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Aims Most cases of acute myocardial infarction (MI) in Sweden are treated with long-term β-blocker therapy as secondary prevention. Case studies and patient reports have indicated negative effects of β-blockers including symptoms of depression, fatigue, sexual dysfunction, and general low mood, all related to reduced quality of life (QoL). To date, no recent large-scale, randomized trial has explored the effects of β-blockers on these factors. Methods and results The ongoing Randomized Evaluation of Decreased Usage of beta-bloCkErs after myocardial infarction (REDUCE): quality of life (RQoL) study is a multicentre, prospective, randomized pre-specified substudy aiming to evaluate the effects of β-blockers on self-reported measures of QoL. Following randomized allocation to long-term β-blocker or no β-blocker treatment, patients complete a total of six baseline measures pertaining to QoL, sexual functioning, and perceived side effects. Data collection is optionally carried out online through a unique and secure portal and repeated again at two follow-up time points. Recruitment began in July 2018. Data from the first 100 patients showed that at the first follow-up, 93% had completed the questionnaires, which decreased to 81% at the second follow-up. The method of digital data collection was utilized by over half of the patients recruited so far. Conclusion Data from the first 100 patients indicate success in terms of study design and recruitment. The RQoL substudy investigates the effects of β-blockers on self-reported measures of QoL in MI patients and will potentially contribute to the limited knowledge of QoL-related side effects reported in conjunction with β-blocker use. Clinical trial registration Eudra CT number, 2017-002336-17; Clinical trial.gov identifier, NCT03278509

Background CVD-patients with higher levels of cardiac anxiety suffer psychologically, as well as being at increased risk for cardiac morbidity and mortality. Therefore it is important to be able to assess CA in a clinical setting. It is currently measured with the Cardiac Anxiety Questionnaire, which has conflicting findings regarding its factor structure, and it has not been validated in a Swedish population. This study aimed to examine the factor structure of CAQ and its psychometric properties in a Swedish CVD-population. Methods Nine hundred thirty patients post-MI were recruited at different Swedish hospitals and completed the CAQ, along with several other questionnaires. Exploratory factor analysis and confirmatory factor analysis were conducted to explore factor structure and to inspect various factor solutions from previous research. Standard psychometric tests were performed for the CAQ to test its validity and reliability. Results The exploratory analysis found a model with the factors Fear/Worry, Avoidance and Attention. The confirmatory factor analysis indicated that a 3-factor solution best fitted the data, but with certain items removed. Additionally, psychometric properties turned out acceptable in a Swedish post-MI population. Conclusions We conclude that the original 3-factor structure of the CAQ is valid, but that the questionnaire could be revised in regard to some items. A shorter 10-items version could also be considered. We also confirm that the CAQ is a valid instrument to measure CA in a Swedish MI-population. Trial registration The study was registered on ClinicalTrials.gov on 05/01/2012 (NCT01504191).

BACKGROUND Web-based interventions are effective for several psychological problems. However, recruitment, adherence, and missing data are challenges when evaluating these interventions. OBJECTIVE This study aimed to describe the use patterns during the commencement phase, possible retention patterns (continuation of data provision), and responses to prompts and reminders among participants in 2 randomized controlled trials (RCTs) evaluating web-based interventions. METHODS Data on use patterns logged in 2 RCTs aiming to reduce symptoms of anxiety and depression among adult patients recently diagnosed with cancer (AdultCan RCT) and patients with a recent myocardial infarction (Heart RCT) were analyzed. The web-based intervention in the AdultCan trial consisted of unguided self-help and psychoeducation and that in the Heart trial consisted of therapist-supported cognitive behavioral therapy. In total, 2360 participants’ use patterns at first log-in, including data collection at baseline (ie, commencement) and at 2 follow-ups, were analyzed. Both the intervention and comparison groups were analyzed. RESULTS At commencement, 70.85% (909/1283) and 86.82% (935/1077) of the participants in AdultCan and Heart RCTs, respectively, logged in and completed baseline data collection after receiving a welcome email with log-in credentials. The median duration of the first log-in was 44 minutes and 38 minutes in AdultCan and Heart RCTs, respectively. Slightly less than half of the participants’ first log-ins were completed outside standard office hours. More than 80% (92/114 and 103/111) of the participants in both trials explored the intervention within 2 weeks of being randomized to the treatment group, with a median duration of 7 minutes and 47 minutes in AdultCan and Heart RCTs, respectively. There was a significant association between intervention exploration time during the first 2 weeks and retention in the Heart trial but not in the AdultCan trial. However, the control group was most likely to retain and provide complete follow-up data. Across the 3 time points of data collection explored in this study, the proportion of participants responding to all questionnaires within 1 week from the prompt, without a reminder, varied between 35.45% (413/1165) and 66.3% (112/169). After 2 reminders, up to 97.6% (165/169) of the participants responded. CONCLUSIONS Most participants in both RCTs completed the baseline questionnaires within 1 week of receiving the welcome email. Approximately half of them answered questions at baseline data collection outside office hours, suggesting that the time flexibility inherent in web-based interventions contributes to commencement and use. In contrast to what was expected, the intervention groups generally had lower completion rates than the comparison groups. About half of the participants completed the questionnaires without a reminder, but thereafter, reminders contributed to both baseline and follow-up retention, suggesting they were effective. Strategies to increase commencement of and retention in eHealth interventions are important for the future development of effective interventions and relevant research.

Background Web-based interventions are effective for several psychological problems. However, recruitment, adherence, and missing data are challenges when evaluating these interventions. Objective This study aimed to describe the use patterns during the commencement phase, possible retention patterns (continuation of data provision), and responses to prompts and reminders among participants in 2 randomized controlled trials (RCTs) evaluating web-based interventions. Methods Data on use patterns logged in 2 RCTs aiming to reduce symptoms of anxiety and depression among adult patients recently diagnosed with cancer (AdultCan RCT) and patients with a recent myocardial infarction (Heart RCT) were analyzed. The web-based intervention in the AdultCan trial consisted of unguided self-help and psychoeducation and that in the Heart trial consisted of therapist-supported cognitive behavioral therapy. In total, 2360 participants’ use patterns at first log-in, including data collection at baseline (ie, commencement) and at 2 follow-ups, were analyzed. Both the intervention and comparison groups were analyzed. Results At commencement, 70.85% (909/1283) and 86.82% (935/1077) of the participants in AdultCan and Heart RCTs, respectively, logged in and completed baseline data collection after receiving a welcome email with log-in credentials. The median duration of the first log-in was 44 minutes and 38 minutes in AdultCan and Heart RCTs, respectively. Slightly less than half of the participants’ first log-ins were completed outside standard office hours. More than 80% (92/114 and 103/111) of the participants in both trials explored the intervention within 2 weeks of being randomized to the treatment group, with a median duration of 7 minutes and 47 minutes in AdultCan and Heart RCTs, respectively. There was a significant association between intervention exploration time during the first 2 weeks and retention in the Heart trial but not in the AdultCan trial. However, the control group was most likely to retain and provide complete follow-up data. Across the 3 time points of data collection explored in this study, the proportion of participants responding to all questionnaires within 1 week from the prompt, without a reminder, varied between 35.45% (413/1165) and 66.3% (112/169). After 2 reminders, up to 97.6% (165/169) of the participants responded. Conclusions Most participants in both RCTs completed the baseline questionnaires within 1 week of receiving the welcome email. Approximately half of them answered questions at baseline data collection outside office hours, suggesting that the time flexibility inherent in web-based interventions contributes to commencement and use. In contrast to what was expected, the intervention groups generally had lower completion rates than the comparison groups. About half of the participants completed the questionnaires without a reminder, but thereafter, reminders contributed to both baseline and follow-up retention, suggesting they were effective. Strategies to increase commencement of and retention in eHealth interventions are important for the future development of effective interventions and relevant research.

Background The involvement of patient research partners (PRPs) in research aims to safeguard the needs of patient groups and produce new interventions that are developed based on patient input. Myocardial infarction with nonobstructive coronary arteries (MINOCA), unlike acute myocardial infarction (MI) with obstructive coronary arteries, is presented with no significant obstructive coronary artery disease. Patients with this diagnosis are a subset of those diagnosed with traditional MI and often need more psychological support, something that is presently not established in the current treatment scheme in Swedish health care or elsewhere, to our knowledge. An internet-delivered intervention might offer patients with MINOCA the opportunity to access a psychological treatment that is tailored to their specific needs after MINOCA and could therefore supplement the existing medical care in an easily accessible format. Objective This paper aims to describe the development of a therapist-guided, internet-delivered psychological intervention designed specifically for patients with MINOCA. Methods The study used a participatory design that involved 7 PRPs diagnosed with MINOCA who collaborated with a team consisting of researchers, cardiologists, and psychologists. Intervention content was developed iteratively and presented to the PRPs across several prototypes, each continually adjusted and redesigned according to the feedback received. The intervention and experience of it were discussed by PRPs in a final meeting and then presented to a panel of 2 clinical psychologists and a cardiologist for further input. Results The outcome of the collaboration between PRPs and the research group produced a web-based psychological 9-step program focusing on stress, worry, and valued action. The input from PRPs contributed substantially to the therapy content, homework tasks, interactive activities, multimedia, and design presentation. Conclusions Working with PRPs to develop an intervention for people with MINOCA produced a web-based intervention that can be further evaluated with the goal of offering a new psychological treatment option to a patient group currently without one. Direct contribution from PRPs enabled us to obtain relevant, insightful, and valuable feedback that was put towards the overall design and content of the intervention.

BACKGROUND The involvement of patient research partners (PRPs) in research aims to safeguard the needs of patient groups and produce new interventions that are developed based on patient input. Myocardial infarction with nonobstructive coronary arteries (MINOCA), unlike acute myocardial infarction (MI) with obstructive coronary arteries, is presented with no significant obstructive coronary artery disease. Patients with this diagnosis are a subset of those diagnosed with traditional MI and often need more psychological support, something that is presently not established in the current treatment scheme in Swedish health care or elsewhere, to our knowledge. An internet-delivered intervention might offer patients with MINOCA the opportunity to access a psychological treatment that is tailored to their specific needs after MINOCA and could therefore supplement the existing medical care in an easily accessible format. OBJECTIVE This paper aims to describe the development of a therapist-guided, internet-delivered psychological intervention designed specifically for patients with MINOCA. METHODS The study used a participatory design that involved 7 PRPs diagnosed with MINOCA who collaborated with a team consisting of researchers, cardiologists, and psychologists. Intervention content was developed iteratively and presented to the PRPs across several prototypes, each continually adjusted and redesigned according to the feedback received. The intervention and experience of it were discussed by PRPs in a final meeting and then presented to a panel of 2 clinical psychologists and a cardiologist for further input. RESULTS The outcome of the collaboration between PRPs and the research group produced a web-based psychological 9-step program focusing on stress, worry, and valued action. The input from PRPs contributed substantially to the therapy content, homework tasks, interactive activities, multimedia, and design presentation. CONCLUSIONS Working with PRPs to develop an intervention for people with MINOCA produced a web-based intervention that can be further evaluated with the goal of offering a new psychological treatment option to a patient group currently without one. Direct contribution from PRPs enabled us to obtain relevant, insightful, and valuable feedback that was put towards the overall design and content of the intervention.

Patients with first-time myocardial infarction (MI) and diabetes mellitus (DM) constitute a vulnerable subgroup of cardiovascular (CV) patients for which secondary prevention is particularly important. We investigated if patients with versus without DM differ in attaining four main lifestyle-related cardiac rehabilitation (CR) targets, one-year post-MI.This national cohort study (2006-2015) identified individuals with and without DM at hospital admission in the Swedish cardiac registry, SWEDEHEART. CR goal attainment was assessed one year later. The study population included 47,907 unique patients with first-time MI75 years at baseline (61.8 mean age, 26.7% women, 14.6% with DM). After imputation, propensity score matching was performed. Analyses were conducted with logistic regression.In the matched population, having DM was associated (OR [95% CI]) with lower odds of attaining the one-year post-MI CR goal for both smoking cessation (0.90 [0.81, 0.99]) and attendance in exercise training (0.88 [0.83, 0.95]), yet with higher odds of the1.8 mmol LDL-C target (1.28 [1.19, 1.36]), and similar odds for the140 mm Hg systolic blood pressure target (0.97 [0.91, 1.04]). In addition, women with DM were particularly unlikely to attend exercise training.Patients with first-time MI and DM are less likely to attain two of four selected CR goals compared to those without DM. The particularly low exercise training attendance by women with DM is of concern. Possibilities for tailored interventions targeting behavioural change for this high-risk group, including focused efforts to increase exercise training attendance in women with DM, should be investigated.

In this talk I progress semi-historically from the potential model as applied to heavy onia states to the QCD string dynamics of light quark mesons. The virtues and problems of the potential model are reviewed. Some of the difficulties are solved by the introduction of QCD string confinement. The method of solving string models numerically is outlined and some recent analytic results are discussed. We end by exploring some consequences of the model and how the observed light quark mesons can be classified simply.

The experimental and theoretical evidence relating spin dependence and long range confinement is reviewed. One of the simplest confinement ideas, the dynamic electric flux tube picture of Buchmüller, can be exploited to yield a complete effective Hamiltonian. In addition to pure Thomas spin-orbit splitting the other relativistic corrections are calculated. It is shown that our effective Hamiltonian is identical to the mechanical relativistic flux tube model and gives relativistic corrections in agreement with QCD predictions.

Starting from Buchm{umlt u}ller{close_quote}s observation that a chromoelectric flux tube meson will exhibit only the Thomas-type spin-orbit interaction, we show that a model built upon the related assumption that a quark feels only a constant radial chromoelectric field in its rest frame implies a complete relativistic effective Hamiltonian that can be written explicitly in terms of quark canonical variables. The model yields linear Regge trajectories and exhibits some similarities to scalar confinement, but with the advantage of being more closely linked to QCD. {copyright} {ital 1997} {ital The American Physical Society}

We discuss constraints imposed on the zero-recoil curvature and higher derivatives of the Isgur-Wise function by a general quark model. These constraints are expressed as bounds for a given slope parameter, and compared with those based upon analyticity properties of QCD spectral functions. Our results also indicate that in the analysis of the experimental data for semileptonic $B\rar D^{(*)}$ decays it may be important to include at least the third term in the form factor expansion about the zero recoil point., Comment: 14 pages, latex, uses epsf macro, 5 postscript figures included

We present an analysis which uses Regge structure and the Bjorken and Voloshin HQET sum rules to restrict the choice of parameters of a relativistic quark model., Comment: Latex (uses epsf macro), 17 pages of text, 2 postscript figures included. To appear in Phys. Lett. B

We apply HQET to semi-leptonic $B$ meson decays into a variety of excited charm states. Using three realistic meson models with fermionic light degrees of freedom, we examine the extent that the sum of exclusive single charmed states account for the inclusive semi-leptonic $B$ decay rate. The consistency of form factors with the Bjorken and Voloshin sum rules is also investigated., Comment: Latex, 27 pages. A few references and errors corrected, to appear in Phys. Rev. D

We present a simple and straightforward method for relating the form factors in HQET, as defined by the covariant trace formalism, to the overlaps of the rest frame wave functions of the light degrees of freedom. We also point out several inconsistencies present in recent calculations of the radiative rare $B$ decays, and also show how these can be fixed even within the framework of the non-relativistic quark model., Comment: Latex, 16 pages of text

We adapt a general method to solve both the full and reduced Salpeter equations and systematically explore the conditions under which these two equations give equivalent results in meson dynamics. The effects of constituent mass, angular momentum state, type of interaction, and the nature of confinement are all considered in an effort to clearly delineate the range of validity of the reduced Salpeter approximations. We find that for $J\not{\hspace*{-1.0mm}=}0$ the solutions are strikingly similar for all constituent masses. For zero angular momentum states the full and reduced Salpeter equations give different results for small quark mass especially with a large additive constant coordinate space potential. We also show that $\frac{1}{m}$ corrections to heavy-light energy levels can be accurately computed with the reduced equation.

A dynamical model of confinement is proposed to replace the potential model. The leading relativistic corrections are shown to agree with nonperturbative QCD. Methods are developed to obtain numerically exact solutions for quantized mesons. Illustrative examples are given for equal-mass and heavy-light mesons.

A recent series of experiments on pion production near threshold provides accurate values of the [ital s]-wave [pi]-[pi] isospin scattering lengths. Combined with dispersion relations we find the [ital s]-wave phase shift difference at the [ital K] mass is [delta][sub 0][minus][delta][sub 2]=42[plus minus]4[degree] and the phase of direct [ital CP] violation is arg[var epsilon][prime]=[pi]/2[minus]([delta][sub 0][minus][delta][sub 2])=48[plus minus]4[degree]. We also evaluate the [ital p]-wave scattering length to be [ital a][sub 1]=0.035 [plus minus]0.001[ital m][sub [pi]][sup [minus]3].

We show that the J/\ensuremath{\psi}\ensuremath{\rightarrow}${\mathrm{\ensuremath{\pi}}}^{+}$${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$ decay is a reliable source of information for the electromagnetic form factor of the pion at t=${\mathit{M}}_{\mathit{J}/\mathrm{\ensuremath{\psi}}}^{2}$=9.6 ${\mathrm{GeV}}^{2}$ by using general arguments to estimate, or rather, put upper bounds on, the background processes that could spoil this extraction. We briefly comment on the significance of the resulting ${\mathit{F}}_{\mathrm{\ensuremath{\pi}}}$(${\mathit{M}}_{\mathit{J}/\mathrm{\ensuremath{\psi}}}^{2}$).

In certain frequency ranges a nonlinear damped and driven oscillator will respond asymmetri‐cally even though the potential energy is a single symmetric well. This dynamical symmetry breaking heralds the onset of a period doubling transition to chaos.

As a step toward a fundamental understanding of hybrid states we demonstrate the close relationship between the relativistic string and lattice simulation results for excited glue states with two fixed color sources.

The properties of two massless wave equations relevant to quark bound states are examined. We establish general conditions on the Lorentz-scalar and Lorentz-vector potentials which yield arbitrary leading Regge trajectories for the case of circular classical motion. A semiclassical approximation which includes radial motion reproduces remarkably well the exact solutions. The conditions for a mesonic tower structure are discussed.

We construct a consistent action for a massive spinning quark on the end of a QCD string that leads to pure Thomas precession of the quark's spin. The string action is modified by the addition of Grassmann degrees of freedom to the string such that the equations of motion for the quark spin follow from boundary conditions, just as do those for the quark's position., Comment: REVTeX4, 10 pages, no figures

The concept of Lorentz scalar quark confinement has a long history and is still widely used despite its well-known theoretical faults. We point out here that the predictions of scalar confinement also conflict directly with experiment. We investigate the dependence of heavy-light meson mass differences on the mass of the light quark. In particular, we examine the strange and non-strange D mesons. We find that the predictions of scalar confinement are in considerable conflict with measured values., Comment: REVTeX4, 7 pages, 4 EPS figures

We demonstrate the equivalence of the relativistic flux tube model of mesons to a simple potential model in the regime of large radial excitation. We make no restriction on the quark masses; either quark may have a zero or finite mass. Our primary result shows that for fixed angular momentum and large radial excitation, the flux tube/QCD string meson with a short-range Coulomb interaction is described by a spinless Salpeter equation with a time component vector potential V(r) = ar - k/r., Comment: RevTeX4, 10 pages, 3 eps figures

Clean predictions are presented for all the spin-averaged heavy-light meson spectroscopies. A new symmetry is identified wherein the energy eigenstates have a universal dependence on both the light and heavy quark masses. This universality is used in an efficient analysis of these mesons within the QCD string/flux tube picture. Unique predictions for all the D, D_s, B, and B_s type mesons in terms of just four measured quantities., Comment: REVTeX4, 6 pages, 9 eps figures

We demonstrate that the Nambu-Goto string spectroscopy with massless quarks is replicated in highly excited states of the linear vector confinement potential. For deep radial excitations we observe that the Regge slope, spacing between daughter trajectories, and absolute state energies agree with those of the QCD string., 4 pages, 4 figures, REVTeX4. Version to appear in Phys. Rev. D. Section II substantially improved, references added

We perform an analytic semi-classical quantization of the straight QCD string with one end fixed and a massless quark on the other, in the limits of orbital and radial dominant motion. Our results well approximate those of the exact numerical semi-classical quantization as well as our exact numerical canonical quantization.

We perform an analytic semi-classical quantization of the straight QCD string with one end fixed and a massless quark on the other, in the limits of orbital and radial dominant motion. We compare our results to the exact numerical semi-classical quantization. We observe that the numerical semi-classical quantization agrees well with our exact numerical canonical quantization., Comment: RevTeX, 10 pages, 9 figures

We outline a connection between scalar quark confinement, a phenomenologically successful concept heretofore lacking fundamental justification, and QCD. Although scalar confinement does not follow from QCD, there is an interesting and close relationship between them. We develop a simple model intermediate between scalar confinement and the QCD string for illustrative purposes. Finally, we find the bound state masses of scalar, time-component vector, and string confinement analytically through semi-classical quantization., ReVTeX, 9 pages, 5 figures

We demonstrate that the B->D(*) l nu form factors can be accurately predicted given the slope parameter rho^2 of the Isgur-Wise function. Only weak assumptions, consistent with lattice results, on the wavefunction for the light degrees of freedom are required to establish this result. We observe that the QCD and 1/m_Q corrections can be systematically represented by an effective Isgur-Wise function of shifted slope. This greatly simplifies the analysis of semileptonic B decay. We also investigate what the available semileptonic data can tell us about lattice QCD and Heavy Quark Effective Theory. A rigorous identity relating the form factor slope difference rho_D^2-rho_A1^2 to a combination of form factor intercepts is found. The identity provides a means of checking theoretically evaluated intercepts with experiment., 18 pages, Revtex, 4 postscript figures, uses epsfig.sty

A new sum rule determines the nucleon sigma term by the \pi N elastic scattering threshold parameters alone. This "threshold" value of \sigma(2\mu^2) provides an independent check of existing values obtained from global dispersive analyses, and also provides a realistic error assignment. Employing a recent analysis of low energy (T_\pi < 100 MeV) \pi N data our sum rule implies \sigma(2\mu^2) = 71\pm 9 MeV., Comment: Additional explanations and references, changes in notation, small numerical changes. 11 pages, Revtex, uses epsf.sty, 1 postscript figure. Version to be published in Physics Letters B

We compare scalar and string confinement mechanisms. Solutions for the massless quark case are found and discussed.

The computation of mode sums of the types encountered in basic quantum field theoretic applications is addressed with an emphasis on their expansions into functions of distance that can be interpreted as potentials. We show how to regularize and calculate the Casimir energy for the continuum Nambu-Goto string with massive ends as well as for the discrete Isgur-Paton non-relativistic string with massive ends. As an additional example, we examine the effect on the interquark potential of a constant Kalb-Ramond field strength interacting with a QCD string., 10 pages ReVTeX, 3 PostScript figures. Introductory material and references added. To appear in Phys Rev D

We consider the effects of going beyond the approximation of a straight string in mesons by using a flexible flux tube model wherein a Nambu-Goto string bends in response to quark accelerations. The curved string is dynamically identical to the straight string even for ultra-relativistic mesons except for a small additional radial momentum. We numerically solve the curved string model in the case where both ends have equal mass quarks and also the case where one end is fixed. No approximation of non-relativistic motion is made. We note some small but interesting difference from the straight string., Comment: 12 pages REVTeX, 10 PostScript Figures

It is well known that a straight Nambu-Goto string is an exact solution of the equations of motion when its end moves in a circular orbit. In this paper we investigate the shape of a confining relativistic string for a general motion of its end. We determine analytically the shape of the curved string to leading order in deviation from straightness, and show that it reduces to an expected non-relativistic result. We also demonstrate numerically that in realistic meson models this deviation is always small. We further find that the angular momentum and energy are the same as for the straight string, but that the curved string has a small radial momentum not present in a straight string. Our results justify the common assumption of straight strings usually made in hadron models., 17 pages LaTeX, 4 figures. Version to appear in Phys Rev D

Recent lattice results for the energy of gluonic excitations as a function of quark separation are shown to correspond to transverse relativistic flux tube vibration modes. For large quark separations all states appear to degenerate into a few categories which are predicted uniquely, given the ground state., Comment: 10 pages, 3 figures, LaTeX, references added and minor corrections

The definitions and properties of elastic and inelastic Isgur-Wise form factors are reviewed. The nature of the "missing" exclusive semi-leptonic decay fraction is identified. The role that completeness sum rules play in relating form factors, spectroscopy, and model building is outlined., Comment: Latex2.09, uses sprocl.sty and epsf.sty. 10 pages with 3 postscript files included. Talk presented at the Conference on B Physics and CP Violation, March 24-27, 1997, Honolulu, Hawaii

We formulate the description of the dynamic confinement of a single fermion by a flux tube. The range of applicability of this model extends from the relativistic corrections of a slowly moving quark to the ultra-relativistic motion in a heavy-light meson. The reduced Salpeter equation, also known as the no-pair equation, provides the framework for our discussion. The Regge structure is that of a Nambu string with one end fixed. Numerical solutions are found giving very good fits to heavy-light meson masses. An Isgur-Wise function with a zero recoil slope of $\xi'(1)\simeq -1.26 $ is obtained., Comment: Latex (uses epsf macro), 18 pages of text, 3 postscript figures included. Revised version, to appear in Phys. Rev. D

A common pattern of large orbital and radial excitations in heavy-light and light-light mesons is demonstrated. Within a general potential model the Regge slopes of the light degrees of freedom for these mesons are shown to be in the ratio of two. The possibility of ``tower'' degeneracy occurs only with pure scalar confinement., Comment: Latex, 10 pages, 2 figures placed using epsf.sty. Z-compressed postscript version available at http://phenom.physics.wisc.edu/pub/preprints/1996/madph-96-970.ps.Z or at ftp://phenom.physics.wisc.edu/pub/preprints/1996/madph-96-970.ps.Z

We present a systematic algebraic and numerical investigation of the instantaneous Beth-Salpeter equation. Emphasis is placed on confining interaction kernels of the Lorentz scalar, time component vector, and full vector-types. We explore the stability of the solutions and Regge behavior for each of these interactions, and conclude that only time component vector confinement leads to normal Regge structure and stable solutions for all quark masses.