoL (R = 0.26).

CONCLUSION

The PBI-AR is a feasible, reliable and valid instrument for the standardized assessment of patient-relevant benefits in the treatment of AR.

Prevalence of chronic pruritus in Germany: results of a cross-sectional study in a sample working population of 11,730

BACKGROUND

Pruritus is a frequent symptom in many diseases; its prevalence in German adults is unknown.

OBJECTIVE

Our purpose was to assess the prevalence, severity and health care of chronic pruritus in the German working population.

METHODS

A cross-sectional observational study was conducted in employees of 144 German companies. Pruritus-specific data were obtained by standardized questions.

RESULTS

11,730 people (53.2% male, 16-70 years, mean = 43.7 years) were suitable for analysis. The point prevalence of chronic pruritus (at least 6 weeks prior to data collection) was 16.8%. The prevalence increased with age from 12.3% (16-30 years) to 20.3% (61-70 years). A quarter of the affected persons had suffered from pruritus for >5 years, 47% had never sought medical advice, and 94% had not undergone any treatment.

CONCLUSIONS

Chronic pruritus is a prevalent symptom in the working age population. A high proportion of people affected are not medically treated.

Nail psoriasis in Germany: epidemiology and burden of disease

BACKGROUND

Although nail psoriasis affects a marked proportion of patients with psoriasis and causes significant psychological stress, only few epidemiological data characterizing patients with nail involvement are available.

OBJECTIVES

To gain robust data on the epidemiology and disease burden of nail psoriasis in Germany.

METHODS

Two nationwide, noninterventional, cross-sectional studies on psoriasis health care were conducted in 2005 and 2007, involving 48 (2005) and 130 (2007) German office-based and clinic-based dermatological centres. Data of n=3531 patients with psoriasis were collected using standardized questionnaires and physical examinations by trained dermatologists. Patients with nail psoriasis were compared with patients without any nail involvement concerning sex, age, disease duration, family history, disease severity, presence of psoriatic arthritis (PsA), health-related quality of life (HRQoL), number of inpatient therapies, and days off work.

RESULTS

Nail psoriasis was diagnosed in 40·9% of the patients; prevalence was 11·2 percentage points higher in men than in women. Patients with nail involvement had a longer disease duration (21·9 vs. 18·1 years), higher disease severity (mean Psoriasis Area and Severity Index 12·7 vs. 9·3), higher frequency of PsA (26·0% vs. 12·7%), stronger impairment of HRQoL (mean Dermatology Life Quality Index 8·9 vs. 7·3), and a 2·5-fold higher rate of inpatient treatments.

CONCLUSIONS

Nail involvement is a relevant manifestation of psoriasis and is associated with a higher disease severity and quality of life impairment. Accordingly, management of psoriasis should include a special focus on nail involvement.

Measuring patient-relevant benefits in pruritus treatment: development and validation of a specific outcomes tool

BACKGROUND

The assessment of patient-relevant benefit is gaining importance in evaluating treatments. The 'Patient Benefit Index, standard version' questionnaire (PBI-S) is a validated instrument to assess patients' treatment needs and benefits in skin diseases. Before therapy, the patient rates the importance of predefined treatment goals; after therapy, he rates the extent to which these goals have been achieved. Thus far, no such instrument has been developed specifically for pruritus.

OBJECTIVES

Development and validation of a patient-relevant benefit questionnaire in the treatment of pruritus.

METHODS

Fifty patients with pruritus were questioned on impairments due to pruritus and treatment needs. Four treatment objectives not already covered by the PBI-S were added to obtain a disease-specific instrument. This was tested for feasibility by 36 patients with pruritus and validated in a sample of 100 patients with pruritus.

RESULTS

The instrument was feasible in clinical practice. There were < 2% missing values. Cronbach's alpha of the needs questionnaire was 0.93. Convergent validity was demonstrated with respect to reduction of pruritus and quality of life.

CONCLUSIONS

The PBI for pruritus is a feasible, reliable and valid instrument that is highly accepted in daily routine for recording patient-reported benefit.

Evaluation of quality of care and guideline-compliant treatment in psoriasis. Development of a new system of quality indicators

BACKGROUND

To date, no standardised indicators for quality of care in psoriasis have been published.

AIMS

Development and testing of evidence-based indicators of quality of care and guideline compliance in the treatment of psoriasis.

METHODS

Indicators of process and outcome quality were extracted and evaluated in a Delphi process according to international standards. The primary reference was the S3 German guideline for psoriasis treatment. The indicators were validated with data from two nationwide studies on psoriasis care involving 1,511 and 2,009 patients.

RESULTS

Eight quality indicators were defined: mean PASI, mean quality of life (Dermatology Life Quality Index; DLQI), proportion of patients with PASI >20, with DLQI >10, with previous systemic treatment, with PASI >20 and systemic treatment, with inpatient treatment, and number of work days lost. All indicators proved suitable for application, and were sensitive to change.

CONCLUSIONS

Guideline-based indicators of quality of care are useful in the analysis of health care and the implementation of treatment guidelines in psoriasis.

X-ray diffuse scattering measurements of nucleation dynamics at femtosecond resolution

Femtosecond time-resolved small and wide angle x-ray diffuse scattering techniques are applied to investigate the ultrafast nucleation processes that occur during the ablation process in semiconducting materials. Following intense optical excitation, a transient liquid state of high compressibility characterized by large-amplitude density fluctuations is observed and the buildup of these fluctuations is measured in real time. Small-angle scattering measurements reveal snapshots of the spontaneous nucleation of nanoscale voids within a metastable liquid and support theoretical predictions of the ablation process.

Carrier-density-dependent lattice stability in InSb

The ultrafast decay of the x-ray diffraction intensity following laser excitation of an InSb crystal has been utilized to observe carrier dependent changes in the potential energy surface. For the first time, an abrupt carrier dependent onset for potential energy surface softening and the appearance of accelerated atomic disordering for a very high average carrier density have been observed. Inertial dynamics dominate the early stages of crystal disordering for a wide range of carrier densities between the onset of crystal softening and the appearance of accelerated atomic disordering.